texts: How to choose a right user interface in PCIe DMA subsystem (AXI Memory Map / AXI Streaming)

texts:
Looking at the PCIe DMA solution offered by different FPGA vendors, there are 2 main user-interface options:

1) AXI Memory Map (Altera use Avalon-MM)
2) AXI Streaming  (Altera use Avalon-ST)

Using PCIe in FPGA world, may i know which user interface is most commonly used?
My interpretation from Xilinx is AXI Streaming is meant for those subsytem developed by pure RTL based while AXI memory map is meant for full AXI sytem design (I assume it refer to SOC / ARM / Microblaze subsystem)

In other words, can i say that AXI memory map is not suitable to the RTL-based design at all?


texts:
I have a NovoPort (PDF) garage door opener and I want to control the door with an ESP32. One of the issues I am having is the warning for "Do not connect any current-carrying cables". In the photo below I have a emergency stop sensor connected which connects to I (24V) and has an input to H.

If the input has to be volt-free how is this emergency sensor working?
I want to provide a second impulse generator (12F, illustration 12b) but I'm unsure how to provide a volt-free input

Note: There is a few versions of this opener, but they all appear to have the same requirements.

Note: The connections on the left (K) go to the motor.


texts: Is it possible to program a hall-effect sensor with an Arduino?

texts:
On pg. 18 Figure 5 of this data sheet you will see a pulse train that allows for programming the sensitivity of the A1362 Hall-Effect sensor.  So far I have tried to manually apply required voltage pulses (high,mid,low) as defined in the data sheet with no success.

Will I have better luck using an Arduino?  I though this link was interesting, but I'm not sure if it is what I need:

http://arduino.cc/en/Tutorial/ArduinoISP

Could someone point me to either a microcontroller that can program a hall-effect sensor or
sample microcontroller code that programs any sensor using PWM?


texts: how can I read the serial port from arduino when I enter the chars and 'enter' in the keyboard

texts:
I want to make a arduino program which can wait in the loop,  until I input some sentience and enter the 'Enter' in the keyboard, so the program can then read all the chars in the serial port and print them out

char line[80];
void setup() {
  Serial.begin(9600);
}

void loop()  {
  char c, *p;
  do {
    if (Serial.available() > 0) {
      //Serial.println("s");
      c = Serial.read();
      Serial.println(c);
      if ( c == '\n' || c == '\r' || c=='\0') {
    Serial.println("break");
        break;
      }
    }
  }while(c != '\n' && c!= '\r');
}

I use while (Serial.available() > 0)  in the hope the program could wait until I enter in the keyboard, but the wield problem is the serial doesn't recognize the '\n' or '\r', so it would print the char each time I enter but never print the 'break'.

How can I do it


texts: Automatically measure voltage over a wide range

texts:
There are voltmeters that can measure voltage over a wide range without the need to switch the range manually.
I'm quite curious how do they do it, because I'd like to make a tiny device capable of the same, up to 1000V. I was thinking about utilising a capacitor - if you connect it to voltage on one side, you'll get opposite voltage on other side, but high current will not flow.

simulate this circuit – Schematic created using CircuitLab

The change in potential should be measurable, shouldn't it?

If that's not the way, what is?


texts: What precisely does dlgStretch do in Eagle PCB?

texts:
The manual of ULP says that this command "Defines an empty stretchable space in a box layout context". It gives the below trivial example:

   dlgHBoxLayout {
     dlgStretch(1);
     dlgPushButton("+OK")    { dlgAccept(); };
     dlgPushButton("Cancel") { dlgReject(); };
   }

This would be used as part of a bigger script containing dlgDialog. The thing is that changing the value of the parameter passed to this function makes no different at all. I am confused what this function is supposed to be used for.


texts: Intel Atom board (DN2800MT) power supply, can I add battery?

texts:
After reading through 20-something posts about 'car/12V/power supply/computer' I've still not found a definitive answer to what I'd like to try here. If this turns out to be a dupe after all, my apologies.

I have this little machine running as a media/file/whatever server in my basement. It's currently (hahaha) being powered by a 65W 12V external 'brick' that came with the box it's mounted in. My (cheapo) kill-a-watt says it uses about 19W, most likely a big part of that are the 2 disks attached to it. Anyway, this works fine but I was wondering if it would be possible to create a 'cheap' UPS for it by 'simply' putting an old car battery in parallel with a PSU (and a 6A fuse).

From my little knowledge I realize that I won't be able to use the 'brick' that's currently powering the setup (need more volt for charging to start with), but I guess I could replace it with a (smallish) car-battery-charger. Going by the technical specifications (see 2.2.3.3 (pdf)) the board allows for an input voltage between 8 and 19 Volts, so I wouldn't be too concerned about things not providing a 'proper' and 'stable' 12V any more.

Am I simplifying things too much? Should I rather use something else than an (old) car-battery?
Assuming the charger is of the 'trickle-type', is it (un)likely to be smart enough to see the battery go down over time and then do a 'full' recharge or would that bring me into the 'profe$$ional' kind of equipment?
And what is my kill-a-watt going to say about this? If this brings my average consumption to like 50W I might just as well rather have the thing crash once a year due to a power-failure.

Alternatively I could go for a sightlier 'more basic' approach and apply the solution found here and make sure my battery is charged "manually/off-line" every once in a while for when it is really needed.

Thanks for any input and remarks!


texts:
I am using a GPS receiver board which transmits a PPS signal into a TTL <-> RS422 board I need to design.

The receiving end (of the RS422 signal) is 15-20 meters away.

Here is my design:

My questions are:

I've been asked by the manufacturer of the receiving end to put a 500 Ohm resistor between The high and low signals. They do not have termination at their end. On the other hand, an experienced engineer told me I need to place two resistors in series with the high and low signals.

So, with the receiving device being not so far away, and having no termination at all, and my signal being very very slow (unless the name is completely misleading, I assume one pulse per second is 1Hz), do I even need resistors? If so, what value?

I thought about putting three 0 Ohm resistors in my design (two in series, one in parallel) that can be later be swapped if this doesn't work. Thoughts?

On the datasheet of the LTC2850 it is said:

  If a high
  driver
  output
  is    shorted
  to
  a voltage
  just
  above
  V
  CC
  ,  a  reverse
  current
  will
  flow
  into
  the
  supply.
  When
  this
  voltage
  exceeds
  V
  CC
    by
  about  1.4V
  ,  the
  reverse
  current
  turns
  off
  ....
  The
   worst
  -case
   peak
   reverse
   short
  -circuit
   current
   can
   be as
  high
  as 300mA
  in    extreme
  cold
  conditions.
  If   this
  current
  can
  not
  be
  absorbed
  by
  the
  supply,
  a 3.6V
  Zener
  diode
  can
  be added in parallel with the supply to sink this current.

So, a few points about this:

this is a very small board and what I showed you is the whole board.
There are no other voltages.
This device does operate in extreme cold conditions.
the power supply board is not of my own design and I
don't really know how it operates.

So, do I really need a zener diode?

This is based on an older deisgn (which used MAX13081E). I needed to switch to the LTC2850 due to having a supply of 33V instead of 5V like in the MAX13081E.
In the older design, there was a 4.7uF electrolytic capacitor in addition to the 0.1uF bypass capacitor. Is there any reason why I need to place this capacitor?
This is the function table from the datasheet:

I only need to receive a PPS signal and transmit it in RS422. I assume the last state is what I'm looking for?

The resistors in the enable pins. There are two reasons why they are there:

To conserve current consumption
So it will be easier to change the function of the device by soldering them to ground if needed. Or just disconnecting them altogether, though I don't think it's a wise thing to do.

So my questions about them are - is it okay to have them at a 10k value (is it not too big or too small that it actually changes the state of the device), or in other words, how do I calculate their desired value in such a way that I have the minimum current consumption and the state of the device is what I intended it to be?

Last - is there a way to simulate this in LTSpice? Can standards like RS422 be simulated?

Thank you!


texts: Can a pull down be used to tie a line to ground?

texts:
From my recent introduction to pull-up/pull-down resistors, I understand that an input with a pull-down will stay low instead of floating.  Since the pull-down resistor leads to ground, couldn't I also use a pulled-down pin as ground?

My raspberry pi has software-activated pull-up/down resistors.  I thought I could use them to perform a reset of my connected Arduino nano.  To reset the nano, I have to tie a line to ground until the nano switches off.  Then I have to disconnect from ground.  The line can float at this point.  I thought this might be possible by pulling the line on the pi down, and then back up.

Is the pull-down resistor too large to properly perform as a ground?


texts: Cheap way to power blue LED on coin cell

texts:
I need a cheap way to take a 3v nominal coin cell and power a 3.3 forward voltage blue led. It needs to be cheap in production on a large scale, so a rudimentary joule theif won't work.

Ideally it needs to be under $1 for my entire circuit, including pcb. I could go with two cells, but there's not many cheap 2 cell holder options. It also needs to be quite small, so that is also a constraint.


texts: TTL voltage shift from 5 to 3.3 Volts "UART"

texts:
I want to make serial communication with a device which works on 0-5 Volt TTL level. But my serial chip uses 3.3 Volt logic. (this is an UART communication)

I know that I need a step down at least for the TX pin of device (which will be RX on my serial chip). I wanted to go with normal resistor voltage divider but I'm assuming it will cause problems in high speed transmissions. Can you recommend a good, easy to use chip for this task?

Also, do I need to have a voltage step up from 3.3V to 5V for the device's RX (my serial chip's TX)? I heard that anything above 2.4 volts should be considered high. What do you think?

And I have question about whether the converter should be inverting or not? How can I determine this?


texts: Recognizing components in a circuit for a really loud personal alarm

texts:
I am a new enthusiast in electronics, trying to realize a first project. The idea would be to use a remote control to scare away pigeons from our trampoline in the back yard. :-)
I’ve got that working on a breadboard, but I am not satisfied with the output volume of the buzzer. So I took apart an existing personal alarm, which works on 3 x 1,5 volt cell batteries. This gadget produces an incredibly loud sound level, and I am very interested in understanding how it works.
I noticed someone asking the same question on a German user forum, but without receiving an answer. If you would care to have a look?
https://fpv-racing-forum.de/thread/13252-identifikation-eines-ics-transistors/
There is a picture of the circuit at the top, and a reverse engineered schematic diagram as well, at the very bottom. The buzzer is connected in the picture at the “BZ” marking, at the top left; the batteries at the very right top and bottom.
Can someone explain the key elements in this circuit? Especially the purpose of the coil (Spule in German), which I first took to be a capacitor? I suppose the general idea is to generate spikes in voltage over the IC - C1 – Y/Q1 – three pin coil; since the volume I think is a function of voltage.
And perhaps some help in finding a likewise component for online ordering, because looking for something like “3 pin coil” does not give similar results.

