texts: Why do I see 0v on electret microphones?

texts:
I've got a few electret microphones and I tried to make this circuit:

It didn't amplify my sound, it continuously buzzed. Without mic it did same thing. So I probed mic and I saw 0.000v. Also 0mA (shorted).

I tested 5 microphones sitting next to each other, they all had same results. There was a neodymium magnet about 3-4cm next to them. Are they broken? Or is there something else wrong?


texts: Guidelines for determining shock hazard of capacitors

texts:
I'm looking for guidelines on how to identify capacitors which have the potential to cause pain, injury or death due to electrical shock if not handled correctly.

I recently purchased a "getting started with electronics" kit from Radio Shack. It contains an electrolytic capacitor of 1,000 µF and 25 V. I'm assuming this particular capacitor doesn't have the potential to cause such harm because it was included in an introductory kit. However, at what point does a capacitor have the potential to cause pain, injury or death due to electrical shock?

Ideally, I'd like links to reference material on the subject.


texts: Temperature stability of capacitor materials

texts:
I am looking for a capacitor with good temperature stability to replace some low value ceramic caps in a bandpass filter. If I understand it correctly, the best types are PPS (poly phenylene sulfide). However, at the values I want, 47p and 82p I cannot find a COTS supplier in 0805 packaging.

What is the next best capacitor type, and how much worse is it than PPS (and how much better than ceramic)?


texts:
Came across some doubts:

What exactly are the differences between a USB host and device? Is it just that who powers the bus?
When two devices connect how the device say "hey I will be the host and you be the device?"
Can one device acts as a host as well as a device. For example, "A" should act as a device when a USB host is connected, and "A" should act as host when a USB device is connected?


texts: Bridge rectifier & transformer to measure mains

texts: So I am trying to use this circuit to read in voltages from the wall and input it into the Arduino Uno. Would an F-1X transformer work for this application?


texts: Driving parallel MOSFETs (IRF540) with IRS2092

texts:
The IRS2092 datasheet shows a 4 ohm load circuit (see image below).
I want to check whether MOSFETs can be paralleled to support low impedance of 2 ohms, instead of 4 ohms as shown. Can anyone please let me know whether it is feasible?
The MOSFETs I plan to use are IRF540.


texts: for a school project I have to do something that needs the environment to work, my plans are to make a solar powered mini fan, now my question. How can I make that the fan ( 6v dc motor) keeps working for little while even after I block the solar panel. Do I simply put a capacitor? If yes, how do I know wich capacitor( values) should I get?. Thanks for the help


texts: LM7805 circuit not working when 12V source is also driving another load

texts:
simulate this circuit – Schematic created using CircuitLab

I have a simple power supply circuit that needs to drive a 5V load and another 12V load, and it's behaving very strangely.

I've used a LM7805 voltage regulator with the input pin bridged to ground with a 0.33 uF capacitor and the output pin bridged to ground with a 0.10 uF capacitor.  The ground pin of course goes to ground. A 5V 0.4W (80mA) micro-fan is connected between the output pin and ground.  12V from a battery goes to the input pin.  This is all as shown in typical LM78xx datasheets (e.g., Figure 1 on page 7 of https://www.sparkfun.com/datasheets/Components/LM7805.pdf, or Fig 6 on page 18 of http://www.fairchildsemi.com/ds/LM/LM7805.pdf).  I also put a switch between the 12V source and the circuit.
[edit: added circuit diagram below as suggested]

When configured as described above, it works perfectly.  However...

(1) When I add another line, this one running from the 12V source to a 12V 160mA micro-pump, and from the pump to ground, the 5V fan no longer works.  The LM7805 also gets much, much hotter, very quickly.  The regulator output is ~ +0.5V relative to ground in this condition.

(2) When I switch off the latter circuit, the 5V fan very briefly spins.  I initially guessed this was because of some charge stored in the capacitor attached to the output pin.  However, it still happens if I remove either or both capacitors.

(3) If I start the circuit with the 12V load disconnected, wait a second for the fan to get up to speed, then connect the 12V load, everything is fine.

Same results with whether the DC source is a battery or a plug-in DC power supply.

Can anybody help?


texts:
Possible Duplicate:
  Good Tools for Drawing Schematics

I'm looking for a schematic editor/capture tool to use in the very initial steps of a digital design. This is, as a block diagram editor, instead of inkscape or similar. The idea is to replicate schemas like this without doing it on paper:

The final design, although it would be perfect to have VHDL/verilog export capabilities, will be done by hand in HDL language. I need a tool to design an initial block diagram, with the main signals/buses and elements, as well as the pipeline of the datapath of a hypothetical custom processor.

I've checked Xilinx ISE, gEDA (gschem) and other propierary tools, but none of them is suitable for this as they are quite specific (ISE) or the opposite (gschem). Here ins stack I've found some questions, as this. However, I looking for a closer approach to processor architecture, datapaths, registers, memories, arithmetic units, etc. A professional look & feel is also desirable.

Any idea would be welcome.


texts: Ideas for a cheap, simple, common temperature sensing component?

texts: I'm looking to make a device to regulate a heater to maintain 100-110 degrees Fahrenheit in a small, moderately insulated container. Specifically, I'm wondering what I might have in my parts drawer that would make a suitable temperature sensing device. It need not be especially accurate or precise. I thought if this device is also in a TO-220 package or similar, maybe it could also be the heating element. Any suggestions or experience on sensing temperature with a common component I already have in my parts bins?


texts:
Anyone know what this silver component is? Tried to google it, but no luck.

Thanks


texts: Induced power supply noise on switch contact

texts:
I have a circuit that has a 24V section and a 5V section, separated by opto-isolators and an isolated DCDC converter.

Both sides of the DC-DC have decoupling caps, and the MCU has one per Vcc pin. There is a internal ground plane pair for 24V/GNDPWR on one side of the isolation gap, and 5V/GND on the other.

There is a switch input (a foot switch with about 2m of cable) on the 24V side that is connected to an MCU by one of the opto-isolators. This switch, when pressed, has quite a lot of bounce and induces a high-frequency "ring" onto the 5V power supply line, (presumably though the DC-DC converter). The ring appears around 100-200ns in length.

In the schematic, C1 is added to try to prevent too much inrush current on the ground plane when the switch is closed, but it has little effect.

The resistor R1 is chosen to limit current in the opto diode, and C4 gives RC of around 0.22ms, so substantially longer than the noise signal.

Disconnecting the opto-coupler output on U1 Pin 4 doesn't make difference, so the noise must be entering across the isolation gap via U2.

This power supply noise seems to be rather upsetting to the MCU circuit, as it causes occasional resets when the switch is pressed (a similar noise signal seems to be imposed on the MCU crystal signal as well).

Switch bounce isn't an issue, as I can deal with that in software, it's just the noise that's concerning.

How to prevent this noise from interfering with the rest of the circuit?


texts: Vehicle battery (NMC) max discharge rate

texts:
I wanted to understand a few things related to secondary batteries:-

Do the secondary batteries not have any limit on how much current we can draw from them?
a. I understand that we have a limit on that due to battery's internal resistance.
b. and the battery datasheets (for example) mentions the max discharge rate (maybe 5C or something depending on battery).

But what will happen if i try to load a NMC 12V/15Ah battery pack (4 cells each with 3.6V/15Ah rating connected in series) with a 1000A load for 1s or 700A for 3s?
Will it only heat up badly for that duration? But will it be able to support that huge current without any voltage dip?


texts: What are transistors used for in dynamic RAM?

texts:
I haven't studied electrical engineering however I am currently studying about Moore's law.

I found an answer to why transistors keep increasing but I still can't get my head around why so many are needed for dynamic RAM.

It says 6 transistors are needed for each bit in dynamic RAM.

What exactly do these 6 transistors do? Are the used to actually store and hold the data since it is volatile?

Sorry for the stupid question but I really can't get my head around it.


texts:
We have dual power supply units (+- 12V DC with common GND) at our college lab using which I am able to implement my project (digital thermometer) which uses op amps as shown in the figure.

I'm using an LM35, three op amps, an Arduino Uno, and an LCD display.
I need to make this a product which can be run using only one external power supply (+12V DC adapter for the Arduino).

I tried using a voltage divider circuit to supply +6V and -6V DC to the op amps. However, when I connect the LM35, feedback resistors and other components, the voltages measured at various stages are not as expected.
In fact, the input voltage itself changes it's value from +6V to +2V and the other voltage changes to -10V from -6V.
One thing I have noticed is that there is a constant voltage difference of 12V between the input pins.

Why am I getting weird values of voltages?
Is this called the "loading effect"?
What are the other possible ways of supplying power to the op amps using the 12V adapter?

EDIT: This is the schematic that works with the dual power supply unit (+-12V) at my college. I want to make this device portable. Hence, I can't use the dual power supply all the time. Need a solution for this...


texts: Will current usage increase with different length of wire?

texts: Given all other factors are same, with only the wire length increased (for example, 0.5meter increase to 50 meters,) will the current consumption/usage increase as well? Can anyone explain?


texts: Noise in opamp amplifiying circuit which can be removed by short-circuiting VDDA and GNDA?

texts:
I have built a filtering and amplifying circuit for an ultrasonic receiving channel. The schematic is shown as below. The +3.3V is the power supply of a microcontroller.

It amplifies the receiving signal around 42 kHz and level-shifts it to be centered at 1.65V.

