texts:
I have an on board J-link debugger on my Infineon Relax kit. I'm trying to use my J-link as a serial interface to my PC. It requires CDC serial port driver and I have installed it. Problem is that, I'm unable to see any COM port in my device manager despite connecting my debugger with PC over USB. It shows a j-link driver though. J-link configurator says that my debug probe does not have VCOM functionality available.

Any help related to serial port setup using j-link or general USB serial interface would be appreciated.


texts: Can I overlap magnet wire when wrapping a toroid or must it progress linearly around the circumference?

texts: I've been playing with inducing magnetic fields in a ferrite toroid with turns of magnet wire.  Can you overlap, e.g. double back over the previous turns so I don't need a larger toroid?


texts: Discharging capacitors with a multi-meter in diode mode

texts:
Recently I encountered this "trick" where you use a multi-meter in diode test mode to discharge a large electrolytic capacitor. I feel that this cannot be a good practice, but the people who were doing insisted that they do it all the time and have never damaged their Fluke meters in the process.

The voltage in the system is max of around 50V and the total capacitance is around 1600 uF. The exact process is that you put the multi-meter in diode test mode, then connect positive to negative and negative to positive. The meter beeps continuously until the voltage is near zero.

So my question is, is this an industry practice? Can it be considered safe for quality multi-meters such as Fluke?

I definitely wouldn't consider it to be safe for cheap meters. But for all I know, Fluke knows their customers will do this and designs the meters accordingly.


texts: Oscilloscope displaying two voltage levels (on the same channel) for square wave

texts:
Please excuse if this is stupid, I've been searching to see if I can find an answer to this on Google, but it seems I'm facing the issue in which I don't know how to describe the issue I'm trying to solve.

I'm using a function generator to generate a square wave with 100mVpp, I'm using the oscilloscope, without a breadboard, to read the signal from the function generator.

My understanding is that an oscilloscope reads the voltage changes and displays it on a time series. However, as you see in the picture below, I have two lines for each peak.

Why are there two lines? Does it represent a range?


texts: What kind of material of PCB should I choose to work at -40 degree centigrade?

texts:
I need to design a PCB circuit to work at (or even below) -40 degree centigrade. Normally, I use FR-4 PCB board at room temperature. However, I have learned from the question "What is the minimum temperature for FR-4 PCBs?" that FR-4 PCBs may have problems below -30 degree centigrade.

So what kind of PCB material can handle such low temperature?


texts: How to bias an AC input composite video signal

texts:
This is a question about biasing 0V-referenced AC input signals to a positive single-ended signal. Even if the best solution for my question would be something else (and I'd like to hear about that, too,) I'd still mainly like to learn about the biasing question.

I have searched all the "biasing analog video signal" posts in here, as well as googled datasheets, and I haven't actually found one that answers the questions I ask here. Just searching the titles of other posts is misleading, because they have other requirements (using other devices, different power supplies, etc.) The suggested duplicate question "AC-Coupling on Composite video" talks about re-processing the signal, which I explicitly do NOT want to do.

Question Background

I have a remote operated robot with a video camera generating a composite video signal going into a transmitter.

I'd now like to switch the transmitter between two separate cameras. I don't need genlock (synchronized pictures); I'm OK with the "glitch" that happens when switching between unsynchronized signals.

Weight is important, and sticking to the current design of the control systems of the robot is important.

I have looked at dedicated "video switching" ICs. The older ones, like MAX4566 and NJM2595, are generally bipolar, and require dual power supplies (+/- 3-12V.) I only have a single end power supply (5V) and ground easily available. (The video signal, generated by the camera(s), is referenced the the ground I have available.) The newer "video switching" ICs (like the TS3V330) are all for digital video differential signals (HDMI etc.) They do not work with input signals less than 0V.

A simple SPDT switching IC like the SN74LVC1G3157 is readily available, but it has protection diodes from input signal to ground and to VCC. This means that the negative half of the input signal swing will be clamped by the diode to ground. (once the diode voltage drop of 0.3V or so has been overcome)

Actual Question

The AC signal centered around 0V is generated by an output stage in the camera (or other video equipment) like this:

The input to the transmitter, and other video processing devices, looks something like this:

(Illustrations shamelessly "borrowed" from the MinimOSD open source project schematics.)

I would like to take two of these video signals in, and switch between them (without any specific sync requirements) into one output signal, which is forwarded to the transmitter input.

I would like to not re-buffer and re-amplify the video signal. I could do that with an opamp with sufficient bandwidth, but that adds more parts and complexity. Call me lazy if you want!

So, my question is: Can I switch this signal by biasing it using a simple resistor ladder, then switching it, then adding an output capacitor?
If so, what should the values for that ladder be?
What will happen to the 75 Ohm output impedance seen by the original transmitter, and the eventual receiver?

Example:

(If the output from the camera doesn't actually use an isolating capacitor, I'm in trouble, though.)

Am I missing something else here, or would this "work" with reasonable signal quality?


texts: Proper way of connecting wires to pins on polymer films

texts:
What is the proper way to connect wires to contacts from a thin semitransparent "plastic" foil (see images). There are slightly different types; the first one with the 4 pins in a row is the more important one)? It is a thinflexible foil with pressure sensors, which are connected via the thin metal streaks to the "pins" on the right.

Just solder, or are there kind of clamps that I can use? Are there any normed/standardized connectors/clamps? I'd like the contacts to be as "non-destructive" as possible (considering my current soldering skills, to be honest, but I can try to improve), and to be absolutely as flat and stable as possible (max. 1 mm (ok, maybe I have to relax that to about 3 mm), must stand a person's weight stepping on them multiple times).

I was searching on the web for a long time w/o success, and realize I may not even know the correct term for this kind/type of electronic constructions on foils, so even that might help a little bit - may I ask you to tell me the correct name?


texts: Data acquisition with Python on a Beaglebone Black - Increasing sample speed

texts:
This is my first foray into programming and using a BeagleBone Black. I have some limited experience in Python, and have used this within the provided Cloud9 IDE in order to capture data and write that data to a pandas dataframe, please see code below.

While the code works, I have tested using the Pins P9_32 and P9_34 with a pair of resistors to generate ~1.29 volts, then reading this voltage as an ADC input on pin P9_40. The sample rate is very slow, 113 - 116 samples per second. The minimum I need for the task I have at hand is approximately 400Hz per channel. While I can sequentially sample channels, I'd prefer to have 4 channels operational for a total of 1600Hz sample rate.

Is a significant increase in the sample rate possible by optimising or altering the Python Code I have? If not, what is the recommend method of data acquisition via the ADC on the beaglebone Black?

import Adafruit_BBIO.ADC as ADC
import pandas as pd
import numpy as np
import time
import matplotlib.pyplot as plt

ADC.setup()
value = ADC.read("P9_40")
voltage = value * 1.8 #1.8V
value2 = ADC.read_raw("P9_40")

print(voltage)
print(value2)

df_ = pd.DataFrame()

timeout_start = time.time()
timeout = 5 #seconds
print(timeout_start)

def DAQ():
    d = []
    count = 0
    while  time.time() < timeout_start + timeout:
        value = ADC.read("P9_40")
        voltage = value * 1.8
        d.append((count, time.time(), voltage))
        count = count+1
        out1 = {'count': count, 'df': pd.DataFrame(d, columns=('count', 'Time', 'Signal Amplitude'))}
    return out1

x = DAQ()
count = x['count']
df = x['df']

print('end loop')
print(count, 'number of iterations', count/(time.time()-timeout_start), 'samples per second')
print(df)

print(df['Time'])
print(df['Signal Amplitude'])

#plt.plot([df['Time']],[df['Signal Amplitude']])
#plt.show()

#plt.figure()
#for count in df:
#    plt.plot(n[0], n[1], label=n[2])
#    plt.axis([0,count,0,60])
#plt.legend(loc=0, frameon=False)

Thank you,

P.S. if anyone can provide guidance on plotting graphs on the BBB I would appreciate it.


texts: Disable buck regulator output on startup and hold enable pin high for 1.5-2ms

texts:
I have a learning opportunity that I need some help with :)

I have current regulator design I put together using the LED2001 IC for driving laser diodes. This is mounted on top of a heatsink module which is mounted to an open frame CNC machine.

Here are the Kicad source files.
Kicad Source

Here is an image of it on my machine.

The issue that I'm having is that when power is first applied to the board, the dim/enable pin needs to be held high for a brief period before the output of the LED2001 will operate on pulse widths of 1-99% (0% being 0vdc & 100% being 5vdc).

If I don't apply this technique when I first power it on, the output will not turn on until I go above 25% on the pulse width. When cutting stuff this is not a problem as the power is usually set to 100% for the cut opperation but when I'm engraving an image and the start of the engraving happens to be in a light area of the image it will not turn on the laser until it reaches a dark part of the image.

At first I thought it might be an issue with my design but I have since found references to similar designs that seem to indicate that this has something to do with the LED2001 IC.

A suggestion was made to me to disable the output while holding the dim pin high for a brief period at start up (to let the caps charge) and then bring the dim pin low and then enable the output, allowing the PWM signal to control the output after that.

I could slap a mcu on the board to do this but I thought that this would be a good opportunity to learn how to accomplish this without using a micro. I have been searching google for ideas but I don't think I'm using the right key words.

If this is trivial and you want to post a schematic, that is fine. I'll take it and try to learn how it works. OR, if you don't mind pointing me in the right direction or helping me learn the parts that would make this work, I can certainly do the research.

Thanks
John

Edit: Here are some screenshots from my O'scope.

16% PWM after applying power to the board.

http://i.stack.imgur.com/cs93p.png

97.3% PWM, not quite fully on yet..

http://i.stack.imgur.com/h5fqn.png

97.7% PWM, the driver is on and full PWM range is available.

http://i.stack.imgur.com/HhGkI.png

back to 16% PWM.

http://i.stack.imgur.com/oV1Kc.png

Edit: since LTSpice didn't have a NOR gates built in, I found an example using some inexpensive BC817 BJTs. Here is what I came up with that seems to work ok based on the feedback provided in the comments.

I ended up with two NOR gates and one NOT gate which seems to do what I need it to do. When the device is powered on, it should hold the DIM pin high for about 1.5ms and then return back to 0V and stay there until the PWM signal is present, at which time it will control the DIM pin.

The output of the first NOR gate is also used to offset the feedback pin voltage at startup which should limit the output current and basically shutting off the output without adding a mosfet as a switch inline with the output.