Photos from the linked forum page:
PCB:

Schematic diagram:


texts:
I have for over a year now tried to figure out both the electronic aspect and the software aspect of my project.
I have somewhat successfully managed to make the overall idea to work,
the bumps I have come along the way are quite frankly stressing me out.
Project description and goal:
Basically a beat-detection device with a very small formfactor.
I am using an Arduino Uno as a prototyping device,
but I have an Arduino Mega, Sparkfun Micro and several other development boards
it stock to use if needed.
I want the microcontroller to read analog audio, convert it to FFT or FHT or
any other easily translated data, read the lower frequencies where the Kick of the
music is presented, and finally measure the timing between each kick to
calculate the BPM of the song.
The frequency range of where the Kick in the music is present is
around the 45Hz to 55Hz range and is most distinguishable in that area
when looking at it in a spectrum analyzer.
This should also be correct when doing FFT/FHT with a microcontroller
due to the nature of raw analog to digital to FFT/FHT conversion.
However, it may differ and is most likely to differ if a microphone is used
to listen to the audio.
What I have successfully accomplished:

Assembling a circuit which allows for audio to be injected to an analog input of the arduino. The circuit can be found here:

(source: interface.khm.de)

Implementing Open Music Labs FHT library to convert the analog audio to a frequency spectrum. The library can be found here: http://wiki.openmusiclabs.com/wiki/ArduinoFHT

So the two most important components of the project is in place.
What I have problems with:

I get a constant peak in the lower frequency area of the spectrum which is present at all times. This is a problem because the Kick of the music is in that area.

Things I have tried:

A guy on youtube tried to help me out by giving me simple instructions and he told me to use a 1uF capacitor between the Audio Surce and the Analog input, as well as trying either a pull-up or a pull-down resistor on the Analog Input.

Results (quote):

When using  a pull-up, the low freq peak increases, when using a
pull-down, the low freq disappears.
So the Pull-down is the way to go.
HOWEVER, with the pull-down present, harmonics of the sinus tone is
introduced but no peak at the lower freq area as long as no sound is
present.
With the pull-down NOT present, the harmonics vanish, but the peak is
present.

Implementing FIR and IIR filters. Results: Audio still reacting to all frequencies.

What more can I try before I throw this project out the window?
Approaches and suggestions need to be component-limited and preferably software oriented.
The light organ needs to have low power consumption and very few physical components,
and if physical components are required, they need to be tiny and surface mounted.


texts: Voltage Divider-like circuit with multiple sources

texts:
I'm extremely new to circuits and am having some trouble with a variation on the voltage divider problems I've been doing.

I'm trying to determine \$V_{out}\$ in the following circuit relative to some \$V_{GND}\$ that I need to determine the location  of

.

I know that in a standard voltage divider, the line to \$V_{out}\$ carries negligible current. In this case, I can't quite determine the current flow because the lines from \$V_2\$ and \$V_1\$ carry current that is equal to \$V_2/R_2\$ and \$V_1/R_1\$ at the point in between the two resistors. How does this return to ground, and how would I begin to apply Kirchoff's Law for the loop?

simulate this circuit – Schematic created using CircuitLab

I would think that ground node positions would be like this, but I'm nevertheless confused about the current flow. Any advice would be appreciated.


texts: Calculate currents in thevenin equivalent methods

texts:
I have this circuit that I am trying to solve for the short circuit current.

I am not extremely strong with analyzing circuits (this is finding the short circuit current for a Thevenin equivalent), but I tried solving for currents two different ways and  am still wrong. I performed mesh analysis using the three squares as loops which yields these three equations (the left loop is 1, the middle is 2, the right is 3):

10*(I1-I2)=0

10*(I1-I2)+12+40*(I3-I2)=0

40*(I3-I2)-5*I3=0

which gives: I1=2.1, I2=2.1, I3=2.4

Then I used the middle and rights loops using KVL with the current labelled as in the picture:

12-40*Ia-10*Ib=0

-5Isc+40*Ia=0

Ia+Ib+Isc=4.5*Ia

which gives Ia=2.4, Ib=-10.8, Isc=19.2

I understand the solution that they give (and I can post it but someone who is familiar with this probably doesn't need it), but what I don't understand is why my methods did not work and why they picked their particular method/loops to evaluate (it could also stem from the fact that I have not analyzed many circuits so I am inexperienced at how to approach).

Thanks!

This is the solution as given:


texts: How to tell if a BJT is PNP or NPN by looking at the circuit?

texts:
Is it possible to tell if a BJT circuit is PNP or NPN simply by looking at the circuit?

For example, for the circuits shown, how can we tell if they're PNP or NPN?


texts: Does a typical mobile adapter draw current when no load is attached?

texts:
Summary:
I am comparing the trade off of wasting my time daily plugging and unplugging multiple chargers at multiple sockets.  I need to know approximately how much Amp is my adapter drawing every second when in no load (have not attached my mobile/tablet).  Will it be mostly 0? On in the ballpark of <10 mA, <50mA, <100mA?

Charger specs : (AK717)
OP: DC 5v 2amp branded
IP: AC 240V .3A


texts:
I have designed a mobile phone charger according to following circuit diagram. Its input is AC220V and gives output DC5V, gives current upto 400mA. fortunately this is working and charging my simple NOKIA mobile phones. but when

(1) I attach a smart phone, the touch pad is disturbed i.e hang and not work properly. I dont know what is this problem with charger.however other chargers from market work fine.

(2) Also I want to increase current rating upto 1A, how can I do this.?

anybody help me out, I will be thankful...!


texts: Can I increase inductance using permanent magnet ?

texts:
I know that when I insert a ferromagnetic core inside an air-cored coil, the inductance increases.

What if I inserted a permanent magnet with a cylindrical shape into an air-cored coil, does the inductance increase or decrease or still constant ?

Is there any effects other than the inductance ?


texts: Operation of a 2 phase servo motorin flight control surfaces

texts: So after doing some research, I briefly know a 2 phase servo motor's operation. I know it has a control and a main winding that is 90 degrees phase different to generate a rotational torque. It also has a rotor. But how does this motor move for example, flight control surfaces? Any help is appreciated thanks


texts: Use of a capacitor to accomodate temporary voltage drop

texts:
I recently added a small circuit board to delay my car stereo powering up.  The idea was to prevent the stereo coming on in the brief period between turning the key from ACC to START and back again.  It played havoc with my Bluetooth connectivity.

Anyway, before adding this little board my stereo was more than happy to accomodate temporary voltage drops such as when I turned on the Air Con or a drop in revs.

It seems the new board doesn't like the drops, so when the revs drop (and the voltage from the alternator drops), the board resets and disconnects the output supply and after another 10 seconds the stereo is powered again.

I was wondering if, between the supply and the delay circuit I placed a diode and then a capacitor to ground might help matters.

[SUPPLY] -- [DIODE] ----- [DELAY BOARD] -- STEREO
                      |         |
                    [CAP]       |
                      |         |
                     GND       GND

Thoughts?
Thanks,
Scott

UPDATE: After checking out a few diagrams, I realised the above diagram is wrong.  The DELAY BOARD is actually actuating a 12V relay - ie, the stereo is not powered directly from the board, rather the same 12V supply it was on, except now that 12V is switched by the board.  So that should remove the possible problem of a voltage drop induced by the board.

So, currently:

                  +---------------------------+
                  |                           |
[SUPPLY] ---------+------ [DELAY BOARD] -- [RELAY]
                                |             |
                                |          [STEREO]
                                |             |
                               GND           GND

Here's a pic (no schematic, sadly):
NB: the pot is to adjust the relay-on delay.


texts: GSM/GPRS antenna noise depending on cable length and position

texts:
A board I designed has a noise problem that is caused by an onboard GSM/GPRS module (the Quectel M66 [1]). This module is connected to a Siretta Delta 2C [2] dipole antenna via 20cm coax cable. The image below shows the layout around the GPRS module:

The GPRS module itself works fine: the signal strength is good and sending/receiving data is no problem.

The problem

We have a few 24-bit ADCs on the board that pick up noise spikes when the GPRS module is connecting to the network. This noise seems to be caused by the antenna and the coax cable.

Noise spikes caused by GPRS module (see the middle of the plot).

Observations

The problem still exists if the GPRS module is powered independently from the rest of the circuit.
The noise only seems to occur when connecting and disconnecting from the network, not while using the connection (sending data).
Adding a one meter coax extension cable suppresses the noise, except when it is positioned in a straight line. This is even the case when the antenna is in the same position as before.
Ferrite beads around the coax cable suppress the noise a bit, but not completely. Maybe a lot of ferrite beads, or another type of beads would be sufficient. Unfortunately these beads are quite large. Adding multiple of them will not fit into the product.
Placing the antenna directly on top of a large sheet of aluminium works quite well, but only if the sheet is in direct (conducting) contact with the antenna. Maybe this forces the dipole antenna to become a monopole + GND plane?
Edit: Even with the antenna disconnected (just the 20cm of coax), the module works as intended, no noise on the ADCs. Even though the module uses more power in this configuration.

Unfortunately the above workarounds are not very practical or reliable enough to use as a real solution.

Hypothesis

I am more and more convinced the problem may be related to common-mode RF current on the coax cable. This seems to come up often when searching for driving a dipole antenna with a coax cable.

Help!

Does this hypothesis make sense considering the situation and observations? Are there other likely causes that could explain these observations?
And finally, what can I do about it?

Edit: about the power supply

The GPRS module can draws large current spikes up to about 2A. In an effort to keep these currents away from the ADCs, the latest board revision buffers most of the power with a large capacitor, as shown in the schematic:

simulate this circuit – Schematic created using CircuitLab

The main power supply only has to deliver up to about 300-400mA. This is enforced by a current limiting IC in series with the power supply. A large electrolytic capacitor buffers the current peaks. The last step is a 4V LDO to keep the voltage on the GPRS module steady at 4.0V.
A total of 80uF of ceramic capacitors is placed directly on the 4V power input of the GPRS module.

When the module is sending, the LDO output drops by 60mV. The Quectel M66 datasheets recommends a maximum drop of 400mV.  Unfortunately I do not have enough reputation yet to add more pictures

[1] http://www.quectel.com/product/prodetail.aspx?id=73

[2] http://www.farnell.com/datasheets/1877150.pdf


texts: The 20mA loop to USB fails midway of connection with unknown reason!

texts:
I'm trying to make a USB to 20mA loop converter to connect to Siemens S5 PLC. I asked a question about selecting a good optocoupler to convert the signals here
@Marko Buršič helped me with a schematic of a RS232 to S5 converter I used that circuit and replaced the Max232 chip with a CH340 (uart to USB) chip. In software when I initiate a connection to the PLC it begins to transfer and transfer some of data correctly but after a few seconds it losses its connection.
I used a logic analyzer to capture the signals at the CH340 pins and it shows that in the middle of the connection it losses the connection.
You can see this capture here

How can I find where the problem comes from?

