texts: Question regarding a resistor in optocoupler/TRIAC circuit

texts:
I'm building a ac motor starter with a optocoupler (FOD4218) and a TRIAC (BTA16), one for each phase in a three phase 400V system.
I have a question regarding the circuits that can be found all over the web, like this one:

(source: electronics-tutorials.ws)

What is really the purpose of the 100R resistor? Is it for voltage dividing or what? In my case where the circuit is between two phases, is it necessary? Some circuits do not have that resistor at all. I have planned to use 600R for the upper resistor.

Thanks.


texts: How to transmit a signal to a reciever over 50 meters?

texts: I'm studying at a technical college in Denmark, and I'm doing an exam project involving emergency calls for elders. I'm currently trying to build a solution, but it involves a transmitter which can transmit at least 50 meters. Is there any way to do this? I'm not that experienced with electrical stuff, but know the basics. Any help is appreciated! :)


texts:
I am designing a circuit that can detect if a cable is connected to mains voltage (e.g. via an external relay or switch). The device will be installed in electric cabinets.

The circuit is tested and works, but I want add further protection. I read about the differences between TVS Diodes, MOVs, etc. and decided to use TVS Thyristors because they seem to be the safest option.

But I could not find out how to properly select a TVS Thyristor. As I said I want to protect 230V AC mains voltage.

At Digi-Key the most important stats are "Voltage - Breakover" and "Voltage - Off State" I assume.
I suppose this is supposed to be the peak voltage (i.e. \$230V * \sqrt 2 \approx 325V\$) multiplied by some safety margin factor and not the effective voltage (i.e 230V).
I don't really want to prevent "small" transients, because my circuit can handle probably at least 400V peak voltage.

Does that mean I have to select as TVS thyristor with a "Voltage - Breakover" of 400V? And what does the "Voltage - Off State" mean which would be between 300V and 320V in that case?

Is this the correct approach anyway or would other protection devices be better suited?

Edit: Added schemtic upon request. The exact ciruit does not really matter, because the question is mainly about the nature of TVS Thyristors in general and not just this specific case.

simulate this circuit – Schematic created using CircuitLab


texts: How to control the gain of FET/BJT/Op-Amp amplifier by input voltage range?

texts:
Assume I have an input voltage ranging from 5-10 MHz and want to amplify it.
The case is pretty simple as any device as FET,BJT or high frequency op-amp can do the amplification well but I have a problem: the input frequency range (amplitude) changes by the frequency as it is 2.5 volt pk-pk at 5MHz and reduces to 5 milli volts pk-pk at 10 MHz.
I need a constant output amplitude ( at any voltage ).
I tried a high-pass filter to reduce the high range at lower frequencies but unfortunately it is not that precise and some changes remains ( even with good frequency calculations and active filters) and some distortion at extremities noticed.
Is there any standard way to do that?
Any helps appreciated in advance.


texts: Information about component quality in general and quality of memory IS25LP128-JBL

texts:
Most of us are faced with component quality especially when producing product in higher quantities. What is he right place to find information about component quality in general?
Currently we faced with problem of IS25LP128-JBL memory. Sometimes it does not hold memory after several read/write cycles. We are getting feedback from 1000 products. In previous product version memory AT25DF641 is working like a charm. Does anybody has problems with IS25LP128-JBL too?


texts: Smallest voltage a peak circuit can detect

texts:
I have been looking up peak detector circuit in different sources but I could not find nowhere mentioning the smallest voltage a peak circuit can detect and what factors determine that value. In my application, I have to deal with signals in few millivolts or even down to hundreds microvolts The theory of operation is well explained in every source I found but when dive into the details, it seems to me every factor matters in optimizing a peak circuit such as op amps GBW, diode voltage drop, diode leakage current, type of diodes etc. I would appreciate if anyone could give me a more analytical details in how we design the peak detector
I have copied the peak detector picture taken from : https://www.analog.com/en/technical-articles/ltc6244-high-speed-peak-detector.html for reference
Thank you


texts: Could a short burn a device with high ESD protection

texts:
I'm prototyping a device whose schematics is open source and available on-line. I have modified the layout to fit it into an Arduino Uno form factor and now I got the PCBs along with components. Once soldered altogether, the device is not getting detected.

It uses several chips I suspect has burnt off but when I check the ground and Vdd connections, it doesn't show any shorted paths on the PCB. Device has a MCP2200 chip as the UART bridge and the datasheet states that its ESD protection is > 4kV HBM. It also uses a PIC24EP256GP204 micro-controller and when I try to connect it to a PicKit3 using MCLR, VCC, GND, PGD, PGC pins, it throws the device ID 0x0 is not valid issue.

I tried removing the PIC IC and still pickit3 shows the same error. It kind of tells me that the PIC is also burnt, isn't it?

The MCP2200 chip should be identified by the PC when connected. So I desoldered the IC using hot air and mounted it in an extra PCB and made the connections similar to a breakout board;

But that is also not detected by the PC. I have a couple of questions in this regards.

Does high ESP protection mean higher tolerance to short circuits? (I'm not sure if the PCB has shorts at all, because when I check every pin to PIC IC I could only read the correct voltages at each pin)
Is there a chance to get the MCP2200 IC and the PIC IC to be burnt while I am testing path connectivities (Using diode check in multimeter)?every pin to PIC IC I could only read the correct voltages at each pin)


texts: How to safely use the power-socket ground for the anti static wrist strap?

texts:
I saw as practice to use the power-socket ground for the anti static wrist strap, I saw this done where there is no available specially designed ground for anti-static pads and bracelets, but this may have some safety implications.

I am thinking here at the following scenario: the ground cable may get cut and there may be some electrical discharge to the earth cable, and then the current makes its through the wrist strap and through your body and the floor.

Is there a way to still safely use the power-socket ground for the anti static wrist strap?


texts: High side current monitor for bidirectional high voltage rail with low current

texts:
I'd like to sense the current at the output of an HV op-amp that will produce +/-200V at up to 15mA, with an output voltage in the 1-10V region. The HV op-amp's rails will be around +/-250V.

Unfortunately it seems that most "high voltage" current sensors are actually rated for 60-100V, and often only unidirectional. Hall effect sensors are also ruled out due to their noise floor - the Allegro ACS722LLCTR-05AB-T, for example, has current noise of ~20mA which is more than the maximum I would want to measure.

It seems the standard way to deal with high voltages is to stand them off using MOSFETs and/or zener diodes, e.g.:

This Linear Technology current sensing application note (p50)
This MAX471/472 based circuit

but the problem with these circuits is that they are unidirectional and I need bidirectional sensing.

I figure the solution to this problem involves powering a current monitor from the HV op-amp's negative power supply rail - using a zener diode and resistor between the output and the negative rail to drop some voltage (e.g. 5V) to power the current monitor IC. Something like the MAX4070 could work. Worse case, the negative supply rail is -250V, and the output is 200V, then the MAX4070 would be powered with 200V at Vcc and 195V at "GND2", the MAX4070 IC's ground (not the same as the load's ground). The output would then be somewhere between 195V and 200V at "Vout2" with respect to real ground. I could then pass this into an isolator, with the secondary side clamped to real ground and a voltage proportional to current that is at most 5V. As the MAX4070 has a 2.5V reference, the output would vary from 0-2.5V for negative current and 2.5-5V for positive current.

Here's a diagram (hastily drawn in CircuitLab - but I've hand-drawn the MAX IC and the LED/LDR is supposed to be an optoisolator):

Now... would this actually work, or am I missing something?


texts: 6W 12V 5A peltier only drawing 1A, I am supplying more current but its only drawing 1A

texts:
I just bought the peltier and its of 60W 12V 5A and its maximum capacity is of 90 watt power. I am using my Pc power supply which have ability to provide 12V and 15A maximum. I connect to that lead and check the current drawing using multimeter and my peltier only drawing 1.5A at start and then keep decreasing until 1A.
However peltier seems to be working because the colder side getting colder but not enaough because its only drawing 1 A. However it have capacity to draw maximum 6A.

To test it further, I connect it with my 12V 80Ah battery and same result. Not sure why it is doing that.

For further investigation I connect two peltiers (Connecting red wire to red and black wire to wire) by connecting red wire to the postive terminal of the power supply and black to the negative and then I check the current draw and its drawing 3A and then keep decreasing slowly slowly.


texts: Strange drop in voltage on Eneloop AAA-Batteries

texts:
I have a device in my flowerbox where I monitor soil moisture.
The device requires about 3.3 v (it's an Arduino pro mini with an ESP8266).

The device is running on 3 x AAA-batteries (should be 3.6 v)

The device runs a cycle of:

Powering on ESP and Sensor
Collecting sensor data
Transmitting it via WiFi
Powering off ESP and Sensor
Sleeping 20 minutes

It's been running fine for almost 75 hours, then it started continuously restarting.

I measured the voltage of the batteries. They were 2.86 v.
Then I waited 5 minutes, measured the voltage. Now they were 3.1 v.
I thought this problem might be caused by low outside temperature. I stuck the batteries in the fridge for 20 minutes, then tested them.
They were 3.1 v.

So question is: How come the batteries voltage change that much?

Best regards
Frederik


texts:
This picture is from an application note from Microchip about LCDs.
I just disassembled a common 16x02 LCD and I want to identify the components shown in the Microchip's figure with the ones from my LCD. Can you help me to figure out how it works ?

Thank you.


texts:
I want to make a circuit that runs a small DC motor for about 30sec to 1min every one hour.
I guess that a 555 timer won't work.
any ideas ?


texts:
We are considering to have the following stackup for an 8-layer PCB we are designing.

What we want with this stackup is to route the signals with approx. rise time of  3ns on layer 6 using a separation between traces of 8mils between them to get a crosstalk coefficient around -26dB.

Questions:

Is the 3mil spacing between Lyr5&Lyr6 and between Lyr6&Lyr7 common?
Do you guys see any possible electrical or manufacturing problem with this stackup?


texts: Is there a difference in voltage/current between a solar panel with 36 individual cells or one big cell?

texts:
When wiring solar cells in parallel, the current is additive but the voltage remains the same. On the other hand, when wiring solar cells in series the voltage is additive, but the current remains the same.
My question is, what would happen if you had one large solar cell that occupied the space of the entire panel (roughly the size of 36 individual solar cells, or slightly larger if you take into account the extra space that you get from not having individual cells spaced out). Would the voltage and current be roughly that of 36 cells in parallel, in series, or some different number?


texts:
How to connect this http://docdroid.net/ngqg LCD Display to microcontroller? It is ILI9341 based.

Is it possible to connect only SPI/LED pins and leave every other input pin floating or I need to connect every pin(HSYNC, VSYNC etc.) and control them myself.

Thank you!


texts:
I am currently going through an interesting situation where I have two MCUs (Let's call them A and B) in my design. One of the MCUs (A) is always powered on and another MCU(B) is powered through a regulator whose enable pin is controlled by the first MCU. There are many GPIOs connected between these two MCUs. And some peripherals and ADC feedbacks are connected to MCU B.

