texts: Pressure Sensor connets 2 stage opamp but i didn't identify it

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I must copy a circuit and top of that it has a pressure sensor and this image shows connection. I think that it connects 2 stage Op-Amp but i didn't identify Op-Amp. Can anybody help me.

This is 2 stage Op-Amp or different circuit component i didn't understand

Pin Connection;

Pressure Sensor pin-1 connects BIM-79Z2 pin-3

Pressure Sensor pin-5 connects BIM-79Z2 pin-1

Pressure Sensor pin-6 connects BIM-79Z2 pin-5

Pressure Sensor pin-3 connects BIM-79Z2 pin-2

My Question is i didn't find something like that 2 stage Op-Amp every 2 stage opamp input pins 2,3,5,6 and output pins 1,7 what kind of 2-Stage Op-Amp is this?


texts: What are the advantages of a internal high-precision oscilator over an external one

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Many lab measurement equipment for analog, radiou and RF purposes, such as frequency counters, arbitrary signal generators, oscilloscopes, etc. have the option to input an external reference clock (almost always 10 MHz, though some micro/mm-wave equipment is switching to a higher frequency reference).

From what I know, using this has two advantages:

It allows me to lock different instruments to each other - if my synthesizer and spectrum analyzer are using the same 10 MHz reference clock, they will relative to each other have no error except for their own internal jitter. This can be very useful since it removes (well, significantly reduces) uncertainty in my measurements.

A second advantage is that this allows me to use a very high-performance clock and share it over multiple instruments, instead of needing a very high performance clock in every instrument.

This brings me to my question:

If I have a lab with multiple devices, (why) would I still want a separate precision timebase (such as a TCXO) in every instrument, instead of just getting a stand-alone reference and provide all of my instruments with this reference?

(Ofcourse, we assume that all our gear can take an external reference clock. I think that this is possible with almost all modern gear that needs a timebase and thus a valid assumption)


texts: Confusion in interpreting NPN transistor's saturation region

texts:
Above screen-shot is from a SPICE simulation of an NPN BJT where it shows the output characteristics Vce versus Ic. Ib is kept constant at 5uA where Vce increased from 0V to 5V.

I'm having difficulty in interpreting this plot at the saturation region. Okay so I'm gonna explain where is my confusion together with what I understand:

The output characteristics of an NPN transistor is obtained by keeping the base current Ib constant at a certain value when increasing Vce and obtaining a plot Vce versus Ic.

So as also seen in my simulation above, when Vce is below 0.2V the collector current Ic is decreasing dramatically. But according to the theory when the Vce is less than around 0.2V the transistor saturates. It acts as a closed switch. So Ic must take its highest value.

I'm confused at this point. Lets say you point the 0.1V Vce at the x-axis of the plot and go vertical until you intersect the curve, and you find 0.6mA. So simulation verifies under 0.2V the Ic decreases. But again at the same time "Vce under 0.2V" means there is saturation which means Ic must be maximum.

Why they shade that region in general? Does that mean that part of the curve shouldn't be taken into account? But then this is what simulation plots and probably I would get the same plot if I measure it.

What am I interpreting wrong here?


texts: output of pwm/ speed controller with input from voltage stabilizer

texts: I am having a voltage stabilizer which is connected to AC and the output of voltage stabilizer is connected as input to a pwm for controlling a 12V, 10A dc motor.The doubt i was having is that the output of pwm is showing 17 V when i am not connecting the motor to it and using the potentiometer i could vary the voltage upto 16V but when i am connecting dc motor to output of pwm i was able to vary voltages from nearly 2-15V. will the output of pwm vary depending on the instrument which we have connected to it or I am thinking in a wrong way


texts:
I am a mechanical engineer and am working on a project. This project consists of a rotating shaft and I would like to generate power from that rotating shaft.The shaft will not be rotating continuously.

What are some basic things I need to know in order to generate power from the shaft? Do I use an alternator? I have read in many places that a generator converts mechanical energy to electrical but whenever I look up generators I end up with residential generators which is what I am not looking for.

Some other questions are do I need to regulate the RPM to create a certain frequency and should I make sure the shaft rotates continuously.

Sorry for being so clueless but I have been searching the internet for a while and this seems like the best place to get my questions answered. Thanks and any help would be appreciated.


texts: What is the purpose of this zener diode from USB Vbus to Vcc?

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tl;dr: The ESP32 DevkitC v4 has a BAT760-7 diode between the USB VBUS and the EXT_5V. What is the purpose of it?
I am planning to make a hobbyist project where I need 4.9-5.1V to an external sensor (a MQ3 gas sensor), and use a ESP32 Devkit (non-branded make, uncertain of which generation it is) to do some data logging. The USB power from my laptop is 5.1V, and I can read that voltage on the Devkit USB connector. That should be fine to power the sensor and the ESP32.
However, the voltage on the VIN pin on the Devkit is merely 4.8V. I do get a signal, but since it is out of spec, I don't accept the readings as reliable. The sensor has a heating coil that draws 750mA, but switching my power source to a 2A USB charger did not change the number, so I assume it is not a problem that my powers ource is too weak.
Trying to understand this voltage drop, I found the schematis for the DevkitC v4: link. The relevant part are copied below.

From these schematics, I see that there is a BAT760-7 diode between the VBUS from the USB connector and the EXT_5V pin, that I try to pull current from. My voltage drop is in practise 300mV, and that is not consistent with the spec for the BAT760-7 see image below, but I guess I have a pirate copy that has used a replacement part... I still have a diode sitting there, so I guess that by learning about the documented version of the ESP32 devkit, I could learn something about my own kit.

My question: What is the purpose of the BAT760-7 in this schematic? What risks and problem would I get if I shorted it to get a 5.1V connection straight from the USB? Is there some other way to pull current off the USB witout getting this voltage reduction?


texts:
I am just getting into electronics, and I thought I knew enough to make a simple fan control circuit. The idea is that I can install a switch into my PC case that I can press in order to add a fan boost.

Initially, I was going to simply cut the PWM signal from the fan off, which would make all fans spin at max (according to an Intel spec). However, I learned that water cooling pumps don't necessarily follow the same behavior. As I also want water cooling when I build my new desktop, I cannot simply cut the PWM -- I have to generate a 100% duty cycle 5V PWM signal -- a steady 5V, as I understand it.

In light of this issue, I opted to use the 5V power from a SATA connector to emulate the 100% duty cycle PWM signal since I can't see any way to convert the PWM signal into a steady 5v without a DAC followed by a boost converter -- which is a little out of my level of understanding at the moment and wouldn't function if, for some reason, the PWM was at 0%.

In the diagram above (I am just starting to figure out Eagle) the left-hand pins are a fan input (ideally from the motherboard) and the pins at the top are the fan output pins. A 4-pin fan header cable will be run from this device to a PWM splitter, making this the PWM master for all fans/pumps.

I have a couple of questions regarding this circuit:

Would this circuit be considered safe? It is my understanding that I should also be using a SATA ground connection since I'm using the SATA 5V, but by my reckoning, when the switch is to the right, the fan circuit should provide the ground. If this is correct, is there a potential risk of overcurrent of the fan pins on the motherboard due to the fact that the 5v didn't originate from the fan pin header?
Also, I considered adding the SATA ground and tying it to the fan ground and perhaps adding a resistor right after the FAN_GND input in order to persuade the current to flow back into the SATA ground instead, but would this be likely to cause problems?

For the experts here, are there any other aspects that I haven't considered here? Any potential problems that I might arise if I were to build this as a circuit right now (I don't have the equipment to build this at home at the moment, so I can't physically test it)?


texts: PIC microcontroller DAC output incorrect

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Using a PIC16F1825 microcontroller I was seeing incorrect values being output on the DACOUT pin. The setup stipulated using the fraction 8/32 * VREF+ where VREF+ was an external 2.5V reference. The output should have been 0.625 but was twice that value.

(have answer myself)


texts: Why E = (Vc + Vr) in a circuit with a capacitor and a resistor in series?

texts:
I want to understand how to think about a capacitor in an electrical circuit. Note: I'm looking for an explanation of the basics that would help me answer this question, not an advanced discussion of the topic.

Consider a circuit with a battery with an EMF of E_batt, a capacitor, and a resistor. The voltage at the capacitor & the resistor may be related to the EMF of the battery by the following:

$$E_{batt} =V_c + V_r \tag{1}$$

My understanding is that because current decreases exponentially during the charging of a capacitor, it will produce a voltage V_c in the opposite direction to the battery's E, so that the net voltage across the circuit is:

$$V_{net} = E_{batt} - V_c \tag{2}$$

Therefore, I can replace V_r in Eq. 1 with E - V_c, thus equating E_batt to itself. To me, this proves the relationship observed in Eq. 1.

However, after considering the smoothing of a bridge rectifier, I think that my logic is flawed. The voltage across the capacitor does not technically 'oppose' the voltage across the battery. It seems like whichever component has a higher voltage, capacitor or power supply, takes over the circuit. The voltages don't seem to  interact at all, except when the voltage across a capacitor drops to below the voltage across the power supply.

Why is the sum of the potential differences across across the capacitor and the resistor equal to the emf across the battery?

More importantly, when considering the smoothing of a bridge rectifier, why doesn't the voltage across the capacitor oppose the voltage across the power supply?


texts: D type flip flop to divide astable 555 by two

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I'm using a combination of a D type flip flop and an astable 555 to get a 50℅ duty cycle. It's connected to a motor driver (receives an inverted and normal input to determine direction) to turn back and forth.

It's working as described, except that it isn't repeatable. For example, on the first run my motor will turn clockwise then anticlockwise for a few runs, then I'll turn it off. And when I turn it back on, it moves in the opposite direction (I.e. anticlockwise then clockwise).

I'm not that familiar with the D type flip flop and flip flops in general, so I'm wondering if there is a way I can set it to not toggle this way?


texts: Is it possible to know what % of routing resources are used in an FPGA

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FPGAs contain logic resources and routing resources to link them together. I think that, for a given number of logic blocks being used, there would be a % of routing resources being used that link them. Is is possible to know what % of routing resources we are using?

I have heard that sometimes a design may not fit in an FPGA due to limitation of routing resources rather than logic resources. I have also heard that, in rare instances, the FPGA may get physically damaged due to some routing paths getting too hot during device operation. Maybe someone can confirm if this is true.


texts: How to get the Forward voltage of a tachometer?

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I am currently in the process of building a circuit board for components that I am going to use on a lathe. I want to use this tachometer.

https://www.amazon.com/dp/B00VKAT8A2/ref=cm_sw_r_sms_c_api_47YOBbE8R9GFR

I have checked out the manufacturer website but it’s not in English. So I was wondering how I could find out the forward voltage on it, if I ordered it. I’d also like to State I would like to avoid a handheld tach if at all possible. Thanks for all the response in advance.


texts: Basic question regarding op-amp output voltage

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When we model an operational amplifier, we say that the output voltage \$V_{out}\$ is proportional to the difference between the inputs \$V_\pm\$, \$V_{out}=A(V_+-V_-)\$. I've read that this voltage is always with respect to ground.

