texts: Microcontrollers with Floating Point Hardware

texts: I know this is a "contemporary" question, but I think it's a useful one to aggregate some knowledge. What are some currently available microcontrollers that sport a hardware floating point unit (i.e. that aren't going to cost me a huge RAM footprint to do floating point math emulation)?


texts: Power Factor Correction increases circuit total power?

texts:
I'm learning the concept of power factor and power factor correction, but I am having trouble to understand some points. Every book/article about power factor says something similar to:

  Power factor can be an important aspect to consider in an AC circuit,
  because any power factor less than 1 means that the circuit’s wiring
  has to carry more current than what would be necessary with zero
  reactance in the circuit to deliver the same amount of (true) power to
  the resistive load.

So, I understand that when we are talking about a resistive load that is forced to receive the same amount of true power, increasing the load's power factor will indeed be a good improvement to the circuit, since the current that flows through the load will be reduced at the same time that the original true power doesn't change.

However, I draw a circuit where the power applied to the load is variable and, in that case, increasing the power factor made the circuit's total power be increased too. The circuit is below:

Original circuit:

Circuit with power factor correction:

So, it is easy to see that fixing the power factor made the circuit dissipates more true power.

However, the power that was being lost in the "transmission" was reduced. I understand that reducing the power loss in the transmission is maybe the most important point about power factor correction, but I always read that correcting the power factor is important to make the circuit more efficient and, also, reduce the price charged by electricty.

In that case, wouldn't the price charged be even higher? Even though the power is now being directed to the load instead of being lost in the transmission, I can't see how correcting the power factor would help when talking about reducing the eletricity bill.

I'm not sure if my question is clear, but any help is appreciated. Thank you very much!


texts: At >5 GHz RF rates, stray inductance and capacitance found inside 0402 resistors and capacitors play a not-insignificant role.  I'm trying to work thru, then, if a 50 ohm AC termination at the end of a transmission line from an unused input or output should have a resistor then a capacitor (to DC) or a capacitor then a resistor (to DC)?


texts: How to calculate the needed capacitance of a start capacitor for a 12V 10A DC motor?

texts:
I want to use a 12V 15A switching power supply for a 12V 10A DC motor which has about 9A start current and 6A no load current, I also want to add a push button switch for on and off function to use it and by that, each time motor stops it’s gonna draw huge current from supply and I’m going to add some caps on to the curcuit; so my questions are:

will this high amount of start current damage the switching power supply with those repeatedly on and off times?
with numerous on and offs will the motor get damaged in long time or be hot more soon than normal using?
if we use cap to provide srarting current, what size and voltage?
where to add the switch? closer to supply or the motor? (in the case we use capacitor/s)

thanks


texts: Regulator/heatsink heating up even though load is only 50% of regulator Imax

texts:
aI have made a small +/- 24VDC liner supply for the use of powering an audio preamp PCBA. LM317 for plus/ LM337 for the neg (both TO-220), 10uf output capacitance added. Even though this circuit doesn't draw more than about 700mA (inly 50% of what these regulators are spec'd to), my heatsinks are heating up pretty seriously after about a half hour. The output of the regulator looks good, but i am trying to manage my heat dissipation issue. The heatsink's I've chosen are larger than what you might expect  (google "SK 104 63,5 STS" you'll see the ficsher electronik heatsink I've selected) transformer secondary voltage is 28vac converted after the bridge to 28 DC via a 4700uf electrolytic. I have only two questions:

Both of my heatsinks are mounted to perf board, and not touching one another, not touching any other component nor ground. If i have not efficiently isolated the output to the heatsink and due to the 317/architecture the base plate is allowing the voltage to flow to the heatsink itself, even though it's really not going anywhere - could the energy just being in the heatsink cause the regulator to work harder, thus generating that heat?

If I add two to-220 package Darlington's to increase the output load capabilities of both regulators, i understand i would have to heat sink them as well, but will that decrease the overall heat dissipation already being generated without them (i suspect not, i suspect it will just radiate out of the heatisnks for the darlingtons)?


texts:
I am an electronics student and today we were looking at the voltage output of a charged capacitor against time, which can be modelled in relation to R, C and e (I forget exactly how) but our teacher then differentiated it to find the gradient and it confused me because it was not how I thought differentiation worked

I thought differentiation meant that ax^n went to axn^(n-1), but this clearly isn't what happened, so if someone could explain this it would be greatly appreciated!


texts: time domain reflectometry on long cables

texts:
Is it possible to use time domain reflectometry on cables with a length of more than 100km?
What kind of problems do time domain reflectometers on that long cables face?


texts:
So I bought a motorcycle voltage rectifier, but as I connected it to bike and tested it turned out that it produces about 15.08V at the peak, which is too much for battery and circuit boards. I wanted to know how i could still use this rectifier but limit the output voltage to let's say 14.20V at peak that could be good for acid battery.
So the question is: how to limit voltage if it exceeds 14.20V and don't limit if it is under 14.20V?


texts: No ACK with i2c Write slave adress to TCA9555

texts:
Running a test on a PIC16F18877 I encounter a problem with i2cWrite.

During sending an adress to a TCA9555 i can not get a proper ACK.
   After I2c start the function is called with slave adress 0x40.
   In fact 0x20 first 7 bits for slave adress complemented with 0 for Write
   on bit 0.
   A0;A1 and A2 are all pulled to GND. Testing with a different TCA9555 gives
   the same error.

I need to see ACK becomes 0 but the return value is 1.

The i2cWritefunction has been used in many projects and tested just now
   with  a DS3231. From this device I get a proper ACK.

Stepping through the function shows the proper SDA high and low signals.
   Even visible on the SDA line itself.

I might be doing something wrong with the TCA9555 but have no idea what.

   bit i2cWrite(const unsigned char Byte)
       {
            unsigned char i = 0;
        for(i=0;i<8;i++)        // Repeat for every bit
        {
          Set_SCL_Low;
          Delay();
          // when it is confirm that SCL is low
          if((Byte<<i)&0x80)    // Place data bit value on SDA pin
            Set_SDA_High;   // If bit is high, make SDA high
          else          // Data is transferred MSB first
            Set_SDA_Low;    // If bit is low, make SDA low
          Delay();
          Set_SCL_High;     // So that slave can ackknowldege
          Delay();
          Delay();
         }
         // Get ACK from slave
         Set_SCL_Low;
         Set_SDA_High;
         Delay();
         Delay();
         Set_SCL_High;
         Delay();
         Delay();
         return SDA;
        }


texts: Op-amp - dual to Single supply conversion to avoid floating of input signal?

texts:
I'm designing a voltage measurement adaptor. And my signals are PWM type which ranges from 0-36V. I thought of using Op-amp to step down to 0-5V range and use an ADC to convert analog signals into digital.

To have a gain of <1,i'm using an inverting Op-amp (LT1630) where I can have split supply of (+18V to -18V) but then I have problem of connecting my input signal to a common ground zero(to avoid floating of input signal), so is it possible to give -36V at negative reference and ground the positive reference ?

LTspice simulation gives expected output (Gain of less than 1) with -18V at negative reference and Grounded positive reference for 36V input.  How is that possible?


texts:
i wanted to make a nand gate circuit for driving a few amp loads using pmfets.
in my desgin im using DMP4010SK3Qfets, and any transistor thats capable of handeling 24+ volts on the collector. my problem starts with multisim, i imported the mfet and got results drastically different to what i got with falstad (in that both turn on). im guessing either i've imported the spice model incorrectly or these something else at work that i've missed.
i wanted to verify it in real life and got a board made from jlbpcb with a SSTA06HZGT116 as the transistor and in testing that with a row of leds (about a 400ma load) they both turn on.
have i gone about this the wrong way ?
i wanted to keep the circuit idea the same as opposed to having drivers and a stmfx to control it.


texts:
I am working on a personal project to make an remote oscilloscope using a PIC32 with wifi module for Android phones.

So far I have did a lot of things, like connecting the wifi module of the PIC32 to android also developing the base software for android.

I am now at a step to get ADC values from PIC32 and display them on the android. I am not sure how can I make this to work like a real scope.

For example, in the software I have set up a timer that depnding on user choice, can read the ADC value from the pic in time intervals of say 1 , 0.5, 0.1 and 0.01 seconds. So lets say the user has selected a TimeBase of 1 second, then the program will request the ADC value on 1 second intervals and connects this data points on the graph to form a wave signal. Is this same as what happening in real scopes?

I don't have a function generator or a real scope in my hands to check this out!

This is the user interface of the software I wrote for android:

So basically my question is, how should I treat the reading process of values out of the PIC32? Should I just stick to the timer in Java, or I should read as much as values possible and draw them on the screen? How should I handle this?!


texts: GPU Shader Hardware Requirements Question

texts:
I have a question which I hope is not out of the scope of this branch of the exchange network and is a fair question (to be fair I have provided a block diagram on what I have so far) on the "basics" of how to implement a per/pixel shader block on an FPGA provided with the three components below.  I have been able to create the core with the blocks in the main box but right now it is a wireframe design.

Can any guidance be provided as to what goes into a shader from a conceptual standpoint and is it feasible to try to create a shader from the resources on the board provided below?
Does coloring proceed shading?

Please advise.

Block Diagram

Block Details

Behavioral Simulation


texts: Can i use I2C level shifters to power digital LED strips

texts:
Can I use I2C level shifters to power digital LED strips, more specifically, WS2812B strips?

I can only find I²C level shifters, are they ok?


texts: Are ferrite beads supposed to be magnetic?

texts:
I have replaced the ferrite bead on my audio cable with new ones that I just bought. But I have tested them and they aren't magnetic, it's just like a cylindric metal inside it, but I thought it has to be magnetic to perform it's task.

Does the choke have to be magnetic, or a more magnetic choke works better? Should I buy a more magnetic one? Please explain it to me how it relates to magnetism?


texts:
I have what I think is simple question regarding the use and data calibration of variable analog sensors (such as a force-sensing resistor). As more pressure is applied to this sensor, its resistance changes. This value can be collected by an Arduino device using the analogRead() function, which outputs a value from 0-1024, with 1024 being no pressure and 0 being the most pressure. I am assuming that analogRead is measuring the voltage, but I could be wrong.

My question is this: If I provide current to these devices from a battery, as the battery's voltage drops with use, will it affect the value read by an Arduino or other device? The value doesn't appear to change linearly as more pressure is applied, so would multiplying the read value by the battery voltage to get a constant work if the value does change with the battery voltage?

Thanks for your help!


texts:
I have got my hands on a Intel Edison system on chip. I would like to use it to detect non-zero voltage. For example I have a test point that could be either 0 volt or 24 volt and I want to detect which using the microcontroller.