Now the situation is that I have to put MCU B in power down mode in my application for some time and during that time MCU A will be functioning normally. I checked that if I don't give any power to MCU B then it gets powered up due to GPIOs connected to it. And I am afraid that MCU B can damage the code of MCU A or self-code or other peripherals because it's powered on when it is supposed to be off. The following block diagram explains the situation better:

One possible solution that comes to mind: putting a buffer for all connections of MCU B and powering that buffer IC through MCU B's power pin so it will be disabled and can disconnect the pins when MCU B is off.


texts: Power MOSFET internal diode: when does it conduct?

texts:
So I'm currently studying power MOSFETs and I'm getting a bit confused about when and how it conducts current.

Let's start with the normal MOSFET functioning. I'm considering a n-enhancement type MOSFET.

So, for \$ v_{gs} <0 \$ (or less than the threshold voltage), there is no inversion layer and therefor no channel. The MOSFET does not conduct.
Now for \$ v_{gs} >0 \$ the channel is formed and the MOSFET can conduct through if a positive \$ v_{ds} \$ is applyed. Everything ok until here.

Now my doubt is how the internal diode takes place here. I know why the internal diode existes (shorting the p substract to the n+ terminal through the metalization) but what I don't know is when does it conduct.

For the situation we already checked: \$ v_{gs} >0 \$ and \$ v_{ds} \ >0 \$ it definitely does not conduct since it's a reversed junction (it has just a small parasitic current). The same can be said if \$ v_{gs} <0 \$ and \$ v_{ds} \ >0 $.

But now what if \$ v_{gs} >0 \$ and \$ v_{ds} \ <0 \$. I was told that until \$ v_{ds} \$ reaches a certain negative limit, the conduction still occurs essentially through the inversion layer. Then, after that limit, the conduction is taken by the diode. Is this correct?

And what about when \$ v_{gs} <0 \$ and \$ v_{ds} \ <0 $. In this case there is no channel but the diode is forward biased therefore, will there be a current? Is this why the internal diode is useful? So that the MOSFET can also conduct when there is no channel and therefore, apply it to reversible converters.

I'm a bit confused if someone can clarify me all this situations it would be very helpful.

Thanks in advance!


texts: Converting Watlow 0-24V controller output to 0-10V for a NI fieldpoint data acq

texts:
In order to record the temperature in a vacuum chamber, I have a watlow PM9C1FA-AAAAAAA that outputs a 0-24V signal from a type K thermocouple. The data acquisition system that it is connected to is an older NI fieldpoint that reads a 0-10 volt signal. Naturally as the signal gets above 10V on the watlow the data acq maxes out.

How should I go about converting the 0-24V signal so that my data acq can read it as 0-10V?


texts: Where is the negative connection of an oscilloscope?

texts:
I have found this circuit from http://vector.com/portal/medien/cmc/application_notes/AN-AND-1-106_Basic_CAN_Bit_Timing.pdf

Please can someone explain to me what is the negative connection of the oscilloscope : does it mean the GND ?
Thanks in advance :)

Pss the oscillo is Tektronic MSO 2024B: Mixed signal oscilloscope


texts:
I'm trying to decide on a portable AC power station to power four laptops for at least five hours. I have the charger units for the laptops, and I'm confused on how to figure out the power consumption from them. Mainly, I don't know whether to look at the input power from the AC source or the output power going to the laptop.

Here are the specifications I see on the adapter.

INPUT: 100-240V ~ 3.2A
OUPUT: 19.5V - 10.8A

So I know that the input is AC and the output is DC. And I'm looking at a 500Wh portable power station, like this one.

https://www.amazon.com/Portable-Jackery-Generator-Flashlight-Emergency/dp/B06XJ1SVPW/ref=sr_1_4?ie=UTF8&qid=1530142151&sr=8-4&keywords=500wh+portable

How do I know that 500Wh is enough to power four laptop for five hours? I know that the laptop can consume 19.5V * 10.8A = 210.6W. Or should I be using the input power, which is 110V * 3.2A = 352W?

With those numbers, there seems no way that 500Wh can power four of these laptops for five hours. But the power station claims that it can charge a laptop 7+ times, run a mini fridge 7+ hours, and power a TV and game console for hours.

My question is: Can a laptop really consume that much power under light use?


texts: Idle state in RTOS, sleep state or lowest frequency?

texts: In real time systems using an RTOS, what how would the RTOS handle an idle period? Would it run nop instructions at the lowest frequency supported by a Dynamic Voltage Scaling capable processor? or would it turn to a sleep state? Can anyone refer me to actual practical implementations. Thanks


texts: Unexplained differences in behaviour between U.FL-terminated antenna and SMA-terminated antenna

texts:
I would like your opinions/advice regarding an unexplained observation between a U.FL-terminated antenna and an SMA-terminated antenna. Both antennas are from the same manufacturer and normally tuned to the 868/915 MHz band for IOT / ISM use, the only difference is the connector termination, either U.FL or SMA.

So the measurements made on a custom made radio operating in the 868 MHz band using the U.FL-terminated dipole antenna shows some behaviour that is different from the same antenna but terminated with SMA.

The transmitter RF power is about 500mW and it comprises of regular and continuous 40ms Tx pulses spaced about 100ms apart. The RF power amplifier supply is monitored with a CRO and its nominal at 3.6V. The transmitter board source current is monitored and supplied from a 3A linear power supply.

So when the transmitter is operational with a standard antenna, the source current drain peaks at about 800mA. This comprises of the peak current drawn by the RF PA (a CC1190 from TI) and then the rest of the steady drain by the other circuitry on the prototype.

The U.FL antenna is tested first (with an SMT U.FL connector on the PCB) and the expected peak current of about 800mA is observed. However when the antenna is touched by hand, the current peaks increase to > 1.6 A! The power supply also dips from 3.6V to about 2.1V. When it's released and floating in air, the current returns to the normal 800mA peaks. When touching the antenna and rotating the U.FL termination, the effect seemed to be moving in & out, in an unpredictable way, almost like it could be a connection problem...

Now one would say, sure this is caused by loading of the antenna by an RF absorbing mass or a similar effect, but we are not observing the same effect with the SMA antenna.

So to compare with the SMA antenna, we replaced the U.FL with an SMA edge-mount connector and used an SMA-terminated antenna of the same type. The tests were repeated, hand-on, hand-off and there was no increase in peak current drains as observed before!

So now you know why one's scratching their head. If the "loading" effect would be assumed it should be the same effect for both, no? Well it's NOT the case and we are wondering if there's something else at play, more along the U.FL vs SMA termination, bad cable or connection ?!?

So generally speaking the U.FL-terminated antennas I've seen are for Bluetooth and/or WiFi use, and then perhaps for more recent IOT applications. And SMA have been in use for decades, well known for their reliability!

Has anybody had similar experiences and is/are aware of limitations of the U.FL-style termination, connection issues such as grounding etc. that may case this unexpected behaviour? Sure thing, SMA is well known for being a very robust, threaded, consistent connector termination widely used, but I was not expecting U.FL to cause such apparent problems to do with grounding or bad contacts somewhere...

Any thoughts?


texts: Truncating negative results of Op amp by rail limiting

texts:
I have a signal that will swing from -5v to 5v. I am interested in the 0 to 5v part only. I will set a reference voltage and give it and the signal into a comparator. The comparator's rails are 0, and 5v.

Is the less than 0 part of the signal that is being input into the comparator's non-inverting input going to damage the comparator op amp?

Will it have some strange behavior?

Will it work ok but just take some time to recover? How much time?

I haven't said if it is rail-to-rail...does it matter?


texts: using 8 AA or Ni-MH batteries instead of one 12V 23A type battery to power a remote receiver

texts:
Sorry for the novice question, but I am thinking there should be a simple solution.  I work as a magician and purchased an effect where a snake puppet in a basket goes up and down on a battery powered telescoping linear actuator.  It's operated by a wireless remote.  Here is what I know, the two button remote (up and down buttons) uses a 12V 23A type battery.  The receiver for the remote (in the the snake basket) also uses a 12V 23A type battery.  There is an on/off switch in the basket to turn the remote receiver off.  Here is what I think I know-the motor that drives the snake up and down must be 18V-I am pretty sure it is powered by 2 9V batteries.
The problem is that 12V 23A battery that supplies power to the receiver just doesn't last-even with keeping the switch off, it get through about 2-3 shows, maybe 15 up and down motions and the battery quits-once it drains down to ~11.5V-it's done and that snake ain't moving.  Any ideas on a better solution to power the remote receiver?  Is there a better choice of battery?  There is lots of space in the basket so the small footprint of the 12V 23A battery is not important.  Here is my concern, 8 AA batteries will generate a lot more current than the 12V 23A-will the extra current blow the remote?  Or will a rechargeable 12V 600mA NiMH battery be the most robust option? thanks for any help...


texts: What makes the THR input well defined in this circuit

texts:
In the datasheet for the MIC1555 there is an example of an rising edge detector, see image.
I can't figure out why the THR pin is well defined in that circuit. If there was a resistor, 1M or so, between THR and ground it would make sense. But now it looks floating to me.

[edit]
Would adding a resistor in the M-ohm range between THR and GND cause problems with this circuit? Given that the INPUT capacitor is matched so that a rising edge is actually detected.


texts: Simulating and Building a Multiple Feedback Band-Pass Filter

texts:
I have a distorted signal, and only want to allow frequencies between 95kHz and 105kHz. The input voltage is at 300mV peak to peak.

Thus, I need a Pass Band of 10kHz and a Central Frequency at 100kHz.

I was reading through various analogue electronics books to find out some commonly used variations and topologies and decided to go for the Multiple feedback filter.

I will be using this circuitry:

According to this document:

This circuit is widely used in low Q (<
 20) applications. It allows
some tuning of the resonant frequency, F
0
, by making R2 variable.
Q can be adjusted (with R5) as well, but this also
 change
s   F
0
.

I then proceeded by follwoing the equations on that same document, or else on the book, Op Amp Applications Handbook.

My calculations and working is listed below:

First, we must determine the centre frequency, bandwidth, and Q.

  The Q is too high to use separate high- and low-pass filters, but
  sufficiently low so that a multiple feedback type may be used.

Before actually building this circuit I want to be able to simulate it. Here is my circuit implemented on Proteus software.

And this is the respective frequency response:

It may not be clearly visible, I apologize, but the center frequency is only at 63kHz.

LM324 datasheet.

At 100kHz the max output voltage swing is only 1V peak to peak, and thus I am keeping my gain levels, low. (AV = 2)

I followed the instructions, but clearly I am doing something wrong.

How can I get an actual center frequency of 100kHz, and what am I doing wrong?

Any tips and/or suggestions would be appreciated.


texts: Basic LC Circuit: Oscillator or Resonator?

texts:
Is an LC circuit an oscillator, or resonator? I just want to make sure I'm using the correct terminology. I've been calling it an oscillator, based on the oscillating waveform it generates.