Here are some screenshots from LTSpice.

http://i.stack.imgur.com/h9JQs.png

http://i.stack.imgur.com/l7kD8.png

http://i.stack.imgur.com/AxG5p.png


texts: How Can I connect My Solar Power System?

texts:
I  brought this 50A Solar Controller now I want to connect an inverter to it and they said to connect the inverter directly to the battery. I also brought a 100W Solar Panel and MC4 Wires, etc

What is these "60A/50A/40A/30A/20A/10A "? I choose the 50A one and wanted to know the Amps are used for DC Load or what's the use of selecting "60A/50A/40A/30A/20A/10A" if it is to be connected to the battery eventually?

The reason for not wanting to connect it to the battery is: The Protections (Load, Over Charging, Deep Charging, etc) go away if I connect the inverter to the battery directly.


texts: 54V 5A DC thru "regular" coax "TV" cable for use as a "poor man's" solar power cable?

texts:
In the effort of saving money without having to buy expensive solar cables (and because I have a lot of extra coax cable lying around doing nothing), I would like to use a piece of coax cable (that looks like antenna cable), to transfer 54V and up to 5A of solar power into the house.  The length would be no more than about 20 feet and can be made even shorter.  This is a very small solar application to charge a small 48V battery bank.  If I do not know the type of cable (such as RG-6) so that I cannot just look up the specs on it, generally speaking, is it fairly safe to assume just about ANY piece of coax normally used for cable TV or antennas can handle 54V and 5A?  I think it is reasonable.  Note that I would not use the end "F" connectors, I would use stripped ends to attach to the solar panel cables and somehow weatherproof them, and on the charger (indoor) side, also stripped ends.

I should mention that the near 5A flow would only be in certain conditions (like when the battery bank is in a mid state of charge and there is full sun directly over the panels).  I would say on average, the current flow should be more like 2.5A to 3A.


texts:
I'm trying to find high brightness UV LEDs appropriate for this project:
https://www.instructables.com/id/UV-LED-Exposure-Box/
which includes: "The most critical parts of this project are the UV LEDs, you are looking for 5mm Ultra Violet LED 2000mcd 395nm, 3.4V 20~25mA."
However, it appears that the mcd (luminous intensity) criteria is ambiguous for LEDs and other light sources that emit a peak wavelength that isn't visible to the human eye, such that a directional (solid angle) emitted power (wattage) criteria would be more appropriate.  That might explain why it's so difficult to find anyone who can meet those specs.  Is there anyone with experience in UV leds who can help?  Thanks.


texts:
I am trying to wire a new motor to a variable frequency drive (VFD) and having some trouble figuring out how to wire the motor to the VFD. The motor is a 1 HP, 3-phase, 208-230/460 volts, and I'm wiring a 120 VAC supply voltage into the VFD, which steps that up to 3-phase 230 V. I have included a picture of the wiring diagram attached to the motor below.

Based on that diagram and the fact that the motor will be operated at 230 V, I gather that wires 9 and 3, 8 and 2, 7 and 1, and 4 and 5 and 6 all need to be wired together - giving me 4 separate wire bundles. The VFD has wire terminals for U, V, and W, so it looks like I have 3 terminals and 4 wires, so I'm not sure which wires go to the U, V, and W terminals on the VFD or what to do with the extra wire bundle. I have included an image of the motor wiring diagram from the VFD manual below.

I was thinking that the extra wire bundle would be a ground, but there is also a green screw inside the wiring box on the motor that I'm thinking is where I connect the ground wire (and connect the other end to the protective earth PE terminal on the VFD), but please correct me if I'm wrong. With the extra wire, I'm also left wondering how to differentiate between U, V, W and whatever the 4th wire is. In the VFD motor wiring diagram, I also can't figure out what the Physical Earth Shielding (PES) is - is it just saying to use shielded wires and attach the shield to ground? The model numbers for the items are: Baldor CEM3546 Motor, and Lenze SMVector ACtech ESV751N01SXB. So my specific questions are:

What is the 4th wire?
Where do I connect the 4th wire?
To ground the motor, do I attach a wire between the green nut and the PE (protective earth) terminal on the VFD?
By connecting the ground wire on the incoming 120 V single phase to that same PE terminal, is the motor grounded?
Is the PES just another way of saying to use shielded wires, with the shielding being attached to ground? Is this really necessary?


texts: How does AS1130 132-channel LED driver work?

texts: I was just checking out the AS1130 and I was wondering how you are able to drive a 12x11 array of LEDs using only 12 wires? Could anyone explain this to me?


texts: Transistor as a mute switch, odd rise and fall times?

texts:
I need to mute (soft mute, no clicks and pops) an audio signal while routing it using a mechanical relay. I use a 2N5089 high gain NPN with a grounded emitter, collector to the signal output and the base is hooked up through a 4k resistor to a micro-controller pin so when fed 5V the current to the base is 1.25mA which is just above the saturation current. To make the transient long I added a 33uF cap to ground from the transistor's base. I hooked this up to a scope while altering the voltage at the pin that goes to the base. For the purpose of clearly seeing the rising and falling edge I connected a DC 1V (through a resistor) to the collector. The fall time of that voltage is 1.6 - 1.8msec and the raise time is about 11ms. I must admit I don't fully understand what goes on here. How come the fall time is so short (this is when the transistor switches ON) even after adding a 33uF cap from base to ground? Tau is 0.132 sec !!!

Any help much appreciated!


texts: What does a logic gate output when powering down?

texts:
For my application, I need to be sure that a logic gate output will stay low during power-down.

I have put together a logic circuit using a 4013 dual D flip-flip. It seems to work as I would like it to: I power the chip up, make an output low, and when I power the chip down, that output will stay low.

What I am worried about is that it would be possible for the output to change state or be uncontrolled during power-down. I have not seen anything in datasheets specifying how the chip powers down, maybe most people don't care about this function?

Does anyone have any information on how logic chips behave while their voltage supply is shutting down? I am beginning to think that I simply should not be relying on the output of a logic gate to behave during power down; maybe that is bad design since it isn't specified/guaranteed in datasheets...

Thanks,

Jensen


texts:
I have an old car battery charger (12V 8A) that has a 3.5 DC volts on its output instead of 12V. Although i found a similar circuit but i could not understand how it works. I am guessing after the center tap transformer there should be two 14 V signals (gr1 , gr2) and a common signal named brown. gr1 and gr2 are connected to the cathode of the thyristors then anodes on the other hand goes to GND!
So i think the circuit works with negative half cycles instead of positive ones! and interestingly there is no capacitor for smoothing the waves. The brown signal propagated through the circuit and act as a positive signal.I sketched the circuit in proteus to trace the input to every circuit nodes:

The RED, YELLOW and GREEN indicate charging, emergency and fully charged states, respectively. G1 and G2 are the Gates of thrystors 1 and 2.
However it does not work. The 47u cap is placed to keep the relay connected. There is connection between gr1 (or gr2 does it make a difference?) and (-)plate of 47u capacitor, if we keep this connection the selected nodes will have voltages look like: Corrupted voltage waves
And by disconnecting this two (gr1 from (-) plate of 47u) the following wave will be gained: smooth voltage waves
However in either case the voltage amplitude is too low.
The charger output is between Brown connected to relay and NULL which h should be ~12 or 13 V.
Could you please guide me find the problem.
the proteus project file


texts: R-2R ladder D/A converter with mutilple non-zero inputs

texts:
PROBLEM:

So I am not used to r-2r ladders where 3 out of 4 inputs are 0V. Here both A and B are 5V, so I don't know how to approach this problem.

This is what i get when i simplify the ladder:

I think there is a virtual short at the terminal between R7 and R8, so current through Rf = current through R8. But I don't know what to do after this.

I haven't had much practice with these types of questions, so any help would be appreciated.


texts: How do I know the polarity of the resultant voltage of these two series-connected alternating voltage sources?

texts:
I was studying simple vector addition on All About Circuits, and the polarity assigned to the resultant voltage (see picture below) confused me.

Link:

https://www.allaboutcircuits.com/textbook/alternating-current/chpt-2/simple-vector-addition/

when the resultant voltage is taken as 2 V 180 degrees, why is polarity like this? I Understand that the 2 V 0 degrees should have the reverse polarity of the latter but I don't understand why the polarity is assigned like this.


texts: Why does the max current capacity decrease with the number of cores for the same AWG?

texts:
I couldn’t find a similar or duplicate question yet but regarding this table for instance a 24 AWG wire can carry max 3.5A current if it is single core. But if it is seven core it can only carry max 1.4A.

Am I interpreting the information wrong?

Is this table valid for DC current as well? What really creates such big difference with different number of cores of the same AWG cable?


texts:
I'm asked to determine the active power (P). (I don't know if that is actually called active power in English?)
The formula of P is = U * I * sin(alpha)
How can we determine the alpha in this case, so that we can calculate the P?


texts: Powers Signs differ between sources and loads?

texts:
Alright, so my textbook specifically states that negative power indicates that power is being extracted from a device (I'm assuming they mean for loads) and then shows a negative power value at a current source as being power delivered.

Is the sign convention opposite for loads and sources?


texts: Buffer IR trigger signal to relay, to supress extra signals

texts:
I have an IR Controlled Relay module (Schematic below). I have programmed it to work with an old Comcast remote (Silver with red select button). The problem I am having is the remote send the power signal multiple times per button press instead of just once. This causes the relay to switch rapidly and often end up in the same state as before you pressed the button.

So what I need to do is modify the circuit so that only the first signal gets through and the rest are ignored. I would assume that using a capacitor to smooth out the signal would be required, but what capacitance, where exactly should it go, and ceramic or electrolytic?

NOTE: This schematic was provided by the manufacturer in Chinese. I translated it but there is one existing capacitor (C1) that is a surface mount and I see no way to identify it.

What about using a 555 and this logic?


texts: Why is the characteristic impedance usually purely resistive?

texts: I know the characteristic impedance to be the square root of the ratio of the impedance (Z) and the conductance (G) of the line, both complex numbers. Hence, the characteristic impedance must be also complex. However, in most problems that I encounter, the characteristic impedance of a given line is almost always just resistive. Why is this?


texts: Is it possible to directly interface a MEMS ADMP541 microphone over I2S with any Microcontroller?

texts:
I have bought a MEMS ADMP541 Evalution kit to record voice samples with arduino controller

MEMS microphone will produce digital o/p , I2S communication protocal

My question is should I directly connect the MEMS microphone to arduino mega/ any controller ?

Or do I need to use any interfacing circuite b/w mic and controller


texts: on-chip low-pass filter with sub-Hertz cutoff frequency

texts:
Sometime ago I had to implement an on-chip (CMOS 65nm) low-pass filter (first order) with very low cutoff frequency (lower than 100mHz). I used PMOS pseudo resistors and momcap, and had to check all the corners to make sure the cutoff freq is low enough. Obviously the output of this filter feeds the gate of another MOS transistor. However, the PDK did not include the gate leakage current, so I used IO devices with large Vth (and other tricks to solve the voltage headroom issues) in the hope of lowest possible leakage current. But that didn't help much and the DC voltage drop across the pseudo resistors made serious issues.