However, when we add a double supply to the op-amp, how is ground defined? Does the circuit take it to be \$V_-\$? Or maybe it is \$(V_+-V_-)/2\$?


texts:
I'm trying to make a buck converter that should carry a load of up to 12A. Probably no surprise, the n-channel mosfet is getting hot quick, even with a heatsink it is getting to hot. (I have currently changed the Q5 to a IRFP1405PBF)

I have then tried to parallel two mosfets (with wires). But, It seems like only one of the fets gets all the load, and gets hot. How can that be? And are there other things that I could do to get a stable buck converter?


texts: How lucky am I to be alive? (electrocution)

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When I was 18 I lived in a new apartment in Florida. One evening I was cooking dinner in the 240VAC electric oven. I had my hand on the oven door and reached over to open the 'fridge. At that moment I learned the hard way that the oven had been wired backwards and had a "hot chassis". 240 volts began flowing from the oven, through my arms, across my chest, and into the properly grounded refrigerator.

It was one of those "stop time" experiences. I remember the pulses of current as distinct events, with thoughts between the pulses:  <WHAM!> "What the hell was that?!?" <WHAM!> "Man, that hurts!" <WHAM!> "What's that sound?" <WHAM!> "Oh, I'm screaming!"

The next thing I knew, I was on the other side of the narrow kitchen with the oven door in my hand. I had been thrown across the room by the violent convulsions of my muscles, and had ripped off the oven door. I'm pretty sure that's what saved my life.

From the reading I've done recently, AC current through the heart often puts the heart into fibrillation. 240 volts through the chest between solid bare metal electrodes seems like a hell of a stress to put on one's heart.

I'm not sure how much electrical engineers learn about the effects of electricity on the human body, but this seemed like as good a place as any to ask this.


texts: Will my project source most of its current from the battery?

texts: I have a video game controller project that requires a battery. This is because the console doesn't provide enough current on the 5V rail to fully power the project. The battery (and charge circuit) is more than capable of running the project by itself, but I do need to connect the 5V rail from the console to the project anyway, since it provides just enough current for the microcontroller to turn on and send a signal to the battery to wake up from sleep mode. After the battery is woken up, will the project source most of the current from the battery, or is it still going to try pulling current from the 5V rail on the console?


texts: high frequency op amp for Arduino frequency counter

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I'm going kind of crazy trying to solve what I thought would be a very simple problem.  I'm not massively experienced but will try my best to spell out what I'm trying to do and what's happening.

I'm trying to build a frequency counter using an Arduino Mega to hook in to a homebrew HF radio receiver I'm working on.  The library I'm using on the Arduino  (http://interface.khm.de/index.php/lab/experiments/arduino-frequency-counter-library/) requires logic (5V) level signals to sample to calculate the frequency of the input signal.  The signal I'm trying to measure comes from an LC tank attached to a SA602AN and in the current configuration runs from ~3 MHz to ~5 MHz, and on my 'scope it measures 180mV peak to peak.  I taking signal via a 10pF ceramic cap to avoid effecting the tank.

No problem I thought, I'll rattle a little 2N3904 common emitter amplifier, nice and simple and we've all built a few I'm sure, but I didn't seem to be able to squeeze any gain out of the circuit - output was 180mV peak to peak.  Next idea, use a LM385, signal to (+) via a 100nF cap, a 25k pot between output and - to adjust gain, and a 1k resistor between - and ground, which I've seen many times online for similar applications.  I had exactly the same problem - in fact wherever I set the pot, the output signal of the circuit was < the input.

Now I'm perfectly happy to accept the idea that I don't know a) what I'm doing or b) what I'm talking about, since this should really be an easy problem to solve but I'm just going round and round in circles.  I have other similar 358-based op-amp circuits in my radio (audio preamp and to drive an RSSI indicator LED), the main receiver circuit has 5 2N3904s slopping around (and a couple of 2N2222s) so I kind of thought I knew what I was doing, but obviously not!  Would anyone be able to point me in a useful direction, toward either what I could be doing wrong or a circuit which would serve the purpose?  Thanks for your time!


texts: Should I consider debouncing my push button?

texts:
Considering a +5V battery source, I have a set of input switches. These switches are push buttons which stay closed upon clicking and open upon clicking again.

One side of a switch is connected to the positive side of the battery while the other is connected to a pull-down resistor, 10 kΩ specifically, and my combinational circuit.
This circuit contains 74LS-series DIP ICs.

With that set-up should I still consider debouncing my circuit or not?

I'm thinking whether this set-up can affect one of my sequential circuit which send pulses when one input is clicked with the use of XOR gates, capacitors and resistors.


texts:
I'm designing a circuit with STM32F407 and a DS3231 chip clock. The MCU has a separate VBat pin that can be used and on the other hand, the DS3231 chip has its own RTC. I'm wondering can I use a single RTC battery for both circuits? I found some circuits that suggest using a common Schottky diode like bat54c before connecting the battery to MCU. Should I use it too or not?
Thanks.


texts: Is there any similarity between MOSFET and BJT terminals? Are they interchangeable? If so, under what conditions?

texts: I'm new to electrical engineering, and I'm a little stuck. I've got this circuit that I want to make, but I don't have any bjt transistors, and I can't buy any right now. I was wondering how base, collector, and emitter would relate to gate, drain, and source.


texts: PWM to vary the light intensity of a 220V bulb

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How is it possible to construct a "light intensity varier" (increse/decrease lighting) of a 220V bulb using pwm? The main requirement is to make use of pwm

I was thinking of this connection:

220V mains --> rectifier --> smoothing --> regular (to convert to dc) --> relay --> 220V bulb
where one end of the relay is connected to the 220V dc and the other end to ground;
and is switched one to the other using the output of a PWM as shown in the block diagram
below:

However, I am afraid that this is a poor design and not safe: no transformer to lower down the ac voltage (so I can drive the 220V bulb); and in effect, other components might blow up.

My problem is not actually on the PWM but on the connection of other components.

Please give me a better solution to this. Diagrams or schematics or even links may help me a lot. Thank you.


texts: What is the equivalent capacitive load seen by the IC if in a datasheet of a chip CLmax=10nF given and I connect an RC filter as a load?

texts:
I have a stupid question where in the quick, the answer does not come into my mind.
If in a datasheet of an integrated circuit, a maximum load capacitance is given, e.g. 10nF, and I want to connect an RC low pass filter to it, how to size the components R and C (for a fixed cut-off frequency) in order to not violate the datasheet specification?


texts: PIC24 bootloader writing the config bits

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I have an embedded system with a PIC24 host which I've just finished off the code for, and have noticed some odd changes to the way my bootloader works but without actually changing anything low level enough to affect this.

I've been using the Microchip USB HID bootloader for a while now, and usually it's quite literally plug it in, load hex and press go. Recently I've had to ensure the config bits are being written also, but my config bits haven't changed in the BL or the main app in months (verified by our git history).

If I write the hex onto the device without programming the config bits also, it either becomes totally unresponsive or acts like there is no app and always defaults into the BL.

It works fine with the config bits being programmed, but I can see how this is a bad move for any production units in the case of a field upgrade, even if it is a long shot at bricking the unit.

The only major change I've noticed is we switched to a large code model in xc16-gcc, but I was under the impression this would only flag the compiler various things about locality of variables etc., and not change any memory allocations.

Has anyone seen this behaviour before? It may very well be something we've missed in the datasheets.


texts: Question about old telephones (late 70's - early 80's)

texts:
This question refers to old landline telephones that would have been used in households in Sweden in the late 70's and early 80's. I would think that this was probably similar to phone technology used elsewhere during that time period (except maybe North America).

I was in my early teens during this time period, and on occasion had an experience that I have since suspected was due to some physical causes.

What happened was that, if I for some reason was near the phone, I turned to look at it just before it rang. My behavior was a bit like as if I would have sensed that the phone had become active, a second (or less) before it rang.

These old telephones did not have any indicator lights so there was nothing obvious like that that could have gotten my attention.

Of course one explanation is that this was random behavior on my part that happened to coincide with that the telephone was about to do. I do accept that possibility. After all it was not like it was happening constantly (this happened maybe twice or thrice altogether, if I remember correctly).

What I became curious about now decades later, is the possibility that the circuitry in these old phones may have caused some sound (that I did not register consciously, e.g. if it was too brief) - or something else - that I might have reacted to.

Do these old phones engage any circuitry that could generate, for example, brief ultrasound, before they start ringing?


texts: How can I convert PSpice model into LTSpice Model?

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I would need to simulate these two MOSFETs ino LTSPICE but I have the Spice Model

IPW65R019C7
Its PSpice model its insiede Nchannel CoolMos C7
https://www.infineon.com/cms/en/product/promopages/power-mosfet-simulation-models/#high-voltage-simulation-models
SCT3022AL
Its PSpice model its at this link
https://www.rohm.com/search/application-notes?Category=3D%20Data|Frequency%20Model|IBIS%20Model|Ray%20File|SPICE%20Model|SPICE%20Simulation%20Evaluation%20Circuit|Thermal%20Model&Title=sct3022al

Can anyone explain me the steps necessary to insert them into LTspice?

Thank You.


texts:
I don't understand the output of the window comparator. How does the window comparator switch from HIGH to LOW? There is no transistor or anything else. Only two OPAMP which outputs are put together.

Can somebody explain it to me?

Here is a image of a window comparator:

Here is the description of the window comparator and the source of the image:

https://www.electronics-tutorials.ws/opamp/op-amp-comparator.html


texts:
I'm trying to drive this solenoid with an inverse logic output (from a 74154).

Here's what I have in mind at the moment.

simulate this circuit – Schematic created using CircuitLab

R3 is actually the solenoid in question.

The application is an automated bell striker, so the duty cycle here is going to be very brief. Even in the most... energetic cases, I'd expect that the coil would be energized only long enough to strike the bell (I'm estimating maybe somewhere in the 50 ms range) and then it would rest for at least 500 ms, and more likely for seconds at a time.

I've simulated this, and it seems like it would work unless I am missing something stunningly obvious. With a 12 volt supply, the collector current should be around 350 mA, and the whole circuit 4.8 watts, which would give the solenoid 30 gf, if I'm reading the data sheet correctly.