Someone with more experience  told me that what I've been calling an oscillator is actually a resonator. But I'm not convinced that's accurate.

Here's a few different examples from the collection of "oscillator" circuits that I'd drawn up (at least that's what I had them labelled as); that he was referring to:


texts:
I have three temperature probes.
Each probe consists of four sensors (NTC) with a common wire.
The sensors wires are connected together and the common wire for each probe is available:

The wiring can not be modified, it is used on a storage silo for cereals, each sensor on a probe is fixed at a specific depth.
If I try to measure for example NTC11, the equivalent circuit will be:

and the measured value is corrupted by the other resistances in parallel with NTC11.

How can I measure NTC11 without caring about the other values in the system ?

Thank you.


texts: Difference between the VNLD5300 and VNLD5090

texts:
I have been looking for a low-side mosfet driver IC and found these VNLD5300 which is a 300mOhm 2A driver and the VNLD5090 which is a 90mOhm 13A driver. I would like to do one last sanity check, the 5090 seems to be a much more superior IC am i right? But what strikes me is as weird for the same package can the 5090 really handle that current? they are priced very close too so i assumed that ST electronics made these 2 version intentionally with different purposes.
My application is controll and inductive coil at 1.5A both IC fit the application, would going for the 13A 5090 good for me ? What could the reason be that there is a skew with an inferior rating, because i dont think its cost, since they are priced that close.


texts: How long can an LED withstand its rated peak current?

texts:
I am working with several 7 segment displays HDSP-F103. According to the datasheet, each segment has a peak current of 45 mA, but it doesn't specify for how long in time or in PWM duty cycle.

It does mention 'average power' (37 mW). So I wonder if it's OK to use this parameter to work out the peak current time. It that case, I calculated the limit of 45 mA at 44.4 % of duty. Based on this, I assume safe to run the segments at 40 mA, 20%, which is my desired configuration.

Do you find any problem with this?
Thanks.

Datasheet: https://4donline.ihs.com/images/VipMasterIC/IC/HEWP/HEWPS00892/HEWPS00892-1.pdf?hkey=EF798316E3902B6ED9A73243A3159BB0


texts: How to convert the Voltage source into a Current source

texts:
I'm confused about how to convert the voltage source into a current source so that I can derive a NAM equation.
I've looked around for help but most of it tended to be of simple examples where the voltage source was directly in series with a resistor.

Any help is appreciated.
Thanks :)


texts:
Im trying to read data from ADC with ADC Inteface Im designing with FPGA.

The data that coming out from the ADC is offset binary with 12 bits.. looks like that:

I want to simulate this results using Matlab for example to see if i getting back the Sine wave with the same frequency as in the input.
Any idead how I can do it? I didnt find any matlab code when I searched the internet. How would you check the results and compare to the analog sine in the input?


texts: Can anyone identify this power connector?

texts:
I'm looking to find the name of this type of connector:

The picture above is from a power adapter I have and provides 10v (not that that matters). If you can't tell from the image, it's basically a rectangle connector with a semi-circle notch taken out of the top-middle so you can't get the polarity wrong.

The rectangle is 13mm x 7mm.


texts:
How would I make a switch that is controlled electronically, and has a ten second delay?

I have a circuit that will output either 3.3V or 0V. I would like to make a circuit that detects 3.3V, waits ten seconds, then closes a switch. The switch should remain closed even if the 3.3V drops back to 0V, possibly requiring manual reset.

Is this easily achievable?


texts: For my certain 240v circuit. I want to know if there is a 2 prong pluggable tester where it can detect if one of the leg of the 240v is grounded or not. Assuming the outlet is only 2 wire. Can one detect whether the 240v is like in Europe where the neutral is one of the two hot legs. Or like in USA where the two hot wire 240v is floating and only the centertap is grounded or the neutral?


texts: Do we ever use the pin capacitance of a digital circuit component (e.g ASIC, FPGA) in doing timing or data integrity analysis

texts:
As far as I understand, the pin capacitance on say an ASIC or FPGA effects the rise and fall time of the signal on it. It is also possible that the impedance offered by this capacitance to a very high speed signal creates an apparent mismatch with the PCB trace impedance and cause reflection. However, as of yet, I have not heard of the pin capacitance being used in any type of analysis.

I understand that the pin capacitance is not needed in timing analysis. When is it ever used?


texts: Can you use 'Rubber,' Specifically Liquid Electrical Tape Between The Plates of a DIY Capacitor

texts:
The above is pretty much all there is to the question. By "can you," I mean will it be properly effective / are there any tips? If not, why? It seems that this ought to work, but I can't find info online.
Thanks.


texts:
I am currently studying the Bode-Fano criterium and how it can be used to design wideband amplifiers.
It's stated that a low load Q-factor (high resistive component with respect to the imaginary one) leads to a lower achievable reflection coefficient.
Taking a look at the criterium for a parallel RC load:
$$\left\lvert\int_0^\infty\ln\frac{1}{\left\lvert\Gamma(\omega)\right\rvert} d\omega\lt\frac{\pi}{RC}\right\rvert$$
I don't understand how, from this equation, does it follow that the minimum reflection coefficient can be achieved only in the presence of a low-Q load. (So, I consider high R and low C.)
Thanks for the help.


texts: Approximation when deriving buck closed loop transfer function

texts:
Can anyone explain why \$\frac{\Delta V_x}{\Delta D} = V_{in}\$ here?   It seems to me that they are assuming that \$V_x = V_o\$ ( this is only correct for average voltage).  However, if they use the assumption \$V_x = V_o\$ for average, then later in LC transfer function, they also should use this assumption to get  \$\frac{\Delta V_o}{\Delta V_x} = 1\$. But from the transfer function of LC filter, we can see that they don't use that assumption.

I am really confused about this. It is not clear when we can use approximation and when not.


texts: EAGLE - Suddenly getting errors about "objects extend outside board space"

texts:
Eagle 9.6.2 Standard License
Windows 10 64 bit.
Very strange.  Suddenly I'm getting an error whenever I try to place components in any quadrant but quadrant 1.  I am dead in the middle of a project where I have all my boards centered on my origin (my preference).  I had not problem constructing these boards placing components wherever I needed.
Just an hour ago, I open Eagle and suddenly I can ONLY place components in the positive/positive quadrant and I can't even edit my previously built boards.
My Standard eagle license seems to be in good order and my file name says "Eagle Standard" in it, so I don't think I reverted  to the free version in any way.  I'm totally stumped.


texts: Powering Arduino and stepper motor from a single 12 V power supply

texts:
I am trying to control mechanism involving a nema 17 stepper motor. I use an A4988 stepper driver and an Arduino Nano both powered by the same 12 V/3A power supply. So far I have fried or crippled 4 Arduinos along with an A4988 or two. I have tried to sketch the connections. The potentiometer tracks the position of the mechanism that is actuated by the stepper motor.
Initially I suspected my poorly soldered wiring (probably partially rightfully) but I have since done the wiring using prototype PCBs and checked for short circuiting quite thoroughly - and this set-up actually worked for some minutes and then stopped. It is some while ago so I am not exactly sure, but I believe that at the time of the latest failure, the connection between the potentiometer and motor snapped resulting in quick motion of the potentiometer by a spring.
Some of the Arduinos are completely bricked but the last one seems to work, only the 5V pin outputs 4V indicating that the voltage regulator is damaged. Before I keep on frying Arduinos I hope someone more experienced could offer some pointers. These are the things I have suspected:

the arduino, the A4988 and a slide potentiometer are all connected to the same ground. Could the motor induce a current back through ground that could fry the Arduino?
the potentiometer is 1kOhm and as far as I can tell this should be a bit low but ok currentwise. I have bought a 1 MOhm potentiometer to replace it but have not powered the circuit yet.
I assume that the potentiometer cannot induce any current even if it is moved quickly?
I have seen several examples where a capacitor is connected between 12V and ground and intend to add this. Could that somehow explain the faulty behaviour?
Is it a problem to power the motor and the Arduino from the same power source (which should be able to supply the required current)? Implicitly the power source also powers the A4988 logic voltage via the Arduino voltage regulator
I have checked the circuit for short circuits quite thoroughly while powered off, but am I correct to assume that powered on the circuits wont expand and create shorts?
anything else?

Eventually I will try the greater resistance and the capacitor but I hope with your help to spare any unnecessary Arduino casualties and get a generally robust result. Any help is much appreciated - thanks in advance


texts: Connecting the instrument to two different power supplies

texts:
I am very new to electrical engineering and this is my first project on it, so any help would be really great:)

I am currently trying to power an instrument, which consists of:

1) Two LEDs

2) Two Peltier elements on each side

3) Two fans to remove the heat from the Peltier elements

Here is how it currently works and how I want it to work.

How it works:

Power supply for Peltier element, fan and LED is connected with +ive and -ive wires (red and black); the remote on/off for LED lamp is connected via one +ive wire (green). So for each group (a group of 1 fan, 1 Peltier and 1 LED) there are red, black and green (2 +ive, 1 -ive) wires.
When supplied to external power supply (24VDC) on the red & black wires, the Peltiers and the fans turn on immediately. If the green(+ive) wire is connected to the same power supply on the positive side, the LED lights turn on.

How I want it to work:

I want to connect the remote on/off (green wires) to a different power supply, but I want to keep the red & black wires connected onto the same power supply as before (because I want to be able to turn on/off the LEDs, while Peltiers and fans would work all the time.
The new power supply or remote on/off provides 23.11VDC. I connect it with BNC connector and on the other end I connect it to remote on/off connector only with the +ive wire (which also might be the reason for a problem?).

What is not working:

When I connect the green +ive wires to a different power supply, the LEDs do not turn on.

I assume that the problem is that the green +ive wires are not anymore connected to the same ground, after I change power supply for remote on/off connector. I haven't made the instrument myself and I cannot disassemble it, so I don't know how the fans, Peltiers and LEDs are wired there together inside.


texts: Why is the magnetic field around a bar magnet represented by iron filings?

texts:
Why would we use iron filings to display a magnetic field interaction and then teach this as the unaffected field of a magnet?

Iron affects the field itself. This is analogous to an observer affecting a quantum event through observation.

Magnetic mappers that contain iron anywhere near the proximity of the target to be measured are inherently outputting false field information.

Where are the true examples of unaffected fields? Could they really be different than what we have been taught?


texts:
I have a synchronous buck converter and my inductor current looks like this:-

To add voltage-mode closed loop control, I need to do the small signal modelling of the converter. I am a bit confused if this would be called DCM (I think not as in DCM the current would have to be zero for some time not negligibly small.)

I know how to do the CCM, DCM small signal modelling in a buck converter, but I am having trouble writing the equations during the dead-time. So far, I have only got the equations for the times when either one of the switches are ON. I need help with the dead-time part.