Problem is sometimes the noise floor increases more than 100%. The extra noise floor appears randomly after each power on/off. Interestingly, it can be removed by shortly short-circuiting the +3.3VA and the GNDA (using tweezers). After that the circuit can work properly for quite a long time (>24 hours), at least I have not encountered the case the extra noise appears later after a clean start.

I guess this extra noise is a self-oscillating of the opamps. Can someone give me some suggestions about how to make this circuit more robust?


texts: Power green LED from microbial fuel cell (MFC)

texts:
I am looking for a way to power green LED (like GNL-3012GD) from MFC which provides 0.2mA @ 0.6V for about 1hr (there should be some drop off period then; 2..3hrs to restore). I understand that the amount of power is too small but what about the energy storage to drive the LED for a while (from a few seconds)?
Any hints or schematics are highly welcomed.


texts: Help with a Closed loop and zero order hold function ZoH * 1/s(s+a) type

texts:
i would appreciate some help in solving this problem, i need to find the transient response for a unit step, i have a brief idea of how to solve, but my graphs in matlab doesnt seem to fit with the graph form i have to reach, i would appreciate any help or advice.

i also attach an example of matlab commands for a example function of ZoH * s/s(s+1), same problem but with a=1, i cant manage to have a response like i attached too since my a is 2 and im trying to work it out with an "adjustment" as can be seen in my process.

Any kind of advice or help, would be very appreciatted, thanks in advance.

Also, i add these images, in case anyone can point whats wrong with my calculations.


texts: 'Leftover' voltage when using constant current

texts:
I came across this circuit,

simulate this circuit – Schematic created using CircuitLab

Which states that the current through the LED is equal to 0.5*R2/1000. I'm not 100% sure how to come to that conclusion, but that is only a part of my question (a part that I am still happy to have answered! :))

My main concern is as follows: Let's say I choose R2 = 40 ohms and the current through the LED is therefore 20 mA. And let's also say that, from the datasheet, the forward voltage of the LED is 3 V. From Ohm's Law the voltage across the resistor is equal to 0.02 * 40 = 0.8 V. What happens to the remaining 1.2 V from the constant 5V DC voltage source?

I'm reluctant to test this circuit without knowing the answer in case it causes excessive heating or damage to my components.


texts: How to get a band-limited digital modulation of X type?

texts:
I am developing a program which should create modulated signals and combine them to  get an RF signal with different modulations on different frequencies with non-interfering bandwidths.

The problem is I am not able to find the equations which show the correlations between the bandwidth of the base-band signal and their configurations (samples per symbol, symbol rate, modulation type, pulse shaping filter, etc.).

The only two equations that I could find were for QAM/PSK and FSK.

  \$ FSK= \delta f +2*B\$.
  \$QAM/PSK= (1+R)*B\$

  \$\delta f=\$ The distance between the two farthest frequencies used in FSK.
  \$B=\$ The baud rate of the signal.
  \$R=\$ The parameter of the raised root pulse shaping filter.

So my question is what are the equations to calculate the bandwidths of modulations that use MSK,PAM,ASK,CPM? Also doesn't root raised cosine also affect FSK bandwidth, shouldn't the B parameter be included in FSK's equation?

P.S.
I just learned about digital-signals and signal-processing in general in the last two weeks, so I do not have a proper grasp on some core concepts. I do have a bit of an intuitive understanding about how they work (e.g. I do know what FFT does but the math behind it is a bit murky for me). Please go easy on me. :)


texts:
I am trying to understand Flip Flops & Latches. I am reading from Digital Logic book by Morris Mano. One thing I am not able to understand is why we clock flip-flops?

I understand why we need 'enabled' or gated latches. But what’s the use of clock? I am not able to understand this. Why can't we just enable the required flip-flops & give them input? As we change input, the output changes. Why do we have to change the output with rising or lowering clock edge (in case of edge triggered flipflop)?

Any help regarding this is appreciated.


texts: Operation of DC power distribution boards/panels/strips

texts: I have purchased a variable bench power supply 0-30 volts and 0-10 amps. I intend buy and to connect this supply to a suitable dc power distribution board, from which I wish to power four led matrix panels which operate at 5 volts per panel, and consume between 5 and 10 amps depending on the number of leds which are lit at any one time. I don't know what settings I should select on the bench power supply. Should I select 5 volts or ( 5 x 4), 20 volts ?. Is the capacity of the bench supply at 10 amps inadequate for this project ? I can limit the number of leds which are lit at any one time, via my Arduino Mega and suitable coding.


texts:
I'm running Virtual Wire between two Arduino's and, so far I've been able to  send characters and receive them on the other side.

Problem is, how do I turn this received 'A' (or whatever I send) into an action to operate a few digital outputs. (it's a relay circuit configured as an H-bridge)

Below is the sample receiver program included with VirtualWire.

// receiver.pde
//
// Simple example of how to use VirtualWire to receive messages
// Implements a simplex (one-way) receiver with an Rx-B1 module

#include <VirtualWire.h>

int twoPin = 2;     //the two pins to be used to control the relays
int fourPin = 4;

void setup()
{
  pinMode(twoPin, OUTPUT);
  pinMode(fourPIn, OUTPUT);

  Serial.begin(9600);   // Debugging only
  Serial.println("setup");

  // Initialise the IO and ISR
  vw_set_ptt_inverted(true); // Required for DR3100
  vw_setup(2000);    // Bits per sec

  vw_rx_start();       // Start the receiver PLL running
}

void loop()
{
  uint8_t buf[VW_MAX_MESSAGE_LEN];
  uint8_t buflen = VW_MAX_MESSAGE_LEN;

  if (vw_get_message(buf, &buflen)) // Non-blocking
  {
    int i;

    digitalWrite(13, true); // Flash a light to show received good message
    // Message with a good checksum received, dump it.
    Serial.print("Got: ");

    for (i = 0; i < buflen; i++)
    {
      Serial.print(buf[i], HEX);
      Serial.print(" ");
    }
    Serial.println("");
    digitalWrite(13, false);
  }
}


texts: Marking laser position with glow in the dark material

texts:
This is a weird set up but I'm trying to figure out at what angle of deflection a pendulum has based on using a laser point reflecting off an attached mirror. I've worked out the math but I'll need to know the height from the laser origin the beam is deflected at in order to figure out all the relevant angles.

This beam cannot be directly observed, however it is possible to observe after a few seconds so I need a way to 'preserve' the last position of the laser pointer for a few seconds.

Here is my current idea:

Take a glow in the dark paint and shine a UV light on it to 'charge' it and make it glow. Then use a 5mW red laser pointer in order to cause the point where the laser hits to lose it's charge so it looks like a dark dot surrounded by glowing green material.

Is there any alternative ways to doing what I'm trying to do? I know that by using a 405nm blue laser it will instead cause the point to glow so I can just make one specific point glow - but I do not have a blue laser pointer on hand so that's why I'm doing it in reverse with this red one.


texts: Is something wrong with my photo-isolator circuit?

texts:
Simulate the circuit of Figure# 7.1 using Proteus, for that you will need to replace the ID LED and IR Photo-Transistor with a Photo-Isolator such as the 4N35.
This is the circuit we got.

This is circuit I change it to.
When I run the circuit this. is what I get in the oscilloscope?


texts:
Suppose we have output signal from a another circuit in range from 0-7.5V. However, this signal is polynomial coded:

function A: +0.5V
function B: +1V
function C: +2V
function D: +4V

... so output voltage of 5V means function B and D were triggered, voltage of 3.5 V means functions A, B and C were triggered ... etc.

Is there an IC that can handle de-multiplexing of this signal and have like 4 outputs which are set to 5V (or similar) when specific functions are detected?


texts: Single phase capacitor start induction motor TRIAC speed control and centrifugal switch replacement

texts:
I have a machine tool with a 1 HP reversible motor. I am looking at implementing speed control by using a zero crossing detector and phase angle controlling circuit. I am planning on using a micro controller such as Arduino to generate the pulses for phase angle control.
The issue is the motor is capacitor start with a centrifugal switch - at lower speeds the centrifugal switch will re-engage.
I am wondering if it is possible, or if there are already designs, to remove the capacitor and centrifugal switch, and replace with another TRIAC to control the start winding?
This could either be controlled by time from the microprocessor, or motor speed if I add another circuit to monitor this (which I may do to display RPM and control an external cooling fan anyway.)


texts: Measure current for Field Oriented Control

texts:
I want to use an AD8418 (http://www.analog.com/media/en/technical-documentation/data-sheets/AD8418.pdf) together with the ADC of the uC to measure the current of a BLDC motor for two phases, that is used for field oriented control. As a driver I use a DRV8313 (http://www.ti.com/lit/ds/symlink/drv8313.pdf) which allows to connect the shunt resistor to the low-side mosfet. My question is now where I should put my shunt resistors to measure the currents:

1.) Directly to the phases of the BLDC motor. This is found in the application note of the AD8418.

2.) Put the shunt resistors to the low side mosfets.

When I put the shunts to the low side mosfets, I need to measure the current only when the low-side mosfet is active. For that, I need center-aligned PWM to trigger the ADC in the right moment. Is this also needed when I put the shunt resistors to the BLDC phases and if yes, when needs the current to be measured? Are there any advantages with method 1.)? The actual PWM signal will be around 25kHz, where the CMRR is about 80dB, that should be still enough.

Here is also a schematic of how I planned to do it with the method 1.)


texts: Change in current for a moving sliding bar?

texts:
From this diagram:

This design is inspired by the classical rail configuration, however, now having all the current flow direction in the -y axis.