What ways are there to achieve this? Is a simple voltage divider the way to go? Is there any disadvantages of doing that?


texts: JL (or maybe something else) misterious branded IC's, what is the origin?

texts:
Edit 12/31/2019: Thanks to Mariano Dupont:

Found it: Zhuhai Jieli Technology zh-jieli.com

Take a look at this example of an IC found on a circuit board:

Brand is found on many PCB's of Chinese/India manufacturers of different kind of devices, mostly consumer based.

For example, there are many printed logo's on IC's listed on this site, however you cannot find this JL (or sort of italic pi?) logo, unable to find it anywhere. Also when this logo is on an IC and searching for the part-number/IC model number, always lead to a dead end, I am never able to find a datasheet.

So what is this misterious brand, is it actually a brand, what's the origin and actual name of the manufacturer? And is the part-number/IC model number really a description of what it is or just a random number?


texts:
As the tittle suggest, I was thinking about making a wireless composite video transmission between a small camera (such as those sold for flying fpv) and a receiver. The two main specs it must have is near-0 latency (the lower, the better) and it must work well when the transmission is made at ground level (multipath is a thing to consider). I would not care about receiving a black and white image or a lower quality video (less bits in the ADC). The distance between transmitter and receiver will be at most 170m, but I can use almost any type of omnidirectional antenna. I know at first this may seem pretty difficult, but here there are the ideas I came with:

The first part of the system is the ADC. Here, as I do not need any sound nor color information (only luminance is needed), we could go fot two different options:

Idea 1: It consists on sending the signal as-is, with an ADC with a sampling frequency of nearly 9MHz (composite video's bandwidth is around 5MHz) and 8bit. Then, the bit speed at the output will be 70Mbit/s. Pros: The original image is sent, so it has good quality and is easier to work with it. Cons: 70Mbit/s is a lot.

Idea 2: It consists on a lowpass filter before the ADC, with a cutoff frequency of around 2.5-3MHz (only luminance is sent). The ADC would the need a sampling frequency between 5-6MHz, and it would also be chosen to code the info with 6bits. The bit speed at the output will be 36Mbit/s. Pros: 36Mbit/s is almost half of the 70Mbit/s. Cons: I am not sure if the filter would destroy the sync information, and that would be an issue.

Since we must fight multipath, the digital modulation to be used will be FSK. I know that before sending the image, it would be good to wait for the whole frame to be digitalized, saving the output of the ADC to a buffer, and the sending the image as a whole. However, on the one hand, I am afraid that this would add too much latency to the process and, on the other one, it seems to be too complicated to be implemented in an efficient way. As either the first 70Mbit/s or the latter 36Mbit/s are huge speeds, another two ideas on how to transmited arose:

Idea 1: Use hardware that works with an already studied protocol which can handle great speeds (maybe p2p WiFi or WiFi direct?). Pros: seems easier to implement and image quality can be great. Cons: distributing the data into packages can add a lot of latency to the whole comunications system. Moreover, if data rate is large, it is difficult to achieve 170m of distance.

Idea 2: As most of ADCs have one output per bit, and the total throughtput needed for each one would be by far lower than the total, the plan is to use, if the ADC codes the information in n bits, n transmitters at different frequencies simultaneously, that handle the ADC output as a serial input of data. My first idea was using NRF24L01 modules, but the can only trnasmit at 2Mbit/s. I would have to find an alternative. Pros: seems easier and faster. Cons: larger probability of receiving erroneous bits at the rx. Besides, I did not find many modules that fit the data rate requirements. If there were a transceiver that did not use package-structured data but some type of serial communicstion based on an input/buzzer it would be perfect.

Will this project work? What would be the best implementation? Do you find doing it in a non-industrial "homemade" way realistic?

Thank you in advantage and sorry for my bad English.

Edit: I also found this website, but I thinkn none of ht methods mentioned there are elementary enought to be developed in a homemade project.


texts: Is there any such thing as a linear panel meter?

texts:
I like to use regular panel meters for showing data. I would like to know if there's such a thing as a linear meter, say 10 cm long or so. By linear I mean that the indicator moves up some scale in a linear fashion - like a bar graph, or something similar. Such a meter would likely take up a bit less space on the front panel of a case, and would likely have a pleasing "look and feel".

Do such "linear" meters exist as a manufactured product?


texts: Can a switch take higher voltage than it's rated if the switching power is low?

texts: I have a very basic toggle switch rated for 30VDC and need it for a 20mA @ 36VDC application. According to the datasheet, it's rated for 6A @ 125VAC, 3A @ 250VAC, 4A @ 30VDC. In the AC rating, 6A x 125V = 3A x 250V. Can I make this same calculation for my DC application, meaning that 4A x 30VDC = 3.333A x 36VDC?


texts: I have an RC snubber that is in parallel to a DC motor that runs forward and reverse. Is this snubber going to work differently in the forward direction than is does in the reverse direction? Does the resistor/capacitor orientation matter with respect to applied voltage?


texts:
As part of my internship, I have to build a home automation solution using zigbee in the BBox( includes both the Set Top Box and the router) that runs linux and has an ARM processor: my idea is to build an RPC application on the zigbee that will play the role of a translator between IP devices and Zigbee devices.
So the first question: is this feasible? The coordinator will be the BBox. After 2 weeks of studying I find myself completely lost, or at least I think so.
What I did this far:

I grasped how cross compilation works and I succeeded in adding my own packages using buildroot.
For the hardware part, I chose the cc2531 from Texas Instruments, I see that it comes configured as a coordinator which is what I want. so my second question: am I gonna need the debugger to program it?.
The Zigbee alliance defines many profiles, for application interoperability, devices have to use the same profile, in my case Home Automation.
For the stack, I still hesitate between TI's stack and ZBOSS's stack, I think I should try them both, for now I am using TI's.
TI's stack offers services to be used using tcp sockets, I think I will be using the HA gateway server, but I can't find examples on how to connect to those servers.

Where I am lost:
I cannot find clear examples on how to use the servers, I looked into the source code of the examples supplied by Texas Instruments but I could not understand anything.
Someone posted this, he said that we can interact with the cc2530 using this library

so the final question: Should I use the library or build my application on the TI's examples?


texts: Charged capacitors and inrush current in an appliance

texts:
Here is a circuit of electronic fan speed controller:

Speed of the fan can be controlled by the following logic levels on various pins:

This circuit is meant to be used with a 220 VAC power line and a ceiling fan which looks like this:

Typical wattage is 60-80 watts for these fans.

I want to optimize the circuit and I feel that I can get rid of R7, R8, R17 and R19. R7 and R8 appear to be inrush current limiting resistors (am I right?) whereas R17 and R19 are discharge resistors for the capacitors.

I tested the concept and it worked fine without those resistors. However I am not sure about the long term effects.

My concerns and questions are follows:

1) Can I remove R7 and R8 without having an adverse effect on life of the circuit and the fan connected to it?

2) With 200K discharge resistor in place, the capacitor discharges from 220 VAC to under 5 VAC within 2 seconds. Without those resistors, it takes around 8 seconds. Complete circuit will be inside a plastic casing. Is this discharge time acceptable? Are there any safety regulations related to this? Will removing those discharge capacitors have any adverse effect?


texts: Logic-Level Converter: How high is the power consumption?

texts:
Regarding the following schematic for a bi-directional logic level converter, can someone explain how to calculate power consumption? Can I use pullup resistors with higher values, e.g. 1M?
I need such a converter in my circuit, but the device is battery operated and should therefore consume as little power as possible.

LV1 is connected to a digital pin of an Arduino Pro Mini 3.3V.
LV is connected to 3.3V.
HV1 is connected to a Water Flow Sensor.
HV is connected to 5V.


texts: Multimeter measuring different values on different probe polarities?

texts:
I have a UNI-T UT33A+ model multimeter and I'm using it to read current values for my assignments. The weird thing is I get entirely different values when I switch probe positions. For example when I measure black to red I'm getting -0.80mA, and 0.42mA when I measure red to black. What can be the cause of this?
The fullscale accuracy according to the manual is $$\pm(1.0\%+2)$$ for 20 mA.


texts: Need help with creating a schematic. LED off when charging, on when battery use

texts:
I'm new to the electric world and was wondering if someone with a bit of knowledge could help me out with a design. I'm trying to make a circuit that will have 2 LEDs on each side of the board. When a solar panel is charging a battery to power the LEDs, I want to LEDs to be off and when the battery is in use (no charge from the solar panel) I would like them to turn on.)
How can I develop a circuit that turn's an LED off to indicate a battery is in use?


texts: Digital Output (MCU) to 2 other Devices with Voltage Divider inbetween

texts:
A digital signal (from an MCU) should go to 2 other devices (ports configured as input). The output voltage is about 3.3V. The input voltage on the other devices should be between 2V and 3V (same devices, directly to transistor, no pullups etc.). I would like to use a voltage divider (e.g. 100/300 ohm). Options are:

a) split digital output signal first and apply for every input a voltage divider (in sum 2, uses 4 resistors)

b) use a voltage divider on digital output and then split signal for 2 inputs (needs only 1 voltage divider with 2 resistors)

c) better ideas?

Which option is the way to go? Any advatages over the other one?

PS.: I am new to electronics.


texts: I spilled candle wax on the video card in my computer, should I be concerned?

texts:
I have just accidentally spilled lavender scented candle wax onto my video card. This is a RX480, the kind with holes that expose parts of the circuitry. the way the candle wax fell, it got onto that side with the circuitry partially exposed and so now there are little drops of wax in there. I have read that candle wax vapor is highly flammable, but there is only a little bit of wax on there.
Would I be better off buying a new video card? It is still in my computer and I am currently using it, it still functions fine.


texts:
I'm trying to make a Marx Generator with a fast rise time (~5 ns). One analysis of the generator's design shows that the largest factor inhibiting the rise time of the generator is the inductance of the capacitors.

My question is: Is there a general design or type of capacitor with low equivalent series inductance (ESL)? General answers are good to have, but a thought towards high-voltage applications would be especially appreciated.


texts:
I recently bought one of these:

When i hooked it up to my 24v power supply and a voltmeter, it was either 0 or 24v with the POT. Nowhere in between. Why is this? Is it becasue this is a PWM device and needs a PWM signal? If so, why did they even include a POT with it...?


texts: How to program modules on assembled PCBs?

texts:
Suppose a Bluetooth module like the HC-05 is part of the PCB design. During production, how/when are the modules programmed? Is each programmed before or after assembly? If it happens after assembly, how are the pins accessed?