Thank you!


texts: Protecting ADC pin from the opamp output

texts:
i am working on a design circuit and i have to measure the current going through the loads so i put shunt resistor 0.1ohms and from the terminals of that resistor to an instrumental opamp, then to ADC pin in microcontroller, my question is can i put a mosfet transistor and switch on/off the opamp supply voltage when i don't want it to protect the ADC pin of the microcontroller (is it of to the opamp or its going to be broken?)or can i put a zener diode?

i want to protect the ADC pin from the un expected voltages, i am suppling the circuit by 12v and the microcontrollers is 5v max
thanks in advance, and feel free to say your opinion or any advice

updated graph


texts: High voltage power lines: helicoptor versus birds

texts:
As can be seen in this video, bringing a maintenance helicopter to the same potential as the high voltage power line is not without some arcing.

Why doesn't that happen to birds?


texts:
I have three i2c devices connected to AVR microcontroller. On the i2c bus on master side there are two pull ups with 2k7 ohm.
What im experiencing is that when i power up the microcontroller devices cannot "drop the line"/initialize. After reseting the uC, everything is ok. On the startup routine of uC there are some initializations that takes around 100ms.
Could this be because of pull-up values or should i wait for more time for initialization ?

UPDATE: Internal pull-up is disabled. Using pull-up for each line.


texts: Why are my p-channel mosfets cutting off in LTSpice even though Vgs is negative?

texts:
I'm running into a weird bug. Part of me thinks that it's LTSpice that's wrong, but that seems unlikely. I'm working on the circuit below, to be able to switch between feeding my voltage regulator from two different sources.

When I run this in my sim software (LTSpice), I see that VSources is 2.2V, but RegIn (the output of my two PMOS transistors) is ~50mV. This is with power source 1 (coming in from the top) floating, and power source 2 (coming in from the bottom right) at 3.3V. The GND at the very bottom is to simulate pulling a GPIO pin low to "open" the mosfet gates.

So I have Vgs = -2.2V, but the gates still appear to be closed. At first I thought that this was because of a high Vth on the mosfets, but I tested another pmos by isolating it and trying different voltage values on the Source input while pulling Gate low and probing Drain, and even Vgs values as low as 1V opened the gate enough to let voltage through to the drain.

So my core question: why are my pmos gates not opening even though Vgs=-2.2?


texts:
I have a 12VDC automotive relay controlled by an open-collector NPN output on a remote device. I would like to be able to have an indication of when the relay is activated. I tried (and failed) the following:

12V buzzer in series with the relay - sound indication OK but relay is not being activated.
12V buzzer in parallel with the relay - open-collector does cut-off, sound and relay are activated continuously (this is weird). Once the buzzer is disconnected, the open-collector will cut-off in a couple of seconds.
12V LED in series with the relay - visual indication weak (compared to regular led light), relay is not being activated.
12V LED in parallel with the relay - visual indication OK, relay activated/deactivated OK, LED dead after one run (I suspect due to relay not having a suppression diode).

How can I have an indication of the relay's state? I would prefer to use the control information, not the relay output.


texts: Circuit analysis on very complex circuit

texts:
I am studying circuit analysis.
Problems contain only 5-6 components. I wonder how can we analyse very complex circuit like a radio reciever which has 30-40 components or some circuit like that. Do I need to solve 30-40 unknown variable from equations (node,mesh analysis,) or there are other means?
Can I break circuits down into smaller modules and analyse each of them?


texts: Conversion error in STM32 MIPI-DSI app note?

texts:
I'm trying to teach myself about the MIPI-DSI interface on STM32 F4 MCUs and came across this graphic and accompanying description:

As I understand it, the data being transferred is actually 0x94 and 0x0E, and the person writing the document just goofed on their conversion. Just double checking in case. This is only one of many issues I've found in this document, so I wouldn't be surprised if it's wrong. STM really needs to get some editors.


texts:
I replaced the cells on my Laptop unfortunately disconnected BMS while doing so.
HP battery check says each cell voltage and Temp correctly and calibration warning but can't calibrate as no terminal voltage. already tried the resistor method but in vain.
the charging indicator goes orange for 8 sec then white. windows shows 0% plugged in. left it overnight but nothing happened. didn't charge.
battery is OA04 4 cells couldn't read BMS IC etched markings they're not clear to read.
Already tried some I2C codes but they showed wrong data.
battery pin out (1 +,2 +,3 SMBus Data,4 SMBus Clock,5 BatID,6 TEMP,7 -,8 -)
https://pinoutguide.com/Power/HP_envy-pavilion_dv6_pinout.shtml
Help
edit: Hp uses two bms one in battery the other on the board. It activates the battery through codes not high or low signal that's why jumpering power didn't work. Bms is working though I can read battery data and voltage but it's locked because it sees capacity below 25% or that's what I think.
2: it charged for a minute then the indicator blinks whitewhen I insulated SMData as in here https://h30434.www3.hp.com/t5/Notebooks-Archive-Read-Only/HP-Battery-Alert/m-p/2597653/highlight/true#M348632


texts: lm2596 fixed 5 volts(usb) from 12v 10W solar panel

texts:
I have got a 10 Watt solar panel & a 10000 mha Battery bank. I plan to use the panel to charge the battery bank.

I have a LM2596(variable configuration with pot), I plan to use it to charge my battery bank /Other device directly from the 10W Solar panel.

I have 2 Questions:

Q1 . If I remove the Pot and short the feedback with load (as suggested in the Datasheet), will it give me fixed 5v Output irrespective of the varying voltages of the Solar Panel throughout the day?

Q2 . The Datasheet suggests for fixed output of 5V the Max input voltage is 12V . the Max output of the Solar panel is 17 V so without fiddling with the circuit much, can this be done ?


texts:
I bought this 1 channel relay module but the board doesn't have any marking on it. Can someone tell me which pins are power, ground, relay on/off signal etc?

Photograph of module:

edit: traces


texts: DC Powered Microcontroller Damaged by Simultaneous Two Power Sources?

texts:
I have a Nordic microcontroller PCB that seems to have a random death syndrome which we think is due to a bad layout or some other design issue.

We were running some tests on the unit and accidentally supplied nominal 3.7V from a LiPo cell plus a nominal 3.7V from a USB powered converter.  The unit was fine for 1 day, and then the 2nd day it would not start again.

This seems like our random death syndrome, BUT -- we accidentally did apply two power sources, and I'm wondering if that could be a factor?

Is it possible that simultaneously DC voltages from the LiPo Cell plus the USB powered converter could damage a microcontroller?  Both sources were nominally the correct voltage but just applied accidentally at the same time.

Say perhaps the voltages are a little different at one given time?


texts: Is there a correspondence between cache size and access latency?

texts: Is there is a correspondence between cache sizes and access latency? All other things being equal, does a larger cache operate slower? If so, why? How much slower?


texts: Are there a way to join 2 I/O control lines using staircase two ways switches approach?

texts:
I am a newbie and would like to have a question and would like to have your advice.
Requirements: Control 1 relay (max current is 20mA) over 1 Arduino pin (pinMode as OUTPUT and state of this pin is controlled by the program over Wifi connection) with an additional touch button (TTTP223 module configured with jumper A opened, B connected so that upon touched, the module will locks at maintaining HIGH on I/O pin and upon touching again the I/O pin will maintain LOW on I/O pin). The TTTP223 module is not allowed to use another pin on Arduino or any pin extender board (like PCF8574 I2C).

When I/O pin of the TTTP223 module is HIGH the voltage rate is 4.2V and drop to 0 in LOW state.
Arduino output pin is 4.9V at HIGH and -0.6 V at LOW state.

With this requirement, the model will be similar to the use of 2 two-way switches to control stair case lamp (turning Switch 1,2 on/off will toggle the lamp state independently). A sample of circuit is here
I am thinking of using a mechanism to detect change state on each of the inputs (Input 1 by Arduino and Input 2 by the TTTP223 module) to toggle state of the output. With some searches over the internet, I found Flip/flop and SR latching (and might be the H-Bridge also with the use of a H11AA opto-isolator) circuits that seemingly be of help.
Please advice me with thanks. I hope my explanation is clearer for now. Please be sorry if I would make you be confused (my English is not very good).
Thank you very much for your attention!
It seems that the TS5A3157 can handle well my requirement!

. This applied the approach of two-way switches for stair-case lamp.


texts: How do I remove the excess wires from this 2/3 way lighting switch?

texts:
I have two sets of lights in my bedroom. There are also two light switches. One double light switch is by one door, and turns both sets of lights on or off (one switch does one set, one does the other).

There is also another light switch near the bed - this is a single light switch. It turns on and off one of the sets of lights regardless of how the double switches are set. I gather that this is either a 2-way (UK, where I am) or a 3-way (US) lighting system.

I am going to be replacing the double switch near the door with some relays so that I can control them over the internet. I don't really use the other switch, and I want to do away with it for simplicity's sake. There are pictures of the light switch and a rather crude diagram of what it looks like from the back attached. Which one of those wires is dispensable?

Bonus points if anyone can provide a schematic for this kind of set-up. I'd like to know how it works.


texts:
I am driving a DC motor with H-Bridge Mosfet using PWM.
The problem is I don't know exactly which frequency should I use.

1- Do the DC Motors have a very specific frequency for their best performance at all or they have a range of the frequencies they are able to work with?

2- What happen if I work with a DC Motor with Higher or Lower frequency that it can work with? Am I damaging that?
(Because I have done that and with higher frequency my Motor make a strange noise like zzzz and with lower frequency it is shaking)


texts:
I have a system (car simulator) which is powered by a 220Vac 60Hz. Within the system there are 6 switched sources, 4 of 24 Vdc, 1 of 12Vdc and 1 of 5Vcd. Loads 1,2 and 3 are dc motors 24vcd. Loads 4,5 and 6 are other peripherals of the system. The GND of all switched sources are on. Some problems listed below are happening.

• Sometimes I hit some metal part of the system (simulator) and I take a small shock.
• When one of the motors requires the current close to the source capacity, the system starts to fail.

I wonder if the system below has the correct links. Should I put some kind of filter on the system road or in the engines?

simulate this circuit – Schematic created using CircuitLab


texts: How do electrical body fat detector work?

texts:
I would like to build me own electrical body fact calculator from a microcontroller (the Arduino), but I would like to know how does it work. I have a 5V analog reader, So I guess I sould calculate the current passing through my skin compared to a 0 body fat skin resistance?

Is that it?

Thank you


texts:
"Consider as an example a typical computer of that era which might have had a 16 bit address field in its instructions and 4096 words of memory.A program on this computer could address 65536 words of memory."

I don't understand some of the terms. What is meant by "16 bit address field" , "words of memory" . And what does "4096" denote ?

I don't get the feel of what the author is saying.Please explain the whole sentence.


texts:
I am trying to build the following circuit that works as a solar power charging controller.
Unfortunately, I couldn't find IC1 named as TLC2272CP that works as dual low-noise rail-to- rail operational amplifier exhibits rail-to-rail output IC.