There are two components, a large rigid conductor shown with \$ L_1\$, and a smaller component(w.r.t the other)  shown with \$ L_2\$, the smaller conductor is a movable bar, a slider that is still connected to the larger rigid one to transfer power.

An exterior force is applied to the slider, and beings to move in +x axis direction:

Would the motion of the slider change the current that is flowing with it?

At \$ t=0\$ current is \$ I_i\$ while it's at rest, when it beings to move is it still \$ I\$ = \$ I_i\$?

Change in current from possible change in \$ R\$ due to the motion?

Or change in current from a possible induced \$ -\epsilon\$ due to the motion?

Even though I modeled the magnetic field of the two components as two separate elements and can't find them affecting one another.


texts: How to make if condition run once in while(1)

texts:
I am intergrating inputs and uart in PIC MCU. My program is if I press a switch, this info is send to terminal but the problem is it keep on displaying until I release the switch. I want it to be displayed just for once regardless of how much time switch is being pressed.

For ex:

while(1)
{
  if(switch == pressed)
  putsUART("switch 1 pressed");

 }

Its just a pseudo code. This keep on displaying as it is in while(1) but is there any logic or some function which displays it for one time, and if some presses the switch again, it prints again for one time.


texts: If current consumption of serial flash SST26VF064B is 15mAq104MHZ then at 50MHZ it is 7.5?

texts:
I am Mohan working in Germany. For my data logger project i choose SST26VF064B serial flash. My data logger should consume lowest power possible. I see that SST26VF064B is consuming 15mA@104MHZ. In my project I use upto 2MHZ or 5MHZ frequency to the serial flash. My question is if it consumes 15mA at 104MHZ then howmuch it consumes at 2MHZ and 5MHZ?.
Does it consumes 7.5mA at 52MHZ? Is it directly praportional?.
Thank you.


texts: Can broken ferrite core be glued and used again?

texts:
While trying to disassemble some SMPS transformers for rewinding I have managed to break the ferrite core. I broke the 'arms' of the 'E' half.

Also, I found broken core transformers in apparently working SMPS. After I removed the surrounding adhesive tape, I saw the core broken in two.

If I glue the pieces together will it have the same performance? The question applies to 'E' and 'ETD' (cylindrical) cores with air gap of 0.5 - 1.5 mm.

And what is a good method for ungluing a SMPS transformer's core?


texts:
I would like to open a door latch with solenoid using a IR reciever (basically remote control).

My questions are as follows:

What kind of signal (AC/DC) will I require through the solenoid?
Is it possible to open the door using off the shelf solenoids (I don't have much experience in electronics)?
Where can I get them and is it possible to repel/attract by changing their polarity?

Edit: I just need movement in one axis: left to right and right to left.

This is the type of door latch I'm using:


texts:
I have this flash chip, and I cannot figure out if it is a NOR or a NAND flash chip.

Here is the
datasheet.

From the capacity of the chip (2M), I am assuming that it is a NOR chip, but I am not sure. How can you tell the type of this chip?


texts: Not sure how to wire my 5VDC to 120VAC arduino relay board

texts:
I have a board with 8 relays on it that will take 5v from my arduino and the relays will flip on my 120VAC devices.

I'm not an electrical engineer by any means so I am wondering how to wire my 120V devices into the relays, and how to wire the 5v coming from the arduino to the board.

This is a picture of the whole board, and I wrote the pins names below the pins:

This is a picture of the output of the Relays:

A close up of the control logic.


texts: Why is my DCDC getting fried when driving a stepper motor

texts:
I'm trying to get a stepper motor running using an L6470 stepper driver. L6470 is connected according to the recommended design.
The motor is a NEMA23, rated 2A, inductance of 5.2mH and resistance of 1.9Ohm/phase.
The L6470 is connected to an MCU the drives it. All parts are from decent suppliers and no black-market/fake parts.

At first, I used a lab power supply to generate 12V in order to run the motor. After some tests all seems to work fine, so I've changed the lab power supply with a 24V power supply (Main power supply for the whole system) and a DCDC converter just for this motor.

Things seems to work fine for 15 minutes before the DCDC is fried. This happened 3 times so I can rule out bad part. The coil on the DCDC is just warm and testing the coil after failure of the module

The MCU and L6470 work fine and and with the lab power supply the motor rotates as requested with no issues at all. Current never goes up above 1.5A (at least what my 100Mhz scope can measure over a known measurement resistor)

I've attached the schematics of the design.
You can find the DCDC schematics here: Murate OKI-T/36W-W40

Any idea what keeps frying the DCDC? Back EMF maybe?

Should I increase the 100uF capacitor?
Should I have any protection against back EMF? Should I worry about Back EMF at all?
Should I add input decoupling capacitors before the DCDC? will this help?

Thanks for your help.

The Design

Murata DCDC, TI IC got fried


texts: Working out how long a battery will last

texts:
I'm hoping somebody can help me understand this. I use a Resmed S9 VPAP ST-A/ S9 COPD which according to documentation at my settings draws a current of 1.4A.

I use a Resmed Powerstation 2 battery. The ratings on the back say 97Wh output 24V 3.75A.

I wanted to calculate how long this battery would last. I know it lasts for around 10hrs but i'd like to know how to work it out.

I started by working out the amp hours by dividing 97 by 24 = 4.041 which I thought was the amp hours. I then divided this by 1.4 which gives me 2.8hrs which I know is not right. I'm no expert on this sort of thing and obviously missing or not understanding something. Please can somebody help! Thanks in advance


texts: Very General Question: Ways to Delay Relay Activation

texts:
This is a general question to round out my knowledge of relays.
Say, for example, I close a circuit that powers a NO relay. How would I go about delaying the activation of this relay for a specific amount of time, with an accuracy of 5 or 10ms?


texts: powering up the arduino and gsm shield module

texts: i am just wondering if what i am thinking is safe for my modules. I want to power up my arduino x which rated at 5vdc/1A and my gsm module rated 5-9vdc/1.5A, using my bandspeed adapter that has an output of 5vdc/2.6A. What I will do is power up my arduino using the adapter and i will tap a parallel connection to the gsm module so that both are powered up. Is it safe? will the current change etc. Give me anexplanation. Please help. Thank you :)


texts:
I have the following loop which is part of a fully connected layer for a neural net:

for (int b = 0; b < batch_size; b++) {
  #pragma HLS loop_tripcount min=1 max=10
    // Output Node Iterator
    array_cpy:for (int o = 0; o < num_outputs; o++) {
    #pragma HLS loop_tripcount min=1 max=1024
      // Set bias
        small_fixedpt output_fixp;
      output_fixp = biases[o];
      //float input_sub_array[1024] = input[o*num_inputs:o*num_inputs+1024];
      small_fixedpt input_sub_array[1024] = {0};
      small_fixedpt weight_sub_array[1024] = {0};
      subcopy:for(int i = 0; i < 1024; i++) {
          input_sub_array[i] = input[b*num_inputs+i];
          weight_sub_array[i] = weights[o*num_inputs+i];
      }
      // Accumulate weighted sum
      input_loop:for (int i = 0; i < num_inputs; i++) {
      #pragma HLS loop_tripcount min=1 max=1024
          output_fixp += input_sub_array[i]*weights[i];
      }
  // Compute activation
  if(output_fixp < 0) {
      output[b*num_outputs+o] = 0;
  }
  else {
      output[b*num_outputs+o] = output_fixp;
  }
}

My input arrays are partitioned in a cyclic manner equal to the number of unroll factor in 'input_loop' which is 16.

However, this loop unrolls into a sequential manner, as seen from the analysis view:

So i can see that my inputs are being read from seperate memory blocks.
I know that i've built an accumulator but I have also tried the method of custom creating an adder tree. That does not seem to work.

I also see 16 multipliers being made (ap_fixed is the data type used):

INFO: [RTGEN 206-100] Generating core module 'fc_layer_mul_mul_sc4': 16 instance(s).

INFO: [XFORM 203-501] Unrolling loop 'subcopy' (../fc_test/fc_layer.cpp:28) in function 'fc_layer' partially with a factor of 16.
INFO: [XFORM 203-501] Unrolling loop 'input_loop' (../fc_test/fc_layer.cpp:33) in function 'fc_layer' partially with a factor of 16.
INFO: [XFORM 203-101] Partitioning array 'weights.V' (../fc_test/fc_layer.cpp:8) in dimension 1 with a cyclic factor 16.
INFO: [XFORM 203-101] Partitioning array 'input.V' (../fc_test/fc_layer.cpp:10) in dimension 1 with a cyclic factor 16.
INFO: [XFORM 203-101] Partitioning array 'input_sub_array.V' (../fc_test/fc_layer.cpp:26) in dimension 1 with a cyclic factor 16.
INFO: [XFORM 203-101] Partitioning array 'weight_sub_array.V' (../fc_test/fc_layer.cpp:27) in dimension 1 with a cyclic factor 16.

Does anyone know what's going on? This is baffling me.

Thanks


texts: Do all USB Type C cables support full power delivery

texts:
USB Power Delivery is able to work over USB Type A/B cables which are specifically designed to support it.

Since the USB Type C was designed much later, I am curious. Do all USB Type C cables support USB PD by default? And do they support a certain level, or the full 100W?

Related: Does USB Power Delivery handle USB cables that are not PD-aware?


texts:
I'm considering to design an audio processor based on the STM32H7. I want to experiment with MCU-based DSP instead of using a dedicated DSP. I chose this high-end ARM MCU to have ample headroom for audio DSP calculations.