Is this a stunningly terrible idea? Any other suggestions for improving it?


texts:
I saw that there has been a push to make a drug detector that can identify cannabis since it has been legalized. I was looking at mouser.com and found this ir sensor: https://www.mouser.com/ProductDetail/Pyreos/PY2435?qs=sGAEpiMZZMvkSJWT1okH7HZM1X5NjtfhYufzstUzGmFpPHtO%2FKJ1pA%3D%3D I also found these IR spectra

The ir sensor has filters for 8550nm(1169cm^-1), 8750nm(1143cm^-1), 9650nm (1036cm^-1), 12250nm (816cm^-1). Also your typical methane detector is at 3300nm(3000cm^-1) so alot of these line up with the absorbance peaks, do you think this will work as a detector? I have seen typically for organic compounds that have aromatic rings or pi bonds UV spectroscopy is typically used but i cant seem to find UV detectors online. Is there an easier way to do this? What is a good estimate of ppm that this ir detector could sense?


texts: I'm currently working on a personal project where, a part of it, is having a spark plug discharge with a time delay after a signal is sent. Below is the schematic I've come up with so far but I'm not sure how to incorporate the time delay or if this circuit will even work. Currently, this schematic will work by having the capacitor store the charge for the spark plug, with a resistor of high resistance to use as a "dump tank" if needed for safety. Any advice/critiques are appreciated!


texts: Measure battery pack cell voltages with analog multiplexer and instrumentational amplifier

texts:
I'd like to measure the voltages of individual lithium based cells (LiPo, LiIon, LiFePO4) in a battery pack (up to 4 cells in series), using an ADC. I was thinking about the following approach, using an analog multiplexer and an amplifier:

The multiplexer is powered by the battery to prevent the cell voltages to be above the multiplexer's supply voltage.
The multiplexer routes each cell's positive and negative terminal to the amp's inputs.
The amplifier is also powered by the battery pack.
The amplifier has a gain of 1 and turns the selected cell's voltage into a single ended signal that is then divided down to ADC range.

I'm looking for an accuracy of 10 mV.

My questions:

Is this a reasonable approach?
What should I look out for in the amplifier? So far it would have to support rail-to-rail inputs, unity gain and high CMRR. Any recommended types for this application?
Channel select and inhibit inputs could simply be driven with an N-channel FET and a pull-up to +BATT. Should I consider other approaches?
What kind of filtering should I have at the amplifier's inputs?
Are there any caveats when the pack has less than 4 cells (in the schematic: BT3 and BT4 shorted for a pack with 2 cells)


texts: How do I convert frequency to data capacity?

texts:
So I am completing my assignment and I am stuck on only this question:

For the voice communication in task 2, it has been decided that a 16-QAM (2 phase shifts and 8
amplitude levels) will be used. If the maximum frequency for this voice circuit is the frequency
calculated for Task 2, then what is the data capacity of the analog line, assuming ideal conditions
(no noise)?

I found the frequency of Task 2 to be 10 MHz. I am not sure how to use this information to convert it into some form of bit rate.

Please help if possible.


texts:
I have attempted to build many amplifier circuits with little luck. The audio is either severely distorted, the gain is not high enough, or I pick up FM and AM broadcast stations.

I would like to build something with variable gain via a Pot, output to drive a small, handheld speaker (1/4 watt or so?) and power from a 9v battery. The dynamic range (from the Adjustment of the Pot) would be desirable to pick up signals from the audio level of a guitar pickup coil.

Is there a circuit which would accomplish this? If not, is there a more general circuit with formulas for my parameters? What is the next step to accomplish a  simple design like this on my own?


texts: How to empirically tune DQ current PI controllers in BLDC/PMSM motor for vector control?

texts:
I need to experimentally set the \$k_p\$ and \$k_i\$ parameters of PI controllers for the DQ-axes of a vector controlled BLDC motor. I have been looking for papers and application notes proposing practical tuning and fine tuning techniques, but could not find much.

Because the DQ-axes influence each other, I feel I cannot treat the two completely separately.

This is how I currently do it. For each point, I apply a 1 A amplitude step response for about 1 second, having the motor reaching a speed of about 400 rad/s:

Tune \$k_{pq}\$
Tune \$k_{pd}\$
Tune \$k_{iq}\$
Tune \$k_{id}\$
Reiterate all gains until they result into instability, then settle them to 80% of their value.

The biggest challenge I face is that at locked rotor, or applying the step to \$i_{d}\$, closed-loop dynamics are extremely easy to shape to my desires, but if I let the motor spin at high velocities (more than 400 rad/s in my case) large disturbances begin to appear (where they come from is a longer and unrelated story) and these can turn my closed-loop systems unstable.

Are there good practical tuning rules for parameters of such control architecture?


texts: Are PCB spreading inductance and loop inductance the same thing?

texts:
Hi there,
there is a mention of power/ground net spreading inductance in the Figure 1. I'm assuming this is the same as PCB spreading inductance. If so, is loop inductance the same thing here? Or does PCB spreading inductance mean just the inductance from the plane/trace?


texts: How to combine batteries in series and parallel

texts: I need to combine S*P number of batteries (same types) to get S times the voltage and P times the capacity. Which of the following combination is better? Is there any difference?    _


texts: Exporting data as .txt file from 8051 to PC

texts: I am trying to first convert an analog signal to a digital using an ADC and save those data in RAM, after that I want to export this data to PC as a .txt file to print the graph in MATLAB. My question is, how can I export the data as .txt file to my PC. Thanks in advance.


texts: Altium view does not show lower part of PCB

texts:
In Altium Designer 16.0, very intermittently, the GUI does not let me navigate towards the lower part of the PCB, somehow freezing the lower part of it, unable to move anything to there, like the windows were "saturated" or limited to see the lower Y coordinates of the PCB.

The following operations do not affect this "bug":

Changing the origin,
Restarting the program,
Reopening the PCB,
Fit Document View,
Dragging an object into the "offending" zone (the GUI is again "saturated")

This affects the 2D View Edition of a PCB.

Anybody have a suggestion?


texts:
I wonder if it's a good idea to put LEDs in parallel, as below:

I've heard that it might not be because the voltage threshold won't be exactly the same for each LED, so they'll shine all with very different brightness and you don't have a way to balance that. Is that true? So does it mean it's a bad idea?


texts: What is the component in bluetooth module

texts:
Last month, I bought a bluetooth audio module on eBay. And I wonder what components are on this PCB.

In the picture, what is the component in the top red box?
What is the component in the bottom red box?  The component marking is "DH=M6C". But I couldn't find any datasheets about "DH=M6C".


texts: Modeling languages for Hardware platforms (embedded systems)

texts:
I'm looking for some modeling languages in order to design hardware platforms in the context of embedded systems.

I already had a look at the following:

AUTOSAR
UMLMarte
SysML

I wonder if there are more modeling languages regarding this topic. So if someone knows one, please share it.


texts: Problems with Wien Bridge oscillator circuit simulation in Mutisim

texts: I am trying to build a Wien bridge oscillator that oscillates at 2.1kHz and that can be switched on by a transistor. The reason for me placing a transistor switch in the circuit is so that I can turn the oscillator on and off from a PIC MCU. However, when I build the simulation in multisim, I get an DC output voltage of 3.0mV and an. I want an output voltage of 5.0V p-p, so can anybody explain to me what the problem with this circuit is? Any help would be much appreciated.


texts: Attempt to implement a scheduler in STM32F4

texts:
I have a question regarding scheduler implementation. I have tried to implement a scheduler according to my understanding.

In this example, i have taken advantage of the Systick handler provided by STM32, so my handler looks somewhat like this:

void SysTick_Handler(void)
{
  HAL_IncTick();
  HAL_SYSTICK_IRQHandler();

  if(ticks_for_scheduler++==100)
      ticks_for_scheduler=0;
}

I have a scheduler.h file which looks like this:

void (*task1)() = read_temp;
void (*task2)() = Display_temp_lcd;

and my scheduler.c looks like this:

extern uint16_t ticks_for_scheduler;
void sched_system()
{

  if(ticks_for_scheduler==20)
      (*task1)();

  if(ticks_for_scheduler==40)
  {
      (*task2)();
  }
}

The function sched_system is called in main(){while(1){sched_system();}My goal is to execute task1 every 20ms, and task2 every 40ms, but somehow I'm not able to get it right. I'm not sure what I'm doing wrong? I don't see the results on my LCD as expected.


texts:
My television (the brand is Philips) died and I'm trying to save it,
When I had open it I had see a dead capacitor (54j 6kv swc), the most similar I saw was on Ali express with (54j 6kv), I don't know if it will do the tricks and the seller have bad reviews.
I don't really understand the meaning of this kind of notations with my basic notions of electronic, is their an tutorial to understand this notation or a capacitor that can work in place of the dead on or a good website where I can buy it?

Thanks for reading this and I hope you have a great day.


texts: Where can I acquire extension/tester cables for Google Pixel 3 cameras?

texts:
Similar to this iPhone 11 Test Cable , but with the correct ends for these cameras.
If I'm counting pins correctly (interior pins, since I don't know the exact names of these connectors, it's 30 pins for the rear camera, and 24 pins for each of the front cameras.
I need to extend these by 5-10cm in order to fit in a computer vision camera array.


texts: How can I combine my knowledge of signal processing with electromagnetic physics?

texts:
Now at University I've learnt both signal processing and electromagnetics, I am curious as to how these two areas can be combined into one.

For example, in signal processing you are required to find the signal as it passes through some filters, or you are required to design some filters.

In electromagnetic you talk about data communication but without going into any details. You just know that something emits an EM wave and another thing receives it (i.e. airplane and submarine), and you are required to find things like what is the optimal distance for receiving a signal.

My question is that how can you combine the knowledge of these two areas given that it has been presented in such a dissimilar fashion in undergrad? Signal processing seems like pure math whereas electromagnetics seems like pure physics, what is the link that connects these two areas?

To be more precise, what is the area that explains how EM field is turned into digital signals and how this digital signal is interpreted?


texts: Do you still need the capacitors to ground on the XTAL pins on an AVR if the internal resonator is used?

texts: When you use a crystal as the clock you use a pair of capacitors on xtal1 and xtal 2. Do you still need them if you're using the internal resonator?


texts:
DC Circuit

I drew this to try and understand why the gate has voltage on it when SW1 is closed. All I'm trying to accomplish is that when the gate has 0V, the 14V supply is connected to the 10k resistor.

With this circuit, when the switch closes, there is almost 7V on the gate. Why is this happening? Increasing sourse resistor decreases gate voltage, and vice versa.

If I decrease the source resistor below 500, the gate voltage oscillates from 0 to 12ish, and this makes the current through the JFET oscillate as well. I want the gate voltage to stay at 0V.

If there's a better option to accomplish this please explain.


texts: Divide 32-bit by 16-bit number on a dsPIC

texts:
I'm working with a dsPIC33EP64GS506, and here you can find its datasheet: link.