Can anyone help me rebuild this circuit design in order to replace it or is their a cheap replacement for it?


texts: Schematic review LiPo charge load sharing with booster

texts:
I'm converting one of my old projects to instead of using non rechargables, to use LiPo batteries. To save space, I'm only using a single cell, and don't have room for a pre baked solution to handle the battery.

I need to be able to use the unit, while charging. For that, I followed the guidance found here, using the MCP73831.

For this project, I have to power a LCD display, which uses a nominal voltage of 5v, so I have to boost the voltage. For that, I used a the LiPower unit as a guide, found here. That uses the TPS61200 for the controller.

I have never designed a LiPo charging unit, let alone one that has to boost the voltage. If you could take a look at my schematic and make sure nothing is messed up I would really appreciate it.

I am using "CR-AA" as the LiPo (Will change to proper symbol when finished)

I try not to ask such a broad question, but i'm nervous about this, since there's a lot to go wrong when using a LiPo.


texts:
Hi all, I was looking for a simple splitter that replicates a line output into multiple of them, looking for the best circuit that meet my requriments I meet the user @Passerby, He had to share that schematic but I keep my mind with some doubts.

Is that circuit designed for line levels? My mean is for the input and the pull-down resistors on the output, while the line output impedance is about 300-600 ohms, those one are in parallel @5.1k, so they'll affect the output at all?

Is there any consideration to make the circuit smoother for a RCA-line based system? Ill use this circuit for a mixer!

Hope u help me to analyze that circuit, i understand that the first opamp defines the input of the circuit (didn't understand that config at all, Ill need to do some research) and that out gives the input for the buffers, a decoupling cap and the impedance set that also works as a filter (Cut-off frequency
fc = 5.4748862432713[Hz]) for ULF.

Do I need something extra to adap that circuit for NE5532?

Cheers!


texts:
As a part of my curriculum, I am required to implement a project on FPGA. However, even the cheapest available boards are out of my reach (blame currency conversion !) and besides, even if I buy one, it would be lying useless thereafter.

So I wish to know whether I can simulate a real FPGA to get an 'all virtual solution' ? If yes, do mention some softwares for the same.

In other words, I should be able to write verilog or systemVerilog code in some software, verify and test the code, and finally upload the code. Then I should be able to do all the stuff which I would normally do on a real FPGA like interfacing displays, keyboards etc. and verify that my design does work on real boards. Just this time, it would be within a simulation environment, much like we have simulators like MultiSim and Tina, where we can simulate hardware.

If we cannot, is there some other way by which I could possibly build FPGA design without having a real FPGA ?


texts: How does a hobby ESC drive a BLDC motor?

texts:
Background: I'm an aerospace engineer modeling the electrical systems of a standard quadcopter. I came across a lot of technically-inadequate or incorrect material while researching the humble yet technically-rich electronic speed controller (ESC), so I thought I'd collect my newfound knowledge for posterity and further corrections by the community.

Thank you, Bruce Abbott, for your clear explanations. I hope I didn't misunderstand them!

Questions:

How does a hobby aircraft ESC drive a BLDC motor? Does it use PWM?
How does the ESC measure back-EMF to calculate speed?


texts: What is an "XY" rated safety capacitor, exactly?

texts:
Please help me understand this. In a prominent, 480v, 6kW AC servo drive, across three input phases, three 22mm "XY" class 10nF caps are placed for EMI suppression. Also, from these three phases, three of the exact same "XY" caps go to chassis ground:

simulate this circuit – Schematic created using CircuitLab

Now it is my understanding that "X" rated caps are designed to fail shorted to take out a fuse. So "X" should be used in the phases. And "Y" rated caps are designed to fail open so as to not electrocute anybody.  So "Y" should be used from the phases to ground.  Obviously, we cannot be doing both here... so what is an "XY" rated safety capacitor, exactly?

The usage of 400/500v-rated safety caps on a 480v bus:


texts:
Say you have some B field from an alternating current, B(t)=B0cosωt. And using Faradays law, e.m.f. ε = turns of a coil × the time derivative of the flux of the B field going through the coil area.
\$\epsilon = -N B \frac{d\psi}{dt}  \$
If my B(t) max has a amplitude of 0.0005 T and a frequency of 500,000 kHz, then does the derivative of B(t) have a 1000000π constant pop out front? This seems wrong, like you can make the ε voltage really high just from the frequency?
What if your B field has a frequency in the Giga hertz range and impedance was knocked out with some capacitors? Then ε would have some 10^9 coefficient out front?
I feel like I'm missing something simple, Thank you


texts: voltage drop calculations single phase ac

texts:
In voltage drop calculations, in one of the methods in case of single phase ac, the formula is given as follows

As you can see, R is resistance per unit length multiplied by length by current and then by 2. Why the 2? Now the reasoning they give us for this, is that the current returns through the neutral, so the length of the path is of both the live and neutral wire.
This makes zero sense to me. To my understanding, and according to this answer to a different question on here :
https://electronics.stackexchange.com/a/38694/218615
To quote : "The voltage is a difference between the electric potentials of two conductors. Hence, to change voltage, only one of the potentials has to change (although both can). In AC power only one of the wires (live/phase) changes it's potential, while the potential of the other one (neutral) remains constant."......"in properly constructed power network the neutral wire is maintained at a potential level close to ground potential, there is nearly no voltage between the neutral and the ground. Hence, touching neutral will not cause current to flow through human body into ground."
End quote.
So according to this quote, and what I understand, the voltage drop would be the difference in potential between point A on the wire and point B relative to the neutral wire which is almost always zero or the reference. Here's an illustration:

Say this is a 220 volts ac single phase source. Voltage at A is say 220, which means Voltage at A compared to neutral is 220. And when current flows from A to B , a voltage drop occurs due to wire resistance so voltage at B relative to neutral is say 218 and not 220. And so the voltage drop would be 2 volts. Is my understanding incorrect? What does the neutral have to do with the voltage drop? Why do I multiply by 2? I feel there is a basic pivotal thing I am missing here. Any help is appreciated. Thx


texts: Proximity of a DC / DC converter and operational amplifier

texts:
There is an operational amplifier LM258WYDT, which outputs a signal with a frequency of 1 kHz. It is powered by an TMR1222 isolated DC/DC converter, which produces +12/-12V.

For example, the DC/DC converter is located at the upper level of the board, and the operational amplifier is at the lower level. Between them is a ground polygon.

How is this arrangement in terms of noise? Can a DC/DC converter affect the operation of an operational amplifier?

Thanks!


texts: Obtaining constant mechanical energy from a DC Machine

texts:
Out of the five types of dc machines:

Separately excited
shunt dc motor
permanent-magnet dc motor
series dc motor
compounded dc motor

which one will be the best for obtaining constant mechanical energy?


texts: Loading fine-tuned MobileNetV3 ConvNet in STM32CubeAI

texts:
I loaded my mobilenetv3 model in STM32CubeAI but when I tried to choose the compression ratio of 4 and 8 to reduce size, the RAM and FLASH requirements are still the same.
Also, I optimized my model in tensorflow lite which results in ~2MB, but when I load it into STM32CubeAI, it still reads the original size which is 6MB?
Please help.


texts: Impedance and resonant frequency derivation

texts:
Afternoon, could anyone help how to derive impedance (real{Z}+Im{Z}) and derive resonant frequency from this circuit?

I tried frequency derivation from admitance, but I'm not sure it's OK.

Resonant frequency:


texts: Is the TP4056 for lithium polymer or lithium ion batteries?


texts: Powerbanks with multiple ports rated at different Amperage: technical difference?

texts:
My SBS TTCB100002UF powerbank, which charges with 10 W of input power,  has two USB ports rated at different outputs: 2.1 A and 1.0 A for output.

The 1.0 A-labelled port also delivered 2 A, just like the 2.1 A port. It could have probably delivered 3 A too, but I have no device that charges 5 V at 3 A.

Now, what is the possible difference between these ports?
Is it about priority on simultaneous usage?


texts: Minority carrier current in p-n junction diode

texts: Does minority carrier current flow through p-n junction even in the absence of any external applied voltage?Is minority carrier current same as reverse saturation current?


texts: Measuring Boltzmann constant using thermal noise

texts:
For my physics lab I have to come up with a way to measure Boltzmann constant using thermal noise.

The circuit that I 'm going to use is something like the one in the figure below:

Than I'm going to attach an arduino UNO board to the output and measure the \$\Delta V\$, using a sampling rate of \$50\$KHz, and by computing the st.deviation, get a value for \$k_b\$.

I've some question about this setup:

Is the LF 355 a good op-amp candidate for my experiment? Considering that the thermal noise input will be very weak and thus very close to the GND value is it better to use a RRIO op-amp?
Is the sampling rate of Arduino enough to see a consistent variation of the \$\Delta V\$? Does the fact that the board can measure only positive difference of potential will alter the calculation of the st.deviation?


texts: switching off 555 timer with trigger button

texts: I am new to working on 555 timer. I am running it in monostable mode. I am triggering it using a button on trigger pin. It works just fine. What I want is the LED connected to the out pin 3 to switch off when I press the trigger button again. If I don't press the button, LED will switch off after the specified time duration by the RC circuit. Is it possible? Thanks in advance. :)


texts: how to choose the transistor for following case?

texts:
I planned to use the following circuit to run unipolar motor.  I got this circuit by surfing internet.  I know how to choose the transistor for driver circuit by knowing the base current, but in this case i dont have idea about current out put of my 4013 ic .

I am going to use 12V and 1A power supply to run motor.

please give me suitable transistor(BC547) and resistor(1k) to replace in that circuit

And instead of Dpdt switch  i would like to use transistor to switch the direction so that i can send digital signal to change the direction of rotation

plase give me an idea, how we can achieve this

Stepper motor

Rated voltage 12V

Rated current 1A

Winding resistance 50 ohms

Winding resistance between center-tap and end coil 25 ohms


texts: Building a DIY projector. LED driver voltage output 24-36V, 100 watt LED voltage 32-38V. The LED driver is short 2 volts, would this matter much?

texts:
I'm in the process of putting all these pieces together to build a DIY projector.

Lens
LCD+Board
Fresnel
Condenser lens
LED

The only part I'm missing in this build is a compatible power supply unit for North America.

I found this led power supply, but it is short 2 volts on the maximum voltage rating.

Would this work well with this setup? I need to power the LED and the wattage is suitable as well the voltage for the most part but the maximum is short 2 volts at only 36 volts when the maximum on the led is 38.

Does this matter much?

I'd like to power the fans from this as well.


texts: Mains AC overvoltage protection using a TRIAC

texts:
I am trying to design a circuit that protects 127V appliances if plugged in a 220V socket (in Brazil 127 and 220V sockets have the same shape and it's easy to plug a 127V appliances in a 220V socket by mistake).