PS:I used Marco's schematic and modified it to resemble my circuit.Thanks Marco Sorry I know it's shame that you draw the schematic for me.

I am using 4N25 instead of 4N37.

I used a 1.5Mohm instead of 220Kohm resistor on base of the optocoupler.

I don't have LEDs on signal lines of PLC.

I used pin1 of PLC as The picture below it is also connected to PLC ground.

PS2: I uploaded a screenshot of the error shown on S5W When I tried to connect to PLC.

PS3: Today I find my RS232 to Siemens S5 cable and captured the(Tx and RX of Max232 IC on this cable) signals during connection. I compared these signals with my prototype of USB version cable. At the beginning all the signals are the same but at the middle of the connection the signals from PC to PLC differs from when the signals on RS232 cable. I upload a picture of the moment that these signals differ(before this time all the transactions are the same). How can this problem arise?

Please Help me this cable is driving me crazy!


texts:
A number of projects I have been working on have outgrown the breadboard phase, and I have been learning how to do PCB layout.  My first tiny project (a cable adapter) went smoothly, but as I have been ramping into more complex designs, things have gotten much hairier.

As a second project, I was trying to assemble a high-performance LED driver (roughly the "typical design" presented here), but every layout I create in that direction leans towards some jabba-the-hut style amalgamation of parts.

What I am trying to understand is what is the typical flow that a (skillful) EE undertakes that results in a well-designed board?  I included the above link as a specific example to talk strategy around, but I would like to know more about general approach that people use to tackle PCB layouts.  Books/links/suggestions all welcome.

Thanks!


texts: Why are there high active and low active signals in a timing diagram?

texts:
I always see such signals (colored in the image) in a timing diagram. Now I've figured out that they're called:

low-activ and for me an OR-gate
high-active for me an AND-gate

signals.

But why isn't it all drawn as high-active signals (so that the blue area is visualized like the red one)!? What's the reason for that diversity ?


texts:
I wonder how far the similarities go between FOC control and SVPWM modulation and from which point on wards they are different from each other?

edit:

Can anyone point out a very basic primer from where I can learn about SVPWM?


texts: Protect first LED (W2812b) in line from voltage spikes?

texts:
I am currently working on a Arduino / Raspberry Pi project, where I am trying to drive a line of 64 PL9823 LEDs which are said to be equivalent to the popular WS2812 LEDs.
Datasheet: http://www.adafruit.com/datasheets/WS2812.

Everything just works fine, but from time to time the first LED in line seems to break (i.e. stays dark) and keeps the data signal from reaching the subsequent LEDs. It seems that this mainly happens when powering on the LED matrix.

Do you have any idea what could be the reason for this and how it could be prevented?
I have already thought about voltage spikes that occur when powereing on the power adapter, but am unsure about how to implement a safety feature.


texts: Is there any chance for BJT VBE to be leaked?

texts:
I tried to design the CE Amp. Everything was fine, but when I tried it on PSPICE, the I_c value differs from the I_c value calculated by I_s and V_BE.
 In my case, I_s=1e-17 A and V_BE=0.872 V, so I_c value should be around 14 A. However, in the simulation, I_c is measured by around 4 A.
 Is there any reason for this? Thanks.


texts: What is the difference between digital and analog input pins declared on microcontroller? In which situations we use analog and in which digital input pins? What will happen if we put an digital signal into into analog input pin, and vice versa?


texts: Single Bit Error Correction & Double Bit Error Detection

texts:
Can someone explain, in their own words, what Double Bit Error Detection is and how to derive it? An example of corrupted data and how to detect the double bit would be appreciated.

I can do Single Bit Error Correction using parity bits as well as correct the flipped bit. Now when I reach Double Bit Error Detection I understand there is an extra DED bit, which is somehow related to the even or odd parity of the bit sequence. However, I am lost.

What I read:
http://en.wikipedia.org/wiki/Error_detection_and_correction

Video on Hamming Code:
http://www.youtube.com/watch?v=JAMLuxdHH8o


texts: Using 12v to supply a Raspberry Pi with a switching regulator

texts:
firstly please forgive any confused terminology, I'm not an electrical engineer by trade!

I have a Raspberry Pi which is operating a series of relays via its GPIO pins. On the other side of the relays are a number of devices; a mixture of mains supply and 12v.

I would like to have a single 12v power supply for all the 12v devices that also powers the RPi, so with a little research it seems I need a switching regulator to convert the 12v into 5v.

My question then is this: given that the load drawn from my 12v supply with be jumping around as the RPi operates the relays is this likely to cause spikes/dips in the 5v supply coming from the regulator or should it be able to cope with this?

For the sake of giving more info:

my 12v supply is 24W/2A; max load with everything switched on ~20W
This is the regulator: http://www.ebay.co.uk/itm/271632729700

Is there anything else I should take into consideration before putting this together?

Thanks in advance


texts: What do the voltage and current labels on a relay signify?

texts:
The relay is just a switch. What do the  labels       for the maximum amount of current and voltage it can handle mean?

As an example, see this

https://www.industrybuying.com/relays-relay-EL.SW.RE.374881/?utm_source=Google&utm_medium=PLA&utm_campaign=0_PLA_LPP&gclid=CIGVkaSOkckCFQKTjgod7TgNQQ

The relay on this page, has written on it. 5A 240V, what does this mean?


texts: Understanding thermoelectric generator and Ohm's law

texts:
I understand the simple terms of U = R * I in the context of a constant voltage - which is approximately the case for most consumer electronics, where the resistance of the load (in a closed circuit) determines how much current is drawn.
However, if the source of electricity is not constant voltage, (e.g. a thermoelectric generator, TEG1-12611, datasheet) and both I and U change, and it's unclear to me what happens if you simply attach a load (e.g. a voltage regulator of 3V, ams1117, ca max ~5V/1A) and a simple LED (max ratings 3V, 20ma). How do I calculate at what point would my components fry, due to overcurrent or overvoltage (if my source is powerful enough)?
Example circuit:

simulate this circuit – Schematic created using CircuitLab
Intuitively, I would try to find an IC that generates a constant voltage output (from variable current and voltage source) and don't overthink it, but I'm actually interested in understanding this.
Sorry if the question is a bit basic, I couldn't find an answer with the topic of Peltier modules.


texts: What causes "hard working" growling sound in a heavily loaded electric motor?

texts:
From my experience just any electric motor when under huge load would make recognizable growling sound. This would happen regardless of the motor type - brushed/brushless, AC/DC, small size/huge size - it would just happen.

Where does this growling sound come from exactly and how does it form?


texts: Difference between Gate Instantiation and SystemVerilog operator

texts:
Today I learned about & and ! operators.
But I can't understand what is the difference between these two:

A=B & C;

AND(A,B,C);

Do they have exactly the same usage?


texts: high side mosfet offset voltage in Phase shifted full bridge converter

texts:
I am working on phase shifted full bridge converter. The input voltage of it is 300 V.

The issue is I am able to see offset voltage (shown in fig below) in the gate to source pulses during turn-off period of high side MOSFET when input voltage of 300 V or even less than that applied to it.

Without input voltage applied the gate to source pulses are clear and there is no offset. This issue was happening only on high side MOSFETs but at the low side MOSFETs the things are not same as upper MOSFET there is no offset voltage.

Why is this happening?


texts: Coarse counter giving incorrect pulse length measurements at high frequencies

texts:
I am using a simple counter to measure pulse length. I have copied the code below, but the counter increments by 1 at each positive edge of the clock. Once the counter is done incrementing for that pulse, the current count is multiplied by the time period to get the pulse length.
I assumed that increasing the clock frequency would give a more accurate time measurement since the period is smaller. However, the measured values at high frequencies are becoming less accurate, especially for longer pulses.
Any idea why a 400MHz clock would give a worse pulse measurement compared to a 200MHz clock? I thought 400MHz would perform better since it's period, and maximum error, is 2.5ns while the 200MHz clock has a period of 5ns.
              ///////////////////////HDL counter code for 400MHz clock///////////////////////
module count    (
out   ,        // output of the counter
in_1  ,        // input signal
clk   ,       // clock input
reset         // reset input
);

    input in_1, clk, reset;
    output out;

    reg [15:0] out;
    reg [15:0] counter;

always @(posedge clk)
if (reset)
begin
  counter <= 16'b0 ;         // if reset is high reset the counter to 0
end
else if (in_1)
  counter <= counter + 1;
else if (in_1 == 16'b0)
begin
    if (counter !== 16'b0)
    begin
        out <= 2.5*counter;
    end
counter <= 16'b0;           // reset counter once the input signal returns back to zero
end
endmodule

                   ///////////////////////Testbench with 400MHz clock///////////////////////
`timescale 1ns/100ps

module count_tb;

//parameter SYSCLK_PERIOD = 20;// 50MHZ

reg clk_1;
reg in_11;
reg reset_1;

wire [15:0] out_1;

initial
begin
    clk_1 = 1'b0;
    in_11 = 1'b0;
    reset_1 = 1'b1;
    #200;
    in_11 = 1'b1;
    reset_1 = 1'b0;
    #1115.4;
    in_11 = 1'b0;
    #200;
    in_11 = 1'b1;
    #423.07;
    in_11 = 1'b0;
    #200;
    in_11 = 1'b1;
    #38.46;
    in_11 = 1'b0;
    #200;
    in_11 = 1'b1;
    #3076.92;
    in_11 = 1'b0;
    #200;
    $stop;
end

//////////////////////////////////////////////////////////////////////
// Clock Driver
//////////////////////////////////////////////////////////////////////
always
    #1.25 clk_1 = ~clk_1;
//////////////////////////////////////////////////////////////////////
// Instantiate Unit Under Test:  counter
//////////////////////////////////////////////////////////////////////
count count_0 (
    // Inputs
    .in_1(in_11),
    .clk(clk_1),
    .reset(reset_1),

    // Outputs
    .out( out_1 )
);

endmodule

ModelSim Waveform at 200MHz clock

ModelSim Waveform at 400MHz clock

Summary of Pulse Measurements at 200 and 400MHz


texts: Lower VPR in SPD (Surge Protection Device) is more protective?

texts:
If you have a universal power supply that can accept 88v to 264v connected to expensive security system. Isn't it if you use a 120v SPD (Surge Protection Device) with VPR (Voltage Protection Rating) of 500v. It's more protective than using a 240v SPD with VPR of 1200?