I also want to program a delay. Assuming I'm using 24-bit samples at 48kHz, a three seconds buffer for a three second delay on a mono channel is already going to take up 432kB memory. Just for fun I looked for the maximum external memory configuration, which is SDRAM with 13-bit row address, 11-bit column address and 4 internal banks, giving 256MB memory (32-bit word length). Two of these can be addressed, giving a total of 512MB.

I checked online to find memory ICs that matched that spec, but did not find any with the correct row/column address lengths and also all of those matching the memory configuration were DDR modules and the STM32H743 does not support DDR.

My questions are:

Can I use a DDR chip on a non-DDR controller?
Is it crazy to attempt to add 512MB of external SDRAM to a STM32H7? Or why are memory modules that match these criteria so hard to find?
Would perhaps Quad-SPI Flash fit better? I'm afraid it's too slow for an audio delay application.


texts: Battery charger vs Voltage or neither - They offer accurate power consumption? (mA)

texts:
I want to measure the power consumption not in theory but in time (after one day of use).

I don't have equipment to measure the power consumption but I have a battery charger that reports mA charged and "arduino" devices that report voltage.

Can I use the batteries, then charge them to measure the power consumption according to the indication from battery charger? Voltage measurement is more accurate or neither methods are acceptable of good estimate for battery life? My device I will hope to draw less than 1mA

Here real data from a device at ~25mA (according to data sheet) and battery capacity 2400mA (NiMH - eneloop type, low self-discharge)

https://www.fdk.com/battery/nimh_e/tech_info/HR-3UTG.pdf

uptime  Voltage
 0d0h    4.3 (start)
 0d0h    4.15
 0d1h    4.12
 0d2h    4.08
 0d3h    4.04
 0d4h    4.02
 0d5h    4.01
 0d6h    3.99

Device at ~1mA (according to data sheet) and battery capacity 350mA (LiPo) (I can't measure the mA of charging in this device)

 0d0h    4.19 (start)
 0d2h    4.02
 0d3h    4.02
 0d5h    4.01
 0d6h    4.01
 0d7h    4.01
 0d8h    4.01
 0d9h    4.01
 0d10h   4.01
 0d11h   4.01
 0d12h   4
 0d13h   4
 0d14h   4
 0d15h   4
 0d16h   4
 0d17h   4
 0d18h   4
 0d19h   4
 0d20h   4
 0d21h   4
 0d22h   4
 0d23h   3.99
 1d0h    3.99
 1d1h    3.99
 1d2h    3.99
 1d3h    3.99
 1d4h    3.99
 1d6h    3.98
 1d7h    3.98
 1d8h    3.98
 1d9h    3.98
 1d10h   3.98
 1d11h   3.98
 1d12h   3.98
 1d13h   3.98
 1d14h   3.98
 1d16h   3.98
 1d17h   3.97
 1d18h   3.97
 1d19h   3.97
 1d20h   3.97
 1d21h   3.97
 1d22h   3.96
 1d23h   3.96
 2d0h    3.96
 2d1h    3.96
 2d2h    3.96
 2d3h    3.96
 2d4h    3.96
 2d5h    3.96
 2d6h    3.96
 2d8h    3.96
 2d9h    3.96
 2d10h   3.95
 2d11h   3.95
 2d12h   3.95
 2d13h   3.95
 2d14h   3.94
 2d16h   3.94
 2d17h   3.94

According to Voltage we have a clear indication in 6 hours that the first device draws more power, but can I measure for battery prediction?

I know that chargers check the voltage to stop / start charging e.t.c. but the mA measurement is reliable / accurate?


texts:
I am high school boy, our teacher gave us circuit and we have to find out the equivalent resistance.
.

Our professor gave us idea that we can solve this question either by either superposition principle or symmetry
I do not what he want to say by this, symmetry for the same current carrying resistance.  Am I right is there any false in my thinking. Till now I have only study the kvl.

Edit:) I am not asking the answer of the question, I just want to know what is this superposition, or symmetry concept.


texts: Need to Determine Power Cable For Old Bose Found In Basement

texts:
I recently purchased a home, and in the basement is a Bose Lifestyle surround sound system. The 5 speakers all plug into a base unit which I have determined is missing a power cable.

In the unit, there is this:

120V 50/60hz 350W Max

I'm not sure what all that means and when I search online I can't find anything exactly matching it. Is it something where 50 or 60 hz both would work? And where anything up to 350W would work?

The cable shape is a cross between a rectangle and an oval (rectangle with two corners rounded). Any ideas in how to identify this?

Edit

Here are some pictures, of the unit, of the cord input, and of the sticker.


texts:
I am using an stm32f042k6 - Nucleo Board. I am using SPI and UART in non - blocking mode initialized through Cube-MX. I am trying to interface an RPI through SPI1 and a BMS through USART1.

SPI1 is configured as a Full-Duplex Slave. USART1 is configured to be asynchronous. Global interrupts are enabled for both.

Pinout:

SPI NSS  PA4
SPI SCLK PA5
SPI MISO PA6
SPI MOSI PA7
UART TX  PB6
UART RX  PB7

The issue is that as soon as I call HAL_SPI_Receive_IT(); in the User Code 2 Section, both peripherals stop working.

In SPI, SCLK, NSS and MOSI work fine. The callback functions are triggered fine and the stm reads the incoming data but MISO is always high. As a result the Rpi keeps getting 0xff.
UART stops working completely with the RX remaining high.

I have tried using UART in blocking mode along with SPI in interrupt mode as well but the same issue happens. I can't use SPI in blocking mode because data from the Rpi can come at any time.

Note that both peripherals work fine separately be it in Blocking or Non-Blocking mode.

What I have tried so far:

Changed priorities of interrupts setting SPI to higher, lower or equal to UART.
Changed the order in which each peripheral is initialized.
Removed the Rpi connections. SPI Interrupts wont occur but USART still fails.
Changed pins to different ones for each peripheral in CUBE-MX.
Enabled I2C interfaced with an IMU to see if it also fails when other peripherals are enabled. I2C works fine in all cases.
Placed a UART state check before the first transmit with SPI enabled.
while(HAL_UART_GetState(&huart1) != HAL_UART_STATE_READY);
Never leaves the loop. Rxstate is 34. gstate is 32.

I can't share the code because this is work related. I hope you guys can point me in the right direction to figure this out. I am not sure what to try next?

Thank you very much.


texts: Device can be powered at 6V or 12V, which is better? Why?

texts:
I got this camera and need to power it. Docs say that I can power it both at 6V and 12V, but laconically say also that it should be better to power it at lower voltage, so 6V.

Can anyone explain me why lower voltage is better?

Since I expect that power usage in both cases should be the same, I actually though that 12V should be better, because it needs a lower current. Am I missing something? Any clue?


texts: The difference between 3 pronged and 2 pronged power supplies

texts:
I'm just wondering what's the difference between a simple power supply with a ground prong and one without. I'm talking about those little DC power supplies with barrel plugs you can easy find on any small appliances. As far as I know a barrel plug has two contacts: one positive and one negative. What's the role of the third ground prong on the AC side for those have it? I hope I'm not mistaken but a small DC power supply like that use floating voltage right? With all plastic construction I don't think it can do much in terms of safety.

Actually I took two PS and toyed with it. One is relatively higher quality with a 3 pronged IEC C13/C14 plug. The other one has a cheapo 2 pronged design. I measured the DC voltage (with a multimeter) between the "wall-socket ground" and the sleeve of the barrel plug. The 3 pronged one resulted a 0 V, while the 2 pronged one showed a fluctuating ~300 mV potential difference. So does that mean the 3 pronged power supply has the negative terminal actually grounded? If it is what's the pros and cons of doing that?

I'll greatly appreciate any input! Thank you!


texts: How do I find the inputs/outputs of an unlabeled transformer?

texts:
I’ve been trying to wire a transformer according to this schematic.

but nothing is labeled on the actual transformer. There only only colored wires.

On the primary side, the Blue and White wire show a resistance of zero ohms when probed.

On the secondary side, both Red wires along with the Black wire show a resistance of zero ohms while probed, while the Orange and Gray wire show a resistance of zero ohms when probed.

The Green striped wire on the primary side doesn’t seem to be connected to anything when probed. Theres no resistance or anything happening.

To measure the resistance I’m using a digital multimeter first set at 200 ohms, which I recieved a resistance of 0. I changed to the diode continuity setting and still recieved a reading of 0 ohms, which my multimeter also beeped.