In the dsPIC datasheet (page 294) it says that it supports 4 divide instructions:

DIV.S    Wm,Wn    Signed 16/16-bit integer divide
DIV.SD   Wm,Wn    Signed 32/16-bit integer divide
DIV.U    Wm,Wn    Unsigned 16/16-bit integer divide
DIV.UD   Wm,Wn    Unsigned 32/16-bit integer divide

Now, when I try to divide two variables in C, a 32-bit by a 16-bit variable, compiler for some reason decides not to use these instructions, but the ___divsi3 function instead, which is a software implementation of the divide algorithm. I use Microchip's free xc16 compiler version. Take this simple C code for example:

volatile int32_t num = 65537;
volatile int16_t den = 16384;
volatile int16_t res = num/den;

compiles to the following assembly code:

MOV [W15-22], W0
MOV [W15-20], W1
MOV [W15-18], W2
ASR W2, #15, W3
RCALL ___divsi3
MOV W0, [W15-16]

How can I convince a compiler to use DIV.SD instruction to divide these two variables?


texts: Overflow detection in a CSA (Carry-save Adder)

texts:
How do you detect overflow when you have a CSA?

I have 3 16-bit two's complement inputs and a 16-bit output and I'm wondering how do I detect overflow?


texts: Cheap sensor for measureing air dissolved in water?

texts:
I have been experimenting a bit with hydroponics lately, and one of the important things when building a hydroponic system is to aerate the water/nutrient solution. This is usually performed with an ordinary air pump for aquariums by hobby hydroponic growers.

I know you can buy professional dissolved oxygen sensors, but these seem to be quite expensive.

My question is can you make or buy some simple sensor that can measure the amount of dissolved air in water?

The sensor does not have to precise in any way, or provide any absolute values. I just want to see some sensor value rise when I aerate the water, and fall slowly as the aeration dissipates (and is absorbed by the plants). This should be sufficient for regulating the aeration.

Note that I am not asking about dissolved oxygen just dissolved air in general. :)


texts: How can I lower output impedance of an accelerometer?

texts:
I'm planning to use an accelerometer with a microcontroller to measure acceleration.  The issue that I have ran across is that in PIC microncontrollers the ADC requires that the connected analog device have a output impedance of less than 10 kOhms, but typical accelerometers have an output impedance of 32 kOhms.

One suggestion is to utilize a low input offset rail to rail op amp to act as a buffer to lower the output impedance, but I am not exactly sure how this works.

Any suggestions?


texts:
I have this circuit with both AC and DC supplies and am trying to calculate the voltage at Node A.

Is it possible to simplify the circuit somehow?

edit:
The voltage will fluctuate 3Vrms above and below the 12V DC. Does that mean  that ideally, on the positive half wave, the Zener will cut the top off the sine wave at 5.1v.


texts: LED behavior during 24 VAC negative half cycle

texts: I don't understand why the green portion of LED3 is able to conduct. Since the path marked in green represents the negative half-cycle of the 24VAC isn't the green LED reverse biased therefore no current flow. Isn't the red portion of LED3 FW bised- shouldn't it be lit? Or since this is AC does the "-" or "negative" have to do with current direction as seen here?


texts: LM317 based power supply with current limiting

texts:
I'm trying to build my own Bench Power Supply but I'm having a hard time to find a good design (circuit/project) for it.

Here are my requirements:

Input: main using a 18V 2A transformer
Output: 0-18V
Current: 0-1.5A
Current Limiting controlled by a potentiometer
Voltage output controlled by a potentiometer
And I'd love it to be based on the LM317

I know there are some designs with two LM317, one limiting current and the other controlling the voltage output, but I couldn't find any good reference for those circuits.


texts: What is 1C charge/discharge rate in battery instruction manual?

texts: Instruction manuals and discussions mention battery charge and discharge rates in terms of "1C", "2C" and so on, without giving an indication of what "C" is. I presume it is not a Coulomb. What is readily available for most batteries or battery packs is the capacity in Ah and the nominal voltage, eg 12V 22Ah golf cart battery pack. The "22Ah" implies a discharge rate of 1.1A over 20 hours. Using Peukert's law we can estimate the discharge at different rates, eg the above battery would last 13 hours at 1.5A discharge rate (assuming a Peukert's constant of 1.3). All that is great - what exactly is the "C" and what do people mean when they say "I would not charge it above 3C" ?


texts: Is there a way to select a group and copy in Kicad Schematic Editor?

texts:
I know we can do that in Eagle by selecting a block and copying them. Has Ki cad Implemented such feature? It documentation says I need to hold "SHIFT" Key and select to copy. Doesn't Work!!

Application: kicad
Version: 4.0.7 release build
wxWidgets: Version 3.0.3 (debug,wchar_t,compiler with C++ ABI 1011,GCC 7.1.0,wx containers,compatible with 2.8)
Platform: Windows 8 (build 9200), 64-bit edition, 64 bit, Little endian, wxMSW
Boost version: 1.60.0
Curl version: libcurl/7.54.1 OpenSSL/1.0.2l zlib/1.2.11 libssh2/1.8.0 nghttp2/1.23.1 librtmp/2.3
         USE_WX_GRAPHICS_CONTEXT=OFF
         USE_WX_OVERLAY=OFF
         KICAD_SCRIPTING=ON
         KICAD_SCRIPTING_MODULES=ON
         KICAD_SCRIPTING_WXPYTHON=ON
         USE_FP_LIB_TABLE=HARD_CODED_ON
         BUILD_GITHUB_PLUGIN=ON


texts: Small Signal Voltage Gain - Analog Multiplier Analysis

texts:
I'm having trouble with calculating the following:

Small Signal voltage gain from input to output at 400kHz (no LO)
Small Signal voltage gain from LO to output at 400kHz (no signal at input)
The demodulated output from an AM signal applied from a function generator to the input. (400kHz carrier and 1kHz sin wave modulation). Signal at LO is 400kHz, 3Vpp square wave.


texts: I need to switch between RS485 signal and Digital input port

texts:
I am looking for a solution where I can use RS485 along with the 2 (two) digital input port on the same line but both will be used one at a time. When there is RS485 communication (selected through software) then that port will act as a RS485 communication to the outside of the device. When used as a digital input same 2 pin port will be used as a digital input port.
Let me know what could be the solution

Thanks


texts: Can two magnets damage or interfere brushless motor?

texts:
I want to get the absolute position of motor shaft, so I have added two magnets on the metallic thread (which holds the motor) and some hall sensors on top of shaft.
Can the magnets in some way interfere with motor or damage it ?


texts:
Please see this circuit attached in this post/.

Basically, I want to build a simple UVLO CCT for my LED controller and I came up with this circuit.

simulate this circuit – Schematic created using CircuitLab

The RL in the circuit is a Voltage divider Load that is connected to my controller (ZXLD1370).

The thought behind this is that when the input voltage goes below 10V, the Vout will also start reducing which in turn will reduce the divider voltage and create a dimming function.
before using the LM4040-8.192 (d2), I was using a normal 8.2V zener diode. this worked well, although it had temperature issues. when the board was getting warm, the Zener voltage was varying and hence the controller was dimming before the board reached normal operating temp.
So I replaced this with a precision diode. Now the issue is that I can see the Input current reduce when voltage is below 10V, but then the current starts to rise again until the UVLO of the controller kicks in (7V approx).

what do you guys think I could do to solve this issue?

cheers
Labmat.


texts: Hello I have used ADXL335 Accelerometer in a gesture controlled project but I have powerd by 5v output from Arduino Lilypad, so it started creating mess by giving wrong outputs. Afterward I came to know that it operates at 3.6V from data sheet but now how to provide 3.6 V to Accelerometer as Arduino gives 5v output.Hope gets solved.


texts: Connecting ADC pin to op. amp. output distorts signal

texts:
I am using a STM32 Cortex M3 microcontroller and have configured the ADC. I have verified that the ADC works by measuring different voltages on the micro controller eval. board.

When I connect my ADC to the output of the op amp (MCP6002) the signal gets distorted. A picture showing how the signal looks at the output before and after I connect the ADC is shown below.

The ADC pin is configured as analog in (as it should). When connecting pins with other configuration the signal is not distorted. The op. amp. is powered by the microcontroller eval. board.

Any help is much appreciated! =)

EDIT:
Added schematic.
Actual op. amp. used is MCP6002 instead of those shown in circuit. When I connect ADC1 to the ADC on my microcontroller the signal gets distorted.

EDIT2:
Additional observation: When scoping and placing the ADC to the 3.3V power rail provided by the microcontroller the scope reads 3.3V. When doing the same with GND i read 0V. But when connecting it to the (3.3V / 2) virtual GND made by one of the MCP6002 op. amps. the result is the same as the distorted picture below.

EDIT3:
I just set up a new ADC with identical settings (I will compare them agian) and it works. I assume I will find some error in code/configuration somewhere. I will let you know.

EDIT4/Solution:
I am again amazed by myself. The same pin has been configured as a digital push-pull somewhere else in code, but no longer used by this module. This code has been present for over a year, but since it probably always have been initialized before the ADC, the ADC have been overwriting the pin configuration and everything has been working fine. This was until the ADC initialization had been moved and done before the other configuration, making the ADC configuration overwritten as a digital input push-pull. I wish to thank all for the great help and input and their time.


texts: I don't understand this question about BJT in Sedra and Smith

texts:
Chapter 6, problem 32.

simulate this circuit – Schematic created using CircuitLab

Design the circuit to establish a curent of 1 mA in the emitter and a voltage of -1 V at the collector. The transistor Veb = 0.64 V at Ie = 0.1 mA and β = 100. To what value can Rc be increased while the collector current remains unchanged?

By applying OHM's law I find RE = 4360 ohms and RC = 4040 ohms. But how do I answer the question in bold? I I don't really understand what concept is behind it. Why would the collector current remains unchanged?

Does the collector current vary depending on Rc or is it Vc that varies depending on Rc, keeping Ic constant?


texts: I think I read somewhere on the internet that an LED could be used as a wavelength-sensitive photodetector. Could any of you point me to a electronics beginner-friendly article or tutorial on how to do this?


texts: Reducing IO Expander current consumption when driving LEDs

texts:
I have an IO expander chip to act as a sink switch for some LEDs.

simulate this circuit – Schematic created using CircuitLab

The data sheet mentions two optimizations to avoid leak currents:

Either to add that 100k resistor or run the LED on a higher voltage level than the chip. I don't understand how that helps avoid any currents. On the voltage level I use the output P1 can be driven to around 0.8V below VDD, so I get that there will be a current over the diode.
I also, sort of, get the idea to pull P1 higher via 100k resistor to decrease current over the LED. But won't that simply run the same current over the resistor? How would that remove the current over P1?

The chip U1 uses PMOS and NMOS transistors.

Fig 14 is even stranger. This has to do with the internals of the chip, right?