VPR or Voltage Protection Rating is the voltage seen at the load for a test surge of 6000 volts, 3000 ampere at 8/20 microsecond.

Even though VPR is a manufacture test parameter. Note it's based on typical surge voltage and current. So in the event your equipment is hit with 6000 volts, 3000A at 8/20 microsecond pulse, the VPR value (minimum voltage) would appear in your equipment. So if your SPD has VPR of 500v versus SPD with VPR of 1200v The one with lower VPR rating is safer right?

Therefore for those countries using 240v like Europe. Do you use 120v SPD with combination of 240-120v step down transformer to avail of the lower SPD VPR?


texts:
I had a PCB board printed that has some relays that are connected to 220 VAC circuit.
Now unfortunately some traces passes near the relays and are affected by this high voltage causing the circuit to fail.

Is there a way to stop the effect of this high voltage on the near traces?

Regards


texts:
I have purchased a ir->serial port cable for reading from the IR-port on electrical meters.
With the included program meter.exe, I can only get this:
C:\extra\Downloads\meter>meter -port=com3
olcdtool version 1.00
Opening: com3, baud: 300
Meter ID: /LGZ4ZMF100AC.M29

then what looks like a question mark in a square.
But no data.
Any clues? Can the power company turn off the port so it sends no data?
EDIT:
The adapter is this: http://www.ebay.co.uk/itm/Optical-Probe-IEC1107-IEC61107-62056-21-with-USB-cable-Windows-10-version-/201922292332?
Here is the reader software: https://www.dropbox.com/s/qjhykezcojkt3g7/meter.zip?dl=0
EDIT:
I have now been told the question is off-topic.
As long as the question and answer stays here for reference, I'm okay with it being locked.


texts:
I have a tiny tube that sprays lubricant but I need it to move between some holes in a line. The total distance is only 10 inches.

So imagine the holes like this:

[ o o o o o o o o o o ]

And I need to move the lubricant tube between them.

I think I need a linear actuator to move the tube, but it doesn't need to be strong at all (less than 1 lb of force) or very accurate. If it lubricates a little bit off center it doesn't matter.

My issue is that linear actuators are so expensive! I'm currently leaning towards building one with Knex or Lego Technic and a servo. But does anyone know of a cheap/weak/inaccurate hobby option for less than $30?


texts: How much power does 5V and 6A provide in Watts?

texts: Am I right in concluding that a unit that says 5 V and 6 A on the back supplies 30 W of power? Or is it that it requires 30 W to be powered? And if so, how do i calculate how much power the unit supplies (output)?


texts: Controlling a NE2 lamp with a 12 V signal

texts:
I have some NE2 lamps i want to control with a signal from my car.  Signal voltage is about 11 to 14 volts and isn't very clean.  I also have 170vdc available to power the NE2s.  I plan on using these for turn signals and high beam indicator.  Components must be able to be on for long periods of time.  I would like to be efficient with power due to limitation of my 170v power supply.

I do have some TIP102's laying around but fear the input voltage is too low.  Is there a 12v version of these?  What resistors should i use to knock it down to the appropriate voltage?  I cant find much data on these lamps and use.


texts: Mosfet pinchoff, why the n-channel moves towards source?

texts:
Suppose we have an NMOS transistor with \$V_{GS}\$ > \$V_T\$. When \$V_{DS}\$ is 0, the channel depth is uniform along the transistor. However, when we increase \$V_{DS}\$, the channel becomes deeper near the source and shallower near the drain. I don't understand why these happens, that voltage should attract electrons towards the drain not the other way.
What am I thinking the wrong way?


texts:
I'm trying to build a circuit to detect intercom rings with a logical input such as the one on an Arduino.
From a few research and testing the ring signal is often comparable to the one in a PSTN circuit
Most of the time ring signal on intercom seem to be between 20V and 90V AC.
The aim of the circuit is to convert this signal to a 3.3V peak to be detected by the logical input. The circuit should draw a minimal load of the intercom line.

the discontinued TCM1520A chip and the following Velleman product might be good starting points:
https://www.velleman.eu/downloads/0/illustrated/illustrated_assembly_manual_k8086.pdf

Thanks for the help.


texts: Is it possible to connect each and every pin of two IC's together and increase perfomance?

texts:
I am a newbie to electronics.
I have a crazy idea in my mind to create a PC with 32 bit microcontrollers.
I chose the ATSAMV71J20 chip. The processor has a maximum CPU speed of 300MHz.
If I connect all pins of the CPUs together (except power pins which will cause current drop) and increase the maximum CPU speed will the speed increase from 300MHz to n(300MHz) where n is the number of CPUs? If not how can I run resource hungry programs with multiple CPUs?


texts: ATtiny85 PWM: why does COM1A0 need to be set before PWM B will work?

texts:
I want to enable high-speed PWM output on PB4 using an ATtiny85. Having read the datasheet, it appears that the following conditions need to be met:

PLL and PCK need to be set to enable the high-speed peripheral clock
The prescaler needs to be set to enable timing
OCR1B and OCR1C need to be set to choose duty cycle
PB4 needs to be configured as an output and the compare mode needs to be set using COM1B0/COM1B1
PWM B needs to be enabled using GTCCR:PWM1B

The code below works - I see PWM output on PB4 and can vary the duty cycle by changing OCR1B - however it only works if I also set COM1A0 in TCCR1. If I don't set COM1A0 then PB4 stays high and no PWM output is generated.

#include <avr/io.h>
#include <avr/delay.h>

int main() {
// Enable PLL and async PCK for high-speed PWM
PLLCSR |= (1 << PLLE) | (1 << PCKE);

// Set prescaler to PCK/2048
TCCR1 |= (1 << CS10) | (1 << CS11) | (0 << CS12) | (0 << CS13);

// Set OCR1B compare value and OCR1C TOP value
OCR1B = 128;
OCR1C = 255;

// Enable OCRB output on PB4, configure compare mode and enable PWM B
DDRB |= (1 << PB4);
GTCCR |= (1 << COM1B0) | (1 << COM1B1);
GTCCR |= (1 << PWM1B);

// Why is this necessary?
TCCR1 |= (1 << COM1A0);

while (1) {}

return 0;
}

Why is this necessary? The datasheet states that the COM1A bits control OC1A/PB1, which shouldn't have anything to do with OC1B and OCRB

The reason I'm trying to use OC1B/PB4 rather than OC1A/PB1 is that PB4 is not used during ISP while PB1 is


texts: Beginner's LTSpice Question: Why does my sine wave look so bad and how can I fix it?

texts:
I'm planning on building a Spice circuit with variable-gap capacitors. The capacitance in general will be something like C = eps*A/(g0+g'), where g' is the oscillation that occurs on top of the nominal gap position, g0. My first thought was to make a behavioral voltage source that would ultimately be the g' variable.
Prior to making the real circuit, I wanted to mess around with this concept in a beginner's fashion. Below is the general idea, where I have some frequency input and an amplitude called "disp," representing the gap change.

Here is where the problem comes in. When the disp variable is 1e-4, everything seems fine (sine wave with the correct amplitude). But when I go to 1e-5, I get the following picture. I imagine this is some sort of resolution issue? But I wanted to ask and see if there is a solution or if my initial plan is not the smartest way of going about things. I also tried using a normal voltage source with the parameters inputted as the frequency/amplitude of a sine wave. Thanks in advance.


texts: BJT vs MOSFET for very low power flyback converter

texts:
I am currently working on a flyback design charging a capacitor in the nF range to 200V from an input voltage of around 1.5V. As the final circuit should be as small as possible, my component choices are very limited.

Furthermore, the flyback switch should be driven by a max. voltage of 2V DC. My current problem is now, that there are currently no MOSFET devices available with a Vdss high enough.

My question now: Are BJTs feasible as a switch (higher breakdown voltage) and if so do they consume any power when turned off? (I am guessing not). Is it possible to drive them from only 2V?


texts: Advice on controlling an unknown dim-able 12V LED

texts:
I have been controlling "5050" RGB LED strips from the GPIO of a Raspberry pi with a simple circuit using mosfets. This is the guide that I followed:
https://dordnung.de/raspberrypi-ledstrip/
It works well, however I need also to use miniature single coloured directional LEDs. I found these LED spotlights which are also 12V and dim-able:
https://www.aliexpress.com/item/32956926521.html?spm=a2g0s.8937460.0.0.40142e0eI4rsrU
An apology here: I know very little about electronics (but can solder up simple circuits).
Will the same basic mosfet circuitry work for these spots? If not, any way of testing for what will work?
This is the only technical information given:
LEDIARY 12V Mini LED Spot Downlights Dimmable Lamp Set Remote Control Ceiling Recessed 1.5W 27mm Cut Hole Silvery Cabinet Lights
1.Material: Aluminum+PC+ABS+ Epistar LED
2.Lamp Size: Diameter 31mm, Height 22mm, Cutting Hole Size: 27mm
3.Input: 85V-265V for the adapter  (12V for the lamp.)
4.Real Watt:1.5W for one lamp
5.Lumen: 100lm  for one lamp
6.Body Color: Silvery
7.Lighing Color: Cold White/ Warm White
8.Controller parameter: RF controller(can control lamp across  the wall or ceiling), and can make stepless control (dim the brightness smoothly).
9.Control distance: 5-10m
10. Power for controller: 3 pieces AAA battery ( Not included, please purchase in local shop.)
The simple IRLZ34N mosfet circuit that I am using for the led strips:


texts: Question regarding the working of slightly different oscillator topologies

texts:
I tried simulating two slightly different versions of the Colpitts oscillator in LTspice.
Here is the first one:

This circuit oscillates at 53.8Mhz. It is quite easy to understand how this circuit oscillates just by looking at it.
Then I tried grounding the main resonant capacitor, C4 from the collector, a commonly seen method used in self quenching super-regenerative receivers.

Initially the circuit did not oscillate, but in reality they do in the above-mentioned receivers. When I selected the option "skip initial operating point solution" from the simulation menu, the circuit fired up to life and began oscillating at 52.3Mhz.
Now, my question is how does the above version of the Colpitts oscillator work?
My thought is that there is no a visible LC resonant loop, apparently. Also, C4 easily shunts any oscillations to ground there by not startup any oscillations.


texts: How to interface a microphone to an I2S input to use HFP

texts:
For my group's SDP/Capstone we are doing a bluetooth headset of sorts. We are using a CYW20706 SoC from Cypress. Specifically, we are using a this CYBT-343026-01 Cypress module whch includes that CYW20706 SoC.

Initially, we were going to use the SPH0645LM4H MEMS I2S microphone from Adafruit/Knowles and after weeks of trying to get it to work we realized that the MCU only takes 16 bits while the microphone outputs 24 bits.