Thanks


texts: What is the difference between a tuner and an antenna?

texts:
I was just told by my TV's customer service that my TV had a tuner but no Antenna as a response to my question - Can I use my TV's inbuilt Antenna to pick up over the air channels?

I was wondering if someone can elaborate on what the differences between these are.

Thanks and please let me know if this is not the most appropriate forum to post it on; I can prob move it


texts: Considering analog meters as displays, which would be more versatile - voltmeters or ammeters?

texts:
Note: I'm here to see if there's an objective reason to choose one type over the other.

I've got some projects in mind that would use a microcontroller to drive one or more analog meters as displays, either with PWM data or a direct D/A drive up to 3.3V.

3.3V voltmeters are relatively had to find (one could scale to 1V though), but a bigger consideration is responsiveness (or lack thereof, with damping).

Is there an objective reason one would choose an ammeter versus a voltmeter when driving it from the output of a microcontroller?

Edit: I'm reminded that both types of meter are fundamentally current-sensitive mechanisms. That said, it may be that one type of meter is easier to convert to its complementary usage (without internally modifying it), so that is consistent with this question.

I've found a variety of projects out there using analog meters - some which use voltmeters and some which use ammeters - but I've yet to see a rationale mentioned for the choice of one over the other. Thus my question here.


texts:
I am controlling motor speed by using PIC16F877A and L298, but motors give Back EMF which can burn the microcontroller. To avoid back emf, I have 3 options:

Diode.
Darlington pair.
Optocoupler.

What would be the preferred method, in your opinion, keeping into consideration the respective problem? A practical example would be very helpful for me.
Thanks


texts: Cost optimization - PCB Area vs. Double-sided load

texts:
If one has an opportunity to choose between laying out a PCB as either a single-side load (components all on one side, so it goes through reflow only once and requires only one stencil) or a double-side load but using half the PCB area (so twice the number of boards per panel), which cost optimization tends to be more economical?

I've read this question, but there is no accepted answer and the two answers that are present seem to be at odds with each other.  One answer shows that single vs. double-sided for the same board resulting in a small savings ($0.161/board), but that answer didn't include a comparison for board area reduction.  It did seem to imply that the single vs. double side load cost different is rather small.

The other answer seemed to imply that single-sided assembly was probably the larger cost driver, but then states that it impossible to know without specifics.

Presume that no components require special treatment (i.e. no gluing or hand-soldering - just a bunch of SMD components).


texts: Powering 1920 leds with 32 strips of 60 ws2812b led strips each (32 meters)

texts:
I'm tring to build a led display with 32 strips of ws2812b led strips with 60 leds each. That's a total amount of 1920 leds.
How many power supplies should I buy? Given the max current of 50mA per leds, that's a 50mA x 60 x 32 = 96A. I'm going to buy to power supplies of 5V 60A (https://www.amazon.it/HAILI-Trasformatore-Adattatore-Alimentazione-Telecamere/dp/B07Y38SMQ3/). What should be the connection of the strips? Should I power every side of each strip? I made a schema:

Do you have any suggestions to connect all these cables with each other? (32 + 32 each side).

The Led strip I'm using is the 1m 60 IP30 + WS2812BECO Black PCB as pictured here:


texts:
I'm trying to simulate using ngspice/kicad a very simple switch mode power supply model, as below.

I would expect that the coupled inductors to model a transformer with a 10:1 (primary:secondary) winding ratio and as such I would expect around 34V on the secondary output (V1=340V DC).  However, what I get from simulation as as below.

The output waveform (one in cyan) hardly does anything.  Why ?  What am I missing to make the coupled inductors behave more like a real transformer ?


texts: The total energy stored in a multi cell battery

texts: is the same for series, parallel, or series-parallel interconnections.please Explain this  with an example.


texts: Reimplement circuit using 1 2x4 decoder and 2 logic gates

texts:
I am a Computer Science undergraduate taking a module on Computer Organisation. There is this typical circuit design question that always appear in my assignment and I'm not sure what is the standard procedure to solve it and what skills do I need for it. This is one such problem where I'm required to get both a solution of 2 decoder and 1 logic gate and 1 decoder with 2 logic gate.

This is the Truth table I have drawnThe only deduction I have derived from it is that 'a' doesn't need to be wired as there is a total repetition in the pattern of b,c,d even as a switches over to 1, and I have to come up with some kind of boolean expression in the form of X.Y.Z where X,Y,Z are booleans formed from some b,c,d as it mimics the wiring in the Decoder with an enabler. The individual expressions inside must only contain 2 levels of boolean operators.

Update: We now have more information on the Truth Table which is similar to a program like

if (b nxor c) return 1, else return b xor d. There isn't a simple case of using the enabler to "zero-out" a case that is definitely 0, as 0 can only be achieved from the else case which required 2 levels of operations, and the role of the enabler doesn't allow us to "one-out" cases that are definitely 1, which is the result we got from the truth table and seemed hardly useful information to wire into the circuit. How exactly do we translate such a checking procedure into an expression X.Y.Z which mimics the decoder perfectly?


texts: Stuck in Ri, Rout and Av calculation for BJT circuit!

texts:
I have been asked to calculate Ri, Rout and Av for the following Emitter Follower circuit:

I s=7*10-16A,  β=100,  VA=5V ,  C=very large

I analysed the circuit in DC and then I drew the small signal model as below:

I stuck in this point! I have no idea how to calculate Ri and Av! Can you please shed any light for me in this problem?


texts: What is the theoretical limit of lumen/watt for lighting systems?

texts: Nowadays we see LEDs with 300 lumen per watt luminous efficacy. They still waste a lot of power as heat. Now what is the limit of electricity to light conversion? Say we build an LED with 100% efficiency, which doesn't waste any power as heat or sound or UV/infrared. All its spectrum is in visible range. What will be its lumen/watt? What is the theoretical roof we would hit in distant future?


texts: Advice for an inter device sequential communication system

texts:
I'm looking to develop a modular IOT system which has a single master component and can be connected to multiple devices which can be used to turn on/off relays separately for my college project.

The main controller is managed by ESP32 is connected to an app via bluetooth. The app is updated with the state of every module and can turn on/off each module separately, each module can read or write to the controller, also each individual switches are rewired and connected to the module instead so that the relay inside the module can control the connected devices.

Here when the switch is turned on or off, the module writes to the main controller, so that it can take the state of the switch and update the app and also update the state of the device physically (this can either be done by the module itself). The modules are controlled by the controller sequentially, ie the first module which is connected to the controller gets updated first and so on. In the hardware i have added a shifting output which enables each module individually.

(This is just a simplified diagram of the shifting style communication that I'm trying to achieve, suggestion of any other method that aids in the end goal of not having to assign individual address for each module is appreciated)
The top and bottom D flip-flops are part of a module and initially the enable is left high while pulsing the first clock which puts the shift register into action. A bit can be set in the top D flip-flop which is the output of the module.
In my design I am using a microcontroller to control each specific module block.
for more details I have added the modules schematic below.

(Here I am using an I2C style communication, after a chip has been enabled by the shifting output)
It would be of great help if you can suggest a better and efficient alternative to create such a system.


texts:
If we have one conductor through which current flows, and we place second conductor near it, the conductor with current flowing will induce electron flow in the second conductor.

Can we detect the (parasitic) power loss in the first conductor which induces the electron flow in the conductor near it? If yes, how?


texts: Inserting Capacitor into CIrcuit causes LED to fade - Why?

texts:
My components are

2x 1.5 V batteries
25V 2200uF capacitor
3v Led
copper cables

My circuit looks like the following.

simulate this circuit – Schematic created using CircuitLab

My understanding here is that as the two batteries are in linked in series, we now have 3v for our circuit.

When completing the circuit the LED starts bright then slowly fades and fades until there is no light at all.
Also interestingly if I dissconnect the batteries, wait a minute, and reconnect them completing the circuit, the LED stays off - It does not start bright and fade again.

What is actually happening here? Is the capacitor consuming all the power?
If I left this circuit complete for a while, would the capacitor gradually consume all the power until it reaches its 25V and then suddenly release 25V instantly? (blowing the LED of course)

I actually ran this test because I wanted to try to fill the capacitor up, and then dissconect the batteries hopeing to see the LED stay alight for a while running from the capacitors consumed power.(if this is even possible, perhaps my understanding is not correct)


texts: A visible light communication question concerning a preamble sequence

texts:
I have a question about preamble and preamble breaker.

I am implementing a simple visible light communication using arduino. I have used a Manchester encoding scheme. While I have understood that a preamble is required in order to have a synchronization at the word/packet level since Manchester encoding is helpful only at the bit level and not at the word or packet level, I am not sure what properties the preamble should have.

At this point I have tried sending a simple message like "Hello World" using a preamble of 10101010. I sent this without much understanding of a suitable sequence for the use as a preamble. I have sent two preambles like that, a "preamble breaker", and a Start of frame byte before the transmission of actual data, ending the whole frame with the ETX(End of frame)

Just before sending the STX(start of the frame), for preamble breaker I selected 00101010 with just the last bit differing.

Could someone please explain me the choice of a suitable preamble and also if such a preamble breaker is necessary because there is already a Start of Frame byte(0x02 in my case) before actual data is being transmitted?

Thank you.

Edited the two extra bits in preamble to make it a byte.


texts: Dual Coil Latching Relay NO and NC Setup

texts:
I am working on controlling a 220V 0.75hp AC motor with a Relay, and came across HFE9-3/12DST which by design is a dual coil, latching relay BUT with contacts in NC position.
I was wondering since latching holds on indefinitely until power is applied to opposite coil, would NO/NC settings compromise the safety/control of motor, ie I could setup the Relay in NO position, and keep it that way, until I need to move in the NC position, knowing that even if power is down, the Relay will not switch.
Additionally, I have the snubber circuit on the AC side for relay arc prevention when motor is turned off, and flyback protection circuit on the DC side when current is withdrawn from the coil.
[
datasheet Link : https://www.alldatasheet.com/datasheet-pdf/pdf/660894/HONGFA/HFE9.html?


texts: How to make my own volume control for headphones?

texts:
I have headphones that don't have volume control built in on the cable, so I thought why wouldn't I try to make one? However, I  don't know where to start.

Is it enough to just use a logarithmic potentiometer, or do I need something more?

If just a potentiometer is enough, what should be its ohmage?
I also use FIIO E3 headphones amplifier. Is it better if I put volume control before or after the amplifier?

At what should I pay attention to avoid creating hum or other unwanted noises?