The only information I saw on the cover was just this:

 100V
 31.9V 102V

 FUSE 2A

And yes, the cover actually does say 102V. Could this be a typo? How do I wire this without breaking it?


texts: Nodal analysis with dependent voltage source

texts:
I need help figuring this problem. I'm reviewing for my final and I can't figure out how to write the nodal equations. What I have so far is:

$$6I_x = V_2- V_1 $$

KCL @ V_1:
$$7A + \frac{V_1}{10} = 0 $$

$$V_1(\frac{1}{10}) = -7A$$

KCL @ V_2:
$$\frac{V_2}{5} +\frac{V_2}{2} = 0 $$

$$ V_2(\frac{1}{5} + \frac{1}{2}) =0$$

I know that the answer will be the matrix:

$$
        \begin{matrix}
        .4 & 1 & =& 0 \\
        .1 & .7 & =& -7 \\
        \end{matrix}
$$


texts: How do I drive 14.3Mhz clock input from 10MHz?

texts: I intend to use an IC which requires 14.3MHz clock input, but want to drive it from a stable 10MHz source - derived from GPS. How do I turn the 10MHz clock into the 14.3MHz that the IC requires?


texts:
I need to design experimental prototype of power amplifier (PA) for a horn speaker. The PA should support 100W RMS @ 8ohm. Power supply voltage is 12V. My first (and probably most simple) idea was to use PA integrated circuit such as TDA7294 (although it is targeted for Hi-Fi systems), not just because simplicity but also because of useful features like stand-by, thermal protection, short circuit protection... PA would be configured as a bridge in order to reduce required power supply voltage and get the proper power for the given impedance. However, this approach still requires step-up converter in order to produce required voltage (about +-25V). Maybe I can use some of the shelf converters (if can find proper for such voltage), but anyway want to avoid its design at this stage.
By searching for existing PA, I found some solutions with push-pull amplifiers with output transformer. I am not sure if my requirements can be achieved like this. In general, by boosting the output voltage with output transformer I compensate impedance limitation (with only 12V and 8ohm, maximal power is less than 18W). But this would require very low transformer primary impedance for the 100W power @ 12V (as the power should be the same of the both sides, assuming no loses). I haven't found such audio transformers. I am not sure if I am missing something. Also not sure if because transformer the back EMF is concern in order to protect other devices connected to the 12V rail.
What is you suggestion? What is optimal approach that should I follow?


texts: Buck vs boost, 12V LED strip with 5V micro and 240V AC

texts:
I would like to control a 2M 5050 12V warm white LED strip from a 3V3 or 5V micro controller, powered by a 240V wall outlet.

To power both the LED strip and MCU from the same switch mode AC adapter "wall wart", I am going to need to use a DC-DC step-down/step-up buck/boost converter for the other device.

I am looking for the most power efficient setup. Candidates:

a) Use a 12V AC adapter and power the LED strip directly, with a buck converter for the 5V MCU.

b) Use a 5V AC adapter and power the 5V MCU directly, with a boost converter for the 12V LED strip.

Common sense tells me option A) would be more efficient as the main load (LED strip) avoids double regulation, stepping all the way down to 5V then stepping back up to 12V.

I would like to both configurations to confirm real world vs common sense. Any advice on how to accurately test each with a multi-meter / temp probe?


texts:
well an IC bring me from a my friend who is workin in a toys company for kids. this IC is coming as almost ready from Chine, all soldering parts are ready and than the company only soldering the battery pins and establish. this IC is a part of kid toys which is cell phone toys and it has touch pad etc.
The problem of this IC is very strange. After all parts establishng and battery connected to device, device not start to working. After removing battery and waiting 10 minute and inserting batteries to device again, the device start to working. I actually did not understand why it works after removing the battery and waiting for 10 minutes when we put the battery back in. ( if we rapidly remove and put battery device also not working).
what is the problem do you have any idea. or how to fix it
this is device an IC photos.

the company only soldering this battery cable right side, (not IC side)

this is close look to IC


texts: Why are audio power supplies center negative?

texts: I see that power supplies for guitar pedals, speakers, etc are always center negative.  Is this a conscious design choice, or is it a marketing trap?


texts: Slow slew rate causes signal inversion, missed pulses

texts:
I’m currently revising a legacy design using an old Lattice MACH 5  PLD. One of the (TTL) inputs to the PLD has a slow slew rate on the rising edge, spending some 25ns between 0.8V and 2.0V, and the 10-90% rise time takes much longer.

It has been my understanding that a slow edge like this can cause oscillation, double-clocking, and heightened power consumption in the input buffer, but I was using the signal strictly as an input to an 8 MHz state machine, so I figured there would be no issue.

Boy, was I wrong! When I tested the system, my state machine behaved erratically. I changed the PLD to buffer and output the signal in question, revealing what I believe to be the cause of the issue:

The bottom trace shows the signal as input to the PLD, and the top trace shows the signal as buffered and output. Look at those missing pulses and inversion! Wow! I never knew such a thing was possible, particularly the inversion. I have reproduced this with multiple PLDs, and the effect does not occur when buffering a faster signal. Has anyone seen this effect before? I have seen oscillation and double-clocking, but nothing like this.

Edit: Brian suggested that it was a synchronization problem, but unfortunately it’s not. Below is an additional scope trace showing the 8 MHz clock at the bottom, the slow signal above, and then the outputs of a 3-long shift register with the slow signal as an input.


texts: How to tell when an LM334 is limiting the current?

texts:
I have an LM334 based constant current source configured to supply a max of 1 mA.

The load has a variable impedance. My goal is to make an alarm of sorts when that impedance exceeds a threshold, and the way I want to do that is to detect when the 334 is in current limiting mode.

When it's passing less than 1 mA of current, I would expect it to be acting like a very low-value resistor, meaning that the voltage drop across it should be low. When the 1 mA of current is reached, it should begin to increase its resistance, thus increasing the voltage drop across it.

I'd like to measure the voltage drop and light an LED (really an optoisolator) when it exceeds a threshold.

At least, that's my thinking at the present. If anyone else has an idea of how to light an LED when an LM334 is actually limiting the current through it, that would work too.

simulate this circuit – Schematic created using CircuitLab

In the schematic, I1 represents the LM334. I don't see a way in circuitlab to represent an actual LM334, so the simulation likely won't operate correctly. R1 represents the ground impedance - the goal is to detect when it's value exceeds 10k. At the moment, I'm thinking I'd like to find a way to light an LED when Vin-Vout > 1V. From there, it's just a matter of tuning either the set resistor of the LM334 or the voltage threshold to trim to the setpoint.

Note as well that the actual circuit ground is on the top side of R1 - Vout is the ground potential for the purpose of this circuit. The actual earth is on the far side of R1.


texts: Device's ground riding on a non-ground signal

texts:
The question is somewhat conceptual, feel free to close if it's too off-topic.

If I take my portable (battery-powered) oscilloscope and try to measure the mains voltage, the connection polarity wouldn't matter much. It would be best if the probe tip connects to hot, and the grounding clip to neutral; but swap them, and the signal will be the same (negated, of course, but if the triggering settings aren't changed, I might not even notice it).
The difference is that if the grounding clip is holding the hot wire, the whole ground plane of the 'scope will be riding on that 50/60Hz sinewave. If my understanding is correct, the scope would make a weak and very inefficient antenna, radiating at 50/60Hz, but since the frequency is so low, its workings wouldn't be affected.

The question is, what happens at higher frequencies?

Again, if my understanding is correct, at sufficiently high frequency, the scope would become an antenna and this could affect its internal workings (the signal present on the grounding clip could capacitively couple to other things inside).

In general, if it's not a scope, but just a device that connects to something else's ground, and there might be high frequencies on that ground, what can be done to mitigate the issues?


texts:
Why do diode rings multiply signals?

I have been playing around with mixers. Home brew diode rings of 1N4148 and the NE602 chip (double-balanced mixer and oscillator).

I think I understand the basic maths of signal multiplication, and getting the sum and difference frequencies, but can someone explain to be why it is that a diode ring or a Gilbert cell, multiply the two inputs? Why wouldn't they just add? What's actually going on in the diodes that causes the output to be the product of the two inputs at any time t?

The electronics articles I have read seem to focus on the mechanics of the diode ring and how the left or right hand pair of diodes act as a switch, but I still don't understand why the two inputs should multiply.

I have missed something I'm sure.


texts: I've got a 900MHz downconverter design which I'm trying to convert for a 100kHz single ended RF input and LO input. I'm not sure how to calculate the required capacitor and inductor values, so any help would be greatly appreciated!


texts: Using a MCP23017 for detecting open door/window

texts:
I'm not a hardware guy. My plan is to read input states using an MCP23017 connected to a Raspberry PI.

My doubt is about the switching circuit. My plan is to use Ethernet cable pairs to wire the MCP23017 pins to magnetic door and window switches.

I might have up to 20 meters of cable between the switch and the MCP23017 pin (20+20 ohm resistance). I'm planning to use a shielded Ethernet cable.

Are 10k pull-up resistors enough to have a reliable and noise free switch detection circuit?
Should I place any other component next to MCP23017 pins to ensure a reliable switch status read?
Any advice on which Ethernet cable class is best?

UPDATE:
In the meanwhile I found this very interesting article: https://www.digikey.com/en/articles/techzone/2012/apr/protecting-inputs-in-digital-electronics

I like the R-C idea (fig.8).

I also have to consider that in my case switches are most the time closed to ground and I have to detect open condition. Does this last point matter on the design?
I'm using 3.3V to power the MCP, what would be the right R & C values?


texts:
I'm new to AVR programming, I got this atmega8A chip and I use avrdude with a USBasp that I made myself, for programming it.

For some reason the chip won't answer if I don't use the -B 3 parameter with avrdude, although I have reset the chip's fuse bits to factory defaults.

Now my question is what is this -B 3 parameter and how can I fix this.


texts: Trying to find a touchscreen that will be compatible with a microcontroller

texts: I was wondering id anyone knows or have experience with building something that is controlled by a touch screen? I want a 3x3inches touch screen , that will be controlled by an "fairly-easy" to program micro-controller, maybe Arduino?. Where to buy it and what do you guys suggest? etc. any help would be appreciated.


texts:
We have used HMC7044 in our custom ADRV9009 design(as per the FMCOMMS8 schematic). In the datasheet of HMC7044, it is mentioned that the specific clock groups need to be connected to specific power supply pins.