I'm just wondering if someone has experience designing on-chip, very low frequency, filters where leakage current is present in the process.


texts:
As per USB3.x specification there is provision of

rx_polarity_inversion

can any one exactly says, what is the reason behind it?

Edit:

Normally connection of Host and Device's Data +/- line connection is like shown in figure. But polarity inversion gives facility, if connected wires are reversed any how, or intentionally reverse connected then also it can work.

But apart from this, it is used for something else, it has some advantage or importance. What was that?


texts: I was wondering if someone had a link to a board file for a TQFP-64 to DIL-64. Similar to this: http://www.core.st/projects/AVR32_Starter_Kit/TQFP-48_to_DIL-48_adaptor.pdf, but for 64 pins?


texts: I got amp which produces 2 x 30W output on 8\$\Omega\$. Is it possible for each channel to connect a 60W 4\$\Omega\$ speaker? Is it possible to do such thing and how I can wire it?


texts: Configuring Frequency Bandwidth and Input Signal for Bandpass filter circuit

texts:
How do I set and configure the frequency bandwidth I want the filter to output to a device?

I am using a physical passive bandpass filter which I intend to take the signal in and filter it and output the result.

So if I have an input signal \$V_{in}\$ which is signal from a .wav file including the frequencies and noise I want to filter. How would I set the circuit or Inductors, Capacitors, and Resistors (because it's an RLC circuit) to output the signal from the frequency from the bandwidth I want. Let's call it \$f: [f_1, f_2]\$. How would I know which ratings of components to have in the circuit in order for it to filter that range of frequencies?

The second question is: How would I exactly input the signal to the circuit from a computer? Should I just connect a 3.5mm jack to \$V_{in}\$ and then play the .wav file?

Thank you.


texts: How do I locate proper radio initialization procedure in order to send IEEE 802.15.4 frame?

texts:
I am using an AT86RF233 radio connected to an MSP 430 micro-controller.

I need to write a function similar to line 92 on this page.  This function (trx_frame_write) is supposed write a frame for the RF230, not the RF233.  I have copied this function and got it to compile on MSP 430 but it has been unsuccessful in sending frames to a Digi Xbee Pro Series 1 radio.

My hunch is there is nothing wrong with the function itself, but rather the radio's configuration / initialization.

I was hoping one of the experts in the community can point me to the pg. in the data sheet that explains how a radio should be configured so that it can send IEEE 802.15.4 frames correctly.  Section 6.3.2 on pg. 17 definitely jumps out regarding how a frame should be sent, but there is no mention of how the radio itself should be configured.


texts: [Digital input over voltage protection solution - varistor or TVS]

texts:
I have to select the best safe solution to protect a 5V input.
Below 4 solution that I have designed to protect my 5V input against over voltage using varistor and TVS.

Different solution are availables. I'm really confused which solution to choose. Have you any advices.
I thank you for your support.


texts: Battery wear on small solar powered devices like watches or pocket calculator

texts:
As I understand, small repeated charges to a battery damages it. How are small electronic devices, like solar powered watches and calculators, designed to deal with this?

Is the battery basically different from li-ion batteries for "bigger" devices, like smartphones, which would get a full charge each day?

Do they have a chip programmed to either use solar or battery, and only charge the battery if it's rather low?


texts:
I'm looking to build a simple board that has a 16x PCIe connector, that seats a compatible PCIe video card.

I can find the connectors and create a footprint, on the board. I can find and understand to some degree the basic pin-out of the PCIe 1x connector  -- but I'm not clear on the full end to end implementation.

I've read the full specifications costs lots of money, and honestly is overkill for what I want.

I'm not super concerned about the actual protocol (like at the physical layer), so not necessarily looking for the official PCIe spec -- just the nuts and bolts implementation.  Which pins go where on the cards, where they are laid out.

I am not certain on signal routing both between the mating connector and the PCIe card, and then where the card signals.

I know Altium provides templates of the actual pads and so on, but I'm more interested in where the signals go, and what each one does, and which signals need to be treated as high-speed signals and so on.

It seems like this kind of information isn't so open-source?  It's not like a video manufacturer is just posting up a datasheet for every person who buys a PCIe card to understand how it is routed from card to the eventual CPU on a motherboard.

For people who are building video cards or whatever for PCIe, where do they learn how to build these devices?


texts: visual studio gui to control stepper motor

texts:
I am using visual studio 2019 and wants to build gui to give commands like speed to control stepper motor through arduino.  I am new to visual studio. can someone share code or can explain?
Thanks


texts:
The transistor circuit in shown in the schematic I have included:

simulate this circuit – Schematic created using CircuitLab

I have tried solving it like this:

First I calculated the potential at node A by applying voltage divider law:

V(A)=(680/680+4.7)*20. The answer is 19.86V.
Now, applying KVL in input loop:

19.86=Ib*R2+0.7V. And this gives the value of Ib to be 0.028mA.
But my text book has the value of Ib=15.45 microA. Why am I getting this much difference in the base current?(Which ultimately causes lots of difference in collector current if gain is high). This is how the textbook has solved it:

I dont know where I am getting it wrong. Would be of great help if someone corrected me. Thanks in advance...


texts: Altium: "Net [] contains floating input pins", but they seem to be connected

texts:
Altium (19.0.10) says the following nets contain floating input pins:

CLR
DIN
LATCH
SCLK

But they seem connected (and on grid) to me (see below). Earlier they were directly connected, no luck. I created an empty project, added this schematic and compiled and got the same errors (and a few bonus errors). Also, I don't want to suppress these errors; I want to fix them.

Even if I connect the schematic to its parent schematic (see below), I get the same errors.

Also, I'm getting "Net [] has only one pin..." errors/warnings for these pins (and many others) in my top level schematic. I've checked and everything is on grid (and I think I have my buses/taps named correctly --e.g. SDO1, SDO2... SDO12 go to SDO[12..1]).

Again, I don't want to place directives to silence the errors. Any other comments are welcome (I'm an Altium newb).


texts: How are Circuitboards with Multiple CMOS Chips Routed?

texts:
For my school side project i'm building a digital clock from 40xx series chips. I'm at 11 IC's now, taking up two regular sized breadboards.

While I could simply solder this all onto solderable breadboad, I do also have some PCB perfboard with pre-tinned thru holes. I can't help but wonder if I could somehow condense the layout to make the board smaller. While the breadboard size would work, it leaves my clock a little larger than desired.

Leaves me wondering... How did people even go about routing boards with multiple, maybe dozens of CMOS chips?

For instance:

What baffles me the most is those chips stacked vertically above one another. My project uses 6 CD4026 IC's to divide time. All 6 are connected to one another for carry outs. I can't imagine any other way to arrange them other than one after another, like this:

And here are my boards.. Possible layout?


texts: Propagation comparison between 868 MHz, 915 MHz and 2.4 GHz

texts: I am looking for  literature for Comparison between 868 MHz, 915 MHz and 2.4 GHz wireless communication system. For example under what condition I should use 868 MHz or when I should not use 868 MHz.  What are the advantages and disadvantages of this frequencies. I am interested only in terms of propagation effect not  other. In environment like indoor/outdoor/vegetation/hill/industrial/ etc  how each of these frequencies would behave?


texts:
In North America sockets and plugs design makes sure you'll be able to plug only in a certain way:
(source)

Why is this important for AC? Moreover, many plugs, such as cellphone chargers, are in fact symmetric, i.e. not "sensitive" to the way they are plugged.


texts: SPI Flash device selection using SCLK, MOSI as well as SS?

texts:
In a system with N SPI devices it would normally take N+3 pins on the master to communicate with them all (NxSS, SCLK, MOSI, MISO).  With N being large and the master device (FPGA) is pin limited, I'm considering the following 2 techniques to increase the number of possible SPI devices in the system; and would like to know if there any (additional) reasons should not be used ? (I've listed reasons I can think of at the end)

Technique 1) Use 'K' SCLK lines (and 'N' SS lines) to effectively "select" NxK devices.  Only 1 SCLK line would be active at a time.

U1: SCLK1 and SS1 (U2 selected but receives no clock)
U2: SCLK2 and SS1 (U1 selected but receives no clock)
U3: SCLK1 and SS2 (U4 selected but receives no clock)
U4: SCLK2 and SS2 (U3 selected but receives no clock)

simulate this circuit – Schematic created using CircuitLab

11 lines (MISO, MOSI, 5xSS, 4xSCLK) could operate a 4x5 matrix of 20 devices).

Technique 2) Multiplex MOSI, using 'J' MOSI lines sending null commands to all devices but one, expecting only the targeted device to reply and the others to remain high impedance on MISO.

U1: MOSI1 and SS1 (U2 selected but receives null command)
U2: MOSI2 and SS1 (U1 selected but receives null command)
U3: MOSI1 and SS2 (U4 selected but receives null command)
U4: MOSI2 and SS2 (U3 selected but receives null command)

simulate this circuit

Again, 11 lines could operate a 4x5 matrix of 20 devices.

Using both schemes together, the 11 pins could be used as 4xSS, 3xMOSI, 3xSCLK, 1xMISO, totaling 36 combinations of uniquely selectable devices (virtually selectable).  Regarding the Atmel 25M01 serial flash, I can't find any problem with using both of the above schemes.  (I know of no SPI master that does this; a custom implementation would be done in a FPGA.)

Concerns I have considered are:

A pulse on SS and not providing a clock might put a slave device into an unknown state, especially if there is activity on MOSI (I doubt it; all "activity" is received via SCLK edges.  The Atmel documentation states that the SPI communication scheme is "reinitialized" after every SS cycle)
An active level on SS might already put a chip's MISO in drive mode (Like the Atmel AT25M01 serial flash, I think most chips would wait for a command before coming out of high impedance?).
Sending a NULL command might still invoke a response; in fact there isn't a definition of a "Null" command, only the concept of an "invalid" command.  (the Atmel documentation states it will not respond to an invalid command and remain in high impedance)
The design might one day be changed and a different SPI device is added.  Do most Flash SPI devices address the above concerns, or am I just lucky with the 25M01?
Some devices such as the Maxim MAX1242 ADC take immediate action solely due to the SS active edge; the ADC starts a conversion on the high→low transition.
Edit: One concern I didn't think of is fan-out. (as mentioned in the answer; I thought it deserved mentioning here)


texts:
How can I convert a .bit (output from ISE Project Navigator) into a .bin file?