My headphones are: http://www.sennheiser.co.uk/uk/home_en.nsf/root/private_headphones_dj-headphones_500156


texts: How do I connect GPS receiver module with USB interface?

texts:
I have a GPS module DS-330R which has 6 connections, two are not used, one is Ground, one is Vcc (3.8 to 12.0V DC) and the remaining two are Data+ and Data- for USB connection. My questions are:

Can I simply connect Vcc to a separate supply such as a wall wart, say 5V, and the two Data to a USB connector, and in that case do I have to connect Ground also?
Could I use instead the 5V available on the USB port of my computer for Vcc and Ground?
Do I have to take any precautions that I have not anticipated?


texts: How to blink LEDs with different frequency?

texts:
I have a pic32mx and three LEDs.
[datasheet pic32mx] (http://hades.mech.northwestern.edu/images/2/21/61132B_PIC32ReferenceManual.pdf)

I need a function that gets the number of LEDs and frequency, and then blinking the LED with that frequency.

For example I need to blink 1, 2, 4 and 8 times per second.
I have some code, but I don't know how to make it blink with the given frequency. Can somebody explain?

void main() {
T2CON = 0x0;                     // Stop and clean Control Register
T2CONSET = 0x0070;       // 16 bit timer, prescaler at 1:256,  internal clock source
PMR = 0x0;                        // Clean Timer Register
PR2 = 0xFFFF;                    //  Load value
IPC2SET = 0x0000000C;  // Set priority level=3
IPC2SET = 0x00000001;  //  Set subpriority level=1
IFS0CLR = 0x00000100;  // Clear the Timer2 interrupt status flag
IEC0SET = 0x00000100;  // Enable Timer2 interrupts
T2CONSET = 0x8000;      // START TIMER2
}

void __ISR(8,ipl3) TimerHandler {

//somecode

IFS0CLR = 0x00000100;
}


texts: MAX44280 spice model gives wrong result when using dual supply

texts:
I'm simulating the MAX44280 by using Maxim's model on LT-Spice.

When I simulate the op amp with single supply (VDD=5V, VSS=0V, V+=2.5V, V-=VOUT, VOUT = RL(1k) tied to 2.5V ) the current consumption is ~800 uA, which is correct.

However, when I partitioned the supply to +/- 2.5V the result is completely wrong. (VDD=2.5V, VSS=-2.5V, V+=0V, V-=VOUT, VOUT = RL(1k) tied to GND). In this case the current consumption is 1.3 mA!

Could you please let me know if this spice model is wrong?  I'm planning to use this device with partitioned power supply.


texts:
I want to create a game like "pimball" using 4 leds to state the game.
One exit to define if the game is still running. And 2 inputs that are switches.

1) To begin with, the first is to assemble 4 FlipFlops to do the ascending or descending sequence circuit, where in the illuminated LED goes to the left or right depending on a control input I, that is, has the sequence from right to the left (taking the binary values 1,2,4,8) or (taking the binary values 8,4,2,1) from left to right:

1000 -> 0100 -> 0010 -> 0001 (left to right) if I = 0 0001 -> 0010 -> 0100 -> 1000 (right to left) if input = 1

2) started to create the game: it's two players, each with a switch.
The left switch is controlled by the player on the left and the right by the right.
The aim is to keep the lit LED led away from the tip of each player.
For this the players each have one switch which jointly control the direction of travel: where two switches are equal (both 0 or both 1) and take the clock, the lit LED moves to the right, otherwise it moves to the left.
My schematic is below. Am i doing this right?

Could someone sho me on Logisim how to implement this? Or any tips? Thanks in advance! ^_^


texts: Should we use a Brushed or Brush-less DC motor to build a solar car?

texts:
We are trying to build a small Solar car

the car's dimensions (Length :100CM, Width 60CM)

the car mass is not going to exceed 2KG

The car speed can be up to 2.5 or 3 m/s

We`ll be using PV modules that each can provide up to 6Volts & 250mA

Those modules have dimensions 65mm x 165mm X 3.0mm along the car surface area

We can connect all those modules in paralle or every 2 in series to obtain a 12V

Wheels will be of a diameter 12CM or 15CM depending on the motor

yet we are confused, what type of motors should we use

A brush-less DC motor ? or a normal brushed motor

i think i`m misunderstanding Brush-less motors as i think they do need huge amount of current to work and in our case we are working with a current limited source [1~1.5Amps] (The PV cells) is this correct ?

Should we go for a brush-less or a brushed motor?

we bought the EMAX BL2212 1400 KV Brushless motor we think we can use gears to obtain more torque and decrease this RPM will this method work?


texts: Could surface mount resistors cause a rise of 10°C

texts:
I'm new to electronics and designed a four-layer SMT board,
I am seeing a temperature rise of around 10°C (17°C ambient to 27°C after a few minutes) of a few components and the PCB, and I'm not sure why or if it's even a problem.
Using a thermal camera I have narrowed it to be in the area surrounding the optoisolators.
Using the probe on my multi-meter the opto's are 27°C after a few minutes.

DIR_F_L ../.. is 5 V from an Arduino 22 mA.
FLOUT ../.. are  5 V with 1k pullup 5 mA.

I believe the resistors could be a potential source of heat generation as they are 0805 1/8 W.


texts:
I am interested in setting up a control circuit for a system that is heated by hotplates. They are standard lab grade hotplates with dials that modulate heat output (arbitrarily scaled 1-10).

In order to set up a control circuit I would like to be able to simplify the control of these hotplates so that I can modulate their power source instead of physically turning the dials. This is mainly because I plan on incorporating a PID controller which operates on a single manipulated variable (like current), and I would prefer not to use a servo on the dials for fear of loss of accuracy.

So:

1) What is the underlying mechanism of current regulation via a hotplate dial?

2) What would be the safest way to attenuate power to a hotpad (with a microcontroller)?

If you are worried about safety (and foresee me burning down my lab), I will not be undertaking this project alone and will be seeking help from an real live electrical engineer. However I would like to have a solid plan and minimize the amount of time they have to spend helping me. My understanding of circuitry is limited to introductory E&M and basic arduino circuits.

Thanks


texts:
My serial monitor in proteus does not appear, is there specific manipulations I have to do ?

I am trying to connect Arduino with internet (I runned Pcap before Proteus), here's the code : https://pastebin.com/Hn2bfVFX

Thanks by advance for your help !


texts: Level-shifting with limited ways to change the board

texts:
I have this circuit:

simulate this circuit – Schematic created using CircuitLab
Where:

U1 is an MCU powered at 3.3V
OUT is a GPIO
the dashed box represents an external hardware that I cannot change (the P-mosfet is a BSS84)

I only can:

remove R1 or change it's value but I cannot change the component type (it's a part of an array of resistors in CAY16)
place any 2-pins component in between (there are two THT pads)
place a 0603 component between OUT and GND

The goal is to turn on the P-Mosfet.
Of course I would know how to solve it if I could modify the board freely.
Please note, this is just a one-shot hack to adapt an existing board that cannot be bought again.
Basically, I'm looking for a way to pull-down the gate to 0V without let the +5V to reach the MCU.
My idea is to put a 2V zener diode in between, with the K towards the gate.
When the GPIO is high, the voltage across the diode is 5V-3.3V=1.7V so the zener is still open.
If the GPIO goes low, the voltage across the diode would be 5V so it conducts forcing 2V on the gate. 2V is the maximum VGS(th) of BSS84 so it should turn on... Perhaps I can try with a 1.8V zener diode but I would leave a few hundreds of mV to be safe.
What do you think about?


texts: Is it safe to connect a power strip to UPS?

texts:
I need to run a PC and multiple raspberry pis (8 nodes cluster) non-stop 24/7. And my UPS machine has only 3 sockets.

Connect a ups to power strip is wrong according to this site: https://www.apc.com/mk/en/faqs/FA158852/

Ok, a UPS should connect to directly into the wall receptacle. But what about, connect a power strip to UPS?
Is it safe? Can I connect my raspberry pis to a power strip and then a UPS?
(One ups socket for PC, other UPS socket for raspberry pi's power strip.)


texts: Instrumentation amplifier & microcontroller ADC protection circuit

texts:
I have a couple questions related to protecting my instrumentation amplifier and the ADC of my MCU.
The circuit is as shown in the image, with the input to the in-amp (an AD8223) being a very weak signal that occasionally spikes to 20VPP. The output reference pin of the in-amp is set at 1.7V (although it's not shown in the schematic), and as one might expect my microcontroller's ADC can only handle 0-3.3V.

My somewhat-rusty understanding is that R1 will limit the current going through the first two zener diodes (D1,D2) so R2 and R3 aren't necessary. Is that correct or am I missing something?

How can I calculate the output current from the in-amp to determine if R4 is necessary to protect D3 and/or the ADC?

Are there any other input protection elements I should add?


texts: Blocking RF on same side as PCB antenna?

texts:
I have a penta-band GSM transciever on a 4-layer board, along with a matched chip antenna. Similar concept to EE.SX/questions/35836/how-do-components-on-a-ground-plane-of-monopole-pcb-antenna-effect-radiation-eff.

First few prototypes placed most discretes on the bottom side, and that worked well. Now I've optimized things and want to put most discretes on the top for DFM assembly.

Question is, even with a top side ground plane, how much trouble is this asking for?

Size is fairly small, 4x3 inches. If no (>\$\frac{\lambda}{10}\$) traces are exposed, is it much of a concern?

How is such a proposition approached? Are there any rules-of-thumb for "exposing" areas of ground plane to minimize RF induction in component leads?

Or grouping / separating to avoid critical lengths?

How about a vertical metal shield strip or fence, the same height as the chip antenna, soldered into the PCB some distance away?

Would that eliminate EMI concerns beyond the strip?


texts:
I'm trying to draw a constant 60mA from a battery but I get a draw that is too high with the following setup. Does anyone know what I'm doing wrong?