We are using the Bluetooth HFP, and we are able to get an output from the MCU to a Maxim MAX98357A amplifier, to our transducers. However, we are looking for alternative ways to implement an input to the I2S_IN and get the microphone working. We posted a bunch in the Cypress forums and unfortunately they were no help.

I realize that we will probably use an analog mic and use some kind of codec, but the issue is we cannot find any codec that takes in analog signals and outputs an I2S signal. Any advice would be greatly appreciated.


texts:
I need to interface a MIPI output from a device to an FPGA. I don't have a lot informations about MIPI output, so I suppose it's most standard possible and works on 3.3v. MIPI should run at max 80Mhz and it's only output to FPGA.

Since I'm new with MIPI interfaces, and I didn't find pratical explainations on google, I want to ask:

Which hardware (between MIPI and FPGA) I need and how I should interface MIPI to FPGA?

ex.
Should I use Pull-UP, Pull-DOWN or inductance matching resistors?
Should I apply a particular layout to this lanes?
Should I connect either Positive and Negative channels or only one Channel or use a particular device?


texts: How do you do Electro-mechanical Assembly Documentation?

texts:
I realize this isn't specifically EE theory related, but I hope EE documentation advice falls within the scope of this forum!
For example, I have an enclosure from a mechanical engineer, and their mechanical assembly drawing.  We worked together to get a board outline, and I have my PCBA and my EE fab/assembly drawings.
I have some "off board" components - switches, buttons - that have wires to the board, and get inserted into the housing.
Historically, I would include a detailed assembly document with step-by-step instructions on wiring external components, how to program the firmware, etc, which would go to techs in production.
Since this company is more prototyping oriented (and I'm effectively the only EE), they'd prefer a more compact and concise drawing package that experienced engineers would be able to interpret and execute.
Something like this image, I imagine:
Electro Mechanical Assembly
Specifically, what I'm asking is what do your drawing packages look like and how do you create them especially to capture that kind of assembly information - wiring an external switch to a PCB for example?
My personal goal is always to have an archivable package that someone new could pull down and recreate the product.  I tend to do it with photos and words, but I'm at a loss on how to do it with drawings (I need to improve my ME skills I think!)
I'd like to share some examples with the team so any comprehensive images or examples would be really helpful.
I've done a lot of reading, I've seen a lot of blog posts on important things to include and advertisements for software solutions - but I've had trouble finding examples of execution.
Any help or discussion would be really helpful.  Thanks!


texts: What purpose do transformers have in electrical interfaces such as ethernet?

texts:
Some electrical interfaces, such as ethernet, specify that the outward-facing socket are to be isolated by a transformer. For instance, see this circuit example from the data sheet of an ethernet controller:

Ostensibly, these transformers are there to "protect" the circuit from external high-voltage transients, such as lightning strikes. I couldn't imagine how transformers might help, so I simulated it, using this circuit (SW4 closes at 200 ms, "starting" the lightning strike and SW6 closes 50 ms later, ending the strike):

Below are the simulation results (click for larger image):

As you can see, the surge is let right through, and the transformer doesn't help at all! So what am I missing? How can a transformer protect against high voltage surges from the outside?


texts: What is this contact on a jack socket schematic?

texts:
I'm looking for a 4-poles (TRRS) 3.5mm jack socket with integrated switch, and stumbled upon this connector schematic:

(this is an extract from the CLIFF FC68129 datasheet)

I understand that pins 1, 2, 3 and 4 are respectively the sleeve, rings and tip contacts, and pin 6 the tip
 normally-closed switch.

What about pin 5 and its associated switch on pin 7? The other pins already yield the right amount of connections for a TRRS jack socket.

My guess is that it could be some kind of "fully inserted plug" switch, but I cannot find the topmost "weird lengthy closed triangle" symbol in other datasheets.

This seller has a 360° photo view of the connector, but it does not help me.


texts: Beaglebone: Unable to boot with custom cape

texts:
I made a custom cape (attached) for my beaglebone black and when I connect it, the beaglebone doesn't boot, only the power led turns on. I'm booting from an SD card and I have disabled the HDMI and eMMC capes. When I've tried booting the beaglebone first and then connecting the cape, the beaglebone would turn off with the message "The power button was pressed" even though I didn't press it.

Thanks


texts:
I am trying to download the contents of a ROM chip following this tutorial however the chip is surface mounted and I can't remove it to put it in a breadboard.

I don't want to solder wires to the chip but there has to be a way of attaching them other than holding loose wires to the pins.

Specifically This chip


texts: Trying to control ethernet port in a raw fashion

texts:
I am trying to simulate JCHT35 switch to control a single actuator.  There are 3 wires with an RJ45 tip plugged into the blackbox j45 female port connected to an actuator inside.  What I am trying to do is connect the cat5 cable to my computer and black box and send a signal down to the actuator.

I guess in simplest terms, how do I just turn on lines on the ethernet port on my computer without using the ethernet protocol? Do I need to write a custom driver or are there any existing drivers that I can use?


texts: What is the difference between IQ mixers and normal mixers?

texts: What is the difference between IQ mixers and multiplication mixers? How do we know which ones to use?


texts: Understanding what Electrode Impedance values mean on Spec sheet

texts:
I want to understand what the electrode impedance values given on spec sheet mean. Just looking to gain a general understanding and what voltages/ currents I can or cannot use. The electrodes are used to record voltage spikes of around 50-90 mV.

"""Electrode Diameter: 10 um or 30 um
   Electrode impedance: <100 kilo ohms for 30 um electrodes....250-400 kilo ohms
   for 10 um electrodes"""

The link to the data sheet can be found here:
http://www.multichannelsystems.com/sites/multichannelsystems.com/files/60StandardMEA_Layout.pdf


texts: What exactly does a High Impedance imply in Verilog?

texts:
When would we want to use High Impedance signals?

In simulation, what causes the result of a high impedance signal? Seeing as its generally a bad thing, what should be looked for in terms of debugging?

Additionally, what are the implications of giving a tri-state buffer a high-impedance control signal?

Thanks!


texts: Why does my parallel circuit turn off when I connect it to a conductor?


texts:
I've created a special microcontroller driven LED display which I need power supply for. The display uses 24VDC and draws any current between 0 and 8 amps depending on how many LEDs are illuminated. Most of the time it's not illuminated and only microcontroller needs a little power.

So far I've used a battery charger as power supply for testing but I will need a proper power supply for it. The power supply needs to be weatherproof as it's going to be installed outside.

But it's very hard to find this kind of power supplies. So far I've found some LED power supplies like Mean Well HLG-240-24. Can I use this kind of power supply for my project? I think not as it's a constant current supply. Am I right? What other options I have?


texts:
There are not too much 4.2V linear voltage regulators on sale. Usually there are adjustable types. I need SOT223 package type fixed one. Microchip's MIC5209 supplies 4.2V but very expensive compared to its equivalents like 1117 type regulators.
My question is: What happen if I feed the 1117 type 5V fixed regulator with 5.1V supply input?
Can it give a regulated output or not work? My load draws about 200-300mA and about 4V output is acceptible.
I've read here Output=Input-Dropout and here zener diode solution is mentioned. Maybe I can coincide zener to sot223 footprint but i'm not sure its stabilitiy.


texts: PCB Layout and Trace Widths for Buck Converter

texts:
I am doing a PCB layout for a simple 12V DC to 5VDC buck converter. The rated output is 3A continuous 5A peak. Here are links to the schematic and first go at the pcb layout. I realize the traces are way to thin.

I am designing this based on the assumption I would use OSHPark to manufacture the board which uses 1oz thick copper layers. This means for the max 5A output I need the output current carrying traces to be 109mill. Currently they are 9.84mills. This leads me to a few questions mostly about current capacity.

1) If the load is drawing 5A will the output of the buck converter on the switching outputs be 5A? I'm assuming that it would be a fraction of that 5A based on the duty cycle but I'm not sure if thats an over simplification. Since the chip I used in my design has 3 switching output pins to share the current load but all together they are still less than half of the 109mill width.

2) The resistor branch is easy to calculate the current for ( 5V / 4.16K = 1.2mA ) so no concerns there at all. I'm assuming the diode should be rated at the 5A.  What about the capacitor branches though? I'm not sure what current capacity those will need. I realize there is no electric current going through them but they are charging and discharging to smooth the ripple so there has to be some displacement current?  Do I need to be thinking about this?

3) What size should my via's be? I have found plenty of calculators and tools for trace width but nothing about vias.

4) The 109mil trace for 5A is actually wider than the pad for my screw terminal. Should I just make those pads larger? Is there a general rule of thumb in terms of pad size verse the trace going into it? What about connections from the other parallel branches such as the feedback resistors.  Is it ok to just drop a thinner trace onto a thicker one?

5) Any other feedback about what I have done with this PCB layout?  Like I said its my first go at designing a PCB.

Note that I do not actually have an application in mind. The point of this exercise was to get experience with PCB layout and KiCAD. This is my first PCB layout.  I will probably load it up with a dummy load to confirm it works and move onto the next project without it ever making it into a case or a finished product.

UPDATE: Revision 2

UPDATE: Revision 3

I realize there are probably still significant problems with this and that I already accepted an answer.  Just including a "final" revision for completeness sake. At-least final kicad version.  I may try redoing it in Eagle or something else.


texts: VerilogIn and Spice out in Cadence or Synopsys

texts:
I want to convert a verilog netlist into a simulatable SPICE (or HSPICE) format. I have seen people talking about verilog-In and spice out in Cadence. How does this process actually work? What are the tools I should use?

I can also access synopsys tools. If you know how to use synopsys tools to achieve the same purpose, that will help too.


texts:
I am trying to understand how to read the schematic for my Creator CI20. My board looks like this:

Looking at the documentation the dedicated UART header has 4 pins:

Which are documented here:

http://www.elinux.org/CI20_Hardware#Dedicated_UART_header

Is there a way for me to tell appart which pin is designated as '1' or which one is designated as '4' ?


texts: Can I download a new program to a Silicon Labs C8051F311 with a JTAG programmer?

texts: Or does that chip require a bunch of weird voltages that can only be generated by a "special" expensive device programmer?


texts:
I have multiplicand 5 , multiplier 7 which they are binary representation :

5 = 0101 , 7 = 0111 (4-bit)

Register A to save the data to be multiplied(Multiplicand).
Register B to save the multiplier data (Multiplier).
Register P to save multiplication results.
Here is what I've tried

Here is my reference on a journal:

Can someone please point out what I am doing wrong? the binary result should be 00100011 (decimal : 35)


texts:
I tried to design the circuit but it doesn't give out the result that I was expecting and hope for and I am not sure why. Any idea on how to fix it?