The circuit should be self-resetting without intervention so a standard crowbar is not ideal because of the fuse which must be replaced. The appliance is fairly high power (1200W) so I couldn't find a resettable fuse that can handle the voltage and current. I came up with the following circuit, which is supposed to turn on the TRIAC when the supply voltage is 127V and turn it off when the voltage is 220V. R2 represents the protected appliance:

My idea is that when 127V is applied, there will be around 3.35V at the output of the LM7805 and the transistor remains "off". Then the gate of the TRIAC is connected to the output of the 7805, which I hope would cause it to trigger. If, however, 220V is applied, the 7805 will output its full 5 volts. This will turn on the transistor, which in turn will pull the gate of the TRIAC to 0V and thus will prevent it from triggering. However, when I try to simulate it in Multisim, the TRIAC remains off no matter what the input voltage is. I think the transistor switches on and off properly though.

I must be missing something significant, but I can't figure out what. I hope someone can point out where my mistake is, or if this circuit makes any sense at all. I am open to all suggestions, including for completely different designs.

Thank you all in advance.


texts:
I want to use Hc-05 bluetooth module with my pic32 controller for communicating with other bluetooth devices. I want to test the hc-05 module with my pic32 controller. I have made the hardware connections but I don't know about the code I have written a simple code to test the module.

But it is not working. The module is not responding to my AT commands. I don't know whether my code is correct or wrong. I will post my code here. Can anyone please help me?

#include <plib.h>
#include <p32xxxx.h>
/* Standard includes. */
#include <stdio.h>

#include "../hdr/Hardware_config.h"
#include "../hdr/commands.h"

#define BLT_BUF_SIZE  512

int BLT();
int i,j;
int ptr = 0;

byte BLT_BUF[BLT_BUF_SIZE];
int BLT_ptr;
char rchar;

void Serial_init()
{
  UARTConfigure(UART2, UART_ENABLE_PINS_TX_RX_ONLY);
  UARTSetLineControl(UART2, UART_DATA_SIZE_8_BITS | UART_PARITY_NONE | UART_STOP_BITS_1);
  UARTSetDataRate(UART2, GetPeripheralClock(), 9600);//57600);//);//57600);
  UARTEnable(UART2, UART_ENABLE_FLAGS(UART_PERIPHERAL | UART_RX | UART_TX));

  SetPriorityIntU2(UART_INT_PR1);
  EnableIntU2RX;

  INTEnableSystemMultiVectoredInt();
}

void __ISR(_UART_2_VECTOR, ipl2) IntUart2Handler(void)
{
  IFS1bits.U2RXIF = 0;
  while( DataRdyUART2())
  {
    BLT_BUF[ptr++] =  ReadUART2();
  }

  // We don't care about TX interrupt
  if ( INTGetFlag(INT_SOURCE_UART_TX(UART2)) )
  {
    INTClearFlag(INT_SOURCE_UART_TX(UART2));
  }
}

void main()
{
  SYSTEMConfig(GetSystemClock(), SYS_CFG_WAIT_STATES | SYS_CFG_PCACHE);
  SYSTEMConfigPerformance(GetSystemClock());
  DDPCONbits.JTAGEN=0;

  Serial_init();

  while(1)
  {
    BLT();
  }

}

int BLT()
{
  RESET:

  memset(BLT_BUF,0,sizeof(BLT_BUF));  //BLT_ptr=0;
  putsUART2("AT\r\n");
  for(i=0;i<1000;i++)
    for(j=0;j<2000;j++);

  if(!strstr(BLT_BUF,"OK"))
  {
    dly_sec(2);
    goto RESET;
  }
  memset(BLT_BUF,0,sizeof(BLT_BUF));BLT_ptr=0;
  putsUART2("AT+ROLE=1\r\n");
  for(i=0;i<1000;i++)
    for(j=0;j<2000;j++);
  if(!strstr(BLT_BUF,"OK"));
}

Thanks & Regards
M.Sivakumar


texts: Confusion interpreting an amplifier module's cut off frequency from its datasheet

texts:
In an amplifier module's data-sheet the section about the filter switch is given as:

The mechanical switch sets the amplifier to 10hz or 6kHz LP filter setting.

I have the following questions:

1-) What does "change-over" mean here?

2-) Normally cut off is defined for 3dB point which means at cut off the outpout power is halve the input power. Here what does -1dB mean?


texts:
A continuation of this project, that I hoped would be done and working by now.
The problem this time appears to be that the circuit is too slow.  The desaturation/grayscale and attenuation seem to work as expected, but the picture is blurred to the right of where it's supposed to be by a few pixels, and looks about as I would expect from an exponential decay.  So something clearly isn't fast enough.
(I haven't tried to invert the colors yet, since that involves a lot of coding, testing, debugging, etc. to get the timing right, so that it only inverts during the visible part and not the porches.  I'd rather not do that until I get a clear non-inverted picture.  Otherwise, the microcontroller is just a glorified shift register that produces DC control signals.)
Here's the current schematic:

And the board:
Top:

without silkscreen:

HiMid:

LoMid:

Bottom:

with silkscreen:

And the datasheets:
OpAmp (U2,3)
Video Switch (U4)
Analog Switch (U1,5,6,7)
Microcontroller (U8)
I thought that everything had enough bandwidth for 1920 x 1080 x 60Hz (~62MHz), but I'm still getting the smearing.
Also, switching the LumMode signal (input to U1B towards the top left of the schematic) affects the output too, when the video switch (U4) is using that signal.  Selecting pin 9 of U1B results in more smearing than pin 7 does.  Am I dealing with some parasitic capacitance here?

Update:
In response to @JonathanS.'s comment on May 14, '21, here's a tentative solution.  I would make it a comment, but I can't put the new schematic in it.
Changes:

Reduced the desaturation resistors (R10,11,12,27,28,29,44,45,46) to give the grayscale buffer (U2D) only a small but present margin of output current in the theoretical worst case.
Reduced the luminance mixing resistors (R1,2,3,5,6,7) to use most of the remaining margin of the input buffers (U2B,A,C), and balanced the two selections for roughly the same impedance looking upstream from the switch (U1B).
Reduced the inversion resistors (R8,9,18,25,26,35,42,43,52) and increased the ballast resistors (R20,37,54) considering both the desaturation buffer's (U4A,B,C) and the inversion switch's (U1D,A,C) maximum current.
The desaturation buffer now sees 470R when not inverting, and ~41.5R when inverting, which is a bit lower than the 150R - 500R that it's meant for but still within the maximum output current of 50mA.
Reduced the sync pull-up resistors (R60,61), considering the NFETs' (Q1,2 - datasheet) saturation current at 3.3Vgs.
Originally intended for 5V sync's, but my 'scope measured 3.3V from an HDMI->VGA converter???  Anyway, it still works.

The silkscreen is of course updated for the new values, but it's not worth spinning another prototype board if these are the only changes - just swap out a bunch of 0603's on this one.  Any other omissions?


texts: About leakage current, standby current and current budgeting

texts:
Am using ST microelectronics NAND Flash device NAND01GW3A0AN6E.

In this datasheet under Dc characteristics table they specified leakage current,standby current,operating current parameters.

What is known as input leakage current IL and output leakage current OL ?the test conditions are given as Vin=0 to Vdd max for Il and Vout=0 to Vdd max for OL
Why TTL standby current is in milliamps and CMOS standby current is in nanoamps?Test condition is CE#= High level input voltage for TTL logisc and CE# = Vdd- 0.2
NAND flash has three operations read, program, erase and each operation drives some current.For example Read current=5mA, Program current= 7mA, Erase current= 7 mA.

Let us consider a scenario where the device is first in standby mode and it is programmed,read and erased sequentially.How to do find out the total current driven by the device?


texts: Why does 50 Ω termination result in less noise than 1 MΩ termination on the scope reading?

texts:
Regarding the following section from the Keysight document "Making Your Best Power Integrity Measurements":

It says that using 50 Ω termination we will see less noise on the scope compared to 1 MΩ.

Can this be explained by modeling what is meant here as an electrical circuit? I'm trying to understand why lower resistance causes less noise on the scope screen.


texts: What effect does replacing the load on a switch-mode power supply with a battery have on design?

texts:
I am working through a theoretical design for a solar charge controller for a battery bank where the battery voltage is strictly greater than the open circuit voltage of the solar array.
Most of the explanations of switch-mode power (a boost converter in this case) treat the load as a simple resistive load. I'm trying to understand what happens when the load produces its own voltage potential. Are there modifications needed to prevent the battery from feeding back into the inductor or discharging when not being charged?


texts: Implement combinational logic using control input

texts:
I need to implement the following block.

LD comes from a clocked control input but Adder and Score Register must be built using sequential logic.
When control outputs 1, I load my score into Score Register but I don't know how to stop/freeze it because once LD is 1, I will be adding Score Register's output with the BUS, then load and then add it and so on.

How do I make my combinational circuit execute loading only once?


texts:
I'm trying to create a simple 4-20mA current loop simulator that I can control using a potentiometer. The idea is to hook up this circuit to an Arduino and use the Arduino's analog input to read in the current loop (by converting it into a 1-5V signal using a 250 ohm resistor). The potentiometer would be used to get a 4mA to 20mA current flowing through the circuit.

I've got a very simple circuit that is powered with 12V using an LED, some resistors and a potentiometer.

I figured I would get around 4mA when using a 2.7K resistor, and about 20mA when using a 560 ohm resistor.

I ended up with the following circuit. This kinda works, in the sense that if I turn the potentiometer to one side I get 4mA (1V) on one end, and 20mA (5V) on the other end, but it's not linear. the first 80% turn of the potentiometer gives me the 4mA - 10mA range, but then I only got a 20% turn left to get to 20mA.

How can I create a circuit that can get me from 4mA to 20mA in a linear way (using a potentiometer)?


texts:
I was reading about event driven simulation. Such simulations proceed after we have an 'event' which is the change in any signal value at the input of any design being simulated. The list of all the changed signals is added to what is called an 'event queue'. An 'event driver' then figures out what gates have these signals (inside the event queue) as input which in turn is passed to a 'gate driver'which calculates the output of the gates and stores the output in the new event queue. This constitutes one time step at the end of which signals in the event queue are assigned to the respective nets.
(For further details:http://cs.baylor.edu/~maurer/aida/desauto/chapter3.pdf)

Thus, I inferred that the signal assignments to the nets are always done at the end of each time step.

always @ (a or b or c)
begin
x = a | b;
y = a ^ b ^ c;
z = b & ~c;
end

Since in blocking assignments evaluation and assignments are immediate. Does this mean that say if a changes then each assignment will take place in one time step and hence the whole series of assignments, of x, y and z, takes three time steps?
Further, since it is an event driven simulation. If only c changes, the assignment of x will not take place, since there is no c in the inputs, and the assignments will take two time steps?
EDIT
Based on the answer below I agree that the assignments will be happening in a single time step. But consider the circuit below:

In the document I mentioned it is said that the assignments at C and Q will take place in two time steps. But suppose I code the circuit as follows:

always @ (A or B)
begin
C=~B;
Q=A&C;
end

Shouldn't the assignments at C and Q take place in a single time step?


texts:
'OFDM is a spectrally efficient version of multicarrier modulation, where the subcarriers are selected such that they are all orthogonal to one another over the symbol duration, thereby avoiding the need to have nonoverlapping subcarrier channels to eliminate intercarrier interference.'