For what I understand, .bit files are similar to .bin but with a header that specifies things like the board and stuff.


texts: How to make soldermask on PCBs for soldering?

texts:
I know how to do a PCB until this step (below image) ugly and not safe by short-circuits.

I found this PCB Plating Tape on Aliexpress (Link to the aliexpress product. I'm not the seller) which I think I can use to mask my PCBs but I don't know how can I leave some copper uncovered (like below image) so I can solder components later.

Do you mask PCBs with a tape or some kind of resin spray?
How do you keep some copper uncovered for soldering?

With tape - Cut it away after applying?
With tape - Heat interested area with the welder so it magically goes away?
With spray - Cover the area with something before of applying and then remove the cover?

Do you use rivets (or Annular ring) on holes?

Sorry for the huge list of questions, I am a big newbie.


texts: PWM driven LED array over a shift register

texts:
I am trying to drive 8 LEDs connected to a 74HC595 shift register with PWM. I want to be able to set each LED to a different brightness. The PWM signal is connected to the Enable Output pin of the shift register (it is low active so the PWM signal must be inverted). By selecting each LED (only one LED at a time) and setting the PWM frequency I thought it would have been done. So currently I have following approach:

set PWM frequency
"activate" desired LED by writing according value to shift register (for example first LED would be 0b00000001
write shift register value to shift register outputs by setting the Latch input to 1 and clear it back to 0
start over again with new PWM frequency and next LED

This is resulting in following fault: When I set the first LED to full brightness and the next LED to no brightness (off) I notice that for a short time the full brightness of the first LED is showing up on the next LED. This behavior gives the second LED a little brightness which is bad because I want no brightness (turn it off). I know I could just jump over the LED to leave it off but I would like to only control LEDs brightness by setting the PWM frequency. Also I have this effect when setting for example first LED to full brightness and next LED to half brightness. There is always the brightness of the preceding LED on the next LED for a short time.

I think it is because I can't control the PWM output like I can control the shift register output by its latch. The PWM frequency is applied as soon as I set it in my code. This causes the short blink with preceding LED's brightness. I also tried to change the order of steps in my approach.

Do you have any idea how to solve this problem?

Some lines of my real code (if the pseudo code is not enough):

OCR0A = 0; // set PWM to full brightness
SPDR = 0b00000001; // select first LED
while(!(SPSR & (1<<SPIF))); // write to shift register
PORTB = 0; // latch outputs
PORTB = 1;
_delay_ms(1);

OCR0A = 255; // set PWM to no brightness (off)
SPDR = 0b00000010; // select second LED
while(!(SPSR & (1<<SPIF)));
PORTB = 0;
PORTB = 1;
_delay_ms(1);

My target hardware is an ATmega168 clocked at 20 MHz. I am using avr-gcc.


texts: Altium supplier search: components with cut and tape packaging are never shown?

texts: When I enter the manufacturing code for different components, I seem to only get options for tape and reel packing, but not cut and tape packaging. Is it possible that there is a setting that prevents cut and tape packaged components from showing? And if so, how can I change it so it shows also components with cut and tape packing, if available?


texts: Flyback AC/DC based on UC28881 - TI's reference design - not working

texts:
I have build the AC/DC flyback converter according to TI's reference design  but ist is not working and I am wondering why. By the way: I have build the 5 V version, so everything connected to T1:9,7 I have not populated.
It seems to me that the controller is not working at all.
So far I have measured:

Rectified high voltage: 328 V
5V Low voltage: 0 V
U1:4: 0 V (after power up)
U1:4: spikes to 40 V and decays (in approx. 100 ms) to 0 V (during power up)

What I plan to do yet:

Verify polarity of the transformer`s secondary windings. (after confirmation from TI about the pin out this is obsolete now)

Do you have any advice what else to look for?

Another question:

Why the reference design is using an external current source, though the controller's datasheet suggests using the internal one (have a look at the block diagram)

Another thing to mention is: In TI's reference design they seem to have messed up the pinning for the transformer (WE 750316908). The primary side is ok but on the secondary the schematic symbol (pinning) does not correspond to the footprint pinout (would be glad if you could double check that).

Meanwhile TI confirmed the erroneous pin out numbering. Their advice is to use the following pin out:

What else to add? If some information is missing please let me know. Thanks in advance for your help.

edit:
Link to transformer

edit (schematic added):


texts:
I haven’t used a buzzer before so I have tried to find out as much I could and finally, I am here to clear my few doubts:

Few details about my application:

Buzzer: AST1240MLTRQ (i was not allowed to post more than two links, but it can be found easily)

Peak-Peak Signal, Single Tone, 4kHz, Piezo, voltage range: 1 ~ 25V, 75dB @ 3V, 10cm, 5mA current-supply.

Power supply from cr2032 (~ 3V). My MCU’s one pin can handle only 5mA current. MCU can handle 15mA in total.

Questions

So, after keeping in mind everything above I have following doubts/ questions:

Recommended circuit (just below question 3) is given in this datasheet at page 8 (http://www.mallory-sonalert.com/Documents/TechAppGuides/PAG-Transducers-External%20Drive-Piezo.pdf or see the image directly )

Since, I have MCU to generate PWM, I do not need oscillator circuit. If I am using transistor with gain 50 and collector current is 5mA according to datasheet then base current should be = (MCU pin voltage – 700mV)/ base resistor. If I use 50% of duty cycle (3/2=1.5V average volttage on MCU pin) then

->base current = (1.5V- 700mV)/base resistor,

->(Collector current/ gain) = (0.8v)/ Base resistor,

=>Base resistor= 8K ohm.
Is that right way to calculate the base resistor?

Now, in this recommended circuit (just below question 3), inductor value is given as a sample value. The question is that, why do we need this inductor, although it is said in the datasheet just below the circuit on page 8 (or see the image directly) that, inductor is optional, what does that line mean (that’s kind of ambiguous (for e.g., is it saying that inductor is optional or is it saying that value of the inductor is optional))?
If that inductor is to be used then how do I calculate the value of this inductor for my application?

Or may i use a collector resistor of 1k in parallel to the buzzer and not use the inductor at all?
I could have posted question with more clarity but wasn't allowed as i don't have community reputation. Apologies for the mistakes, i am still learning to walk in hardware design.


texts: Error while simulating vhdl code for 4 bit counter in vivado 2015.2

texts:
Sir,

Whenever i simulate my vhdl code of 4 bit counter in Xilinx vivado 2015.2, i get the error message like following.

  ERROR: [VRFC 10-724] found '0' definitions of operator "+", cannot determine exact overloaded matching definition for "+"

My vhdl code is

library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use ieee.numeric_std.all;

entity my_count is
Port ( clk : in STD_LOGIC;
       clr : in STD_LOGIC;
       y : out STD_LOGIC_VECTOR (3 downto 0));
end my_count;

architecture Behavioral of my_count is
begin
    process(clk,clr)
    variable temp: std_logic_vector(3 downto 0):="0000";
    begin
        if(clr='1') then
            temp := "0000";
        elsif(clk='1' and clk'event) then
            temp := temp + 1;
        end if;
        y <= temp;
    end process;
end Behavioral;

test bench is

library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use ieee.numeric_std.all;

entity my_count_tb is
    --  Port ( );
end my_count_tb;

architecture Behavioral of my_count_tb is
component my_count
    port(clk,clr: in std_logic;
         y: out std_logic_vector(3 downto 0));
end component;

signal clr,clk: std_logic;
signal y: std_logic_vector(3 downto 0);
begin
    process
    begin
        clk <=not clk after 5ns;
    end process;
end Behavioral;

please help me to solve this error


texts: Quartus II: Pin incompatible with a bank it is not on

texts:
I am using the pin planner of Quartus II to place my I/O signals on my Cyclone IV pins. I am stuck on the following fitter error:

  Error (169029): Pin adc0_in[0] is incompatible with I/O bank 3.  Pin
  uses I/O standard LVDS, which has a VCCIO requirement incompatible
  with that bank's VCCIO setting or its other pins that use VCCIO 3.3V.

The Cyclone IV is organised in banks that should have the same VCCIO. The strange thing about this error message is that the pin adc0_in[0] has been placed on bank 8, not bank 3, so there should not be any contention. (Figure 6-10 from the datasheet shows that bank 8 and bank 3 use VCCIO8 and VCCIO3 respectively.)

I am also getting the error

  Error (171169): Previous compilation results are reused as part of
  this compilation and may cause the error on this compilation.

but I have made sure that incremental compilation is not enabled (as suggested here) and that the database folders have been deleted (as suggested here).


texts:
I would like to power a speaker using two separate power sources and I would like the selection to default to 18V AC-DC wall adapter first, if available.  If that source is not available (unplugged), I would like the circuit to instantaneously (will explain this in a bit) switch to the alternative power source which is a 3.7v lipo battery.  The 18v source should feed the following:

Option 1: 30W 12-24V input amp -> speaker

Option 2: 18V to 4.2V buck converter -> 3.7V protected lipo battery -> 3.5-5V input 3W amp -> speaker

Both options are driving the same speaker.  Option 1 should be the default but if the 18v source is unplugged i would like the circuit to switch to option 2 in a timely manner. Meaning that if the speaker is playing music and being driven by the amp in option 1 and power is suddenly unplugged, I would like for the circuit to quickly switch to the battery and continue from there.  Additionally, when the 18V is connected, the circuit in option 2 should be charging the battery but power should not be fed to the 3w amplifier. Conversely, if the buck converter is not on, the battery should be feeding the 3W amp (any additional protection necessary here if buck converter fails while 18v power source is connected?).

I come from a mechanical background and only do this as a hobby so please understand that my electrical knowledge is limited to basics. I was looking into schottky diodes but I'm not sure what the selection criteria is and where in the circuit they should be put. Any help or additional resources on this topic is greatly appreciated.

Cheers!


texts: NHD-0216HZ-FSW-FBW-33V3C Black Boxes in Line LCD Display

texts:
I installed a NHD-0216HZ-FSW-FBW-33V3C with an MSP430g2553. I tried to initialize it for 4-bit mode in assembly language but black boxes still shown and initialization is not completed I think.