Regards

EDIT: Sorry I added the wrong measures. It should be correct now

simulate this circuit – Schematic created using CircuitLab


texts: Which would be better, a MOSFET transistor, or a relay?

texts: (Keep in mind I am fairly new to electronics, and I have the knowledge of one high school digital electronics course)I am working on making an Arduino controlled door lock. I want to actuate a 12VDC electric strike using one of the digital I/O pins. Which would I use, a transistor or a relay? If it'd be okay to use either, which would be easier?


texts: What precautions should I take when mixing analog audio and digital on the same board?

texts:
What precautions should I take when mixing analog audio and digital (uC control) on the same board? I don't want to hear the I2C bus in my speakers. I'm thinking about

  Separate power supplies
  Separate ground planes, with each part within its own ground plane
  A single connection over a ferrite bead between ground planes
  Lots of decoupling, preferably by RC instead of simply a C
  Slew rate control, esp. on serial buses (lots of edges!)
  Physical distance between both world

The RC decoupling may or may not be overkill, but it costs only a resistor.
Other suggestions?


texts:
I'm trying to measure the inductance of a toroid with the use of a 555 in astable mode. Hopefully, by putting the toroid in parallel with a known capacitor and driving the circuit with a low duty cycle (~10%), I should be able to measure the frequency of the underdamped oscillation, as well as the damping factor, and thereby deduce the undamped resonant frequency and hence inductance. However, I'm not too sure as to how to solve the differential equation. I know how to solve for LC, RC circuits and so forth, but this is a little different.

simulate this circuit – Schematic created using CircuitLab

My interpretation goes as follows:
The 555's output, which goes through the diode, charges the inductor and capacitor. The 555's frequency is a lot lower than the time constant of the components so at the start it should be at a steady state, where:

At t = 0, the 555 should switch off, so the only voltage & current in the circuit should be as a result of the inductor and capacitor oscillating (the diode is there to isolate the RLC from the 555). However, there's an immediate issue: I can't apply Kirchoff's laws since now the circuit is effective a series RLC, which means that the current through all components should be the same: but the current through the capacitor can't change instantly, right? As a result, I'm not sure how to derive the differential equation, which means I'm not sure if the standard result for resonant frequency and damping coefficient are the same as normal.

Note that I have tested this with an oscilloscope and it has produced an underdamped oscillation, so I'm that it should work in theory.

I've looked elsewhere but I can't seem to find the derivation for a non-driven RLC circuit.


texts:
I have few questions about a general extruded heatsink. As example, we can use this from Farnell.

Let's say it is long 20cm with a given shape, sold to have a Thermal resistance of 10°C/W.

Q1: (theoretical question) if I apply a single TO-220 in the middle of such heatsink long 20cm, can I consider it to have a Th of 10°C/W?

Q2: (theoretical question) if I cut it in half along its extrusion dimension, I have (roughly) 2 heatsinks of 20°C/W each long 10cm?

Q3: What about the heatsink in the link? Can I use it with a single, "small" TO-220 and pretend to have around 3°C/W?

EDIT: Here a picture of 2 kind of extruded heatsinks.

In the center of the flat side of the grey one, I will put a circular component (it is a metalized PCB, nothing standard) which will be inside the two holes of the grey one. Now the update of the question:

Q4: conceptually, assuming that the two heatsinks in the picture are providing the same thermal resistance, is it better the black one, since it is squared? (More regularity ecc). And, conceptually again, is it better the grey one to dissipate the heat from two components of half power (wrt the single component placed at center of the black one) placed near the two holes?

Because from the comments I had understood the concept of the extruded dimensioning, but not so well on how to use the longer ones with single components, and if it is valid to use them in such way.


texts: Is this cable meant for metal case grounding?

texts:
I opened a heat pump cover and saw this little cable screwed onto the case but it appears to still be insulated from case and is supposed to be used by an electrician. Is this meant to ground the metal case of the machine?

Since there is no other external pin on the case, is this internal wire meant to be in contact with the case itself and in case of a malfunction that would put case under current, it would provide the current a path to the ground by going (I assume) to the same place the power supply cable ground cable connects to internally?
Or could it potentially be connected to the case on the other side (not visible on image) and is expected from electrician to pull this cable out through the case and connect it to some external grounding wiring? Or could it also be used just for bonding with other conductive items in the area?
I understand this requires professional. I am just curious to know if this is a rough explanation of what it does. The instruction manual provides no explanation and both seller and manufacturer failed to provide any response so far.


texts:
Can open-circuit voltage be treated as voltage to find power dissipated?
I combined all the resistors (including Vlamp) to get one resistor of 40/6 Ohms (Correct me if I'm wrong). Using Ohm's law to find the current doesn't work since I don't know the voltage, Thus the title. I don't think so but I wasn't taught this in detail and Googling doesn't benefit since Wikipedia has a page

I already figured out that:
Battery has open circuit voltage of 4V
R1 = 5 Ohms
R2 = 5 Ohms
k = 0.2A/V
When lamp on and Vlamp = 2V, Rbat = 10 Ohms

The lamp turns on if the voltage across the lamp is greater than 2V. When the lamp is on it has an internal resistance of 10 Ohms, and when it is off it acts like an open circuit.

This is what I calculated:

I'm getting Ilamp as 1/5, still trying to see how that will help...
EDIT:
My answer has been suggested as a duplicate.
Is it the same question? NO.
Is it the same answer? NO.

The only thing that is the same is the circuit, any objections?


texts: Microcontroller with a long wire for digital input

texts:
I have the doorbell button on my house wired into a GHI EMX dev board.  The software evaluates the time of day and determines whether or not the doorbell should ring.

  Side Note: This was implemented as a way to deal with ding-dong-ditch pranks that I was receiving.

This all works great except for one problem, the wire connected to the EMX board is around 50 feet (~15 meters) long and generates enough interference for the board to think that someone has pushed the button and thus my doorbell rings at random intervals throughout the day.  Both my wife and my dog do not appreciate this (but the kids think it's great fun).

I've tried fixing the problem by following the advice found in this article and implementing the following circuit:

This didn't fix the problem, but I did find that putting a 3k resistor in the for 1k and replacing the .01uF capacitor with a 40uF worked a little better, but anything more than 3k causes a noticable delay when pressing the button before the bell rings.  The difference for my circuit is that the board runs on 3.3V instead of 5V (which I assume makes the problem worse) and instead of connecting to ground the switch completes the circuit (i.e. two wires go between the microcontroller and switch).

The wire that runs between the switch and the microcontroller is standard doorbell wire which isn't shielded or twisted.  Replacing the doorbell wire with shielded wire is, unfortunately, not an option since that would require that I tear drywall off.

I've looked at the following question here, but that seems to be dealing with a ADC which might be a little different from my problem.  Any help would be much appreciated.

Update
After reading more of the documentation, it appears that although the microcontroller is powered by 3.3V it is 5V tolerant on it's I/O pins.  I can adjust to a higher resistor value if I use 5V, but will this help anything?


texts: The accuracy of Force Sensitive Resistors (FSRs)

texts:
I am trying to make a large scale resistive touch sensor with 4 FSRs, one for each corner of the rectangular sensor. The pressure that I'm going to be applying will  be a moderately pressured finger press. I have heard that FSRs are mostly inaccurate as far as precise pressure goes.

For example, the Interlink 402 says in its datasheet that its accuracy is within 2% of its resistive value, and changes with time at a rate of 5% * log10( days ).

As far as tap sensitivity goes, the FSR seems decent, at 10% change after 10 million taps.

I'm wondering if with a passive load of 2kg, and a dynamic load of 1kg, would the 4 FSRs be sensitive enough to make a decent (512x512 (9-bit accuracy)), reliable resistive touch screen, or are other materials better for the cost? If I were to make this, what would my theoretical accuracy be?


texts: Implementation of Current Source for a Current Mirror

texts:
let's consider this simple example of current source:

It is a current source because each load I connect to it, it will receive a value of current equal to Vbias/R, which does not depend on the value of the load. So, it is correct to represent it as a current source, like in the scheme at right.

Now let's consider this example of current mirror, whoose aim is that of generating a current for the block called "circuit" equal to that provided by the source current we have previously created:

In theory, to realize this last circuit, I would put the initial current source with op - amp inside this current mirror. But It seems strange to me: the op amp feedback results open, and the current flowing in R is not more Vbias/R. Where is my mistake?


texts:
I have had a battery power bank from anker (powercore 20100mah) for some time now and it stopped working. Upon opening the case i saw a blown up transistor and i am having trouble identifying it. It says X04V 1A. On the circuit board where the part sits it says Q4. Figured I might change it and go from there because I don't want to scrap a power bank with some life in the 18650 cells.
This is the picture of the part https://drive.google.com/file/d/1awlKVwYiXqPgU9bCaWnTlCcFwTszKaeU/view?usp=drivesdk
To what I can understand this is an LDO regulator. Problem is i don't know the specs! Could you please help find an alternative to it? Thank you!


texts: Why does the STM32L4 ADC have a 12-bit SAR and 16-bit data register?

texts: I'm working with the ADC on STM32L476RG. I found that the SAR used for the ADC is 12 bit whereas the data register (ADC regular Data Register (ADCx_DR)) is 16 bit (16 bit reserved). Why is it like this? Will the higher (MSB) 4 bits always be zero?


texts: Using Battery (li-ion) with higher capacity

texts:
Just got portable radio Ambient Weather WR-111B. It is using CR123A 3.7V/800 mAh rechargeable lithium ion battery.

On ebay I see CR123A 3.7V for a different capacity than 800mAh: 1200mAh or 2200mAh.

My question: is it safe to use for this radio (or any other hardware) a battery with right voltage but with a higher capacity (800 mAh vs 1200mAh or 2200mAh)


texts:
see this question.

OP wants to breadboard a PC motherboard design, which is, er, funny, but raises the question: how are motherboards designed? Breadboarding, with incremental improvements, is out, you have to build a PCB from the start. How are these evaluated and debugged? I guess you can't simply tamper with it, nothing would work anymore. Is this really first-time-right?


texts:
Up front I have almost no experience with this kind of thing. I'm a computer scientist so I understand logic gates and the like but I know near nothing about electricity.

What I want to do is build a device that has 2 buttons and a series of LEDs. When one of the buttons is pushed the leftmost unlit LED should light up and stay lit. When the other is pushed the leftmost lit LED should unlight. So it can be used to manually keep track of a count of something. I'm estimating that I'd have around 10 round LEDs.

I want it to be battery powered, as opposed to wall-powered. I was thinking about using a disposable 9 volt battery as a source. With typical LEDs that use 20 mA a piece, I found that the minimum current that this device would draw is 200 mA.

I've found a few beginner's guide type things that have counters but they're usually not button controlled or don't use lights and I've never seen one that has a button to go backwards.

Originally I thought this would be fairly easy but the more I research the more I'm getting completely lost.


texts:
Is there any way to tell the difference between a slow blow and a fast acting Fuse? I had one blow in my amp and I know its 125v 5a, but i'm not sure if it is a slow blow or fast acting fuse.

Is there any way to discern the difference after one has been blown?

Is there a different schematic symbol for the two?


texts: Can a 240V 3 phase input battery charger be somehow used with only 240V single phase?

texts:
I was wondering if a battery charger rated at 240V 60 Hz 3 phase input can be somehow made to work properly if I only have 240V 60 Hz single phase available.  I know there are expensive phase converters available on the market but I want to try to avoid those because of cost reasons.  So would 240V single phase possibly damage a device designed for 3 phase input?

The requirement on the input side is up to 11A at 240V (3 phase) but the charger is also rated at up to 13A at 208V.  I might be able to get a 3 phase feed from my local power company but as of right now, I only have split phase 120V which means I can easily get 240V.