We have missed this point and made the connection as follows:-
SCLKOUT7 and #SCLKOUT7 to VCC8_OUT instead of VCC4_OUT
SCLKOUT5 and #SCLKOUT5 to VCC8_OUT instead of VCC4_OUT
SCLKOUT3 and #SCLKOUT3 to VCC2_OUT instead of VCC9_OUT
What might be the impact of this? Can somebody help me with this?
Thanks in Advance


texts: How to build a low pass filter with limited resources?

texts: I need to build a low pass filter, to filter frequencies that are over 550Hz. By the cutoff frequency formula fc = 1/2piRC, RC has to be around 1/3500 so that fc is approximately 550Hz. I have a lot of resistors, from 220 ohms to 10k ohms, but my capacitors are ceramic ones that range from 2pF to 100nF. Even with the 100nF capacitor, my resistance would have to be huge in order for the calculations to match approximately 1/3500 (this sentence could be wrong, I'm new to electrical engineering). Is there a way to combine the resistors and capacitors that I have, in order to build a low pass filter that filters frequencies over 550Hz? Do I have to buy bigger capacitors?


texts: How can this isolated DC/DC converter claim a 3kv rating?

texts:
I'm referring to the Murata Power Solutions CME series DC/DC converters.

Datasheet: http://www.murata-ps.com/data/power/ncl/kdc_cme.pdf

If you look at the footprint of package (the -3C variant), there is no way that a pin spacing of 2.54mm is a good clearance/creepage for a 3kv transient. The -DC package variant would be more acceptable, but it is rated for only 1kv. What am I missing?


texts: Vcc and ground PCB layout for a 60 watt single layer LED panel

texts:
How can I spread the ground in an LED panel design?
I know that if I decrease the clearance between GND and VCC is the same as adding decoupling capacitors that will help in case of power supply voltage fluctuations.

Are there any recommended layout considerations?
There are many parallel mid-power LED lines. Should I copper pour ground net around these lines?


texts: Generating +65 V (positive) and -65 V (negative) voltages from two 12 V batteries using cheap step-up converters?

texts:
I need to power a 300 W class D amplifier with positive and negative 65 V.
As I'm a do-it-yourself guy, I didn't know about positive and negative voltage and ordered a bunch of these normal step-up converters which were fine for my last projects, where I didn't require + & - voltages:
https://www.ebay.de/i/232461793739
I did some research and found that it is quite easy to get +/- voltage out of two batteries, but I read also that cheap bucket step-ups don't isolate the ground so it can create short-circuits - this was mentioned in posts using ONE battery. As I'm using TWO, is that case not relevant for me?
Here is how I would wire it:
/-------------\ + ---------- + /-----------------------\ + ------ +65V
| 12V Battery |             in | 20a Step-Up Converter |out
\-------------/ - ---\  /--- - \-----------------------/ - ------ GND
                  | ----- |                                                 300W Amplifier
/-------------\ + ---/  \--- - /-----------------------\ - ------ GND
| 12V Battery |             in | 20a Step-Up Converter |out
\-------------/ - ---------- + \-----------------------/ + ------ -65V

I'm especially unsure if wiring the lower batteries - to the + of the step-up converter is correct? Also I'm unsure if it will work this way, as I experienced these converters have incorrect polarity protection built-in, to prevent damaging it if you accidentally connect it the wrong way around.
I'm happy if someone can give me a hint how I can get my amplifier to work, without buying other stuff.


texts:
I've got a m1000 automated tape dispenser and I've just recently found this sensor at the cutting blades.

As far as I know the wire from the cutting blades to the main board was only for automatically printing tape endlessly when switch is switched. And I doubt that the sensor's used for measuring the length of the tape. Because even though when the tape is empty it will continue cutting the air. Measurement of the tape is done by a hall sensor measuring the rpm of a motor. And so does the cutting blade itself. It's also measured with a hall sensor to check the blade position.

And how do I use this sensor?


texts: calibrating vector network analyzer with \$75\Omega \$ coax

texts:
I am new to electronics and I just began to use a vector notwork analyzer for some measurements.

I calibrated my vector network analyzer with both ports connected to 50\$ \Omega \$ coax cables with the other ends connected to each other via a coaxial cable coupler.

Every component I've used is 50\$ \Omega \$ impedance matched but I started wondering if I could use 75\$ \Omega \$ rated components instead and be fine conducting the same experiments if I just calibrate S parameters correctly.


texts: How to scale my hal ratiometric sensor output?

texts:
I have a UGN3505 sensor that converts magnetic flux to voltage. The output at zero magnetic flux is 2.5V and the difference in the flux depending on the polarity varies the voltage from 2.5V.
I want a circuit that keeps the 2.5V as the normal output but let me select the sensitivity of the sensor to magnetic flux.
I know I can use an MCU to read this voltage and scale the output. But is it possible to do so with no MCU?


texts: Input voltage/current required for LM1117 3.3 Power Regulator

texts:
Can I use Mobile charger having Output Rating of Voltage 6.0V / Current 300mA as input to LM1117 3.3 Chip.

  If possible - Will it be able to provide 800mA current when
  required and how?


texts: Photodiode in photoconductive vs photovolatic configuration

texts:
I want to use a photodiode to measure light intensity, but I am not sure if the photodiode should be used in photoconductive or photovoltaic mode.

From my understanding the photovoltaic configuration will have a leakage current proportional to light intensity and the photoconductive configuration will produce a current proportional to the light intensity. Both seem like the would work for my application.

Will either configuration work? and is there a benefit to using one over the other?


texts:
I'm new to electronics. I'm trying to interface my lcd with an avr but I don't think my code is initialising the lcd properly.

At the top of header file for the library am using, I have this

define LCD_LINE_LENGTH   0x40

Am told by the manual that this might need to be changed. It's not blindingly ovious in the data sheet for beginners.

Here's the link to the datasheet:

http://uk.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=7200235
What does it mean and where is it stated in ds


texts: What does it mean "positive" or "negative" polarity in VGA's HSynch and Vsynch?

texts:
I have been trying to study how VGA signals work and I stumbled upon this this page with all the different VGA timings.
What isn't clear to me is what it means by "polarity horizontal sync pulse is positive".
Does it mean the hsync signal stays low and the pulse is positive or vice versa?


texts: Identify the connector on Alphasense OPC-N2

texts:
This popular dust sensor (Alphasense OPC-N2) uses a teeny 6-pin connector:

Does anyone recognize it? At least one forum user had guessed it was Molex MicroClasp the pitch is too small (1mm vs 2mm).


texts: Oscilloscope with 400 MHz but only 100 MS/s?

texts: The Tektronix TDS430A is a 400 MHz 100 MS/s oscilloscope. I know other ocsilloscopes which could be toggled between analog mode and digital mode, so that these numbers would make sense. However, it seems the TDS430A is digital only. How could they possibly measure 400 MHz with only 100 MS/s?


texts:
I was considering the synchronous design model.

If I understand it correctly, it can be represented as so :

(excuse the awful schematic made with Paint)

The state switches within a stage are conditionned by the states of the previous stage and are triggered on the rising edge of the clock.

What I wondered was the following: on the rising edge, the stage number n switches, but so does the stage n+1, whose inputs are function of the states of the stage n.

That would mean the switch of the D input of a flip-flop is simultaneous to the clock, which lead to an indeterminate state of the flip-flop.

The problem may be solved if there is some delay between the Q outputs of the stage n an the D inputs of the stage n+1, and that delay should be greater or equal to the hold-time of the flip-flops of the stage n+1.

But that would mean that the circuit wouldn't work for any flip-flop.

Am I wrong ?

Thank you


texts: There are many examples of logic circuits that have the clock signal, such as the JK flip flop and the clocked SR NOR Latch, but I still wonder what is the purpose of the clock. Why do people think of adding the clock signal into the circuit? Isn’t it simpler and easier to learn without the clock?


texts: About 25 years ago I found a small light strip at a surplus shop which appeared to contain NE-2 neon bulbs, but they light green. The glass is clear so it is not a fluorescence effect or something. I have never seen anything like them anywhere else. They began to flicker and degrade much more quickly than NE-2s, so eventually I threw it away. Any idea what they are, or what gas they use? I would like to find more, but it would be like finding Nixie digits.


texts: Oscilloscope -> Parallel port pins not sustaining high/low

texts:
So I'm using port talk (http://retired.beyondlogic.org/porttalk/porttalk.htm) on windows 7 to really simply set/unset pins on a parallel port via some c code.

I've plugged in an oscilloscope to ground and one of the data pins, and setting it high, waiting a second, setting it low, waiting a second, etc...

On the oscilloscope, I'm seeing a like, millisecond pulse up when I set the pin high (then it sets at 0 for the rest of the second), and then seeing a millisecond pulse down when I set the pin low (after which it again sets at 0 for the rest of the second).

So, I first assumed I was using the API to set/unset the pins wrong or something, so I tried just constantly setting the pin high as often as possible (probably hundreds of times per second) for a second, then setting it low as often as possible for a second, etc... and the output on the oscilloscope was exactly the same (that is, really quick high blip when it first gets set high, then really quick low blip when it first gets set back to low).

Still not sure what was going on, I tried just setting it high, waiting a second, then setting it high again, etc..., and the behavior I was getting was, the first time I set it high, I saw a blip on the oscilloscope, but then each subsequent "set high" was totally invisible to the oscilloscope.