My connections are: DB4-DB7 --> P1.4-P1.7 respectively, RS --> P2.0, R/W --> P2.1, Enable --> P2.2

Here is my code:

Init:     bic.b     #0xFF,P1OUT  ;Clear P1, P1 = 0
      bis.b     #0x01,&P2OUT ;High RS = 1
      bic.b     #0x01,&P2OUT ;Clear RS = 0
      call      #Delay100ms
      mov.b     #0x30,&P1OUT
      call      #Nibble      ;Wake up 1
      call      #Delay10ms
      call      #Nibble      ;Wake up 2
      call      #Delay10ms
      mov.b     #0x20,P1OUT
      call      #Nibble      ;Wake up 3
      call      #Command28
      call      #Command10
      call      #Command0F
      call      #Command06
      ret
Nibble  bis.b      #0x04,&P2OUT ;Enable High
      call       #Delay1ms
      bic.b      #0x04,&P2OUT ;Clock Enable - Falling Edge
      ret
Command28     mov.b     #0x28,&P1OUT //Data in port
      bic.b     #1,&P2OUT    //RS = 0 : Send Instruction
      bic.b     #0x02,&P2OUT //R/W = 0 : Write
      call      #Nibble      //Send Lower 4 Bits
      mov.b     #0x28,R4
      push      R4
      mov.b     #4,R5       ;Rotate Left Counte
C28           rla.b     R4
      dec       R5
      jnz       C28
      mov.b     R4,&P1OUT   //put data in output port
      call      #Nibble     //Send upper 4 bits
      pop       R4
      and.b     #0xF0,R4
      mov.b     R4,&P1OUT
      ret

This code is following the code in the NHD-0216HZ-FSW-FBW-33V3C datasheet from http://www.newhavendisplay.com/specs/NHD-0216HZ-FSW-FBW-33V3C.pdf. If someone can help me.


texts: High Level Synthesis of a Microprocessor

texts:
I am working at an FGPA shop right now using Xilinx FPGAs. I do not have a ton of experience with designing logic, especially when it comes to microprocessors. One of the big movements my team is looking at is to adopt High Level Synthesis (HLS) which translates an algorithm written in C down to RTL that can then be placed and routed onto an FPGA or even forwarded to an ASIC design.

A similar question was asked here Convert C to FPGA, but I want to direct the response of this question directly to the architecture of a microprocessor.

My question is what would it take to implement an algorithm for a microprocessor? You obviously have the ISA, so I am assuming the your inputs would be each operand, depending on how many your processor takes, and the op code? I am assuming there would need to be some buffer allocated to represent the caches/registers for the architecture? Also, you would probably need to allocate space for RAM since ISAs have register indirect operations that might require those type of memories to be already allocated.

For example, lets say I want to make an Intel 8008. Can you give me pseudocode to demonstrate the algorithm that can be put through a high level synthesizer to get that hardware?

Edit

When I ask for pseudo code I obviously do not mean a full product. I just want the major steps that would be involved in the design of the algorithm. I am guessing it would revolve around fetching, decoding, and executing the input to the function. The comments with the emulators and the AUGH look like they will be a big help.


texts: TP4056 and ST32F103C8T6 shorting after few uses

texts:
Complete schematic:

Top part:

Lower part:

This is the circuit schematic, top part is sensor, bluetooth, microcontroller, oled and pins related all working from 3.3v coming from regulation of a charge pump; bottom part is power regulation part, smart load sharing for LiPo, battery charging and battery protection circuit (though battery has its own) and ESD protection from DC barrel jack.

I am using TP4056 as battery charger, stm32f103c8t6 (ordered from LCSC) as uController, 82402305 for esd protection and ltc3240 as a charge pump below 3.3 volts and voltage regulator above that up to 6 volts.

After a few stable uses the system smokes and at some point each of this components has been found shorted, three times the system has failed being the first time the uController the one which failed through shorting and minimally heating(though I didn't use the system as expected and injected voltage several times through OLED pins and power switch and I think I could have connected something wrong so it was my fault) and the second and the third time being the tp4056 the one which first smoked and shorted immediately after connecting dc barrel jack (polarity and voltage checked in  open circuit) with the curiosity that the third time something happened (I let dc barrel jack connected longer compared to second time where I saw the smoke and disconnected it immediately) that made ESD protection, ltc3240 and uController short (which makes me believe that tp4056 is not the problem but something in the uController) with the fact that neither bluetooth, sensors nor OLED screen have ever damaged.

More detail:

1st fail: Soldered everything, injected 3.3 volts through oled pins and 5v through switch so it passed through charge pump so I could test it; after several time of using the system (programming it and related stuff) found a short after and OLED not displaying anything, ARM cortex is shorted, changed it and everything works (it maybe was my fault but ARM cortex is found damaged on third fail though)

2nd fail: Tp4056 smokes after connecting barrel jack now I decide not to inject voltage, a short is detected, tp4056 is the fault, change it, everything works again and achieve one complete charge cycle from 3v to 4.2 volts.

3rd fail: Battery drains to 3v I connect barrel jack-> magic smoke, 1 short but this time 82402305, tp4056, ltc3240 and arm cortex are shorted, remove and change, everything works again

Thanks for your precious time


texts: Optimal time needed to balance lithium cells

texts:
I want to balance a lithium cells with 65 Ah capacity, the threshold to start balancing is SOC=101%;
In order to calculate the  balancing current,I need to fix the balancing time,
so what's the optimal time to balance cell with such capacity (1hour,30 min....)?


texts:
Would 2 ideal inductors in parallel carry currents according to current division even if the excitation is DC?

I am asking this because my spice simulation is showing they will carry equal currents, despite having unequal inductances.

A possible explanation what I have thought is, since the inductors become short for DC, so they carry same current. Correct me if I am wrong.


texts: Location of diode bridge on transformer circuit?

texts:
I'm designing a full bridge rectifier that takes 110vAC to 4-16vDC for input into a 5v switching regulator.

I opened a few 5v power supplies and they place the bridge on the high voltage side. Why not use the low voltage size so the diodes are smaller/cheaper?

Also, I notice they use an IC on the high voltage side, what is the purpose of that IC and is it required?

Most circuits I see online are basic like this one which should give me full wave recification:

This is the transformer I'm using:
http://catalog.triadmagnetics.com/Asset/FS10-600-C2.pdf


texts: What to do when pouring polygon if you didn't use a GND?

texts: I designed a test board for connectors and it doesn't have any ground net. I am new at designing pcbs and I always used ground polygon pour. I don't know what to do without gnd polygon. What should I do? Should I leave the polygon without any net or is there any way to pour ground in design without gnd connection?


texts:
Could someone advise me on what would be a good practice to interface the CoolRunnerXC2C256 with an external clock? I wish to use KC5032A20 crystal and have it to drive  global clock GCK2 (pin 38).

Do I connect output pin of the crystal directly to GCK2 pin, or I should have some intermediate components (pull-up resistors, buffers, etc.)?
20MHz for this CPLD is slow. Would it be a good idea to configure GCK2 pin as Schmitt-triggered?
Should I use separate power supplies for each Vcc, each Vccio1, and each Vccio2 pins, or one power supply per bank is good enough?
Should I use separate power supplies for the CPLD and the Crystal?


texts: Factors determining number of turns in field winding of Sychronous generator

texts:
the question is simple, based on what factors do I choose the right number of turns in field winding (for synchronous generator)?

It seems like the less turns there are, the more DC current is needed to sustain the magnetic field. Thus the lower limit is the current itself and generated heat (Assuming the winding is made of copper, not super-conductor).

Is there any upper limit then?

My (faint) idea:

Field winding on the rotor turns, therefore if I connect load to armature winding, there is magnetic field produced by armature winding itself. This can induce voltage in field winding and burn it (because the wire is not thick enough). But this idea seems incorrect, because the DC source for field winding would suffer from hude changes of Voltage during normal function.


texts: Parallel trace signal integrity: Increasing width to match characteristic impedance vs increasing trace gap

texts:
Imagine you are routing a large number of single ended high speed traces through a long narrow gap on a PCB. Lets say these are ultra-high speed SD signals, so a 208MHz clock. The traces should be 50mil to match the impedance of the source and receiver.
However, as you are short on space you have to choose one of the two options:

Route at the correct width for impedance matching, at a cost of reducing your inter-trace gap to 10mil (i.e. 0.2W), thus greatly increasing crosstalk
Route at 10mil width to achieve a larger gap of 50mil (i.e. 5W), at a cost of a significant impedance mismatch.

Which of these two options is the lesser evil and why? If the answer is somewhere in the middle, how do you evaluate the tradeoff? Does there exist any rules of thumb for prioritising characteristic impedance vs crosstalk?


texts:
I apologize for the basic question - I'm just getting into electronics and have come across a diagram that I don't understand (or more accurately, don't want to risk frying my Arduino with not understanding).

I recently bought a relay from Radioshack. I've copied the diagram:

I assume that I apply the large current through 2 and it goes out 4, and then either 1 or 3 is to switch it off and on? Can someone confirm or correct me on that?

Thanks!


texts: Can electrodes be used to transport currents generated by piezo crystals floating inside conductive gel

texts:
I have an idea and want to know if this is feasible. The idea is to put little piezo PZT crystals inside a conductive gel, the gel itself is contained by a membrane which receives stress from outside factors. On the inside of the membrane I want to place electrodes who's job it is to transport the generated currents to somewhere outside the membrane.

Is this something that can work?


texts:
I am doing a case study on battery back up of a wind system with the following specification:

System size: 10 kW which runs continuously for 5 hours per day.

Battery Calculations:

Battery type: lead acid
Energy generated per day: 50,000 Wh
Back-up days: 1
Depth of discharge: 50%, so 50000 Wh/0.5 = 100,000 Wh

Battery de-rate factor based on temperature (NJ max. = 63°F)

De-rate factor = 1.04, so 100,000 Wh x 1.04 = 104,000 Wh

Battery voltage: 48 V.

104000 Wh/48 V = 2166 Ah.

The next size up is 2200 Ah.

Can some one help me verify my calculations and also how to calculate the charging time and discharging time for this battery?

Thanks any guidance is much appreciated


texts:
Is there a circuit which can detect how much amps are flowing through it, and if the amperage falls below a certain level to output some signal?  (e.g. to direct the voltage to a different output)

Due to getting only vague answers on the question How to attain a topping charge for a lead-acid battery?, I decided to rephrase what I need in a different manner.  I am very new at these things, so I apologize in advance if there is some way I am not explaining myself well; or maybe this is completely trivial to look up somewhere, and that's the reason I have not gotten any answers other than those of the type "Yes, this can be done".


texts:
I am trying to build an amplifier circuit using TDA2003, I found a common type of circuit for this purpose in almost all the websites. I tried building it in Multisim and after some seconds of simulation many capacitors and resistors blow up, even with 9V of power supply.

You can see short-circuited capacitors and blown up resistors in the screenshot. Please tell me what I am doing wrong, I just copied it from the circuit available in the datasheet.

I used the TDA2030 IC for simulation because TDA2003 is not available in Multisim. Please instruct me whether the circuit is correct or not? Or there is the issue with the simulation or simulation software?
Should I try it building in practical with the same values without any risk? Please suggest any other circuit available.


texts:
I am going to wind an tapped toroid inductor for a LCR circuit in an equalizer.
I have calculated the number of turns I need for each winding.
This is my first time winding an inductor so I need to get some things straight.