The purpose of this very high output charger is for just that, rapidly charging a large battery bank that can handle it.  My existing other chargers are quite slow so I wanted to possibly use this one instead.


texts: Verilog Testbench - wait for specific number of clock cycle edges

texts:
In my testbench, I want to wait for two events in sequence: one after 60000 clock cycles and next after additional 5000 clock cycles

I know I can wait for clock edges using statement @(posedge clk), however how do I wait for specific number of clock edges, say 6000th positive clock edge etc.


texts: (Noob question) Placing parts of a byte in different (parts of) registers

texts:
Background: I'm trying to get a gLCD working with an Atmega328p. I got it to work quite easily, but there was one catch: the library that I found, used portB for the datapins. This was unacceptable, because I had an external oscillator hooked up, which already uses PB6 and PB7. I modified the library to use portD instead. Now everything worked flawlessly, but... RX and TX are on PD0 and PD1. So if I use this port, I can no longer use U(S)ART.
That leaves portC, but sadly, this port only has 7 pins, instead of the usual 8 (and I need all 8 of them to drive the LCD).
So, that forces me to use pins of two different ports.

This was the original code (snippet):

#define GLCD_IO_DATA_OUTPUT(data)       PORTD = (data)
#define GLCD_IO_DATA_DIR_INPUT()        DDRD = 0x00;
#define GLCD_IO_DATA_DIR_OUTPUT()       DDRD = 0xFF;

The last two lines are used to switch the Data Direction, I'm guessing for some kind of feedback. The first line places a full byte in the dataregister for the lcd to use. I want to free up PD0 and PD1, and use PC0 and PC1 instead (because I figured this would be the easiest).

I tried this:

#define GLCD_IO_DATA_OUTPUT(data)       PORTD |= (data & 0b11111100);\
                                          PORTC |= (data & 0b00000011)
#define GLCD_IO_DATA_DIR_INPUT()        DDRD &= ~(0b11111100); DDRC &= ~(0b00000011)
#define GLCD_IO_DATA_DIR_OUTPUT()       DDRD |= 0b11111100; DDRC |= 0b00000011

Sadly, this didn't work.

Because I have nothing else hooked up (for now), I guessed there is no reason to not use the full port, for now:

#define GLCD_IO_DATA_OUTPUT(data)       PORTD = (data); PORTC = (data)
#define GLCD_IO_DATA_DIR_INPUT()        DDRD = 0x00;   \
                                                DDRC = 0x00
#define GLCD_IO_DATA_DIR_OUTPUT()       DDRD = 0xFF;   \
                                                DDRC = 0xFF

It places the full databyte in both ports, but only the relevant pins (PC0-1, PD2-PD7) are connected.

I guessed this HAD to work, but it didn't. Maybe there's something obvious I'm missing, or some hardware limitation that prevents this method from working?

So... What would be the best way to implement a change like this, and what did I do wrong in the code above?


texts: Feature 'logo/labels' on cases of self made devices

texts:
Not really an electronics question however has something to do with the tech you have used for your own projects. For example, on any consumer device with USB support, Bluetooth, HDMI 2.x etc there is a tech feature logo/label present that indicate the tech supported/involved. Of course you can use a marker or something similar however is there a way to do this more neat and professionally?
I have searched on many different keywords and only found some (car-) brands, car features - 'turbo' and such, custom logo's, NFC stickers etc however no 'default' consumer tech/feature label stuff. Does it exists and if not, how did you do this? I think this a very common thing to label the features the device support. Also when you extend an existing device with a new feature, like I do, for example adding Bluetooth. It is nice when the added feature logo is present on the case because normally you don't expect this.
Are there any generic/default options at this field?


texts: What's the difference between mismatch and return loss when talking about filters?

texts:
I have been learning about filters recently, but am confused about what the difference between mismatch and return loss is. Could anyone explain the difference to me in an easy to understand way, or point to to a resource that does?

Thank you!


texts:
I'm new to StackExchange. I am trying to repair a Yamaha digital radio tuner model TX540 made in early 1990s. I don't have a schematic.

I have been desoldering components and checking them with a DMM or ESR meter (for the capacitors). There are a number of small resistors, all marked the same, that read OL on the DMM. Initially I thought the first one I checked was open, but another 3 are showing the same.

The resistors are only small and the colour banding is Brown Black Orange Grey Brown. I checked this on a dissecting microscope, although the grey band could be silver. If grey is correct, then that indicates a 10 GΩ resistor. That seems ridiculously large for a small resistor in a domestic radio tuner. I'm assuming the resistors are OK, but outside the range of my DMM which is a Brymen BM257. I have also checked with another DMM, with the same outcome.

I'd appreciate any thoughts anyone might have on this.


texts: Rail-to-rail op-amp only reaches 90% of VCC, works sometimes, not everytime

texts:
I have created a simple data acquisition module for measuring 5V signals.  There are 18 analog inputs on this board, all of which are a copy of the schematic below.

Each input has an op-amp (MCP604) with unity gain.  This op-amp should work to within 60mV of VCC, but in half of my circuits, it won't get any higher than 4.3V.  (Notice the 100K pull-up to 5V, the input pin disconnected, should output very close to 5V.)  In the other half, the circuits operate just fine.  I have two of these boards built, and most (not all) of those circuits are limited to 4.3V.  Under 4.3V, the circuit will behave in a linear fashion.

It doesn't appear to be a glitch at power-up, the circuits that work always work, the circuits that don't always don't.

I've cut the trace at the output of the amplifier to see if the A/D converter was clamping it somehow.  No effect.

I've tried adding load to the output, with different values of R50, 10K to infinity.  No noticeable effect, maybe a couple of millivolts.

Probably an unnecessary detail, but for the sake of completeness...
I need to get the zero input of the signal within the linear range of the amplifier, so I boost it slightly with the 20K/100K voltage divider.  This lifts a 0V signal to 0.833V.  The device connected to this circuit may provide an input voltage of slightly less than 0V (sometimes a low as -0.5V).


texts: Finding asymptotic stability of RLC circuits

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Given the state model for an RLC circuit, how can I show that it is asymptotically stable?
So my state assignment is as follows:

x1 = Vc

x2 = iL

And using the KVL and KCL equations I can get a state model for the first derivatives and can get the corresponding matrices and transfer function.

How can I find the asymptotic stability now?

Any help is appreciated!


texts: Arduino with mosfet resets when switching on/off fluorescent lights

texts:
I'm working on this project for opening a lot of solenoids and to turn on/off lights.
When I'm testing, everything seems fine, but in production, the Arduino resets or even behave strangely by opening solenoids or starting the buzzer randomly.

I've noticed that It resets when I switch on and off the lights (fluorescent light, 12 of them, so a lot of spikes)
Here is the original schematic.

I want to add the optocouplers 4n35, that are not currently in the scheme.

Can anyone advise, if there is something wrong with the orignal schematics.
Are there any improvements that can be made in order to make this work?
Is the solution I've proposed going to solve the problems?

Note, that the 24V is actualy 12V but from a different power source just to separate the spikes from solenoids.

Thank you an best Regards,
Mircea


texts: In 3 phase induction motor how many phase will be generated in wound type and squirrel cage rotor? If we consider a generator when the rotor rotates there will be voltage induced in every pole of stator but for motor case our assistant said it is 1 phase.


texts:
I have a differential signal which will be transmitted from a system (transmits and receives the data through 2 wires only, there is no GND wire).The differential signal has 3 voltage levels -12V , 0V and +12V. I have measured this differential signal with the help of oscilloscope by keeping one wire to GND of oscilloscope and one wire to positive of Oscilloscope.
The differential signal was shown below.
I need to decode this data i.e, convert to single ended signal but here the issue is when this differential is converted to single ended signal using AM26LS31CDBR IC, 0V logic level is either converted to High or low, but it is not following the same logic i.e. High or low.
I need a transceiver which converts this three state differential signal to single ended signal and it also should convert the same converted single ended signal to differential which should be same as three state differential input signal .
Can anyone suggest me the solution for reconstructing the differential signal.


texts:
I'm trying to use a Saleaa Logic 8 to find data pins on a 20-pin header from a board with a Intel X Scale (ARMv5) PXA270 processor, but I can only find what looks to be data on pin 9, I've tried (I think) all the rest of the pins, is it possible to get JTAG debug data from a single pin? Is there a typical pinout for JTAG 20 pin to know where to look? I just have a rising edge trigger. I want to read the firmware with a Bus Pirate v3.6. Here's what I see:

Someone mentioned it might be something like serial, looks like this logic analyzer supports it:

with some options:

The decoded ASCII just says '255' for channel 0, which is pin 1, but nothing about pin 9, where the data seems to be:

Should I be using some other protocol besides async serial? Here's the whole 30 second capture:


texts: Do cascoded MOSFETs need to be in their own wells in order to properly connect bulk to source?

texts:
I am learning to design CMOS layouts. When creating the layout for something like a cascoded current mirror, are individual wells needed to properly connect the bulk to source?

For example, for the cascoded current mirror seen in figure 1, does there need to be 3 individual p-wells? M1 and M2 are both source to ground, so they can go in the same well in order for bulk to be connected to source/ground. However, the sources of M3 and M4 are connected to the drains of M1 and M2, respectively. Do M3 and M4 each need to be in their own individual wells such that bulk can be connected to their source/the drains of M1 and M2?

Figure 1: Cascoded current mirror.


texts:
For testing purposes, is it ok to assume that every ground pin on the EV board is the same? even if not connected to each other explicitly?

i.e. when using measurement probes is it ok to stick the ground ends of the probes on any random gnd pin, or for accuracy purposes should they all be attached to the same ground?


texts: Will I need a heatsink for this voltage regulator

texts: I am making a USB battery backup with an old laptop battery and a solar panel. I know most regulators have heatsinks, but will my 5v regulator need one? And if I do, how hot will it get?


texts:
Can you use Fritzing to create a 4 layer pcb?