So, I'm assuming from the computer's perspective, it thinks the pin is just constantly high from the point I "set high" forward (and ditto for low). I'm admittedly pretty ignorant when it comes to electrical engineering and the like- is this indicative of anything particularly obvious? Like, I'm reading the oscilloscope wrong, or I have it wired in such a way that the pulse is or isn't getting correctly routed from one place to another? Is there some protocol to dealing with a parallel port where I can't just treat it as high and low pins?

Another odd point- for debugging, I just set all 8 data pins to high and low at a time. But depending where I plugged the oscilloscope, the higher # pin seemed to generate a bigger pulse... is that just a quirk of "the spec just says it has to be above some threshhold", or is that also indicative of me wiring it up wrong?

Any direction or help would be greatly appreciated!


texts:
I would really like to know what these are before I start playing around with them, tried to translate everything and can't find a thing — then again they say made in the USSR (СССР) so maybe no one knows?

    МБГО -2
   1 мкФ±10%ОТК
 300В  87 079
СДЕЛАНО В СССР [Made in the USSR]

(Transcription of the small one only.)


texts: Is it possible to generate different PWM Signals for same duty cycles(e.g. 50%)?

texts:
Let us expect we have a duty cycle of 50%. Is it possible to reach that duty cycle with different PWM Signals (waveform)? With different I mean variants in the number and lengths of the "active time". What are the expected impacts on noise and virbation resulting from these different PWM waveforms?

The context of this question is considering a 9V DC-Motor without any load where different virbation and noise should be generated. My motor is similiar to this one: https://www.alibaba.com/product-detail/25mm-battery-power-9v-12v-dc_60208528733.html?spm=a2700.7724857.normalList.41.3fe858e1928WCB

I hope the image explain what I mean:


texts:
I am using the ICL7660 charge pump IC to generate a -5V supply from a +5V. When using the IC on breadboard with a DIP package (ICL7660CPAZ), with two 10µF electrolytic capacitors, it works perfectly fine.

However, when I change the chip in the circuit for the SMD package (ICL7660CBAZ + SOIC to DIP adapter), the output voltage stays 0V or is slightly positive.

I have tried different chips, manufacturers, adapters, capacitors, soldering temperature... SMD components never worked!

Any idea on why the package is changing the behavior of the circuit?

simulate this circuit – Schematic created using CircuitLab


texts:
I have to transmit B&W images (about 30fps) with resolution of 1980x1080 pixels. I would like to use a HDMI link between the generating device and the imaging device (to have standard connexions and signals). Is the HDMI standard specification take into account the B&W? I mean is HDMI able to use a lower frequency transmission rate that take into account this particular signal?
A low frequency rate is required in my application since I have to transmit the signal over a length of 10m to 15m.
Is HDMI standard foreseen such signals?

Regards,


texts:
In this video at 0:40, what is the equipment he is using to power the motor? It seems to be some sort of torque leveraged device (forgive my ignorance).

http://www.youtube.com/watch?feature=player_detailpage&v=6kgzrXFSDwA#t=40s


texts: Why the OFDM symbol length is the total number of original modulated symbol, but not one symbol length?

texts:
Recently, I am learning the principle of OFDM, and the reference is http://defenseelectronicsmag.com/site-files/defenseelectronicsmag.com/files/archive/rfdesign.com/images/archive/0101Puegel30.pdf.

Everything is reasonable untill page 3 at the left and middle column.

  The IFFT takes in N symbols
  at a time where N is the number of
  subcarriers in the system. Each of
  these N input symbols has a symbol
  period of T seconds.

Then, in expectation, the output of the IFFT, aka a OFDM symbol, should be combined with N symbols that are arranged to N orthogonal sinusoids. That is, a OFDM symbol with period of T seconds. However, at the middle column, the description is out of my expectation.

  The block of N
  output samples from the IFFT make
  up a single OFDM symbol. The length
  of the OFDM symbol is NT where T is
  the IFFT input symbol period mentioned
  above.

Why the OFDM symbol period is N*T but not just T? A simple example in my understanding will be:

If it is, then the OFDM should not have the higher transmission rate or speed, because it costs the transmission time the same with the original modulation method that without the OFDM modulation.


texts: What was the point of an "alignment scope" like Kikusui 5091, and can anything be done about it's dismal horizontal bandwidth?

texts:
I got this Kikusui 5091 used for US$ 50 bucks, as a reward for my pretty successful attempt to create a digital raster display from scratch on my oscilloscope, and finishing off my Game of Life in hardware that updates a 256 x 256 pixel field at real time 60 Hz frame rate (with the option of going up to 512 x 512). I find my oscilloscope screen too tiny.
But after buying that Kikusui 5091 scope I found out that it might be very different from a normal oscilloscope, as it's vertical frequency bandwidth is specified DC - 10 kHz only and especially its horizontal bandwidth is specified as only DC - 1 kHz. Only one kiloherz? That would limit the frame rate for 256 lines to only 4 frames per second! 4 Hz frame rate is bad.
So, why would that be so bad? What would be the point of such a scope?
Let me see if I understand this right on a high level:

Real oscilloscopes use electric field deflection which allows for much higher bandwidth because you don't have that massive inductive impedance of the deflection yoke to counteract. You apply voltage and with resistance held low the deflection field generating "capacitor" is quickly charged and discharged and reverse charged. Not so with a coil where you must pull current changes with crazy voltages against massive momentary impedance.
But the CRTs for real oscilloscopes need to be much longer for the screen size, so essentially if you want a larger screen, the mechanical trouble of a tube that might have to get a meter in length is just not worth it any more, so that's why they invented all these intricate complicated "fly back" circuitry, and added significant horizontal blank time to video standards such as NTSC to allow for the fly-back to occur.

Is that about right? And this means, if I want to have a prayer to use this Kikusui scope for anything like video, I would have to modify that horizontal deflection stuff, or maybe I would flip X and Y sawtooth and image coordinates such that I scan up and down lines that go right to left. Then at least I could get a 40 Hz frame rate at the 250 x 250 resolution.
Any other trick?
Might it at least be good for a vector screen? (Which is another thing I want to experiment with soon.)


texts: How to detect electrical leakage in water tank?

texts:
I have a 50cm x 50cm x 80cm water tank and I am heating water with two 1500 watt water heater resistances. I think they are stainless steel or chrome plated but I am not sure about it, I can't contact with the manufacturer. Also, they work at 220V AC.

My question is how do I know that there is an electrical leakage in the water in case of deterioration of the coatings of resistances?

Can I simply measure it with multimeter, like one probe connected to the ground and other is in the water? Or can I build a circuit that will alert me if there is a electrical leakage?


texts: I  am reading about the characteristics of an ideal transformer and it is mentioned that self inductance of each coil is infinite. Could someone help me to understand the physics behind it? When self inductance goes to infinity that means that the voltage across the coil goes to infinity and I have a large magnetic flux and current. I was wondering if this is a right conclusion.


texts: Why are some common-mode chokes rated in ohms instead of henries?

texts: Some common-mode chokes, including this one, are rated in ohms instead of in henries. Why? Isn't the impedance injected by the common-mode choke entirely frequency dependent? Is there an assumed frequency at which the specified ohm-age is calculated?


texts: Silicon-graphene battery energy density?

texts:
A startup called CalBattery is touting that their silicon-graphene anodes for li-ion batteries "will improve the anode specific capacity performance of lithium battery anodes by a factor of 3X."

Will a 3X improvement in anode performance translate into a 3X improvement in energy density of the overall battery, or not? (In other words, is battery energy density anode-limited?)


texts: How does transistor bandwidth affect stability?

texts:
I was watching a video where Dave Jones of EEVBlog interviews Rod Elliot of Elliot Sound Products. Rod was discussing that he tends not to use digital chips in his designs because the chip will become obsolete 6 months after the design is published. He goes on to say that most analog components don't have this problem and goes on to give this quote:

  Although transistor types and everything do change, ON Semi for example a lot of their new transistors, they're brand new. They're labelled as being older devices but they're not; they're modern technology. But I try to make sure that my circuits will work. If they update the transistors and they get faster, more linear, that never hurts anybody. If they get faster, usually that makes the amplifier more stable, not less stable.

I don't understand the last part of his statement. Given a standard audio voltage/power feedback amplifier, how does a faster transistor tend to improve stability? If anything, I would have thought that a slower device would improve overall stability. Doesn't more bandwidth offer greater opportunity for higher-frequency poles (caused by reactive passives and parasitics) to interact with the active device's open-loop gain and cause phase shifts which may lead to oscillation?


texts:
I plan to use Infineons PROFET BTS5016 in a coming project.

https://www.infineon.com/dgdl/Infineon-BTS5016-2EKA-DS-v01_00-EN.pdf?fileId=5546d4625a888733015aa41a5e161129

I will not use the diagnostic pins. The datasheet states that unused pins can be left "opened" or connected to GND through a 4.7k ohm resistor. I want to avoid extra components so I was planning to leave the DEN and DSEL pin floating. Also the input pins IN0 and IN1 will be floating when the microprocessor is not on (The power rails will always be on). So it would be beneficial to be able to skip pull-down resistors to save space an assembly time.

This figure from the datasheet shows the input circuitry.

Question: I cant figure out from the datasheet the exact behavior when the pins are floating, will they read high or low or be unpredictable?


texts: Specific color sensing, is it possible in an economical way, without using camera/image recognition?

texts:
While I understand that color sensing with camera and sufficiently powered processor running image histogram logic (or other such algorithms) can determine presence of certain colours fairly reliably.