I'm confused about the bandwidth tap, how should I wind this on, just one turn to the core?

Also the 10 kHz tap, should I twist a wire with the 12 kHz tap in
order to have two taps with 31.4 mH?

Info:

Core type MPP

OD 39.90 mm

ID 24.1 mm

HT 14.5 mm

AL value: 740 +/- 8% (nH)

MPP Permeability: 550 (μ)

Wire gauge: 34 AWG

16 KHz - 29.9 mH 194.851 turns
Wire lengh 8.829 m

12 kHz - 31.4 mH add 4.827 turns

10 kHz - 31.4 mH twist a loose wire to 12 kHz ^?

8 kHz - 48.2 mH add 47.761 turns

5 kHz - 67.5 mH add 45.325 turns

4 kHz - 87.9 mH add 41.324 turns

3 kHz - 156 mH add 110,982 turns

Bandwidth?

Help is much appreciated!


texts: Select N-Channel MOSFET to drive speaker and LEDs

texts:
I have 3 circuits with MOSFET gates routed to MCU's PWM / IO and I would like to drive with them a Speaker, RGY LED and Backlight of LCD.

There's a lot of parameters in MOSFET's datasheet. I am not sure if this is the right MOSFET for each of the circuits here. Can you help me to determine if this is the right MOSFET?

I have chosen the MOSFET by Vgs(fit to MCU max Voh), max Vds and Ids.

Speaker circuit:

LED circuit:

LCD backlight circuit:

Thank you.


texts:
I want to use a photo resistor to make a circuit like this

But instead of light causing the led to turn on, I want darkness to cause the led to turn on.


texts: Which capacitor for DC blocking in audio applications?

texts:
Which capacitor (electrolytic, film, ceramic) do you use for DC blocking in audio applications? From what I have seen most people use electrolytic capacitors.
But, also from power decoupling theory we know that we need to add a 10uF electrolytic capacitor with a 0.1uF ceramic capacitor for removing the high frequency components.

But, isn't it the same idea for DC blocking applications? Shouldn't we put electrolytic and ceramic capacitor in parallel?


texts: Can we represent circuit with only text?

texts: We normally use circuit diagram to represent circuits. Is there any markdown language for circuits, so that we do not have to use images to represent a circuit.


texts: Getting small pulses on the output of an AND port, even though inputs are always low

texts:
I am building circuit and in that circuit, I have an AND port (7408). When using a logic analyzer, measuring both inputs (on 24 MHz) they stay low.
However, when measuring the output, I see some noise. Never longer that the sampling time though (24 MHz, so ~42ns).
Is there a reason for this, and how could I prevent / mitigate this? The pulses on the output are used as a clock signal, so the receiving end is getting more clocks than I want.


texts: ground plane on 2 layer board with wifi module

texts:
I have a 2 layers PCB that I mount a Wi-Fi module. Components (SMD) are placed on the bottom layer and the Wi-Fi module is on the top layer.

I apply ground plane on both layers, as I read, it is good for the EMC compatibility. I know multiple layer design is even better, but now I need to have only 2 layers design.

I wonder if the ground plane might interfere or disturb the RF signal or block the signals coming from the other part of the board?

In this sense, is it fine to keep the ground plane on the both layers or make some holes on the PCB to prevent Farady's cage kinds effects?

Edit: here is the link of datasheet of the WiFi module http://www.zcomax.com/embedded/ZCN-722M/ZX-ZCN-722M-DS.pdf but it is a very simple one


texts:
I'd like to buffer the output of an operational amplifier using a source follower.

The operational amplifier produces a sinusoidal wave like this.

I would like to buffer this signal. To do that I use a source follower like that.

I tried a few things.

But I see only small signal at the input of the mosfet. And mosfet doesn't enters into saturation region. I tested this circuit seperately and it works fine on his own.

This is the seperate version of the source follower. I'd like to replace small signal sinusoidal wave with output of operational amplifier.

How should I bias the MOSFET using LTSpice simulation software?

Update :
I added a voltage divider resistor network to the non-inverting input of operational amplifier.

The input signal is a triangle wave. It's frequency is about 2.7 kHz.

Actual input signal, the green one in simulation looks like this:

Source follower is as before

This time output of source follower looks fine.

Isn't the input voltage of the source follower is quite high? Shouldn't the input voltage be very small? E.g. 500 mV etc.

Update 2:

Decoupling capacitors

At first glance I used decoupling capacitors instead of non-inverting input of the operational amplifier.

As you'd see input and output waves are almost identical.

Biasing from op amp non-inverting input

This time hopefully I should be able to find the non-inverting input.

There is about 3.5 volt bias voltage on the output signal.

This time I removed the first decoupling capacitor at the gate of the source follower to be able to operate mosfet in saturation region.

Also this time, the output of the source follower looks fine to me.


texts: 555 timer IC unexpected pulse wave width problem in monostable mode

texts:
I was trying to make a monostable timer for a specific project which should trigger output high for around 5 seconds. For that, I have chosen a capacitor of 4700uf and a resistor of 1K.
According to the formula of monostable mode (\$T = 1.1 * 1000 * 4700\$), it was supposed to trigger a pulse width of about 5 seconds,  but when I built it the timer pulse width is something more than 5 seconds, around 10-15 seconds
Here is my schematic:

simulate this circuit – Schematic created using CircuitLab
What mistake did I make here? Please point out the mistake with valid schematic if there is any.


texts:
I have seen a few different ways of adding DC bias to an audio signal. I have simulated them and they all give me similar results, but I can't figure out why choose A over B or C. My audio source will be a Line Level Audio -2V to +2V AC passed through a 220uF coupling cap and then a low pass filter(RC, 2 pole). The signal will be read by an ADC.

First way is using a Voltage divider:
Simple Biasing Circuit

This is pretty self-explanatory and I understand how it works. I have also seen this same design using a diode but could not find an example.

Next example: How to read an audio signal using ATMega328? - picture is from endolith's answer.

Another one that I have seen is: I don't quite understand this FET-BJT preamp circuit

And the schematic is for a pre-amp, and there are 2 versions and both add a bias.

My question is what is the best practice for adding the bias to an audio signal? What are some of the other ways to add a DC bias to the signal?

Edit/Update: Looking at the answers - using the second one looks like it will work best for my application, using something like this. Are there any other improvements I can make? Other then Stable Vref/power rails.


texts:
I've been looking for a fun project to do and wanted to make a GPS tracker like this:

https://www.cooking-hacks.com/documentation/tutorials/geolocation-tracker-gprs-gps-geoposition-sim908-arduino-raspberry-pi/#shield

The goal would be to set up an arduino controlled device that I can ping for location and then display this on my computer. However, it seems like I need a SIM card for that.

If I wanted to make a tracker but avoid paying some monthly fee to have a SIM card, how would I do that? Is there some SIM card that is pre-paid and allows for a certain number of messages each month?

Is there a way to send small messages over satellite communication? A GPS tracker would not be of much use if it is dependent on cell towers.


texts: misunderstanding of Voltage output of a 3-phase rectifier

texts:
I simulated a 3 phase rectifier :

I obtained V1 and V2 as plotted below :

I dont understand that waveform as i'm supposed to obtain a DC voltage.
Can someone explain me how it comes that i got this waveform ?
Thank you in advance.


texts: making two wires short when arduino gives 1 on digital output

texts: I want to short two wires when arduino gives 1 on specific digital I\O. Transistor is the best solution I have got but I am not able to find transistor Ic for 3.3 v switching. Do share with me if there is some other solution than transistor. Can somebody tell me the name of transistor which works for 3.3v when base is given 1. Thanks


texts: Supply voltage for MOSFET driver in high-voltage (110v) PWM regulator

texts:
I am designing PWM speed control for 110v DC motor. Since it is 110v, I am going to power it from bridge rectifier connected to mains, with MOSFET on low side for switching.

For driving MOSFET I plan to use dedicated driver (though it doesn't matter for the question I have, so let's assume I drive gate directly from the low-voltage schematics).

For low-voltage side (microcontroller/logic) I want to use typical wall charger, which is switched power supply, as I understand.

The tricky part here is that driver supply voltage (or gate voltage) will have to be applied relative to the "power ground" ("-" of bridge rectifier/MOSFET source). This means "-" of the 12v switching power supply will be connected to the "-" of bridge rectifier. If the 12v power supply was transformer-based power supply, it wouldn't be an issue since 12v part would have been isolated from the mains and connecting two grounds would be fine.

However, somehow I think that connecting these two grounds in case 12v is provided by switched power supply would result in a short, since, as I understand, there will be no galvanic isolation between 12v and 110v DC (bridge rectifier output).

So, the first question, if I am understanding the problem correctly?

Second question is, what options do I have for supplying power for gate driver/MOSFET gate? I can isolate logic part using optical isolator, but I would still need low voltage power supply for driver/gate.

It seems to me that simple option (without using transformers) would be to use resistive/capacitive power supply connected to the bridge rectifier? Although driver should be able to provide relatively high current to the gate (let's say, 5A), as I understand, what matters is how much charge is actually transferred. Assuming Qgs = 150nC and switching frequency of 20kHz it would be Qgs*F per second, which gives Isupply = Qgs * F ~= 150nC * 20kHz = 3mA. Which means, resistive power supply providing 50mA would be plently. 50mA with 100v drop would give 5W of burned energy, which is OK.

So, the third question, am I right in these calculations?

Here is the schematics, but there is not much to draw. I omitted all other components (like snubbers, etc). Box on the bottom is switched power supply. L1 is motor. Imagine I want to open MOSFET by applying 12v to gate-source. My understanding is that I cannot just connect two grounds and connect 12V to Vg -- this would result in short.

simulate this circuit – Schematic created using CircuitLab

P.S. I think, I am wrong about switched power supply. It seems like some of them (most of them?) are actually isolated. Which means I should be able to use it for MOSFET driving circuit.


texts:
I'm continuing development from this question.

The schematic given by Jasen worked as a charm but little did I know that was with the connector plugged out, as soon as I plugged the connector in I found out that it no longer works. After a bunch of tries and failures I determined that while I'm essentially connecting a pair of pins, another one must be disconnected(?).

The connector consists of 4 pins in total which I've labeled P1 to P4 below, which correspond as shown to the previous question:

P1: Unlock
P2: Common
P3: -
P4: Lock

Basically to unlock pins P1 and P2 need to be connected and P3 must be disconnected, or open. To lock pins P2 and P4 need to be connected and P1 needs to be open, where by open I mean there must be no connection between the plug and the socket.