Also, in real life, what is the maximum limit of layers we can use to create pcbs? is it 4 layers?


texts: LED specs: difference between nominal power and power consumption?

texts:
I have have a question regarding the technical specs of a LED. In the specs are two values given:

Nominal power: 30W
Power consumption: 6,6W

What is the difference between these two values? The meaning of the values itself is clear, but why are there two of them? From what value can I calculate the overall current consumption?


texts:
Is it recommended to stack extension boards?
Output of 1st extension board - Input of 2nd extension board - Output of 2nd extension board - Input of 3rd extension board and so on ...
https://www.google.com/search?q=3+pin+extension+board&prmd=sivn&sxsrf=ALeKk03HYYNQX7eInEIX9WLxgfbuchHOfA:1595735413808&source=lnms&tbm=isch&sa=X&ved=2ahUKEwiW-vrTgerqAhWEbSsKHd4vBVsQ_AUoAnoECA4QAg&biw=360&bih=592


texts:
I'm trying to build a median filter in Verilog using a comparator to sort out the highest pixel value and erase it, then sort out the next highest etc. until I have only 5 pixels left (I'm treating groups of 9 pixels) and the highest value of those is the median. I modelled this problem by having a initial state, one state to receive pixels and 5 states to find max. (Each state sorts between less bytes so at the end of my fifth state I'll have the median). Both code snippet below shows what I described above.
Sorting module:

module MED #(parameter WIDTH = 8,
            parameter NUM = 9)
            (input [WIDTH-1:0]DI,
             input DSI, BYP, CLK,
             output [WIDTH-1:0] DO);

logic [WIDTH-1:0] R[0:NUM-1];
wire [WIDTH-1:0]MIN, MAX;
wire [WIDTH-1:0]D1, D2;

MCE #(.WIDTH(WIDTH)) MCE1(
    .A(DO),
    .B(R[NUM-2]),
    .MIN(MIN),
    .MAX(MAX)

);
assign D2 = (BYP) ? R[NUM-2] : MAX;
assign D1 = (DSI) ? DI : MIN;
assign DO = R[NUM-1];

         always_ff @(posedge CLK)
     begin
         R <= {D1, R[0:NUM-2]};

         R[NUM-1] <= D2;
     end

endmodule

Whole filter:

module MEDIAN #(parameter WIDTH = 8)
        (input [WIDTH-1:0]DI,
         input DSI, nRST, CLK,
         output [WIDTH-1:0] DO,
         output logic DSO);

     logic BYP;

     MED #(.WIDTH(WIDTH), .NUM(9)) MED1(
         .DI(DI),
         .DSI(DSI),
         .CLK(CLK),
         .BYP(BYP),
         .DO(DO)
     );

     //Compteur mod 8
     //Le clk de sortie sera utilisé par la machine à états finis.
     logic [3:0]counter;

     always_ff @(posedge CLK or negedge nRST)
     begin
         if(!nRST)
             counter <= 4'd0;

         else if(counter == 4'b1000)
             counter <= 4'd0;

         else
             counter <=counter+1;
     end

    //Machine à états finis

    logic [2:0] state;
    localparam INIT = 3'd0;
    localparam S0 = 3'd1;
    localparam S1 = 3'd2;
    localparam S2 = 3'd3;
    localparam S3 = 3'd4;
    localparam S4 = 3'd5;
    localparam S5 = 3'd6;

    always_ff @(posedge CLK or negedge nRST)
    begin

    if(!nRST)
        state <= INIT;
    else
        case(state)
            INIT: if(DSI)
            begin
                counter <= 4'd0;
                state <= S0;
            end

            S0  : if(counter == 4'd8)
            begin
                counter <= 4'd0;
                state <= S1;
            end

            S1  : if(counter == 4'd8)
                state <= S2;

            S2  : if(counter == 4'd8)
                state <= S3;

            S3  : if(counter == 4'd8)
                state <= S4;

            S4  : if(counter == 4'd8)
                state <= S5;

            S5  :
                state <= INIT;
        endcase

    end

    always_comb
    begin
        if(state == INIT)
            DSO = 0;

        else if(state == S0)
            BYP = 1;
            if(counter == 8)
                BYP = 0;

        else if(state == S1)
            BYP = (counter == 4'd8) ? 1 : 0;

        else if(state == S2)
            BYP = (counter > 4'd6) ? 1 : 0;

        else if(state == S3)
            BYP = (counter > 4'd5) ? 1 : 0;

        else if(state == S4)
            BYP = (counter > 4'd4) ? 1 : 0;

        else if(state == S5)
        begin
            BYP = 0;
            DSO = 1;
        end
    end

endmodule

This is the waveform I'm getting. Top row are my pixel values, bottom row is my current state and above that is my counter. Above the counter is my bypass signal, which would erase the max value and proceed to sort the next highest. What I wanted to have is have bypass set for when I have counter = 8 and state 2, then bypass set for counter = 7 and 8 when in state 3...

Is there any way to fix this or should I model my FSM differently (I'd like to keep the principle of sorting by highest value and erasing them, though).


texts: Control 5 V buzzer using 5 V microcontroller (which can't drive it directly) and a single 5 V power supply?

texts:
I have a PB-12N23PW-05Q buzzer and I'm trying to use it with ATmega 162. I can't connect it directly to pin, because from what I've read from 162's datasheet, it can source at most 20 mA. The buzzer takes 50 (or around 25, if we take a look at the graph), so I don't think I can just directly connect it to the microcontroller.

My initial idea was to connect it to a transistor and use the transistor as a switch.  Unfortunately, it didn't work. I used BD237 and my idea was that the microcontroler will pull the pin connected to the base high and the transistor will operate the buzzer. In my setup, I had buzzer connected to Vcc, buzzer's negative port connected to collector, GND connected to the emitter and 162 connected to the base. Transistor is of NPN type. Somewhere I read that this way some problems related to the voltage drop on the transistor can be mitigated, but to me it looks like the voltage drop is the main problem here.

Here's the schematic. The mc is used instead of switch on the real thing.

Right now, I'm looking for other ideas on how to connect the buzzer.


texts: What is the purpose of PLL in a general microcontroller

texts:
An ARM Cortex-M4 based microcontroller like TM4C123GH6PM is designed with multiple clock sources with a processor core clocked at 80MHz provided by the PLL, which, from what've read in NI-What is a PLL? and All About Circuit - What exactly is a PLL?, is some sort of feedback x oscillator circuitry that detects phase shift and stabilizes input frequencies through feedback. I don't understand how PLL relates to microcontroller. I'm not sensing any phase shift or trying to stabilize any signal here, and I don't get how the PLL magically produce a 400MHz clock.
Why is this PLL embedded in the microcontroller? If I want my processor to clock at max 80MHz as written in the specs then I just use an 80MHz external crystal. If some peripherals like USB require faster clock sources then I use a faster crystal and divide the clock to supply multiples of slower clock to other devices. External crystals are more accurate than internal oscillators anyway, so why bother stuffing a PLL in between an accurate external crystal and the processor, especially when I'm not dealing with any high frequency or RF application?


texts: Control relay from Bluetooth on ATtiny85

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I know someone else has made a Bluetooth transmitter to a relay so i wanted to ask a few questions about it being possible? I am an almost newbie at electronics but i do know a few things, so first of all I want to power my ATtiny85 from wall power because i want my ATtiny85 inside the wall of my house to control the roof light and i want it to be powered always how would i do that? Second is it possible to switch a 220V AC relay from the ATtiny85 if not would i be better off with an arduino?
Thanx


texts:
I have a string of LED fairy lights (5v) that when I connect to power, only half of them light up. If I reverse the polarity, the other half light up. It’s my understanding that I need a h-bridge to rapidly switch back and forward polarities. I’m waiting to ensure that there is no chance that I will see flickering (hence need something in the kHz range?).
I’m wanting information on the type of h-bridge I should be looking for given the intended usage, and how I would wire it in? I looked around and see many options, but non stood out as being the obvious one to use.


texts: STM32WB55 Nucleo bluetooth stack firmware binary in bootloader mode

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I want to upgrade the firmware for the bluetooth stack on the STM32WB. It requires the device to be in boot loader mode and power from the user USB not ST-LINK usb. However I've not programmed a device in this way before, should it be programmed through the user USB interface, or should i use an ST-Link device and wire up SWDIO...etc to be able to connect to the device?

Instructions provided are below: but they make no reference to using ST-Link.

Following the instructions as is I cannot connect to the device (it doesnt appear in device management) when just connected via USB User.

Should I be using an ST-Link device in addition to the USB user? or any other suggestions?

STEP 1: Use STM32CubeProgrammer

    Version 1.4 or higher.

    It gives access to Firmware Upgrade Service (FUS) (AN 5185) through Bootloader.

    It is currently available as Command Line Interface (CLI) mode.

STEP 2: Access to Bootloader USB Interface (system flash)
    Boot mode selected by Boot0 pin set to VDD
        For NUCLEO-WB55.Nucleo :
            Jumper between CN7.5(VDD) and CN7.7(Boot0)
            Power ON via USB_USER and Jumper J2(USB_MCU)
        For NUCLEO-WB55.USBDongle :
            Move switch SW2 to Boot0
            Connect WB55.USBDongle

STEP 3 : Delete current wireless stack :
    STM32_Programmer_CLI.exe -c port=usb1 -fwdelete

STEP 4 : Download new wireless stack :
    STM32_Programmer_CLI.exe -c port=usb1 -fwupgrade [Wireless_Coprocessor_Binary] [Install@] firstinstall=1

Please check Binary Install Address Table for Install@ parameter depending of the binary.

STEP 5 : Revert STEP 2 procedure to put back device in normal mode.


texts: How can I control a chain of LEDs/buzzers from a single Arduino pin?

texts:
In an effort to make a wearable piece of electronics, I would like to be able to control a large number of buzzers, sewn together on a string, from a single output pin on my Arduino.

The idea already exists: Several companies offer ready-made LED chains which can be controlled through a single pin (see for instance here). These purpose-made LEDs have 4 pins: Two for electricity and two for receiving and transmitting a signal. If I understood it correctly (and please correct me if I am wrong), this is simply a serial shift register: Bits are pushed through the system until all are in place, then only requiring a latch signal to activate them.

However, in my case, the buzzers I intend to use have only the electricity wires and have no way to be chained together, yet controlled separately.
So this got me thinking: Can I, through simple means/tools, construct my own chain which I can address through a single pin on the Arduino? If so, what would I need to do & buy to accomplish it?
In essence, what I am trying to achieve is maybe captured in this picture.

I am aware that this could be solved with shift registers and/or I/O expansions, but this causes problems for me because I would need one wire per buzzer, and so with a large number of buzzers, I would be forced to purchase a big number of shift registers and sew a large amount of conductive thread to serve as wire.

I have seen similar questions to this one (see here, here and here), but the answers there always tended to go for solutions which would allow me to create 8 wires out of a single one (so using shift registers, 1-wire 8-channel switches, etc.), which is exactly what I am trying to avoid, if at all possible.

Edit: Clarification - What I mean by more wires is this: If I can link and control all the buzzers (which will probably be upwards of 30), through a single chain, that means that I have 3 distinct wires, as in the example website for the LED design I gave above: two power lines and one to send controls over.