How does orthogonality of subcarriers reduce intercarrier interference?


texts: Will the WiFly Shield from SparkFun labs be able to connect to a Bluetooth network?


texts: I have assigned an engineer to use lock-in detection to measure a signal that is being modulated at a specific frequency near 8 khZ.  The signal is modulated internally by the device he is measuring, and because he could not find a way to output that signal to the lock-in reference input he used the lock-in's internal reference, which he set at the same frequency as the signal he is trying to measure.  I told him that this would not work, since two separate oscillators could never maintain the same phase relationship even if they are at the same frequency.  However, he showed me that he actually could produce a DC output from the lock-in (R channel), and that it disappeared if he varied the lock-in internal reference frequency slightly.  After a while I realized that he was using a time constant that is very short relative to the time that the phase relationship of the two oscillators was changing, and showed him that if he increased the time constant to >1 second his DC output dropped.  My question however, is whether using the internal oscillator at the same frequency as the external signal, combined with a short time constant, is a valid method we can use on this system.


texts: What's the effect of parallel resistor and MOV?

texts: What is the effect of connecting a metal oxide varistor in parallel with a resistor? Does the resistor make the varistor more responsive in case of a surge?


texts: how is this circuit working as an amplifier

texts:
The green points are from the video controller output, and yellow point is to the CRT base driver.
ideally small signals are fed to the base of the transistor but here it goes to the collector via diodes. wondering how  these transistors will do the job of amplification of the signals.


texts:
I have set a pin on a Cortex M3 to act as an rising-edge triggered interrupt and it's not firing for some reason. What it should do is receive a 1Hz pulse, trigger an interrupt and start a 12.8Khz square wave.

__main and EINT3_IRQHandler are defined in startup code created by the program, Keil uVision 5. The GPIO interrupts share the EINT3 interrupt vector with a different external interrupt. I figured it would only be a matter of activating the GPIO and EINT3 interrupts then putting the handler within the EINT3_IRQHandler label.

The GPIO interrupts are described on page 129 of this data sheet.

http://www.nxp.com/documents/user_manual/UM10360.pdf

I also tried to just set it to read the interrupt status by using

check
    CMP [status_register], #1   ; Check interrupt status
    BEQ wave_gen                ; If triggered, start square wave
    BNE check                   ; else keep checking

and use that as a trigger but that didn't work either.

This is my code.

    AREA main, CODE, READONLY
    EXPORT __main
    EXPORT EINT3_IRQHandler
    ALIGN
__main
    LDR     R1,=0x2009c000      ; Pointer to base of port 0
    LDR     R2,=0x00000001      ; To control pin 0 for square wave
    LDR     R3,=0x00000001      ; For XOR to invert pin 0
    STR     R2,[R1,#0x00]       ; Set pin 0 to output mode (base+0x00)
    STR     R2,[R1,#0x14]       ; Pin 0 HIGH
    LDR     R4,=780             ; Set up timer

    LDR     R5,=0x40028080      ; GPIO Rising Edge Interrupt
    LDR     R7,=0xE000E100      ; Set EINT3-enable register

    LDR     R6,=0x00000002      ; For pin 0:1
    STR     R6,[R5,#10]         ; Activate 0:1 as rising edge interrupt

    LDR     R6,=0x00200000      ; To enable ENINT3
    STR     R6,[R7]             ; Enables EINT3
    WFI
wave_gen
    SUB     R4, #1              ; Decrement timer
    CMP     R4, #0              ; Compare to 0
    BNE     wave_gen            ; If !0, keep looping
    LDR     R4,=975             ; Reset timer
    EOR     R2,R3               ; Invert bits
    STR     R2,[R1,#0x14]       ; Invert pin
    MUL     R3,R3,R3            ; To waste cycles, ignore (1*1=1)
    MUL     R3,R3,R3
    B       wave_gen            ; Restart loop
EINT3_IRQHandler
    B       wave_gen    ; Start square wave
    ALIGN


texts: Is it possible to tap a wire without breaking it?

texts:
There are plenty of ways to connect to a wire and measure what is going through it that involve breaking the insulation around the wire (such as positap connectors).

It is my understanding that a wire with current flowing through it creates a magnetic field around the wire. Could this effect be used to measure the amount of current flowing through a wire without breaking them? If so, can it be done with a small enough component to make it comparable to positap connectors?


texts: Trying to make an AC 3 phase motor run as smooth as possible at low speeds.

texts: Is there a benefit in smoothness of rotation by increasing the outer rotor magnetic poles? Is there a rule of thumb for a 24 slot core vs number of magnetic poles?


texts: Finding specifications for digital signal processors (DSPs) for given audio application

texts:
I'm finding difficulties choosing an adequate processor solution for my application from my null experience with DSP:

8ch 24-bit @11025Hz I2S TDM Input
Beamforming + ASNR
MSS Multi-source selection
DRC Dynamic Range Compession
Frequency domain analysis (Real FFT)
5 seconds STFT
Peak Finding
Comparison algorithms
Connectivity (Bluetooth @ Low Transfer Rate, just notifications)

I'm considering both a design which includes a Host MCU or just the DSP.

So far I'm looking at SigmaDSP processors:

Pros: Provided I2S TDM interface, arithmetic blog for beamforming, cost
Cons: Buggy and limmited Graphical Programming Interface (no c programming), only Radix-2 Complex FFT and 50% overlap analysis window are available, lack of documentation for sending a signal via SPI to Host Controller

I'm also considering SHARC processors, which I find overkill for my application (no codecs, no output, single input port, etc.):

Pros: C programming flexibility, no need of Host Controller, provided I2S TDM interface
Cons: Lack of experience with DSP programming, cost of processor, development kits, emulators and software

My questions are:

How to determine required system sources (memory, clock frequency, etc)?
Any guidance/recommendations/other families/brands I should look?

Hardware I'm using...
2x Mic Array: https://www.notwired.co/ProductDetail/NWAUDICS52000-NotWired-CO/605574/?ProdId=605574&
I2S TDM to USB: https://www.minidsp.com/products/usb-audio-interface/usbstreamer

Thank you so much,
Pedro


texts: Why would venting an engine create a negative amperage on a generator?

texts:
I'm writing simulation software for a civilian helicopter.
The helicopter has two engines and two generators.

Normally, we calculate the amperage reading of a generator through Ohms.
I = W / V.

However, there is a venting switch on the overhead panel, that "vents" a particular engine.  From what I've read, this also enables a starter relay, and I've been told that it is similar to "spinning up a generator without actually starting the generator."

By observing videos from the actual craft, venting an engine immediately drops the corresponding generator amperage from 0 to -270.

I do not know enough about electrical engineering or automotives to explain why this happens.

Why does the generator drop to a negative amperage?
Is the engine somehow providing a negative load to the generator?

  Image shows an arrow to the venting engine.
  The negative amperage of the generator is circled.


texts:
recently i was using ESP8266(ESP-01) with mega8A to log temperature to Thingspeak.com.Setup was running successfully.But after a long run of 4 days,my esp8266 failed for the first time.I flashed different new version of firmware 2-3 times,but soon after 2/3 hours of run,every time the ESP8266 failed.Now it's returning garbage characters on UART randomly all by itself(without giving any command to it).
I think these modules are pretty cheap and they have no guarantee for long run.Although i ordered another ESP8266(ESP-12) for second testing for long run.

My question is:Is it worthy to stick with the ESP8266 modules and use another version for stability or should I consider another alternative?? Xbee-wifi looks promising but will Xbee-wifi fulfill my needs regarding this particular project aspect??Please answer and also mention if any other alternative available....


texts: Can I use a Microwave Capacitor as a Motor Start Capacitor?

texts:
Recently I had a garage door opener stop working and it was replaced. I decided to take it apart and realized the capacitor had blown a hole in itself. The motor, despite being about 20yrs old, seems to be flawless. I would like to possibly repurpose the motor for a future project. However I don't have a replacement starting capacitor, but I do have 2 capacitors salvaged from microwaves.
My questions are:

Will these caps work (even poorly work?) without the risk of damaging them or the motor?
Could attempting to start the motor with no capacitor at all possibly harm the motor in anyway? Would it even start?

What I believe is that there is no harm in using these capacitors to start the motor, and that at most, they will simply fail to get it started. I'm just mainly concerned with any sort of catastrophic failure such as the motor setting
fire, or the caps exploding (probably unlikely, but rather be safe than sorry).

The motor is rated @ 120V 60Hz 5AMPS
The microwave capacitors are rated @ 2100V(ea.) .95μF & .76μF 50/60Hz(Both)
Here are some pictures of the motor, original capacitor, and MOT capacitors I'm working with.


texts: Problems with mbed LPC1768 double precision

texts:
I have a motion profile generator which calculates a position 1000/sec.
During the decelerating portion of the move, the following calculation is used:

pos = pos - accel_2 + vel;
vel = vel - accel;

Where all variables are doubles, pos is calculated position, accel is acceleration, vel is speed, and accel_2 is acceleration/2.

The end of the move is when either vel <= 0 or pos >= target position.

I've calculated the point at which deceleration starts correctly, such that by the time velocity is 0, we should be at the target position.

I've tested the profile generator on a desktop computer and can confirm that it works as expected (of course the position may exceed its target by a fraction, but precision is finite, and the error is insignificant).

However, when run on my LPC1768 (using mbed OS), I find that the generated values differ to those generated by the same code on my desktop (i.e. position reaches it's target before deceleration has completed).

When graphed for speed and position, I can see that speed drops off noticeably towards the very end of the move, as position reaches its target. This causes a slight "skew" in the position/time graph as deceleration completes.

I tried changing the profile termination condition such that we only check that vel <=0, therefore allowing speed to to finish decelerating, which results in a more symmetrical and smoother looking position/time graph, although as mentioned above, position overshoots its target.

I've observed that all of this seems to be less of an issue with larger values for accel, speed and position, which leads me to believe that this may be a precision issue with double. Are doubles represented with 64-bits in the LPC1768, and are they implemented in the same way as other platforms?

What else could be causing this?

Below is a position/time graph, where the first profile compares position with target, and the second one doesn't. Notice the difference at the very end.


texts: PRU UART on the BeagleBone Black Problem

texts: I am trying to get the PRU UART of the BeagleBone Black to send/receive 9-bits data. I used the stick parity to emulate 8M1 and 8S1 modes but when testing the parity bit is always a 0. it's like always 8S1 mode. I even tried to emulate the 8M1 mode to 8N2 mode but the test shows only 1 stop bit is sent. Any solution ?


texts: Analysing system response in the time domain from Bode plot (intuition)

texts:
The following question was asked :
Given a Bode plot with a frequency response as illustrated by this Bode plot find the amplitude of vout for a symmetrical square wave inpute of +-10V at 2KHz. The Bode plot describes an asymptote of -40dB which crosses the 0dB line at 700Hz.