This slightly complicates and adds on to the schematic from the previous question, here is what I came up with:

I see how it can probably be slightly confusing, labeled P1 to P4 are coming from the car and P1' to P4' go in the socket on the door, I've omitted P2' and P4' because they are directly connected to P2 and P4 (spliced connection).

I'm using an LM2902 as a logic not gate, since I already have it and I'm using only 1 channel of it so I decided I'll just use 2 more instead of buying a not gate. Basically the paths from P1 to P1' and P3 to P3' should be broken respectively as described in the scenarios above.

I also found out that the voltage between P2 and P3 (12V/0V) tells me the state of the lock but that's not relevant to the question - I'm just mentioning in case someone wonders.

Now there is definitely something wrong because only the lock part works and the BC556 that's connected to P1 and P2 immediately gets hot when it shouldn't especially as there is no signal on the unlock line to begin with. Cables around it got brown - that hot. After replacing it, that is. First one had decomposed with it's collector leg broken apart. I'm probably going to go ahead and use relays because I've spent way too much time on this problem, but I really wish to know what's wrong with my current plan because I just got excited about transistors..

PS: I apologize there are no labels on the components.
PS2: All 3.7k resistors were replaced with 3.3k resistors except the one on the state divider, but it probably doesn't really matter.


texts: Wi-fi chipset with SDIO interface in SPI bus mode

texts:
I want to connect a Wifi-chipset, which offers an SDIO interfaces to a microcontroller that only supports SPI.

As far as I understand from the specifications, every SD card can be connected to a host microcontroller on its respective SPI ports and then be operated in SPI bus mode. Now there are also certain Wifi-chipsets that have an SDIO interface for the connection to the host microcontroller. Maybe my question is trivial, but do also all Wifi-chipsets that offer an SDIO interface support the SPI bus mode? Or does it have to be explicitely supported by the manufacturer? Does the supported SDIO version have an influence?
Because in the datasheet of the Wifi-Chipset it does not mention the SPI transfer mode.

Edit: I am not looking for a suggestion which specific chipset to use. I know there are wi-fi chipsets that support spi or spi transfer mode.


texts: synchronous buck converter with different MOSFETs

texts:
do you know if it is possible to use different type of MOSFETs in a syncronous buck converter for the hi-side and the low side switch? How does this improve the converter efficiency?

Thank you


texts:
I am new to electronics and I can't get this simple circuit to work.
Can anyone please tell me if the circuit is drawn correctly and the values are right?
It is supposed to run on 5 to 12 volt.
I am using 10 volts  from a 7805 rigged to output 10 volts from a 12 volt battery.


texts:
From JLCPCB it lists many type of clearances.

However in KiCad, it only lists one type of clearance, and I don't know what it is.
0.5mm is the highest value for clearance in JLCPCB and in KiCad it's 0.2mm by default. Should I just change it to 0.5mm for all type of clearances?  Any solution is much appreciated. Thank you in advanced.


texts: I would like to use the 5206-2G H-bridge for my wireless power transfer circuit, but i can't find the switching frequency which the FET's can tolerate. I have looked several times at the datasheet, but i can't seem to find it.


texts: What is this effect causing a flash on video when a model aircraft collides with the ground?

texts:
When recently flying a model airplane with friends, I was recording on a smartphone camera (I believe CMOS, 720p, 120fps), and saw, in one of the videos, a flash that was not visible to the naked eye, that covered the whole frame of the video. This occured at the same time that the aircraft collided, about half a meter from the camera. The frame appears to be almost pure white (#fefefc), with the left side (farthest from the brushless motor) having a slightly weaker white (#fefefb), although this is after the video was compressed. There are no visual artifacts or effects in the frames before and after.

The airplane has a single brushless motor, with an ESC (electronic speed control) attached. I don't currently know the specific specs of the motor and ESC, but can readily obtain them later today. The collision happened when the motor was still powered and spinning.

I am suspecting that the sudden collision while the brushless motor was still being powered caused some kind of electromagnetic effect (when it collides, the rotor is mechanically restrained by the ground), but I am not sure what actual effect is going on. I suspected simply a small electromagnetic pulse, but am not sure how it would affect only the camera module and not cause data corruption or crashes by affecting the CPU/memory. It's likely that the camera was set to a very high ISO/sensitivity in order to record at 120fps.

Could someone shed some light on how it was caused by the motor/motor controller itself, and how it managed to cause the camera to register a large flash?


texts: Balancing of 18650 battery with parallel cells

texts: Does a 1S4P 18650 battery need balancing? I read a lot about balancing around the internet. To me it seems like this only applies to the cells connected in series. An all parallel setup would not need balancing. Is this correct?


texts: 120v AC to 220v AC converter, most cost effective way

texts:
I bought a vintage russian tube clock on ebay, it expects 220v AC.

What is the best solution I can build myself? With the intention of installing in the case and soldering connections to.

I am also open to small existing products that can be modified.

The clock : https://www.glaver.org/blog/?p=419

The page linked above mentions modifying the internal transformer to take 120V, however it does not go into detail about which jumper to remove to achieve this. How would I determine which jumper to remove on my own?


texts: Physical Properties of Memristor from I-V characterestics

texts:
I'm trying to understand what an IV plot of a memristors tells me in terms of physical properties. So these are the questions with the relevant plots:

If I have a pinched hysteresis loop that does not cross the origin (as in the image below), so either displaced on the x-axis or y-axis, or both, what does that physically signify? How does it differ from a memristor whose curve crosses the origin?

How does a tilted pinched hysteresis loop differ in physical properties from one that is not titled? What does a rotation/tilt by an angle theta physically signify for a memristor ?

What does the area of a pinched hysteresis loop resemble - if my input variable is voltage (so a voltage controlled memristor)? And what do different area values signify in terms of physical properties of memristors? And what is the effect of scaling on the physical properties of a memristor?

These are more generic questions that I am not sure of and I am not able to find answers to in the original Chua paper, answers or suggested references would be very helpful. Thanks in advance!


texts: What is a good communicaton device among teensy and arduino besides "XBees"

texts:
I have been using XBees to communicate my teensies so far.
However, as you know, XBees are really expensive and when I want multiple devices to communicate with each other, I have to pay for several teensies + several XBees, which
come up to be more than 200 dollars.

Also, An XBee is for between two designated teensies. I want all of my teensies to communicate with each other

Is there any communication device out there that I can hook up to multiple teensies or arduinos at once without buy as much XBees?
Or what is a communication device that lets everything within the range to communicate with each other?
Or any other way to let them communicate without using individual teensies?

If you can answer any of them, please help me out!!


texts: CircuitMaker: Nets Wire JACK_IN_GND has multiple names, why is this bad?

texts:
There is a solution here: How can I resolve the error "Net wire X has multiple names"?

However, JACK_IN_GND and JACK_OUT_GND will go to two different directions (one input cable and one output cable). And GNDs should be tied together.

Why is having two names so bad? Should I simply call it GND? And assuming since it's next to another wire (JACK_IN_SIGNAL and JACK_OUT_SIGNAL) that it is a GND signal for IN resp. OUT?


texts:
I cannot find a clear answer to my question on the web, so I hope you can help.

I have a Sony VAIO VPCX11s1e/b netbook (11.1 in.) with a 10.5V input for a powersupply.
I want to use it with a solar power system, but the lowest DC output on this is 12V..
Will it work ?
Does anyone know about this specific VAIO model ?
Thank you so much in advance :)


texts:
Why the circuit theory works well when a lumped-parameter system has dimensions of one tenth of the electromagnetic wavelength? Why not one third or any other ratio of the electromagnetic wavelength?

Book Ref: Electric Circuits, by James William Nilsson, tenth edition.


texts: Does this require a larger series resistor?

texts:
I am connecting a switch to an input pin on a Nexys A7-100T FPGA development board, like shown in the below image:

The circuit has a 10K pull down resistor (R1 on drawing above) to ground and the FPGA has an internal 200 ohm resistor in series with the input pin (See below image from the FPGA datasheet). I am using pin 1 on the JA PMod connector with the 3.3V and GND pins 5 and 6.

Do I need a larger resistor in series with the FPGA input pin like a 10K? Or is this ok as the FPGA is configured as an input and is high impedance?


texts: Thermal Management for Arcol HS50/HS100 50/100W Wirewound resistors

texts:
I'm designing a 100W dummy load for a guitar amplifier using Arcol HS50 and HS100 resistors. Here's a link to the datasheet:

http://www.arcolresistors.com/wp-content/uploads/2014/03/HS-Datasheet.pdf

This is my 16 ohm dummy load. Worst case it will see 100W at its input. R1 is the resistor I'm concerned about.

I have never used these resistors before and I'm wondering if they might end up overheating or warping my board in my design.

You can see my first attempt at creating heat sinks here. R1 is a 16 ohm HS100 (100W) resistor, while RZ8 is 16 ohm HS50 (50W). There will be a switch to connect RZ8 in parallel with the 16 ohm load to present an 8 ohm load to the source.

Will this be enough to keep these resistors in a safe temperature range when the input is pushing 100W?

My thermal vias have a drill diameter of .1mm and they are spaced 1.2 mm apart connecting to the ground plane on both top and bottom layers. I've placed a stop mask to expose the ground plane under those resistors on both the top and bottom layers of the board.

I know this is a deep subject and I'm not asking anyone to go through and do all the math for me. I'm looking for someone with experience with these resistors to let me know if it's clearly going to end in catastrophic failure or if my heat sinks have a chance of doing the job.

I'm also curious how other people use these in their designs. Can anyone show me how they've successfully mounted these resistors to a PCB and how they were able to manage the heat?

Please let me know if I've left out important information. Thank you.


texts: RS-485: what happens when bus contention occurs

texts:
I'm refering to an half-duplex RS485 application which consists of a master and multiple slaves like in the circuit below (I'm using an ST3485).

simulate this circuit – Schematic created using CircuitLab
From my understanding, the drivers outputs are tri-stated (high impedance when receiving, high/low when transmitting). As RS-485 transmition is done using a common mode signal, I believe that the devices do not neccessarily have to share common ground (is that true?), but in my case, the master provides the slaves with power, so I'm going to have a ground connection.
My question is, what will happen in case of a bus contention, so if e.g. both slaves transmit data at the same time? Sure, the data received by the master will be corrupted, but does this also harm the drivers?
If yes, what measures are typically taken to protect the drivers?


texts: Cost-sensitive way to maintain a 220C temperature

texts:
I'm building a device which is designed to be built by people of varying skill and education levels.  Part of it needs to climb to and maintain a temperature of 220C, but I don't need very tight regulation.  Swings from 215-225C are acceptable, but not desired.