The datasheet in question: http://www.nxp.com/docs/en/data-sheet/VR5100.pdf

EDIT after next-hack's answer

Ok, mea culpa, I had rushedly posted a link to the wrong datasheet, this is the one I used, but practically equal to what next-hack already had deduced to be the component in question, keeping the validity of the information he posted.


texts: Identifying this component adapter/socket

texts:
I'm sorting an old collection of electronic components, some of which I don't know what they are used for, like this one:

This component is about 7 mm wide. Does anyone recognize this? Thanks in advance!

EDIT: with scale


texts: I want to know, How Letters will display from following three types?


texts:
I am trying to implement an UART protocol to make communication between two boards. data are ascii encoded and messages length's are variables. I've chosen to implement a packet in order to "encapsulate" information.

Packet: {STX, DATA, ETX}.

STX is "Start of text" in ASCII table. Its Hex code is 0x02, ETX is "End of text". Its Hex code 0x03. Every byte in DATA field can take any value from 0x00 to 0x7F except 0x02 and 0x03.

Problem 1: Data length
How to send variable data lengths over uart?
Example: {STX, Hello\0, RTX} and {STX, This is a long text\0, RTX}

I've been digging in the internet and I found that the best approach is to use a FIFO circular buffer. The problem is how to fix BUFFER_SIZE in this case? Let's say that I've done some maths and I figured out that the longest message I am going to transmit over UART is 90 Bytes and the shortest one is 4 Bytes. should I #define BUFFER_SIZE 90 or I need to take a larger buffer?

In both cases how does FIFO works in these cases:
Case 1: DATA length < BUFFER_SIZE.
Example: {STX, ABCD, ETX} and BUFFER_SIZE = 90 Bytes.

Case 2: Buffer is full but data are still coming in.
Example: BUFFER_SIZE = 13

Packet: {STX, READ_X, ETX}{STX, REMOVE_Y,ETX}.

In HEX, these messages are
0x02 0x52 0x45 0x41 0x44 0x5f 0x58 0x00 0x03 0X02 0x52 0x45 0x4d 0x4f 0x56 0x45 0x5f 0x59  0x00 0x03

Buffer is full when we reach 0x4d (in Italic). How does it deal with this situation?


texts: How to design an inductor which consists of four separate windings in the same core?

texts:
I need to design an inductor such that there will be four separate windings at the input side (each input is coming from a different DC-DC converter) then these four windings are combined at the output. All these actions will occur in the same magnetic core.

"The different converters are interleaved but they have their own power source so they can be thought as independent at each other until the inductor. The inductor will be employed in the LC filter of the DC-DC converters.

I have attached the schema of the configuration and the voltages of each winding.

I have modeled it in Simulink by using the magnetic domain blocks (electro-magnetic converters and reluctance blocks) but can't be sure if it theoretically makes sense or not because the simulation gives different flux (for each winding flux) results at each run, although other currents or voltages on the simulation are same at each time.

My research on the web did not end up well so far. I would highly appreciate it if anyone can give an idea or show me a reference.

Figure 1: Inductor configuration

Figure 2: Winding voltages


texts: Magnetic attraction/repulsion with motor/generator and similar systems?

texts:
With generators and motors, is there a form of magnetic attraction or repulsion between the conductive element(rotor/solenoid) and the magnet's magnetic fields? If so, what formula would be best to calculate the magnetic forces given each element's magnetic field and distances?

I'm somewhat confused, because when a motor's conductor experiences a Lorentz force(ILxB) simultanously the conductor is being attracted/repelled to the electromagnet due to the magnetic fields? Likewise with a generator,aside from the Lorentz force opposing the input mechanical energy, there is a magnetic force as well?


texts: What can you do with UART ports in Microcontroller?

texts:
In my Microcontroller there exist UART ports. But I have not understood well how they can be used. Can I use them for TTL or RS232 communication? And would it be also possible for me to use them to receive DVP signal from CMOS image sensor like OV7670?

Thank you


texts:
I have this Bosch 3-way valve that I use in a hydronic system.

If I run 12V to energize the valve, it gets very HOT!

Is that normal with such valves?


texts: Understanding current, wire size, and voltage drop

texts:
I am trying to understand the relationship between these. I have 24AWG 300V copper PVC insulated wire. From what I have learned, this wire can be used to connect a Panel LED that draws <20 mA @ 110V to a 110V main power terminal strip.

I have read that voltage drop would be a problem with increasing lengths of wire at smaller gauges. This wire's length is less than 2 feet and at room temperature. Using a calculator, the Vdrop is on the order of a thousandths of a volt. Am I doing my math correctly? I have only been able to find examples of this situation where people used 14 gauge wire, which has to be way overkill.


texts: What are the 'knuckles' on through-hole LEDs and photodiodes for?

texts:
I am using an IR LED and a photo diode, and I have designed the PCB according to the specifications that I found on the datasheet - i.e. hole sizes for the pins being 0.6 mm. However, on these components there are 'knuckles' (see below image) and these are wider than the hole size they quote for the pins.

So the issue is the component doesn't go low enough into the board because of these knuckles.
Why are they there? How can I know how wide they are in order to make my holes account for this?


texts: Bipolar power from unipolar supply, but accounting for DC offset

texts:
I've been researching this one during the past week. I've found lots of examples of split rails, but nothing which addresses my concerns.

I'm creating a new circuit board for an existing cv/expression pedal for a synthesizer. This is basically a pot that lets you output a voltage between two values. The values I need to support are 0 to 5v, 0 to 10v, and -5v to +5v. The current requirement is extremely low (in the 10s of ma).

Because I'm modifying this existing pedal, and because I would like to provide this replacement board to other people to use, I'd like to use the existing 12v DC power supply that the pedal is typically used with.

The twist: I don't think a virtual ground can work because the synthesizers already have a ground reference (sleeve on the 1/4" jack) that this will need to work with (the reference is based on standard AC power). If I use a split rail design with a virtual ground at something like 6v (using op-amps, resistors, or that cool TI chip), won't I have a 6v DC offset that needs to be subtracted out somehow before the signal leaves the pedal? If so, how would I go about offsetting that?

I know there is a way to do this, because I've seen another pedal which does exactly this with a standard DC unipolar power supply. The only part of this that is giving me problems is figuring out the -5v to +5v part.

I'm self-taught in electronics, and so there are lots of things here that I'm ignorant of, but I'd appreciate any pointers.

Thanks.

Pete

Update: This is how I'll switch between the three voltages. The original pedal had a slide switch on the opposite side of the photo. I'm going to replace it with a small 3-way slider.


texts:
So I've started working on a small project (small at the moment) and I'm seeing some issues in my prototype plans, and I need your help with this.

Short answer: I need a led touchscreen with NFC capabilities.
I made a figurine (kind of those you see for games like Skylanders,...). It has a built-in NFC plate that is setup correctly. Now my problem is, when I place that figurine on the screen, I need to exactly know where it has been placed. This could be done really quickly if there was only one figurine, not even an NFC tag needed if the touchscreen can detect the figure.

Now the problem is, I need to know which figurine has been placed on the screen, and on which location. Kind of a live feedback of where everything is actually. Is this duable in any way?

I was thinking of a think touchscreen and then 40-50 NFC tags underneath it to cover everything but I don't feel like that is a good idea. And it will not be very acurate.


texts: How to make a synthesizable Instruction Memory in SystemVerilog?

texts:
I am designing a MIPS processor on SystemVerilog. The instruction memory is made like this:
module instr_mem
#(
    parameter SIZE = 7 //64
)
(
    input logic rst_n,
    input logic clk,

    input   logic [31:0] addr,
    output  logic [31:0] rd
);

logic [31:0] rom [0 : SIZE-1];

assign rd = rom[addr];

initial begin
    rom <= {
        32'h0,
        32'h2408000F, // a = F
        32'h240A0000, // res = 0

        32'h01485021, // (*) res = res + a
        32'h2508FFFF, // a = a - 1

        32'h1500FFFD, // if (a != 0) goto (*)
        32'hAC0A0ADD
    };
end

endmodule

But this code doesn't synthesizes as a 'black box'/separate module etc., the Top Module looks like: "Core, Data Memory, < a big mess of something instead of Instuction Memory >". I tried to make IM combinational (assign rom = {..}), but synthesis goes the same way.
How can I make a synthesizable Instruction Memory? Btw, is there any guides to write surely synthesizable code?


texts:
beginner here, searching for some guidance as I set up my first multiplexer.

My breadboard was wired as follows:

The T4 refers to my Teensy4.0 microcontroller, its hooked up to the breadboard ground and I have tried using both the 3.3V and 5V power pins hooked up to the red line on the breadboard and had identical results between either. The signal pins of the mux are routed to my digital pins on my T4 and the signal is hooked up to an analog pin on the board. The larger components in my diagram are potentiometers and the smaller ones are tactile buttons.

With this wiring hookup, adjusting the first potentiometer from the left appears to change the signal reading for most of the other input channels. Pressing the first button from the left also was effecting the readings on channels 8-11, and one of the buttons was effecting the readings of a channel nowhere near it.

Obviously I'm doing something wrong here, but the first thing that confuses me is that before attempting this wiring with the multiplexer, I was attaching the  knobs and buttons directly to the input pins on my T4 which worked no problem. Why was the wiring ok without a multiplexer but stopped working when it was added? A friend of mine noted that my wiring wouldn't work because the buttons were just floating, but it worked fine when directly hooked up to the digital input pin.

When I looked online to see how other people were wiring multiplexers for their projects, it appeared as though they were doing the same thing I did in this diagram, with the exception of adding a resistor between the current and the knob/button. Will this solve my problem? What value resistors should I be using?

If anyone could help me design a wiring setup that will work for me I'd really appreciate it!! I'm scrambling to finish an overly ambitious Christmas gift that has had a lot gone wrong and I'm in the final stretch!!


texts: PCB trace routing trick: how safe is it?

texts:
In a 2 layer PCB I routed some tracks under unused pins of a MCU to avoid GND polygon crossing, and also saved few vias. For example, using this trick 2 SDIO traces on the left were routed nicely together with other SDIO lines (and have a nice continuous GND on a bottom layer).

Assuming "standard" PCB/soldermask quality, how safe is to use this trick on volume production device (few thousand)?

I'm asking because I didn't see such routing in real-life products (did I invented new hack? :) and nothing on the Internet.

Unused GPIOs could be set to inputs and polled up/down internally, to be on a safe side if somehow soldermask is broken under them.


texts: Minimal power circuit for recupating three phase motor drive on DC

texts:
A thee phase motor (like an asynchronous motor or an brushless DC motor) can be driven from DC power by using a half bridge on every of the three phases (for example by six FETs) if I'm right.

What is the minimal power circuit that -provided the right control- would be able to also generate on the motor, while feeding back to DC on any occasion? Meaning the circuit should not dissipate any power despite of losses, any power should be transfered from or to the motor.