On the other hand, if I placed multiple shift registers (I'd probably need at least four chained shift registers?), I'd need one wire from the SRs to each of the buzzers, which means I would need two power lines and 30 wires, which is a nuisance.


texts: How does one compute the ripple currents seen by a boost converter output capacitor?

texts:
Suppose one is designing a boost converter, with a known maximum current load, and a known inductance:

The ripple current seen by the output capacitor is critical. If that current is too high, the capacitor will heat up, and its lifespan will be reduced. But how does one compute the ripple seen by this capacitor?


texts: Scratched capacitors at the top. Should I care?

texts: I've ordered a couple of big capacitors and one of them (the one on the right) seems to have been repeatedly hammered by the other's leads during transportation. So much so that it has some considerable marks at the top (see picture). Should I be concerned about the capacitor performance or safety given those scratches?


texts: Is it possible to replace STM32F407 Internal Bootloader

texts: I am new to the STM32 world. I know that all STM32 MCUs come with an internal bootloader. Is it possible to replace it with custom boatloader?


texts: How to distinguish between a pure resistance R and circuit whose equivalent reactance is R (when in a black box)?

texts:
We were given the following question in our circuit theory class:

  Find the relation between \$R,L,C\$ such that the net reactance across
  terminals \$A\$ and \$B\$ is \$R\$.

simulate this circuit – Schematic created using CircuitLab

I followed the generic method (equivalent parallel reactance):

$$\frac{1}{R}=\frac{1}{R+j\omega L} + \frac{1}{R+\frac{1}{j\omega C}}$$ to get the required relation (after eliminating \$\omega\$).

Upto that is okay. But I'm confused about something:

Suppose the system is inside a black box, with only terminals \$A\$ and \$B\$
outside. In that case how can we possibly distinguish between a black box containing this circuit vs. a black box which contains only a resistance \$R\$?


texts: Differential LC LPF and Impedance Matching Circuit

texts:
I used this online calculator to generator a LC low pass filter with impedance transformation for interfacing a Variable Gain Amplifier (VGA) with an ADC. However the result is for a single ended input and output.

R1 200
C1 7.95775e-11
L1 0.000127324
C2 5.45612e-12
C3 2.54526e-12
R2 2000

Would it be possible to use this as a starting point to figure out what values I'd need to do this differentially?

VGA: AD8369 has differential output impedance of 200 Ohm.

ADC: MAX1438 has differential input impedance of 2k Ohm.

The low pass has a cutoff at 20 MHz and the matching is for 5 MHz.

Edit: There is an example circuit in VGA datasheet, but it is for an ADC with a 1k input impedance and I'd like to also add a low pass filter in front of the ADC.


texts: I have heard a lot of the time that "the core is not large enough to handle the current, and will reach saturation". What is saturation and why is it a bad thing to reach saturation?


texts:
What exactly are the main voltage standards called for all the common voltages we see?
3.3V, 5V and 12V are some of the most common DC voltages but what are they known as exactly and what's with their significance? i.e. Were they picked as it sounded like a nice value or for an electronically significant reason?


texts:
Suppose I have a TV plugged in and it is connected to a power outlet which is also turned on. This appliance is "turned on" and on  "stand by mode". It consumes energy I think just to light up that little red LED to tell you it's switched on (does it use electricity for anything else?)

Now suppose I have a laptop or mobile charger that is plugged into a power outlet that is permanently turned on. If this charger is just sitting there without being plugged into anything .... is it consuming energy? Is this considered to be another "stand by device" which consumes energy for me? Will this impact my power bills?

In the extreme case: if a power outlet is turned on, is this consuming any energy?


texts:
I have studied the datasheet of an NPN transistor, in datasheet MAX-POWER OF transistor is mention as 400 mW.

What is the meaning of max power?

Can it be generated by itself or do I have to give 400 mW to the transistor??

Thank you


texts:
I just have issues with the RGB LED flickering under low duty-cycle like 10% on time with 780 Hz. I tried changing the PWM frequency to lower and higher rate but I still see flickering at low duty-cycle (on time). This flickering only happens when I connect a bunch of MCU (PIC18F87J11 with  8 MHz oscillator) to a single voltage source (15 volts). I need some feedback so I can understand what's causing the problem since I don't know a lot about electronics. Here is a quick summary about the issue.

With 1 MCU connected to 12 volts , regardless of the PWM frequency or the duty-cycle, there is no flickering at all.

The more MCU I add, the more flickering I would see. In my case, I have 15 MCU connected to 15 volts power supply. At low duty-cylce I see flickering of the RGB lights. However, at high duty-cycle there is no flickering at all. Also lowering the PWM frequency a little bit helps with flickering on low duty-cycle but overall the flickering is visible and annoying.

Some questions ..

What is the best-recommend PWM frequecny for RGB lights?
Can I still avoid this flickering without any hardware changes just software?
Can you help me understand how and what's causing the flickering?

Thanks!


texts:
I am designing an ALU for my computer architecture class. The rubric states that we need to simplify each logical part to make it as clear as possible. My group condensed the 4 NOT gates and 4 AND gates into their own components which are still represented using the NOT and AND gate symbols.

Question: Using the AND and NOT gate symbols, is it correct that they have multiple outputs? Or should their symbols now be rectangles with a title because they are a 'non standard' component?

Before

After

EDIT: I had to remove the entire schematic images because this assignment isn't due yet and other teams could potentially cheat. I hope this is still helpful!


texts: How to add an emergency stop switch in a circuit?

texts: I am into a project, where I have made a a bot, which has a 6 degree of freedom robotic arm with four wheels. I need to add a kill switch that is connected to a relay, which stops all the 10 motors. I don't know the circuit connection between the switch and the relay which then goes to the motors. It is powered by a 24V battery.


texts: Does anyone recognize this chip? B9930 FLC5068

texts: I can't find it. Does anyone recognize this logo?


texts: how does current go to infinity in an ideal LC circuit at resonance?

texts:
Consider an ideal LC series circuit, excited by a sinusoidal source at resonant frequency. Assume zero initial conditions, for capacitor voltage and inductor current.

simulate this circuit – Schematic created using CircuitLab

1) Can anyone explain how does the current amplitude go to infinity, at resonance?

I understand the impedance goes to zero,which explains the steady state current as infinite.
But can you explain the same by simple circuit analysis?I mean  the voltage across inductor is Vsinωt - Vc =   L di/dt, so based on derivative being positive, the current increases.But what makes the current go to infinite? After all for a simple L only circuit, the voltage across inductor is Vsinωt  =   L di/dt and it is not getting infinite

2)Now at resonance what happens internally, from an energy perspective?Is there any transfer of energy between inductor and capacitor OR Source is throughout supplying energy to inductor and capacitor?

3)Will the nature of current differ if we have initial conditions?


texts: How to power 2x 12v computer fans with batteries & 1 switch

texts:
I am a total electronics newby (besides the odd solder repair) -
I'm trying to create a robot with my son out of an old tower PC and he'd like to use the fans for eyes.
I've seen that a fan can be run off a battery so could buy a case with a switch so he could turn them on and off, but can anyone show me a super simple diagram of how I connect 2 fans to 1 switch and preferably 9v batteries (limited space inside robots head!)?
1 fan label says 12v 0.10A and had 2 cables, sadly in his excitement he removed the other label and all cables!
I am OK with soldering cables back and figure I'll need to be soldering in a switch anyway.
Better still - if we can also add a coloured LED to the centre of each fan that would be awesome. What LED spec would we need so they don't burn out??
Any help gratefully received - he's only 8 and busting to make this work
Thanks


texts: How can some guys discern all parts of a MCU?

texts:
Today, when I was searching for find some dies, I saw these pictures:

Now I'm curious that know how can some guys discern all part of a MCU?
Is there any points that I use those to discern all part of a MCU?
they can discern RAM, FLASH, Clock generator unit and etc...

refrence of picturess:

http://blog.ioactive.com/2007_11_01_archive.html

http://www.eetimes.com/document.asp?doc_id=1255032

http://www.mdpi.com/2079-9268/1/1/109/htm


texts: Why does the output of NOT gate (in a 74LS04 IC) equal to one when the input wire is not connected to anywhere?

texts:
I have a 74LS04 integrated circuit, like this:

source

I put this IC on a Bread Board and connect the negative and positive parts of the Bread Board to negative and positive parts of a 5-volt source, respectively. Then, I connect the pin number 14 to the positive line of the Bread Board and the pin number 7 to the negative line of the Bread Board (representing Ground).

Now if I connect pin number 1 to the negative line of Bread Board (thus feeding 0 to the NOT gate) and measure the first NOT Gate's output (pin number 2) with a voltmeter, I see the number 5 volt (meaning 1). And if I connect pin number 1 to the positive line of Bread Board (thus feeding 1 to the NOT gate) and measure the voltage of pin number 2, I see the number 0 volt (meaning 0). So far everything makes sense.

But if I leave the pin number 1 unconnected and measure the voltage of pin number 2, I see the number 2.6 volt, which I've been told that it means 1. Why is that?


texts: Reliability Testing of Complex circuit using Arrhenius Linear Acceleration Model

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I am interested in conducting accelerated life testing on a complex amplifier PCB with multiple amplification and filter stages.
Doing some research and reading I have identified the UG-311 Analog Devices Reliability Testing Handbook as a useful resource.
If I assume that:

The accelerated test conditions don't introduce new failure mechanisms
Extrapolation from accelerated data is possible
The thermal activation energy of the failure mechanism is 0.7eV (p. 13 of AD handbook)
Tstress temperatures at 125C and 135C
Use of Chi-squared distribution to inform confidence intervals

Can I use the Arrhenius model to predict the time to fail at Tuse using the time to fail at Tstress?
AT = t1/t2 = Exp. [− Ea/k (1/TTEST − 1/TUSE)]
I know that the model is used primarily for predicting transistor failure rates but the AD handbook seems to suggest it can be applied to ICs.
Thanks for your insight and let me know if you have questions.


texts: Compare the phase of the voltages across components of a series RLC circuit

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Suppose we have a series RLC circuit with equal impedances connected to a 50Hz 240Vrms AC. We use an oscilloscope to measure and compare the voltages across each component.

1) Are their "VOLTAGES" all in phase?

2) If not what "VOLTAGES" are out of phase with each other?


texts: KiCad problem, schematic to PCB layout generates empty PCBnew window

texts:
I am using KiCad 5.0.0, after I built my schematic I annotated schematic symbols, assigned PCB footprints to the schematic symbols, then generated the netlist, and finally when I clicked on the tab of Pcbnew to layout printed circuit board it generated a blank Pcbnew file, nothing inside!

Any idea what might causing this problem, please?