My normal goto for this is a microcontroller, thermistor, MOSFET, and heater cartridge.  I know for a fact this is above my target audience's skill level.   My next goto would be digital PID controllers, and those are going to be out of my budget by a significant portion.

My project has 5v & 12v available (5v would be preferred actually, saves me a 12v power supply).  I've seen temperature fuses, but those seem to be one shot so as not to set fire to something.  I've seen PTC thermistors, but ... I don't know how well strapping one of those to the hot part of this assembly is going to work.

Any suggestions?  My ideal solution could be had from either a local B&M store, or Mouser, for $5 or less qty 1.


texts: Is is possible to produce a resistance that represents the average of two thermistors?

texts: For example, if I want to connect 2 thermistors to a thermostat in a circuit and then return the average resistance between the two of them to the thermostat's ADC.


texts:
I'm using a SiLabs USB->UART converter.  In the documentation, it recommends a specific TVS diode.  The diode in question has four positions/pins, and appears to be a diode array.  I have never used a diode array before, and am not entirely sure that I understand the wiring of this.

The diagram for the converter is:

The pinout for the diode is:

Is it correct then that I need a single TVS array, with pin 1 to GND and pins 2-4 to VBUS, D+, and D-?  I'm presuming that's correct, but figured I'd ask for advice from folk who may have actually used a diode array before.  Thanks!


texts: Troubleshooting Assistance Over Heating Regulator Due to GPIO?

texts:
Great site.  Thank you for taking the time to help me with my issue.
I am pretty much intermediate to novice in electronics.  The more I review schematics and look at circuit boards, starting to recognize common components, so making progress!

Working on repairing an existing board that uses a C8051F387 (MPU?  Micro-controller) to do everything.  Reading through the 320+ page datasheet, this thing is pretty amazing to me, such a little package.

Anyway, when everything is connected as it should be, the 5V regulator on the board gets super hot and will eventually start to make the board smoke. The C8051F387 does not get hot and continues to operate 'normally' despite I suspect 2 or 3 of the gpio pins are internally shorted.

Using some tricks, amp meter, temporarily cutting traces, lowering input current (slows down heat), measuring load on the amp meter,  I tracked down the area that makes the regulator 'smoke'..
This clearly is not the intention of the design as the heated area on the board has changed color..  It just doesn't look right.  Something is wrong.  Also notice the resistor R1 looks like it got very hot too.

If I can figure out how to post some pics, will gladly do so.

Pins 23 (P1.3), 24 (P1.2), and maybe pin 22 (P1.4).  These pins/traces lead to edge connectors with what looks to be a 100Ohm 'pull up' resistor (R1, R2, R3) coming from +5, and a transient voltage diode going to ground which I assume protects against spikes on the edge connector.

When I cut the +5 going to the pull up resistors, the regulator no longer gets hot, the resistors no longer get hot.   The device that plugs in to the edge connector also does not work.  I have yet to get this (last) part working with +5 or without +5 on the pull up.

It was working at one time, so there should be +5 going to these resistors.

The C8051*  does not seem to care.  It keeps functioning, does not get warm..
I find it odd that it operates as normal and maybe those GPIO pins are just fine.
The other GPIOs on that port do not over heat but have different readings from the one's that cause the 'short-circuit'... Same 100Ohm resistors..

My questions are how can I confirm -
1) if the port 1 GPIOS 2,3,4 are internally shorted or still work?
2) if the other GPIOs on the same port are OK?

I guess I've seen some situations where GPIOs broken internally and the rest of the chip functions..
Need someone else's input beside my own.

Thank you.

Now for some pictures...

This picture shows 2 traces I cut to stop the over heating on the regulator.
The blob of solder between R1 and C2 is there to patch over a previous cut, it is the +5 feed from the bottom side.  The via on top of C2 there...
R1 gets super hot.

Removing +5 from between C2 and R1 stops all over heating, even when the traces circled in blue are connected.

Restoring +5 leading to R1 and cutting the lower blue circled trace (R1's pin/trace) going to the microcontroller, the result is R2 and R3 get hot.
Cutting out R2 and R3 seemed to make R1 heat up faster.  It seemed to me they share in the heat/resistance sharing.

The vias on R3, R2 go to the two vias just below the lower blue circle.

Could it be D12, D13 are hosed?

Are these indeed pull up resistors?

Why are they being pulled up?

So many questions.

Here is another view, sort-of zoomed out.


texts:
I tried to use a single directional coupler to create a reflectometer and was hoping to measure both amplitude and phase of reflected signal.

My setup is a follows:

The directional coupler is from MiniCircuits ZFDC-10-182-S+

simulate this circuit – Schematic created using CircuitLab

I have tested my design with different loads, 0R, 50R, 100R, 100R||3.3pF ect.

But only the magnitude (VMAG) measurements are correct, the phase (VPHS) measurements does not seems to be correct. And I cannot find any relation, between different loads and expected vs. measured phase.

So should it possible to measure phase information with a directional coupler?

Or am I doing it wrong ?

My measurement:

50R:  VPHS=0.88V,  VMAG=0.16V

Open: VPHS=1.500V,  VMAG=0.76V

Short: VPHS=0.282V,  VMAG=0.69V

100R: VPHS=1.455V,  VMAG=0.50V

100R||10pF: VPHS=0.58V,  VMAG=0.66V

100R||3.3pF: VPHS=1.18V,  VMAG=0.57V

Edit: My open load now seems correct, before I measured open load as "no load" in the cable, but this resulted in a capacitance in the cable end SMA connector. I have now made an open load as an trimmed down SMA connector. I still don't get why the magnitude i higher, but that is maybe related to the load on the source being changed.


texts: Pic Microcontroller - Secondary Oscillator

texts:
I am planning on using a 32.768KHz crystal as a real-time clock and connecting this to a pic microcontroller via the SOSCI and SOSCO
The Crystal is a Seiko SSP‑T6 32.768KHz watch crystal in 8 × 2.1 × 1.6mm surface‑mount package. 20ppm accuracy. 7pF load capacitance. 55KΩ series resistance.

Here's a similar datasheet link

Now The datasheet recommends the following setup with a resistor R of 100K (see image below):

On the Internet I have seen designs whereby the resistor value is in the Mega Ohms range. Can anyone answer the following questions:
A) Whether a watch crystal is appropriate in this design.
B) What the purpose of R is here and whether a value of 100K is recommended as opposed to say using a 20M Ohm resistor?
C) What would happen if the resistor was left out as is the case for higher value crystals?


texts: 4 ways DC power connector KPJX-PM-4S mounting method

texts:
I came across a standard 4-ways DC power connector like the Kycon KPJX-PM-4S, for panel mounting.
What I was not able to find on the producer website nor on the web is a standard method to secure this connector to a panel.
If I have a panel cutout of the shape of the connector (and according to the specifications found in the datasheet) how can I secure it to the panel?
I got a standard industry stainless steel panel of 1mm thickness.
Should I use screws and nuts on the other end? Or are there specific mounting brackets? Or is the connector supposed to be mounted on a thicker panel??


texts: When is a uC power supply "smooth enough" e.g. when some noisy (inductive, switch) load is around?

texts:
I'm building a battery/solar-powered 12V thingy that has an ESP32 microcontroller (5V generated from the 12V) and PWMs a 12V pump. The pump produces all sorts of voltage spikes on the 12V, and I'm trying to keep those as far apart from the ESP32's 5V power as possible with assorted capacitors and separate wiring.

(Note: I have read and am applying https://electronics.stackexchange.com/a/202530/110207)

When in my process should I declare it to be "good enough"? The goal is that the ESP32 won't crash on me or burn out or such. Is there a rule of thumb? What kind of noise on 5V power is normal and acceptable for microcontrollers?


texts: Do design of a VHDL module as APB Master has any practical difficulty?

texts: I went across VHDL codes for memory architectures, which contains modules designed as AHB masters, AHB slaves, Bridge, and APB slaves. But no APB slaves. Is there is any specific reason for excluding this module or I is just because design is not requiring a APB master ?


texts: Gradually increase and decrease voltage on this circuit

texts: I am using this circuit for a model lift up and down functionality. Vin is +12V. The output voltage is controlled by the 10K linear potentiometer that varies the final output from 3V to 12V. The DPDT controls the direction of the lift by reversing the polarity of the output voltage. The only problem is, when the pot is adjusted, the voltage drops or increases instantly giving the lift a jerk. Is there a way to smoothen the process so that the Voltage drop or increament is delayed over a few seconds? I have tried to increase the value of the output capacitor to 1000uf but it did not help.


texts: Looking for efficient battery supply to power 3.3V circuit

texts:
I have been searching everywhere for the best way to power my circuit and I can't find straight forward information.

My circuit needs 3.3V and the maximum current it draws is 50mA.  It will run at 50mA approx 1% of the time and 99% it will run at .004mA (not including the draw of the regulator).

I'd like the physical size to be something close to 3 AA batteries (or smaller).

It has to be rechargeable, have high capacity 3200mAh or more (5000mAh would be great).

So far the best information I see is to use a li-ion rechargeable battery and a TPS63031 voltage regulator.  I would like some input regarding if this will even work and if it is an efficient way to power my circuit or if there are better ways.


texts: why nonperiodic signals still has the concept of frequency?

texts:
I'm new to EE from CS background, just a question on nonperiodic signals.
I don't understand why nonperiodic signals still has the concept of frequency/frequency domain?
The definition is :

Period refers to the amount of time, in seconds, a signal needs to complete 1 cycle.
Frequency refers to the number of periods in 1 s

Since nonperiodic signal doesn't have cycle(does't form a pattern), therefore it shouldn't have the concept of Frequency neither?


texts: I have a CO2 sensor that output signal values 30-50 mV. I need to translate these voltages to 0-5 V for my microcontroller with the highest resolution. I understand that I can amplify the voltage using a non-inverting op-amp circuit, as shown, to a range of 3-5 V, but is it possible to expand that range to 0-5 V in order to get better resolution of sensor values?


texts:
I have a power supply that is rated rated:

Input:  100v-200v

Output: 900 ma (constant)  DC 6v-10v
https://www.amazon.com/gp/product/B01N9UXZ4C

I want to power a single 10Watt LED module,
Input 900mA/DC 4V-5V/10 Watt)
https://www.amazon.com/gp/product/B01DBZK53C

Yet, I'm confused how a 10watt output can be obtained by a 5v at 900 ma.  By my math, this would need to have a resistance of 5.5 ohms (to have 900 ma of current at 5v), but then could not be more then 4.5 watts.

So, if I use a supply that is limited to 900ma, but says it is 6 to 10 volts, will that burn out the diode?  Since, ir order to have 10watts, I need to have 900ma at nearly 10volts.