I guess FETs alone won't do the job, as motor generating voltage may be lower then source DC voltage, so some kind of up conversion would be needed?


texts: Why is the load voltage greater than the supply voltage in an AC circuit?

texts:
I was playing with electronics and testing the equation:

$$X = \frac{1}{2\pi f C}$$

where \$X\$ is the resistance of the capacitor, \$f\$ is the frequency, \$C\$ is the capacitance.

The supply is just a 220V/10V transformer without a rectifier, so it produces an AC current. Frequency is 50-60 Hz.

I calculated \$X\$ from the equation and it is equal to 2.8 K .

I wanted to test my calculations so I measured the AC voltage on both \$R\$ and \$C\$, and I would expect that the ratio between voltages will indicate the ratio between resistances as.

I noticed something strange, which is the sum of the voltage across \$R\$ and the voltage across \$C\$ is really greater than the supply voltage: \$V_C + V_R = 14.5\$ volts !! And when I measure the total voltage across \$R\$ and \$C\$ together it is 10.5 V.

Also, the ratio between voltages does not indicates the ratio between resistances.

I made this experiment with different resistors and caps but I got the same issue.

Why is the sum of voltages is greater than the voltage of the supply? Am I missing something?

simulate this circuit – Schematic created using CircuitLab


texts: Capacitors and simple circuit understanding

texts:
I'm reading through Make: Learn Electronics and it has the following schematic for charging and discharging a capacitor. (Figure 2-80)

I understand that if I close switch A then I'll be creating a complete path for the electrons to flow, so the capacitor will charge.

Now, if I release A and press and hold B the book says the capacitor will discharge. I'm unsure how this happens, if the capacitor has now a voltage (9V) and I close B why would the capacitor discharge?

Wouldn't the capacitor discharge anyway without closing B? (there's already a complete path?)
What is the exact path the electrons will use when B is closed? (visually)


texts: How to implement this function in transistor level?

texts:
I need to design a circuit that has this function. There is an input signal whether ON or OFF. I need this: Once the input signal is ON first, my output must be ON also and after that it has to stay ON no matter what!

Like the timing diagram below.

S1 is the input signal and S2 is supposed to be the output,

when the input signal is ON for the first time, I need to output ON and after this, input signal may change but my output should stay ON! How can I implement this in transistor level?


texts: Why would someone prefer halfwave rectifier over bridge rectifier?

texts:
The other day, out of curiosity I was measuring the current wave shape of a laptop charger. The wave shape indicated a spike only in one half cycle. I'm guessing half wave rectifier here.

One thing that kept me thinking was Why would someone prefer a half wave over full bridge and full wave rectifier?
I'm guessing lower BOM cost / the 1.4V drop across the diodes.

Or was it just the designers choice and there's no point in thinking about it ?


texts: Boost converter can't power load. What are the limitations?

texts:
I'm trying to power a nixie lamp with a 9 volt battery. The boost converter charges up to 160vdc, the nixie lights, but quickly goes out (or half lights) as it pulls more current ~= 5mA. My boost circuit can't provide more than 3mA without dropping voltage to 125vdc? 125vdc isn't enough to keep a nixie lamp lit.

What limits the current output of a boost converter, or, what are the main limitations?

My boost circuit has a
470uF input cap
2.2 uF output cap
100uH inductor
irf740 mosfet
and a 400v diode without any markings.

The switch signal is from a 555 astable with R1=240 ohm, R2=12 Ohm, and a 10nF Cap.
This makes a 95% Duty at 546.6kHz. I'm using a higher frequency to try and lower the current ripple on the indutor since it's only a small axial inductor. I have three 300uH inductors in parallel to share the current.

Should I use two 9 volts in series?

Any ideas or input? Two 9 volts in series works, but I wanted to be able to fit one in a small package.


texts: Type of DCDC Buck Converter for Variable Output

texts:
I am checking how to design variable output power supply, with DCDC controller Buck. The idea is, to have 20V in the input(Up to 5A), and have a variable output between 5-16V, and 2A. The point here is, I will use DCDC converter, in this case the idea is to use controller with external MOSFET/s. I have been checking and I am not sure, and that is why I would like to discuss, which should be the best control mode for this application.
Voltage Mode Control

Robust and consistent response even with parameters changing...
Slow Response

Current Mode  Control

Faster response than VM
The control loop is bit more critical

Hyteretic Mode  Control

Very fast response
Frequency changes which affect to the inductor
Capacitor in feedback needed for good control

I am between the Voltage Mode and Hyteretic Mode.
Since the requirements related to the response speed are not really strict I am thinking to go to the VM.
I have been trying to work and do some tests with the LM3485 from TI (Hysteric Mode), doing some simulations and also stability analysis, but since the Tina suite is not working properly with this Pspice Model and AC simulations, I could not perform this simulations because if I want to change the output voltage (Offsetting the Feedback with DAC or PWM filtered) I need to know if the circuit is stable in all conditions.
Maybe the Hysteric Mode is more suitable to supply Core voltages for processors and this kind of applications which require really good transient response.
Thanks!!


texts: How are cpus enumerated/identified/counted by BIOS and other low-level routines?

texts:
By what mechanism is a BIOS or a kernel able to "see" (enumerate,identify,whatever term is right) other CPUs in an SMP system? How is the boot CPU able to initialise and then "launch" the second or third, fourth CPU?

This is not a question on how a user program has his thread scheduled on another cpu, thread affinity etc, but really down to the nitty-gritty lowest-level mechanism by which this works.

How I vaguely understand this might work is that an MMU temporarily keeps the second CPU on hold until the first one has initialised everything for itself, then for the second CPU, then receives a signal from the main CPU to start the other one. Still then it's not certain what the first thing is that the other cpu executes in an intel system; i.e. would it also start in 8086 mode first, requiring it to run the routine that enables A20 and jumps into PM?

I have coded in ASM in a previous life so I can understand well-explained theoretical answers but I have very little real-life coding experience so just being redirected to Linux kernel source (which I'm already going to try anyway) won't be an answer to my Q :-)


texts: High Side Driver Array Against ULN2804 For Motor loads Such As UDN2981, TD62783, TPIC6B595

texts:
Building a circuit to drive a few DC motors with UNO, 74HC595 and ULN2804. I had no issues with coding, connections and timings.

Then I started searching for high side driver arrays to control polarity of motors individually. I can't go for an H-Bridge, as the result will be bulky and expensive. Upon searching the web since 3 days, I found a few solutions like UDN2981, UDN2987, TPIC6B595, TD62783 and similar ICs and individual transistors like BC327 etc.
But they're falling behind the requirement Of 500mA of continues output current for at least 100ms when all channels are active.

Few of the above are giving 500mA output, but At one active channel or at 10% duty cycle.

Please help me to find the one, or suggest the best way to use the above.


texts:
If I'm getting a voltage of 240 V on an open circuit, the voltage drops to about 200 V when a heavy load is connected to it. (Plasma Cutter in my case. Hence it wont work)

Further on, is there a way to compute the drop in voltage if I know the voltage on the open circuit as well as the wattage of the load.

We tried using Stabilizer but plasma is very sensitive towards voltage. And Stabilizer has response time more than sensitivity of plasma. Till stabilizer stabilizes voltage until plasma get turn off.


texts: How to determine number of devices that can be connected to 3v3 pin of ESP32?

texts:
I am not an electrical engineer. I’m experimenting with an ESP32 Dev Kit.

I was looking at this image:

I had a couple if questions.

In this diagram, there are two devices connected to the 3v3 pin. Is there any limit to the number of devices that can be connected to that pin, so as not to damage anything?
Multiple i2c devices are connected to the same pins (21,22). How can I determine how many more devices I can connect to the same bus without damaging anything?

I guess what I’m trying to figure out is, when looking at the data sheet for my devices, what should I look for, so I can compute how many I can connect to a single esp32 in this fashion (same i2c bus, same 3v3 and gnd pins).


texts: Building AC dimmer - digitally controlled

texts:
I'm looking for help about making a design for a digitally controlled AC dimmer to control some AC lamp light intensity.

I've searched for ideas and found these:

http://www.inmojo.com/store/inmojo-market/item/digital-ac-dimmer-module/
http://www.sunrom.com/power-control/dimmer-module-digital-control-16-steps

They are very proper for my application, but I'm not able to buy them currently.

So, my question is:

How can I build a circuit to control the AC lamp light intensity using digital input which is the output of a microcontroller (AVR)?  What are the recommended designs?
How will this circuit behave (How the control process will occur) ?
[I mean how the dimming process will happen logically]?


texts:
We have these diodes in the bell driver circuit of the local church.

On the casing it reads D246A in cyrillic. After a quick search I found this site. I have not been able to figure out the diodes direction - the multimeter showed 0.7V voltage drop in one direction, it showed around 0.4V in the other. I have seen no markings on the case (the light conditions and my eyes were/are not ideal) and there is no marking on the drawing either.
Note: I was not able to remove the diodes to measure them, I had to test them in-circuit. So I might have measured multiple diodes at the same time. Because of this, I'm unsure regarding the plausibility of the measured voltage drops.
Is this a TVS or a normal diode? If normal, which end is the Anode/Cathode?

I do not want to post the circuit at this time, I'll ask a separate question regarding that.


texts: Tweeter speaker crack on turn on/off when ultrasonic signal is played

texts:
I wired a Fostex FT17H to a YAMAHA R-S202D receiver and put a 1µF capacitor on the + line (like the manual suggests). If i play now a "normal" audio file (<20kHz) everything is great but when I play an ultrasonic audio file (>20kHz) the tweeter speaker emits a crack/pop sound when starting the audio and when its finished.
The speaker and receiver are brand new.
Why is this happening?


texts:
I'm aware that the structure of a balanced cable is an integral part of maintaining signal quality.

If I was to solder two XLR cables together in an effort to make one longer XLR lead, what would be the potential consequences? Would the it lead to a degradation of the signal because of an interrupt to the shield and twisting of the pairs? Is there any difference to just plugging two XLR leads together?


texts: In the circuit of a serial adder (below), what exactly is the function of the D flip-flop? Since its characteristic equation is \$Q^+ = D\$, couldn't it be simply removed (replaced with the wire) without changing anything since the present \$C_{out}\$ will still go to the next \$C_{in}\$?


texts: Arduino VS Stand-alone Microcontroller for a Beginner

texts:
Wes geo hal,

I am relatively new to microcontrollers, and I intend to start with them in my electronics hobby and school projects. Although, I am rather confused whether I shall initiated with Arduino, PICAXE, or straight into static microcontrollers, that is PICs, AVRs?

Before you identify that Arduino is a microcontroller, I mean what environment shall I practise, that is the fully supported development boards and programming of Arduino, or the direct programming of static microcontrollers? I enquire this, because I have found people stating on other forums of discussion that Arduino does not help beginners get into understanding microcontrollers fully while researching this enquiry.