Original Transfer Function ^

Block Diagram

Expecting Result with Matlab simulation

Circuit design

Simulated Result (green line as input and red line as output)


texts: What is this antenna called, and what does the polarization and radiation pattern look like?

texts:
I was searching for helical antenna designs and stopped here to look around when I saw this antenna (below). I am guessing it has a somewhat omnidirectional characteristic that would be advantageous to put on a car/plane/'copter to communicate with a helical "command station" antenna which can be manually pointed back.

What is this antenna design called?
What does the radiation pattern look like in three dimensions? Is it somewhat similar to a vertical dipole with isotropy in the horizontal plane and nulls at the top and bottom, or is it substantially different?
What about polarization - linear? circular? azimuthal? mixed?

I've tried a translation, but it does not seem to describe the antenna itself. These can also be seen at the extreme left of the second image.


texts: Beginner Q: Measuring current via USB charging cable

texts:
I was trying to use the multimeter to find out what current does my charging cable actually provides to the phone. How do I accomplish this without completely destroying my cable?

Right now I can measure the voltage (~ 5.15 to 5.2 V) and V~ (Ac voltage? which is around 10-11 ) but not able to figure out a proper way to find our current. Will be very grateful for any pointers.

Thanks


texts:
The output impedance of an ideal opamp is zero. The output of an ideal opamp acts as an ideal voltage source. The output of the opamp should be able to output very large currents (to source) and  (to sink) without the magnitude of the output current having any influence on the output voltage source. Note that with a real opamp the possible output current is limited. For example, the opamp can source a maximum of 10 mA and sink 2 mA.

What is the meaning of to source and sink and how does it influence the output voltage source of an opamp? The input current of an opamp is 0 so, how is it able to supply a output current? Explain me please!!


texts: Torchlight LEDs in series, is this possible?

texts:
I recently got hold of 2 broken LED torchlights and I had the idea of putting the LED heads together (after I cut them off) in series to make 2 lights for a camping powerbox that I want to make (LEDs are fine, torch body was unusable.)

I am asking for your help, because I am totally new to electronics and just lost in all the calculations involved.

Tried to get forward voltage and LEDs lit up, but nothing registered on my multimeter except the 1 sign (used the diode setting, am I doing something wrong.)

Anyway, here are the specifications. I had and I hope someone can help with some good advice.

I will power from my 12v battery.
The LEDs are a cluster of 9 at 0.07w, 4.5v (there are 2 of these.)

Good Guess Souradeep with the cheapo yellow Chinese made multimeter..
Anyway, I am added some new info that you wanted

This the reading I get from attempted forward voltage reading,as you can see the LEDs light up dimly but they are super bright when connected to the batteries

Here is the Specifications.

Thanks in advance... (sorry for the incorrect grammar, or its too long of a post)


texts: Is the curl of a B field at a point on a wire infinity?

texts: According to this text, curl is defined as a limit of the surface area approaching zero. If the point where the curl is evaluated at is near the wire, B is evaluated at a decreasing r value, and divided by a decreasing s value, it seems that the curl will approach infinity. Is this a correct approach in evaluating the curl of a B field?


texts:
I'm building a laser target with photoresistors and a 90FPS camera (which will probably become CPU bottle-necked) and when yesterday I went to shopping I just saw a barcode scanner and begun thinking: "Well, these things are relatively cheap in terms of hardware(ignoring the software), are bloody fast, and are excellent detecting patterns of black and white when illuminated by laser light", then I recalled that mouse sensors work the same way, and questioned myself if there is a much simpler and more effective way of building the target with those.
Can one of such sensors be used to detect red laser light hitting a white surface (with a blackish circle on the middle) a few centimeters away?  Since they take hundreds/thousands of frames each second, I'll assume that they can detect 10 laser pulses in 15~25ms, correct?
How hard is to use one of those for DIY projects?
Since you are electric engineers (and know the stuff) is there any other way to do it?
A camera+photoresitors will probably work (working on it), but it feels hackish and is not in compliance with the official sport regulations (unable to tell if its one solid shot or 10 short pulses at every shot). How would you do it?
EDIT:
Forgot some specs.
This is a target that can be used in competition (Modern Pentathlon):

Its sides are opaque and the front is only slightly opaque so the light can go through. It is about 20 by 20cm, and 25 thick, but some simpler targets are as slim as 5cm.
The lasers have a 630nm to 650nm wave, 3.5mW intensity, and the maximum of 1cm dispersion at 10meters.
The target needs to have the maximum of 100ms reaction time, so photo-resistors should be enough, and it needs to tell the location of the shot with 0.5mm precision at the very edge of the black circle (to distinguish an in from an out), some separation should do the trick.
Can you guys tell what is that target made of just by looking at it? It is hugely overpriced (800€-950$), since the low end targets (that only distinguish in from out, and give no position) are made with a diode and a controller cost almost 300€(~350$). I'll assume that the real cost is about 200€, what can be done with 200€ worth of electric material?


texts: Can two voltmeters connected to the same terminals show different values? Circuit with induced EMF

texts:
The circuit shown below consists of two resistors connected in series that form a closed loop. No electrical sources are in that loop.Let’s assume that the resistance of the wires that connect the resistors and form the loop is zero.Inside the loop is an external changing magnetic field that induces inside that loop a constant EMF of 1 V.

The current inside the loop is calculated using Ohm’s Law :

The problem was introduced by former MIT professor Walter Lewin. The problem was introduced in this video (starting at 35th min of the video):
8.02x - Lect 16 - Electromagnetic Induction, Faraday's Law, Lenz Law, SUPER DEMO
In the video is shown that two voltmeters connected to the same terminals show different values.
Can two voltmeters connected to the same terminals show different values?
My solution to this problem would be:
To measure the voltage between points D and A, the circuit has to be divided into two halves, the left half of the loop and the right half of the loop. If the induced EMF is considered to be equally distributed through the loop then in every half of the loop there is an induced EMF of 0.5 V:

The polarity of the the induced EMFs is according to Lenz law.

The voltage between points D and A by writing the equation trough the left half of the loop is:

The voltage between points D and A by writing the equation trough the right half of the loop is:

The conclusion is that there is a unique voltage value between points D and A, and the measured value should be 0.4 V.
Now let’s connect to the circuit between points D and A two voltmeters. The two connected voltmeters together with the wires that connect them to the main circuit form a second loop. Let’s assume that the resistance of the wire that connects the voltmeters and forms the second loop is zero. The left half of the second loop is connected to the voltmeter between points C and B, the right half of the second loop is connected to the voltmeter between points F and E. There is also an induced EMF of 1V inside the second loop. If the induced EMF is considered to be equally distributed through the second loop then the final circuit can be represented with the model shown on below.

The voltage between points C and B is defined with the following equations:

The voltage between points F and E is defined with the following equations:

The calculations above match the measurement performed by professor Walter Lewin.
My main question is : What is the theoretical potential difference between points D and A?


texts: Time taken to produce an output in a serial and parallel divider

texts:
I read this statement in a textbook on VLSI design:

Parallel divider use combinational circuits only, thus faster in operation than serial one, which has less hardware equipment

Here a serial divider is a sequential circuit which performs an operation repeatedly to get the result. Parallel divider is a purely combinational composed of full subtractors and multiplexers.
Why are the serial dividers slower than parallel dividers?
Since the integrated circuit of a serial divider is smaller, I thought that the time taken for a signal to reach from one end to another should be lesser.


texts: What is the maximum voltage I can set up on the AFG2125 function generator?

texts:
So, I'm picking up signals to work on the lab with the AFG2125 function generator. I have this generator on the lab https://www.gwinstek.com/en-global/products/downloadSeriesDownNew/5412/442 and on page2 it says:

AMPLITUDE RANGE <20MHz : 1mVpp~10Vpp(50 ohm); 2mVpp~20Vpp(open-circuit)

My question is, should I care about the 50 ohm termination or the open-circuit generator. What is this 50 ohm termination thing? I need to use the maximum voltage possible, as my circuit will attenuate the signals a lot. But is 10Vpp the maximum I can do, or can I go for 20Vpp?


texts: Why do some electrolytic capacitors increase in capacitance with age?

texts:
All in the title really; I've been repairing music equipment for years and replace electrolytic capacitors quite often.  Many times I've measured the capacitance of an old cap and it will read double or even more of the original capacitance.  How does this happen, and what other phenomenon occur with it (ie: increased ESR)?

Thanks


texts: Step-down converter and ceramic minimum ESR capacitor

texts:
I'm building a step-down converter, based on the TI TPS5450, which provides a reference design and various considerations on the capacitor. Even on the minimum ESR required.
But when states

"The minimum ESR of the output capacitor should also be considered. For good phase margin, the ESR zero
when the ESR is at a minimum should not be too far above the internal compensation poles at 24 kHz and 54
kHz."

And talks about this zero in other parts of the datasheet. How can I find this zero introduce with the C and the ESR? I did something like this:

$$ Resr = \frac{1}{(2*\pi*f_z*Co)} $$

where the Co is the output capacitor, f_z the target zero freqeuncy which should be not so far over the indicated pole frequency.

The problem is that I will need a ceramic capacitor, because the regulator will work in a high vacuum condition, and the polarized ones like tantalium can have problems. But when searching for a ceramic capacitor, it is not stated the information about the ESR, but only the dielectric type (for example the X5R).


texts:
I've read on the internet that MOSFET is faster switching device than bipolar transistor, however, i don't understand why. Considering the fact that transconductance of bjt is grater than transconductance of MOSFET  i thought that BJT is faster and can operate better at higher frequencies.

Can anyone clarify this a bit? Any answers appreciated!


texts: Simplest way to send data to and from FPGA

texts:
I've got a Basys2 board and need to transfer data between the FPGA and my PC(linux, transfer in both directions).

It doesn't have to be fast, but it should be easy to implement and not take up to many gates. What would you recommend? I2C, rs232, USB or something else?


texts: How does the resistor at the tail act as a current source in a differential pair?

texts:
Here is a version of differential pair:

I can understand the working principle of differential pair above. When Ic1 increases Ic2 decreases that's the thing. And for that to happen the tail current must be constant. And the above differential pair example is using current source at the tail which makes this idea work. But have a look at below:

In the above version there's no current source but just a resistor at the  tail. How is the tail current kept constant by that resistor Re? Or am I misunderstanding something here?

Edit:

Finally after reading τεκ's answer I started to understand. Below is an example how we can replace a "voltage source in series with a resistor" with a "current source in parallel with the same resistor". I added disturbance to see how much the current is regulated. I and II shows that source transformation which was the keyword to make things sense. Black plot of the current for I and II is identical which proves this. In III I've increased the source impedance of that equivalent current source and that shows us that moving to an ideal current source makes the current variation much smaller as shown in the red plot.


texts:
Left looks like genuine (logo), right looks like fake. Is it, really?