The attempt of a solution:

The fundamental of the input has pulsation of \$\omega=2\times10^{3}\times2\pi=4000\pi\$
 . Which is way larger than the cutoff pulsation: \$\omega_{c}\approx300\times2pi=600\pi\$

We can therefore approximate H(s) by \$H(s)=\frac{R(s)}{E(s)}\approx\frac{1400\pi}{s^{2}}\$.
 .

If we analyse the response in the time domain we have \$r(t)=1400\pi\times10\int{}_{0}^{T/2}\int{}_{0}^{T/2}e(t)dt=1400\pi\times10\times\frac{T}{2}\int_{0}^{T/2}dt\$ with \$\frac{T}{2}=2.5\times10^{-4}\$

So we get \$r(t)=1400\pi\times10\times(2.5\times10^{-4})^{2}=0.00274889V
 \$

I saw an example for a simple integrator but I am not so sure this double integral, sould it be an indefinite integral then evaluated on the half period? I also have some intuition problem on going from the freq to the time domain, how would this work for a more complicated filter, say an elliptic one which has ripple in the band-stop. First question on the forum so sorry if some rules of etiquette have been broken here.


texts: Why is it preferable to use NPN transistors for both high-current-output devices in a push-pull amplifier?

texts: With reference to the below circuit why is it preferable to use NPN  Silicon    transistors for both high-current-output devices in a push-pull amplifier?


texts: Do the ground marks in these two circuits have different meanings?

texts: The diodes in both circuits are ideal. I drew the circuit on the right to make a comparison. As the answers given for V and I in the circuit on the left are 1 V and 4 mA, this means D1 and D2 are not conducting while D1 is. I have not really seen a ground mark placed beside the circuit, so I can't be sure what it means. I can only guess, according to the given answers that it means the whole branch D1 is in is connected to the ground, thus meaning there is 0 voltage across D1, is that so?


texts:
In Wikipedia's positive feedback article it is stated that given the closed loop gain $$A=\frac{a}{1-af}$$ the system is unstable if \$af>1\$.

I don't really get this. If \$a=10\$ and \$f=0.5\$ (just to give a very simple example), I just see that \$af>1\$ but \$A=-2.5\$, which is not infinite. So what is really happening here?

I know that a system is unstable if the transfer function (i.e. the gain in Laplace domain) has poles in the right-half complex plane. But here, \$A\$ would be a constant so I don't see why unstability would occur.

This question arised when I was trying to analyze a Schmitt trigger using feedback. Quantitavely, I see why the output will go to saturation voltages. I just don't see it mathematically. Suppose that the Op-Amp was ideal (so it has infinite gain and it doesn't depend on frequency). Then why would, mathematically, anything diverge in this circuit, if \$A=\frac{-1}{f}\$ which is a finite value? That's the question that led me to thinking about positive feedback and unstability in general.

To sum up:

Why is positive feedback often related to unstability?
Why does \$af>1\$ imply that a system is unstable if using positive feedback?


texts:
I want to know about the forward voltage \$V_{f}\$ parameter of a diode device, given an I-V charateristic curve and in ambient temperature. What is the criteria to define the \$V_{f}\$ for any diode? How can I define it if I work with this
 current expression \$i_D = I_s (\exp^{v_D/V_{th}}-1)\$?
Sometimes I see the value of this parameter like \$V_{f}=0.7\ \mbox{V}\$ for some type of diode, but how can I calculate given any \$i_D\$ expression?


texts: L298N H-Bridge : Powering 4 motors using (6) aa batteries vs (4) aa

texts: I am currently wiring up my raspberry pi, H-Bridge and (4) 3-6v ratting motors. My question is, how will performance change based on me using 6 or 4 batteries to power motors? I noticed some tutorials using (6) aa batteries totaling 9V. Why waste two extra batteries and risk too much voltage? Besides the motor ratting is 3-6v; wouldnt 9volts fry the motors? Ive read the H-Bridge has a 5v regulator. Does this mean even if you supply more then 5volts the h-bridge will keep it at 5v?


texts:
I have a problem when I send some character from an hyperterminal through an uart frame, I receive the wrong character. I use a PIC 18F46K80. In some test I did, I got these results :

Test 1 :
Character sent : 'A' (=1000001)
Character received : '_' (=01011111)

Test 2 :
Character sent : 'B' (=1000010)
Character received : '/' (=101111)

Test 3 :
Character sent : 'C' (=1000011)
Character received : '^' (=1011110)

I don't know what is the logic of the transmission. You can find bellow my code:

#include <stdio.h>
#include <stdlib.h>
#include <usart.h>
#include <math.h>
#include <p18f46k80.h>

//CPU Configuration
#pragma config FOSC = INTIO1    // internal oscillitor
//#pragma config BOREN = ON       // Enable Brown-out Reset
#pragma config WDTEN = OFF      // Watchdog timer is disabled
#pragma config XINST = OFF      // CPU Extended mode is disabled

typedef unsigned char bool;
#define true    1
#define false   0

unsigned char msgData[100];
unsigned char cTemp;
unsigned char cTemp_0;

int i=0;

void ports_IO_init();
void init_UART();
void FOSC_Config();
void start_UART();

void main()
{
    bool b=0;

    int J=0;
    unsigned char len=0;

    start_UART();

    while(1)
    {
       if (PIR1bits.RC1IF==1)
       {
           cTemp = RCREG;
       }
    }
}

void ports_IO_init()
{
    TRISCbits.TRISC6 = 0; //Le port RC6 en sortie TX1
    TRISCbits.TRISC7 = 1; //Le port RC7 en entrée RX1
}

void init_UART()
{
    //Configuration of TX
    TXSTA1bits.TX9 = 0; //8-Bit Transmit Enable
    TXSTA1bits.TXEN = 1; //Transmit is enabled
    TXSTA1bits.SYNC = 0; // Asynchronous mode
    TXSTA1bits.SENDB = 1; //Sends Sync Break on next transmission
    TXSTA1bits.BRGH = 0; //Baud rate selected at high speed

    //Configuration of RX
    RCSTA1bits.SPEN = 1; //Serial port is enabled
    RCSTA1bits.RX9 = 0; // 8 bits reception
    RCSTA1bits.CREN = 1; //Enable receiving

    //Configuration du bauderate
    //For a FOSC of 8 MHz, a desired baud rate of 9600, in Asynchronous mode, and 8-bit BRG
    // SBRG1 = ((FOSC/Desired Baude Rate)/64)-1 ((8000000/9600)/64)-1 = 12
     SPBRG1 = 12; // 12 = 0xC in Hex
}

void FOSC_Config()
{
    // Configuration for a frequency of 8Mhz
    OSCCONbits.IRCF = 110;
    OSCCONbits.SCS1 = 1;

    OSCCON2bits.SOSCRUN=1;
    OSCCON2bits.SOSCDRV=1;
    OSCCON2bits.SOSCGO=1;

    OSCTUNEbits.INTSRC= 1;
    OSCTUNEbits.PLLEN = 1;
}

void start_UART(void)
{
    FOSC_Config();
    ports_IO_init();
    init_UART();
}


texts: What type of power supply should i use for led strip?

texts:
I like using led strips to create various pieces of lighting around the house for myself and also for friends.  I buy the cheap 3528 analog reels from Amazon, (the stuff that gets shipped straight from China), and I go to Goodwill or other thrift stores and find small 12v plug-in power supplies to run them.  I don't know what some of the classifications mean though, or which ones I should, or should not, use.
For instance, some say "class 2", while others don't state a class classification at all.  And a lot say I.T.E. use only.  I did Google that and found that it stands for information technology equipment, but what does that really mean??  Can those only be used with equipment that turns on and off constantly rather than staying on for very long?  Are either of these types okay?  Our should they be avoided?
Are there any other markings that I should be looking for?
Thanks for the help.


texts: Is time-division multiplexing really a multiplexing method or more of a protocol?

texts:
If my understanding is correct, when we are multiplexing, the stations are not supposed to be aware of the multiplexing.

For example, if we have computers 1, 2, 3, & 4 talking to computers a, b, c, & d, respectively, through a time-multiplexed channel, each pair must be communicating with each other as if they are directly connected. The stations must be oblivious that they are connected to a mux/demux. And if I want to add another pair, it will be just plug-and-play, that is, I will just plug the first one on any vacant port on the mux and plug the second one on the corresponding port on the demux, at anytime.

But from Principles of Electronic Communication Systems by Louis Frenzel, on the section about time-division multiplexing, it says:

Now that's confusing. If each input will transmit on its time slot and then "halt", then the stations must be aware of the multiplexing. They must have some way to know when is their time to transmit. And if you will add a pair of stations, they cannot communicate immediately as if you have connected them directly because they must first inform other stations about their presence and ask for a time slot.

Isn't it more like a channel access protocol than multiplexing? Or my understanding is incorrect at the first place?

Follow-up questions:

1) If the highlighted statement is true, how do they know when to transmit?

2) If stations only take turns in transmitting, why is the output rate the sum of the input rates, like in T-carrier system? Shouldn't the output rate be just the rate of the highest input rate since they are just taking turns?


texts: Johnson Noise in Differentiator: Does the input C have an effect?

texts:
I have a homework problem that asks me to find the spectral noise voltage density at the output of the following circuit:

I identified it as a differentiator with three noise sources: The Johnson noise at the resistor R1, the input current noise of the OpAmp and the input voltage voise of the OpAmp.
Now I am stuck actually calculating the output noise contribution of the Johnson noise. I am unsure what's the effect of C1.

Theory 1: C1 has no effect, because the OpAmp feedback holds the negative input at (virtual) ground, so the capacitor is short-circuited. The resulting output noise is the Johnson noise amplified with Gain=1.
Theory 2: C1 filters some of the noise so I get less noise at the output. The amplification is still 1,but I have to multiply the (white) Johnson Noise with the Transfer function of the R1C1 Lowpass.
Note that I am just looking at the Johnson noise, ignoring the other noise contributions for the moment.
I think that my problem is that two of my intuitions are colliding here, on one side thinking about C1 as a short at high frequencies and about its influence and on the other side thinking about the OpAmp according to "Golden Rules" of zero input difference voltage.
Can C1 be ignored? When does the assumption of zero difference voltage not hold anymore?


texts: Help me hack this speaker, where would I introduce DC voltage

texts:
I have a speaker that runs off of AC (there is a switching converter within the speaker) I'm attempting to convert it to battery power, From my understanding the speaker runs off of 5V (someone else did a similar conversion). so here goes

Where would I solder a wire to run directly from DC. I'm assuming it would be after the switching mode power supply. Also I know that there is some conditioning going on there, so I'm not sure the implications of bypassing it.

Attached are photos of the unit

enter image description here