Essentialy, my question is am I better to start with Arduino environemnt, or PICAXE, or a stand-alone microcontroller development?


texts:
I have calculated the transfer function of my system to apply a PID to it. With MATLAB and the PID Tuner tool I got the Kp, Ki and Kd parameters of my PID controller. For example in my case they are 0.175, 371.22 and 0 respectively.

Now, I need to use this values in my DSP but the PID algorithm uses the Q15 fractional format for everything. I know how I should scale the input and output values of my PID:

If the max input value is x, divide it by x if it goes from -x to x, or do (x/2)-1 if it goes from 0 to x and then convert to Q15 fractional
For the output value just scale it to your needs

But how do I convert my PID parameters Kp, Ki and Kd to Q15 correctly? If I apply some factor to them like I do for the input and output values I'm actually changing the loop response so how is this done? I think this should be a fairly common thing to do when designing digital PIDs.


texts: Measure pulse width generated in one pulse mode using HAL

texts:
I need to generate pulse in one pulse mode and measure width of this pulse using HAL. I'm using STM32F446RE board. I managed to configure timer to generate pulse but I have no idea how to implement pulse measurement. I found that it can be achieved with input capture but i couldn't find any example.

Here is my timer config:

void MX_TIM5_Init( uint32_t timerPrescaler, uint32_t timerPeriod, double timerPulse)
{
  TIM_MasterConfigTypeDef sMasterConfig;
  TIM_OC_InitTypeDef sConfigOC;

  htim5.Instance = TIM5;
  htim5.Init.Prescaler = timerPrescaler;
  htim5.Init.CounterMode = TIM_COUNTERMODE_UP;
  htim5.Init.Period = timerPeriod;
  htim5.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;
  if (HAL_TIM_PWM_Init(&htim5) != HAL_OK)
  {
    _Error_Handler(__FILE__, __LINE__);
  }

  if (HAL_TIM_OC_Init(&htim5) != HAL_OK)
  {
    _Error_Handler(__FILE__, __LINE__);
  }

  if (HAL_TIM_OnePulse_Init(&htim5, TIM_OPMODE_SINGLE) != HAL_OK)
  {
    _Error_Handler(__FILE__, __LINE__);
  }

  sMasterConfig.MasterOutputTrigger = TIM_TRGO_RESET;
  sMasterConfig.MasterSlaveMode = TIM_MASTERSLAVEMODE_DISABLE;
  if (HAL_TIMEx_MasterConfigSynchronization(&htim5, &sMasterConfig) != HAL_OK)
  {
    _Error_Handler(__FILE__, __LINE__);
  }

  sConfigOC.OCMode = TIM_OCMODE_PWM1;
  sConfigOC.Pulse = timerPulse;
  sConfigOC.OCPolarity = TIM_OCPOLARITY_HIGH;
  sConfigOC.OCFastMode = TIM_OCFAST_DISABLE;
  if (HAL_TIM_PWM_ConfigChannel(&htim5, &sConfigOC, TIM_CHANNEL_1) != HAL_OK)
  {
    _Error_Handler(__FILE__, __LINE__);
  }

  sConfigOC.OCMode = TIM_OCMODE_TIMING;
  if (HAL_TIM_OC_ConfigChannel(&htim5, &sConfigOC, TIM_CHANNEL_2) != HAL_OK)
  {
    _Error_Handler(__FILE__, __LINE__);
  }

  HAL_TIM_MspPostInit(&htim5);

}


texts:
I'm looking at this datasheet for the ANT-433-HETH antenna. In the box labeled "Suggested Board Layout" I see a dimension labeled "Minimum Distance to Ground Plane" of 0.5 inches.

I always thought you should basically have your antenna feed point be directly over (or embedded in for through hole) a ground plane... am I sorely mistaken?

Is it a common practice to have your antenna feed point separated from your ground plane by (at least) some amount?

The idea of a minimum distance to the ground plane also begs the question of what is an "appropriate" distance, because if the ground plane is far enough away then what's the point?


texts:
I design a wearable, battery-powered device with a watertight enclosure. It will have a waterproof USB connector for battery charging. Here is a schematic.

J2 is the USB connector, MCP73831 is the battery charger and U8 is a step-down buck converter. Do I need an additional reverse current protection here in case the device is immersed in water (maybe seawater) when VBUS and GND USB pins will be short-circuited or connected through some resistance?
I believe that MCP73831 has some, but not sure.
Thanks beforehand.


texts: Designing circuit in Eagle with two boards and ribbon cable

texts:
In order to fit my circuit in my enclosure neatly I need to create it as two PCBs connected by ribbon cable. It's logically one circuit. It certainly makes sense two design it using a single schematic. And ideally I'd like to have both boards in the same .brd file, I think this will make it easier to visualize and maintain the board layout. How should I arrange the board file? Should I draw a second rectangle on the dimension layer to represent the second board? Or maybe draw one rectangle and then draw a line thru it to divide it in two? I've been using PCBWay for production and I understand they support V-Scoring and Tab Routing, are these a good solution for my case and if so, where could i find info on how to define them using Eagle?

Related to this, I'm wondering how to indicate a ribbon cable (or any inter-board connection) in such a way that while it will form a logical part of the schematic Eagle won't draw airwires between my boards. The airwires will simply go to the connectors where the ribbon cable terminates.

I really appreciate any guidance. I'm quite new to Eagle and I'm not sure where to look for more info on this. Thanks!


texts: PAM nonlinear amplitude compression in lower eyes

texts:
I needed some help to understand why at Rx, we observe different effective SNRs in individual eyes for higher level PAM signalling. If you need additional info,
http://literature.cdn.keysight.com/litweb/pdf/5992-0527EN.pdf

How valid is it to tell that we have lesser SNR for lower transitions. Is there any better way to explain it?

Thank you,
Veena


texts:
I made a device with a stm32f107 and sim800l gsm module . Module is in data mode(PPP) and I'm using LWIP library . My MCU clocks at 72MHz .

My problem is that I get frame error and noise error when gsm module wants to send data. I tried to lower my baud rate step by step. Started from 115200 and at last I used 1200 bps(!!) but problem still exist and even its getting worst.

The funny thing is that I use a uart debug port to monitor my log and at the moment I get frame and noise error I get garbage in my terminal too.