Edit: this part is expected to be IRF7821.


texts: If the propagation delay of a gate is said to be 10ns, what will happen if a pulse of width less than 10ns is applied ? Say a buffer has prop. delay = 10ns. Will it swallow the pulse like in Z2 ? Or propagate it with a delay 10 ns like in Z1 ?  Propagation delay is actually inertial or transport delay ?


texts:
This is an update to my previous board here, which I made after implementing the useful suggestions offered in that post.

In the schematic I have added decoupling capacitors, programming header and a pullup resistor to the RESET pin. I have also removed the loading caps on the RTCs crystal as it was not needed.

The wire of the label is not being displayed in Eagle (idk whats wrong but no time to figure it out right now). Please take note of the following pins:

PB3 - MOSI
PB4 - MISO
PB5 - SCK
PC6 - RESET

Now onto the board. In the board I have used a ground pour on both sides. I used a simple trace to route VCC to all the required parts, because I was having some difficulty with a VCC polygon. Now I surrounded the crystal with the ground plane as best as I could. The vias around the crystal connect the bottom and top ground planes.

So once again, suggestions are needed. Also I have 2 questions:

Can someone please check if I connected the decoupling capacitors correctly in the board.
There are three vias that are coming under the TQFN package of the AVR. Now the production house I use does make copper filled vias so the connection will be ensured. I want to ask will it be fine soldering the chip on top.

I am looking forwards to your feedback. Thanks a lot.

EDIT:I modified it to move the decoupling capacitors closer to the pins. But the problem is that now the crystal is a little further away. I don't know if this will cause any problems.

PS: Ignore the silkscreen for now, I will clear it up later.


texts: Hardware triggering multiple devices from a single source for long distances

texts:
I need to trigger remote devices through their hardware trigger inputs simultaneously (within 1 ms) from a single trigger source which has a timer output. So basically the 0/5V pulse-train at around 40Hz will trigger many devices simultaneously. The distance between the trigger source and a device is varying between 5 meters up to 200 meters. Total number of devices can be around 10.

I'm planning to use the following scheme:

simulate this circuit – Schematic created using CircuitLab

I can add an opamp buffer just after the the trigger source that is not a problem. But I really want to minimize extra components or electronics in between unless it is ready made modules ect. in the market that I can buy.

Is there any problem to use this scheme in this case?

One of my worry is whether I need a termination resistor at the device trigger inputs, because the sharp rising edges of the pulses can be an issue for ringing?

Another worry is the false triggering due to glitches due to interference ect. RC filters needed at the device inputs? (I plan to use coaxial cables)

Or is there another robust way to implement for this scenario?


texts: Is it possible to solder a capacitor to SMD board using regular iron?

texts:
I need to replace the C219 of the following SM design:

Is it possible to accomplish this task using regular soldering iron (used for through the hole design soldering) and some solder? Can I use a regular legged capacitor to replace the capacitor with, or does it have to be SMT? I have extra set of hands available, so holding it in place should not be an issue.

Are there any precautions I should take as to not damage the board (very expensive)? There is some PSU wires next to the part (can be seen on the right) that apparently can't withstand a lot of heat. What temperature should I keep the iron at?


texts: start a LTSpice simulation using code in MacOS

texts:
Help me please, I'm looking for the solution how to automate spice simulation with python on MacOS, currently, I'm thinking to use LTspice. However, I'm open to any proposal.

I want to make approximately <1000 simulations and extract data from simulation (e.g. value of the output voltage at the particular time) and after start a new simulation with another input parameters for the circuit.

I have checked a big number of pages, however, haven't find something which would give me a python + spice setup.


texts:
this is a follow up to my last question. I am working on a hand crank battery charger project. My current set up is that I am using a geared nema 17 stepper motor as a generator and have a bridge rectifier on each coil.  I have the both of the two rectified coils wired in parallel to get max current output. I also have a 25V 4700uf capacitor across each rectifier to stabilise the output. I then feed the rectified voltage into a buck/boost converter to step it down to 5V which is what my 18650 li-ion BMS requires.
However I notice that when I first turn the crank there is a 10V spike from the output of the buck/boost module before for about 1 second before it stabilises to 5V (slightly less under load).
My question is what is causing this and is it a problem for my BMS circuit? If so how can I avoid it?  I have a feeling it’s to do with that capacitors but I don’t know for sure. Help wound be much appreciated, happy to provide more details if need be.
Thanks
Billy.


texts: LTSpice, can I have separate plot panes?

texts:
I have LTSpice for mac.
I can add more than one plot pane in the same window.
Can I have plot panes in separate windows? (In order to have diagrams with different dimensions on my desktop)


texts:
We have a task in hand to sniff a RS232 protocol in a certain industrial automation setting (we have been asked to do this legally by the manufacturing company itself). We are planning to send a technician for this task (as it is overseas) and provide him with a hardware/software serial port sniffer/analyzer so that he can send us back logs with timestamps and protocol definitions and inturn our software team can define the protocol looking at those logs.

Does anyone have any ideas for a  hardware/software serial analyzer solution that can log data and timestamps that can satisfy our task?


texts:
I'm currently working on protecting 1000Base-T Ethernet lines from EMP using filter connectors such as described on page A-7 of this doc:

http://www.glenair.com/catalogs/mil_dtl_38999_cylindrical_connectors.pdf

One manufacturer can provide a minimum capacitance of 30 pF from each connector pin (TX+,TX-,RX+,RX-) to the connector shell which is connected to chassis.

I'd just like to know if anyone sees any trouble here?  I don't think they'll load down the signal since they're connected to chassis and not across the lines.

But I might be wrong.  Thanks.


texts: Coaxial Switch Using Arduino and Multiplexers

texts:
Hi maybe someone can help me here, basically I am trying to build a computer controlled coaxial switch. I am using a regular Integrated circuit multiplexer to handle which channel is patched to output. So basically I have:

              (8 X Coaxial Inputs)
              I I I I I I I I

microcontroller ----> | Multiplexer | --------------- I (1 X Coaxial Output)

The idea is so that I can use a computer to control which of my 8 video feeds that I can watch. I thought that because the connections are straight through I wouldn't have to worry about attenuation as much, but I tried a sample setup using a breadboard and I can barely see the picture. Any ideas as to how I can make it work?

I am currently using a breadboard with all the components I listed Plus some small gauge cables (so that they fit on the bread board)

UPDATE:
This is what My setup Looks like http://img6.imageshack.us/img6/6320/49195403.png
the MUX is a UTC 4051 Data Sheet is Here http://alldatasheet.com/datasheet-pdf/pdf/173652/UTC/4051.html


texts: Cypress FX3 CyU3PToolChainInit Understanding help

texts:
I don't understand the purpose of the CyU3PToolChainInit function that is written in assembly source code for the FXE. As for as I know it clears the BSS area and enters the main function, but how is this function generated? What is a tool chain? I mean I understand it's everything from a compiler to a link but what initialize it in a micro controller?

SDK API Manual

Programmer's Manual


texts:
I have many N-channel MOSFET and i want to know is there a way to use as an alternative of P-channel (Q1) in this circuit?
This circuit is responsible of switch between battery and power source.


texts:
The problem can be seen below. I understand how to find the poles and modes and the zero-input solution but I have two questions about the characteristic polynomial.
First, do I need to divide by 6 first or is it defined as having a coefficient of 1 in front of the second derivative? I haven't found a definite way to handle a coefficient in front of f(t).
Second, when finding the characteristic polynomial, do I neglect the $$ -sy(0^{-}) - y'(0^{-}) $$ and similar terms and just use $$ s^{2}\hat{Y}(s)+2s\hat{Y}(s)-8\hat{Y}(s) $$ ?

Determine the characteristic polynomial P(s), characteristic poles, characteristic modes, and the zero-input solution for each of the LTIC systems described below.
$$ \frac{d^{2}y}{dt^{2}} + 2\frac{dy}{dt} -8y(t) = 6f(t) ,\ y(0^{-})= 0 ,\ y'(0^{-})=1 $$

Thanks


texts: Why the pinout on the Raspberry Pi Pico development board, are labeled under the board?

texts:
It may seem a stupid question, because it is common for many careless manufacturers to print the pin markings under a development board; but not for a company which is known for its user friendly designs and a big audience in maker and hobbyist communities.
When installed on a breadboard (which is intended use for same form-factor dev-boards), the labels are underneath the board. without a pin-out card or picture available at hand, we have to remove and find a pin and put it back on the breadboard. even for a permanent use, (soldering it on a motherboard), it would make the troubleshooting harder.
The PCB itself doesn't seem very tight. a little reordering of graphics or parts would make it possible:

Is there any specific reason for that? or it's just because the designer forgot to pay much attention to details?


texts:
I was cleaning my 36v dc 5.5 amp SMPS today. I was playing around with the wires and goofed up. A spark happened and later I found that a Y Cap had cracked.

This cap value is:
Yf222m 2200pf 250v x1:400v y2:250v

I went to the component store and the guy searched his inventory and handed me what he had. The only info given on this cap is:

E 222m 2kv

I argued with him whether this was compatible and he "guessed" or hoped that it did.

Now I'm back home wondering if I should solder this component in my smps and hope that it doesn't blow up.

edit:

Yes, the one I got from the store looks like a Y cap but it may not be a Y cap.

Anyway, even though the 2kv range is much higher than the original 250v ac rating, I have gone ahead and soldered it in and it seems to be working. This smps is part of my sound amplifier. I have a tiny active voltage monitor module installed on the amp front display and the reading i'm getting is 36.0v constant +/- 0.1v as before.

I initially took the smps out because I was not getting FM reception. Initially, I thought my USB fm audio playing module was broken. Then I took my amp closer to the FM broadcast area(within 5km) and was able to get good FM reception albeit with tiny dots of noise(like the noise in old projector films) so I figured the class D amp was increasing noise and lowering the chances of getting FM reception. The amp used here is a class d chinese tda7498 commonly found on aliexpress. After reading around on the internet I found that almost all class D amps kill the FM reception and the tda7498 is, as I found out in my experiment, is a confirmed FM killer. I will have to get back to internet radio again.

I can order the correct rated Y cap from aliexpress but unfortunately, it will take a month for it to arrive so haven't bothered to order one yet.


texts: SPI transfer doesn't quite work on Netduino -> led driver

texts:
I have a TLC5916 led driver (manual here) that can power 8 LEDs as commanded through SPI by a microcontroller.
The writing end of the SPI is a Fez Panda (.NET MicroFramework) uC. When I send data, I sometimes get correct results, but usually it's something that looks similar, but not quite like, what I sent.