here is my uart configuration

~~~
 GSM_UART_Handler.Instance = GSM_USART;
 GSM_UART_Handler.Init.BaudRate = baudrate;
 GSM_UART_Handler.Init.Mode = UART_MODE_TX_RX ;
 GSM_UART_Handler.Init.OverSampling = UART_OVERSAMPLING_16;
 GSM_UART_Handler.Init.HwFlowCtl = UART_HWCONTROL_NONE;
 GSM_UART_Handler.Init.Parity = UART_PARITY_NONE;
 GSM_UART_Handler.Init.StopBits = UART_STOPBITS_1;
 GSM_UART_Handler.Init.WordLength = UART_WORDLENGTH_8B;

 HAL_UART_Init(&GSM_UART_Handler);

 __HAL_UART_ENABLE_IT(&GSM_UART_Handler,UART_IT_IDLE);

 HAL_UART_Receive_DMA(&GSM_UART_Handler,DMA_Buffer,DMA_BUFFER_SIZE);

so here are my questions

How does MCU detect noise error?!

Is it possible my main clock source(crystal 8MHZ) deviate when GSM is in transmit mode? How can I see the deviation?(oscilloscope or Logic analyzer )?

May problem disappear if I lower my overall clock frequency (maybe 36 MHz)?


texts: Modding a Class II switch mode power supply to have output dc- shorted to earth

texts:
As above, what are the disadvantages, risks and dangers involved in modding a class II switch mode power supply i.e. a double insulated laptop charger that is ungrounded to have the dc- output shorted directly to earth?

I know this question has been asked countless times before here, but I did not feel that there was a satisfactory conclusion.

Some of the threads I have reading with more elaborate answers are listed:

How to safely ground a switching power supply with floating outputs?

What does the Y capacitor in a SMPS do?

What I gather now is that what the mod essentially does is bypassing the y-capacitor and I will probably lose all of the EMI insulation class II designs provide. My primary concern here, though, is safety, not just in normal operation but when a fault occurs e.g. loose/frayed wires, shorts.

I may be very wrong, so please correct me where I'm totally mistaken.

Not so necessary background information:
I want the power supply output dc- to be referenced to earth to stop the tingle/small shock from touching devices with metal casings powered by such power supplies. I have scouted around for grounded power supplies that supply 15V but they are hard to find and expensive.


texts: Kicad: How do just drill holes and have solder pads for external connections to a PCB?

texts:
I'm having trouble finding this, so my apologies if this is a stupid question. I am creating a PCB that where my schematic has 5-6 pots. These pots will be mounted on an external panel, not the PCB. All I need the PCB to have is a few holes and solder pads that can accept wires from that run to the external panel.

Is there a footprint I can use for a pot that just has three holes close together? I can seem to find a generic way to do this.

Thanks!


texts: Is the product of open circuit voltage and short circuit current meaningful? Does it have any significance (in a generator, for example)?


texts: The process of implementing a discrete model in C++/Arduino

texts:
I have developed an embedded electronics system centered around the Arduino Due. In my application, I am controlling the force of the end effector of a rigid object using a DC motor. The feedback force sensor has a lot of dead-time and I am unable to get the performance I expect with a standard PID. I am now looking into model predictive control, however at first I will try to use a Smith predictor. To do this, we need to develop an internal model describing the system we have. I have never done this and I need some guidance on formulating a discrete model and implementing it in C++/Arduino.

So far, I developed a continuous-time model based off of input-output data using System Identification Toolbox in MATLAB. Then I performed appropriate discretization (zero-order hold) to get a discrete model, \$H(z)\$, in the z-domain. To implement this in C++/Arduino I believe I am supposed to perform the inverse z-transform to get \$h[n]\$. \$h[n]\$ is then written in a interrupt service routine (ISR) to get the model output.

For instance, my continuous model is:

$$H = \frac{1}{5s+10}$$

Using zero-order hold at 100 Hz, the discrete model is:

$$H_{zoh} = \frac{0.00198}{z-0.9802}$$

Sample time: 0.01 seconds

Using the z-transform table, the inverse \$h[n]\$ is:

$$h[n] = 0.00198 \cdot \mathcal{H}(n-1) \cdot 0.9802^{(n-1)}$$

So far, is what I have been doing on the right track? If so, how would I implement this in an ISR?


texts: I have 5 gates and  a moving car. I would like to know in which gate the rc car just past by. The gates does not have a power source. First I thought I can use rfid to identify the gate number from the car,  however this requires to much power in order to read the passive  tags from a 20cm distance. The other idea is to use something like the bar-code scanner with my arduino. Can anybody recommends other easy to implement solution on an arduino?


texts: Realizing an XOR expression using NAND gates

texts:
I've been trying really hard to understand the construction of a logical circuit using only NAND while also trying to minimize the number of gates. The minimization of gates is what is really confusing me, so my thought process is like so.

1) Start with the desired expression of the end
2) Work backwards with the understanding that the output(s) were also derived from a NAND
3) Run intermediate expression through K-Map to get most simplified form
4) Attempt to convert to an AND if it isn't already using DeMorgans law
5) Rinse and repeat steps 2-5

I attempted this approach with XOR using only NAND and did indeed get 4 gates, but it's different than ones I see online and just wanted to validate if it's correct or not and if not, where my errors are.

I'm worried that the first NAND where I feed the output into two separate gates isn't valid, so looking for some confirmation on that as well.

Thanks.


texts: Keeping pest deterrant device running during power outage

texts: I have a holiday home in a remote area subject to frequent power outages. I use pest repelling devices powered from 9 Volt mains adaptors but when an outage occurs the little furry rascals rush inside and create havoc. Can I rig up a 9 Volt charger and battery and connect the load in parallel so the battery takes the load during outages. I have heard of chargers which provide a power path but can only find them for industrial use and very expensive.


texts: I am currently looking at this schematic and I'm clueless about the part on pin 5 where the ground on the capacitor should be connected into something that is labeled "To Large Signal GND". What does it mean? (Chip: LA4597)


texts: Can faulty USB 3.0 device break USB 3.0 circuit in my computer?

texts:
can a faulty USB 3.0 hub with Ethernet port break USB 3.0 circuit in a laptop so that only USB 2.0 in those USB 3.0 ports works after that? Consider no device connected to the USB hub, only Ethernet cable.

I have suspition that this could have happened to my laptop. So I don't know if it's safe to try plugging it again or to return this USB device.

Thank you.


texts:
I have a step file and I want to simulate it in HFSS but it seams that the structure it is not made with solids, but with attached sheets because when I import it in HFSS I cannot define materials and everything is under sheet.
Do you know a way to convert it in a 3D model to be able to simulate it? Either in HFSS or AutoCad


texts:
I'm using an Arduino for a home project.

Say I have 2 wires, connected to a breadboard in different columns (not shorted).

When one of my digital outputs on the Arduino is HIGH, I'd like to short these 2 wires.

I can't seem to think of a component or function that would let me do this, but it seems super simple so I'm probably missing something -_-

Help would be awesome, thanks!


texts: Output current and voltage levels regulation in ac/dc adapter

texts:
On the picture below is the output circuit of AC/DC adapter. I understand how voltage level contol works, but I don't understand how exactly current limitation works  and how should I calculate resistors to get output current 2A for example? Could someone clarify this?

Thank in advance.

UPD.
I find another example of almost the same circuit. It's from datasheet to AP4310A. I still have no clue how current limitation works...


texts: Placement of linear voltage regulators (L7806CV & L78M05ABV) and N-Channel MOSFET (P30N06LE) circuit for maximum power efficiency

texts:
Two simple questions I hope.
I'm running a circuit powered by 8 NiMH batteries and need to drop the voltage from 9.6 to 5V (L78M05ABV) and 6V (L7806CV) to power different components.
Currently, I have the 9.6V line running separately to the 5V and 6V regulators. The subsequent 6V line is controlled with a N-Channel MOSFET (P30N06LE) after the linear regulator in the circuit, which powers on for two seconds and then turns off.
The questions:
Would placing the MOSFET before the 6V regulator increase the efficiency of the circuit?
If not, would it increase the efficiency to have the 9.6V line pass through the 6V regulator and then the 5V regulator, rather than each of them separately?
My understanding of how linear regulators work suggests that it would, but I'm looking for a second opinion. I'm considering a buck converter, though the voltage drop is fairly low at a maximum of 1.5A.


texts: Why does my PSU die everytime I test with multimeter

texts:
I've set up my PSU to use as a "lab power supply", I'm trying to obtain 12 Volts at 14 amps. I have the red, orange, yellow, black wires separated, and connected the green wire to ground to keep the PSU on.

That being said I feel that the problem is not necessarily with those first few steps. Every time I connect my multimeter between all the black and red, or black and yellow wires the entire PSU shuts off and won't restart until I touch the power wires to a grounding source (Some plates of metal I have).

I'm trying to figure out how I can test the connection with my multimeter without shutting off the entire PSU.


texts: DC--> AC Inverter Connected to a single battery in a 6 battery series

texts:
I have 6 x 8V batteries connected in series (i.e.48V) and have a 48V smart charger attached which charges them from regular electricity main supply.

What happens if I connect, say, a 24V DC to AC inverter (i.e. 24V DC --> 220V AC) as I connect that across THREE of the batteries only?  i.e. 3x8v = 24V in series.

The real question I have is whether the other batteries connected in series 'charge' the 24V batteries I have the the DC->AC inverter attached to?  I.e. As the three 8V batteries deplete (24V), do the other 3 batteries connected in series re-charge them as the inverter depletes them?

The 8 volt batteries are lead-acid batteries -- Trojan T875 batteries to be exact.  They are deep cycle batteries used in a golf cart - which is where I have them.  I basically want to use my golf cart (which is always charged unless used) as a power backup that can supply 220V electricity for a short period during power outages.  The 24V inverter is substantially cheaper than the 48V inverter and I wanted to explore what would happen 'if'.


texts:
I find this formula for an op-amp written in a book:

Unity Gain Bandwidth=A*Fo

Where, A is the open loop gain of the opamp

Fo is the break frequency

What I inter from this expression is that the open loop gain of an apamp is generally defined at break frequency. But I could not find it written explicitly. I did not want to make any conclusion without being sure. Can someone tell if what I infer is correct?


texts:
In the schematic below I was wondering why my professor added Vs(0-)/s when doing KVL. When I applied KVL I had Vs(s)=RI(s)+I(s)(1/cs)-Vc(0-)/s. The reason I subtracted was because after assuming current flows clockwise that meant current would enter Vc(0-)/s through the positive end and go out through the negative end, meaning I'd have to subtract. Why did he add and not subtract?

simulate this circuit – Schematic created using CircuitLab


texts: Precision resistor on ADC voltage reference pins

texts:
When reading an RTD temperature using an ADC, the following topology is usually used:

Most guidelines insist that a precision resistor (0.1%) be used for RREF (inside red rectangle). I believe the reason for this practice, is to use the full range of the ADC device (correct me if I'm wrong). Would any problem arise if I don't need to use the full range of the ADC and I use a normal resistor with 5% accuracy instead of a precision one? Keep in mind that a full scale system calibration will be performed and I have also performed all calculations to make sure nothing goes outside the acceptable limits of the ADC.


texts: How to interpret the FFT of the mains voltage in this case?

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I coupled the 230Vrms AC mains voltage to a scope channel through a 10Vpk-pk step-down transformer. I can imagine the transformer will already filter high freq. noise but I thought I can still see some spectrum for at least narrower bandwidth. So then I saved the time series data using the scope's SAVE function. The scope apparently sampled the input with 250kHz sampling rate.

Here is the time series data plotted in Python:

Here is the FFT:

And below is the zoomed view of the FFT where the horizontal axis is set to linear:

(left-click to zoom the view)

Regarding the last spectrum I have the following questions:

I marked the harmonics of the fundamental 50Hz in red color. As you
see the highest harmonics are at 150Hz, 350Hz, 550Hz, 750Hz. These
are the 3rd, 7th, 11th and 15th harmonics. Is that order of
significant harmonics something common in the world or
completely random?
I marked the highest non-harmonic FFT components after 50Hz in
green. They are 60Hz, 70Hz, 80Hz so on. I'm confused here because I
thought the real distortion in mains would come from the harmonics.
But here there are 60Hz, 70Hz, 80Hz ect. whose amplitudes' are
greater than the harmonics. What could these be? Am I interpreting
something wrong here?


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I want to control on isolated  H bridge  that powered with 100V and can drive up to 0.5A low frequency 3HZ but Pulse width of 200uS .
the response times should be is US so i cant use Solid State Relay (Photo MOSFET).
I tried to use photo transistor like this MOCD217M but the current is low (not passing 150mA).

please see below this Sample circuit that work at low voltages.

I ask:

what changes can be done  to match it to 100V?(VGS driving problem)
Is there any other  Simplified way to achieve the goal?

Thanks
Aharon


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The more work I do in the field of EE, the more I realizing that my general circuit analysis skills are usually the root of my confusion and could use improvement. Even after putting on my break-a-big-problem-into-smaller-pieces hat, I still find myself confused about the relationships between parts (especially when multiple parts share a net).

I'm sure that years of experience down the road will eventually provide this, but I'd like to create a solid foundation sooner than later (and hopefully avoid a lot of the frustration and embarrassment I'm already dealing with).

That being said, my main question is this: what advice would you have for a focused, targeted studying approach for quickly becoming fluent in circuit analysis?

I've known people who are similarly aged as me (young) who can cruise through analysis in no time at all, and I too want to work toward having this superpower. Should I start at a modular level and fully understand each component type (i.e. Make's Encyclopedia of Electronics) before moving forward? Should I slowly wade through the newly revised tome of EE? Should I dive into certain types of circuits (e.g. current mirrors, voltage regulators, etc.) to better understand topologies? Is there a resource that compiles a large number of circuit problems that start out very simple and increase in difficulty, accompanied with thorough explanations (sort of like a Khan Academy approach)? I have nearly a dozen books, but most just offer the answer and lack elaborate explanation, so even when I get the answer right I'm still unsure of many aspects.

Another way to look at it: if an arbitrary/tight time limit of, say, 25 hours, was imposed what circuit analysis topics and best practice approaches to studying them would you use?

Thanks for any help with this! My head's spinning and feeling overburdened, so any clarity would be greatly appreciated. (It'll also help alleviate me burdening this forum with a laundry list of questions :) )


texts: What's the difference between a laser diode and ordinary LED?

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What are the discerning properties that distinguish them; determining their different characteristics?

In other words, I'm trying to do a compare / contrast:

What do they have in common?
How are they different?


texts: How to amplify a low Amplitude, High frequency signal from Ultrasonic Transducer?

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I am working with some ultrasonic transducers, the receiver gets a signal of around 10 mVp-p at 125 kHz and for its purpose needs a gain of around 10.

So far have a simple inverting OP-Amp setup, however, unable to get a gain at all(Gains are achieved using a signal generator setup, with the same circuit,rather than an actual transducer as the input). I am thus led to believe it is something to do with the input impedance, i.e that of the transducer itself.

Moderate success using a unity gain buffer first, which could then be amplified? As the input impedance to the second op-amp would be easier to deal with.

I am wondering what sort of setup is required for this application? I've seen some posts about using multiple op-amps, but for this application, I want to keep the power consumption as low as possible. Powered using a 3 double A batteries, with a normal operating mode less than 30 uA. For test mode up to around 600 uA.

Thanks for reading.