It usually looks like the sent byte got left-shifted one bit, or got some of the bits flipped.

Trying to send the same byte again and again usually yields the same (wrong) output, but even there, I've seen slightly different outputs for the same input crop up every once in a while.

Note that the LED driver is powered at 5V (PC ATX source), and the Fez has 3.3V outputs.

Also, I've tried to read back the values from the LED controller (it has a SPI output pin for chaining multiple controllers). This time, the 5V values are read perfectly by the Fez uC - the values I read corresponded with what physical LEDs were lit. (The Fez documentation does say that 5V inputs are supported, so I guess this was expected)

I tried changing the sampling setting for SPI (rising/falling CLK edge), but same results for either setting.

Any suggestions for debugging?

I don't have an oscilloscope or digital probe :( .


texts: What if you put a capacitor betwen the plates of another capacitor?

texts:
Based on: Is there a dual of the transformer?

The picture of the capacitor inside another capacitor seems viable to me. If a transformer is two inductors with a common magnetic field, its dual would be two capacitors with a common electric field. The voltage transfer ratio would be a function of the relative capacitance of the two capacitors, again like a transformer and the relative number of turns.

So is this done? If not, why not? Would it just not transfer energy, or would it work but be inefficient in some way? Size? Speed? Heat?

What would be the properties of a capacitor actually constructed this way?


texts:
I have a mini solar panel 5.5 V 1 W 180 mA and I want to connect it to my DC motor 3-6 V. I tried directly but it didn't work. After some research I found that I needed a inverter.
My question is: do I really need a inverter? if I do what inverter should I get?

I'm new to this so sorry if i didn't make any sense.

Solar panel: https://www.banggood.com/pt/5_5V-1W-180mA-95mm-x-95mm-Mini-Solar-Panel-Photovoltaic-Panel-p-999056.html?rmmds=myorder&cur_warehouse=CN

DC motor: https://www.banggood.com/pt/5Pcs-DC-3V-Mini-Motor-For-Arduino-DIY-Smart-Car-p-999094.html?rmmds=search&cur_warehouse=CN


texts: SO I just bought an external microphone but just noticed that it uses a pretty rare battery, an RC2 3V one and I was wondering; Is there any chance I can somehow power it up using a USB cable?


texts: How to delete graphics from PCB board view in Eagle?

texts:
I am making my first PCB, and I have a numpad and a 16x2 LCD in the schematic. When I go to make the board, it also brings in the graphics along with the pins, but I will not be soldering them directly to the PCB and I don't want the graphics showing up on the PCB. I will likely solder pin headers, before connecting the devices via jumper wires.

Should I replace these parts with pin headers in the schematic? Or is there a way I can disable the graphics?


texts: How to identify a coax connector vs twisted pair connector

texts:
I need to have a connector that will bring in COAX input to my PCB.
I have this Rosenberger HSD Connector Catalog.
On page 33, "99S12D-40MA5-y" - is this connector a twisted pair connector or Rosenberger connector?
I am not sure that it is a Coax connector. Can someone please clarify which are the coax connectors in the catalog.


texts:
If I understand correctly, the state diagram of a sequential circuit simply shows  the different states the circuit goes through. However, if I'm trying to build a 2's complementer using a shift register and a flip-flop, how does the state diagram look? Seeing as what goes through the flip-flop depends on the digit put in the register, I'm not sure how to draw it.

Thanks


texts: Waves on raspberrypi camera feed, Ground loops? electrical interference?

texts:
I run a video recorder in a vehicle built on Jetson Nano (Very Similar to raspberry pi). It runs on 5V . The vehicle has a 24V power supply. I power the video recorder with an automotive-grade 24V to 5V converter.

The Jetson nano is connected with a Raspberrypi Camera with a Flat ribbon cable. When I record video, I get a wave-like noise on the video feed at random times. And if the wave appears, it appears in a 1 second interval(only from what I see, no measurements/tests done) .  This is the connection diagram and voltage differences between nodes.

The ground of the Jetson board and Ground from the vehicle body are not connected, there is a potential difference of some mVs. That is what is depicted in the diagram.

The software guys working on the camera driver say this could be electrical interference. We have a similar setup in our lab environment and we are not able to reproduce the noise. We doubted the power supply, vibration, 4G LTE interference, GPS interference. The cable used to connect the camera with the board sometimes touches the HDMI/display ports of the Jetson Nano board.

Datasheet Camera : https://cdn.sparkfun.com/datasheets/Dev/RaspberryPi/ov5647_full.pdf

Sample video : Video1
Video 2
Color lines

Sometimes the lines are coloured and some times the are white

What could be different from a vehicle and the lab environment, how do I ensure the grounding is good in the vehicle. And how do I test and ensure if this is due to electrical interference? Or any other interference?

Is this caused by ground loops?

This is the convertor used, the sellers say this is non-isolated buck converter and there are isolated ones which are used in radio related devices for less noise, does this have anything to do?


texts: Implementation of an amplifier in LTSpice

texts:
I need to implement the following circuit in LTSpice but I don't know if my schematic is ok. Also, I don't know what  values for I should use for Cinf and R2.

The following constraints are imposed:

VCC= 10V
VCM = 1.5V
Vgis a sine wave with a frequency of 1 kHz. Its amplitude will be chosen so as to ensure minimal distortion of the output signal (i.e. v0 should also be a sine wave)
R1= 15kΩ.

I need to choose a value for R2 and Cinf in order to have a (theoretical)gain value Av=1500.

How can I compute the theoretical expressions of the DC collector currents of bipolar transistors Q1–Q8, considering VBE≈ 0.6V and the theoretical expression of the small-signal voltage gain Av= vo/vg?

The first picture is the schematic and the second is the LTSpice implementation.

What I found is that:

ICq5=ICq6=ICq7=ICq8=(Vcc - Vbe)/R2
ICq1=ICq2 = [ICq7 / 2 ] * [Beta/(Beta+1)]
ICq4=iCq2-current of Q5
ICq3=ICq1-current of Q3-current of Q4
Beta in my case is 182.1 because I'm using a BC847A transistor.
A=Vo/Vg = Gm_q2 * Beta_q5 * R1Gm_q2=ICq2 / Vt that is approx 40*ICq2

How can I find the value of R2?
This is what I have now, an sine like wave for Vg


texts:
This is more of a general question to see which methods are the most common to improve the detection of a signal which is buried in noise. Currently, we are building an optical system for medical imaging and the signal that is being detected is 1000x lower than the noise floor.

Currently, we are looking at methods such as lock-in amplification/detection and other types of filtering but it was an open question to see which are common methods to improve the detection of a signal in a noisy background.


texts: If many EM signals exist in same time/place, when would interference occur?

texts:
If electromagnetic waves can experience interference from same or different frequency transmitters in surrounding region; Then why do we not experience interference when many people use their mobile phones at once in the same place?

This is the part I don't understand.
Is it to do with phase?

EDIT - Thank you everyone for your answer. I did read on Frequency Hopping, but my issue is in trying to "envision" what happens. I attached a pic of what's in my mind. If 2 Transmitters transmit waves... they "may" (and certainly will in far field) cross each other. Do the red circles not pose interference even if amplitude or frequency is different via spread spectrum? Or I'm missing something? Can the 2 waves ever end up being in Superposition even if they hopped frequency?


texts:
I'm looking at building a bench supply using a 24V 1.3A DC power supply and a ON Semiconductor MC34167. Along with an appropriate inductor and MOSFET as suggested in the datasheet. I want to make the bench supply adjustable between something around 5V and 30V.

Now the problem I'm having, being an uneducated hobbyist only starting out, is figuring out exactly how to make the circuit adjustable with a potentiometer. I'm also wondering how to determine what voltage the filter capacitor should be, I know the one at Vin should be at 40V to accommodate voltage peaks and the Vout one should be the same for a max output around 30V. I don't want the solution handed to me, I'm just looking to be pointed in the right direction. Perhaps something I should research. Any help would be very much appreciated, thank you. :)


texts:
I am working on interfacing to a L3G4200D Gyroscope breakout board .

I am using it in I2C mode, and the microcontroller I use is the 8051 (via bit banging).

I havent connected anything to the SDO pin, so it is high by default.

My code is here.

The problem is that I always get 0xFF, when I try to read anything from the gyro.

Any suggestions on the mistake I am making?

EDIT:: Solution
While reading from the Gyro,using I2C, it needs a repeated start signal. I did that and it worked.


texts: Over-voltage protection system for a 7 - 20 A Load with 4 - 5.5 V output from PSU

texts:
The power supply used on the product, is a DC-DC buck controller 24 V in (3 - 5.5 V out).

I need some suggestions to help protect a load (LED Display) which draws roughly 5 - 15 A the power supply on the product outputs 5.5 V and is capable of delivering 18 A - 25 A, the IC on our PSU can fail from time to time and cause over-voltages that destroy the LED drivers and LED displays.

I've looked into Zener clamping circuits, SCR crowbar circuits and Varistors,

But I don't know how well and how to calculate whether they would survive with the high current flow on the output of the PSU.

Any ideas?


texts:
I have an RC phase shift oscillator design.
I need to design this circuit's load effected version.
I always get confused by the feedback's load effect.
I assume I have to design RBB//(base emitter resistance) + R5 at the output and R5//RBB//(base emitter resistance) at the input Vin.
Can you help me about it? (RBB means R1//R7)


texts: Can I use a PNP Transistor with an Electret Microphone to get an non-inverting output for my Arduino?

texts:
I'm looking to simply read the generic sound level from an Electret Microphone. I've seen a number of schematics with NPN transistors, that will provide an inverted output (~5V when quiet, ~0V when loud, linear operation in between).

Here's an example:

However, I would like non-inverted output (linear operation, super quiet input gives ~0V, super loud input gives ~5V). I realize I could easily correct for this in software, but it just seems backward to me in a way and I cannot find any examples of a non-inverting output with a PNP transistor.

Is there a reason for this beyond being uncommon? If it's possible, could anyone provide a schematic of an electret microphone and PNP transistor that will give ~0V when quiet and ~5V when loud?

Further, is there some reason why this is so uncommon, or undesirable? NPNs seem to be used much more often than PNPs, why is this?

Edit

It seems I was rather confused in what I would get as output from the NPN preamp, which would be 0V for silence, and +/- Vin / 2. Here's what I want instead:

0V when silent, ~2.5V in medium sound levels, ~5V in maximum sound levels. This could be read by the ADC easily into 'sound level' without much work at all. However, I cannot feed voltages < 0V or > 5V to the analog comparator. It looks like I want the above with an envelope detector, however that would only get me from 0V to 2.5V. How do I make it vary the full 0V to 5V, 0V being 'quiet' and 5V being 'loud', with everything in between linear?