However, are there other, significantly more cost-effective mechanisms to determine presence/absence of certain color (or it's close shades), at close range, using simpler/cheaper sensors and lower computational requirements ?

I am guessing that things like pH sensors, or other chemical sensors might use such methods. In my case, the application is such that I need to detect presence/absence of a specific colour (a shade of light blue), in a small area, at close range.

Edited:
By 'close range' I mean something between 1-5cms, though this isn't a very strict requirement. I was thinking of "close" relatively, i.e. there is no direct irradiation from light source to sensor, kind-of a double barrel, such that only reflected light hits the sensor. So closeness is a function of physical sensor placement, and I am open to suggestions (including completely alternative / orthogonal approaches).


texts: 50A Accurate Current Sensing Circuit Design

texts:
I'm trying to design a current sensing circuit that can achieve a 0.01A accuracy across 50A DC. It is a battery powered brushless DC motor drive (battery --> current sensor --> controller --> motor). I need the accuracy because I am trying to determine efficiency and therefore the current reading is quite important. Most of the time, the system only draws 5-10A. I only need to measure current in one direction at a sample rate of 50Hz. I don't mind using a current shunt however I would prefer not to lose the power.

I have a 16 bit ADC that I am trying to interface the sensor with. I've considered sensors such as the ACS759.I have looked at data sheets, application notes, pretty much everything I can find on the topic but I can not find any circuit that achieves this kind of accuracy. Any help would be appreciated, if anyone knows of a circuit or a sensor. Thank you!


texts: Best way to pair a DC-DC boost converter and a MOSFET to compensate for MOSFET voltage drop

texts:
I'm building a PWM fan controller, and would like to use a DC-DC Boost converter to compensate the voltage drop across the MOSFET.

What I would like to get an opinion on is if it's more efficient to boost the voltage before the MOSFET, or after.

I think it would be better to use the boost converter after the MOSFET since it will automatically adapt to any variation on the MOSFET output caused by operational temperature changes.

I'm not in any way an engineer, and don't have enough knowledge to make calculations, I'm still learning that part...

For prototyping, I'm using an IRF830, which will be replaced by logic level MOSFETs on my final product. The DC-DC boost converter is a MT3608 2A, but I'm planning to include something like it in the final project.

Thank you in advance for any inputs on this.

Edit: Insert a basic schematic.

simulate this circuit – Schematic created using CircuitLab


texts: STM32 Timer - Issues with generating 1 us pulse on GPIO

texts:
I am using Nucleo-F767ZI board which has STM32F767ZI controller on it, and am in need of sending out a particular structure of elements bit-by-bit through a GPIO pin once every microsecond (1 MHz freq.). After a few other trials, I decided to use DMA with a corresponding Timer (DMA2-Stream5 with TIM1 - Page 249 of reference manual) that triggers the DMA controller every microsecond - causing a DMA interrupt. The DMA interrupt handler must take care of setting the bits on the GPIO pin.
The issue I face currently is that I am never able to get the DMA to output to GPIO pins exactly every 1 us at all. The TIM1 is on APB2 whose clock is 32 MHz in my project, and the DMA clock is 64 MHz. The GPIO pin's speed is configured to GPIO_SPEED_FREQ_VERY_HIGH. I tried the following:

Adjusting the prescaler and period values for the TIM1 to get it running at 1 MHz, this causes the entry into the DMA interrupt handler regularly but the periodicity of the pulse generated on GPIO pins via DMA does not seem to match with what is configured at the Timer. Even though I configure it to 4 us for e.g. (250 kHz) the pulse outputs every 14-15 us (verified on oscilloscope).

Increasing the clock frequency of APB2 clocks to its maximum of 108 MHz (as per STM32F767ZI datasheet) and repeating Step 1 did not help much, as I faced the same behaviour

I also tried creating an STM32 project with only one Timer(TIM14) interrupt with 96 MHz clock, configured to toggle a GPIO pin, and absolutely nothing else, to see how accurate this is running, and this is what I observed.

96 MHz clock, In Timer configuration, Prescaler - 96 and Period - 100

Expected timer interrupt every 100 us, Observed value - ~103 us

96 MHz clock, In Timer configuration, Prescaler - 96 and Period - 10

Expected timer interrupt every 10 us, Observed value - ~11 us

96 MHz clock, In Timer configuration, Prescaler - 96 and Period - 1 (Also 12, 8 or 16, 6)

Expected timer interrupt every 1 us, Observed value - ~4.3 us

With 1 us, there seems to be an interrupt every 4.3 us which is unacceptable compared to the higher values. What could be wrong in my approach? Is it just a limitation of implementing this using only one microcontroller?
Tool used: STM32CubeIDE, Version: 1.4.0


texts: How to design a low voltage astable multivirator

texts:
I am currently trying to design a solar powered energy harvester. It requires a DC to DC boost converter to increase the output voltage and keep it regulated. I found that this can be achieved using the IC LTC3105. But unfortunately this IC seems to be unavailable in my locality. So I have started to look for alternatives.

One Idea that has occured to me is to use a simple boost converter as shown in the picture:

However this circuit will work only if the state of the switch is continuously kept changing. This circuit employs A MOSFET. Turning it on and off can be done simply by providing a square wave from an astable multivibrator.

But the real challenge arise here. I want to operate the solar panel under indoor lighting condition under which the output voltage is around roughly 300 to 700 millivolts. I want to be able to increase it to around 5 volts for powering small devices. This can be done easily with LTC3105 as mentioned earlier.

Now since my input voltage is such a low value, how do I power up the astable multivibrator for switching the MOSFET? Is there a good design for low voltage astable multivibrators? Are there any other alternate boost converter designs?

Please note that I am not allowed to use additional voltage sources.


texts:
simulate this circuit – Schematic created using CircuitLab

Will this circuit work with the raspberry pi and will the rpi be safe? I want the motor to turn on when GPIO_2 is set high. It is a DC motor and the transistor is a BC635 (I couldn't change the parameters on the diagram).


texts:
I'm curious how well a hot air gun would work for reflowing an entire board. My circuit board has about 250 components (including 0402 passives, and a couple of 0.5mm pitch TQFPs) and it's a bit of a pain to assemble it using a soldering iron.

Here's what I was thinking might work:

Apply leaded solder paste via a stencil onto the PCB.
Place components using a vacuum pick-up tool. Use a stereo microscope to place the more fine pitched parts.
Once all the components have been placed, place the PCB onto a pre-heater and raise the temperature to, say, 100˚C.
Start the hot air gun and slowly sweep it over the board as the paste reflow. I could utilize a fixture like this to keep the gun perpendicular to the board and just move the gun in the x-y plane.

It would take some time to sweep the gun over the board and ensure all of the paste has reflowed and during this time the pre-heater would still be on. Could this possibly damage the board? What about all the parts? Are there any other pitfalls that I might encounter or would this method work well?

I know there are better methods to reflow a board, like a reflow oven, but I'm specifically interested in how this method would work.


texts:
I want to use the USB 2.0 multiplexer TI TS3USB221ARSER. But on the PCB the D+ and D- pins of one connection are crossed (see attached image).

Is it okay to change the D+ and D- pins on all sides of the multiplexer to fix this? The two alternatives are:

use a via on one signal trace to switch to the other side (I always read one should avoid vias in high speed connections?)
avoid this problem with long connections (see second attached image. Trace lengths/trace impedance not calculated in the image).

Which is the best solution?

Thanks!


texts: Why the control hazard is worse for deeper pipelines

texts: I'm studying compute rarchitecture and read that "control hazard are worse the deeper the pipeline is". But why is this the case? Is the branch deeper and therefore takes longer time to run?


texts:
I have the task of implementing an embedded webserver (using ATMega328). Broadly, the system would provide the following functionality

Allow user to change system parameters using the web interface
Periodically check the time (using NTP or such) and update the internal RTC with the right time

My questions are

Should I go with ENC28J60 or Wiznet5100 or higher chip. ENC28J60 seems to be more popular with tonnes of tutorials, search results etc. But it seems that Wiznet5100 series come with integrated TCP/IP stack which should make things easier on the mcu side
Any suggestions for the web server? Ideally I would like it to look polished with images and such.
For time part, should I go with NTP or the simples (but older) alternatives such as daytime or time?


texts: I read in some articles the difference between the earthing and bounding. But i still don't understand when we use bonding. I think Earthing is the more important part to grounding and protect from electrical shock. Any examples to understand the difference ? can we use bounding without earthing ?


texts: I'm working with an avalanche photodiode with a 320 pF capacitance. What exactly are the downsides of suc a photodiode with large capacitance values? I assume they would be slower due to the narrower bandwidth, but in an application where speed is not so relevant (up to my knowledge, anything apart from optical communication), are there any other performance issues related with a large capacitance?


texts:
I wish to build an automatic watering system for my greenhouse and I would like to get some advice on how to do it.
Here is a sketch of the greenhouse system:

What I have right now:

Solar Panel (10W, 0.55A, 18V);
Arduino Uno Board;
Humidity and Temperature sensors;
Raspberry Pi;
5 Li-ion batteries (18650) - 2.4Ah and 3.8V each

What I would like to do:

Charge the batteries using the solar panel;
Use the batteries to power the Raspberry Pi and the Arduino Board;
Make a website on Raspberry Pi so I can read the humidity and the temperature online;
Water the plants when the humidity is under a certain value.

I would like to know:

How to build a solar charger for the batteries?
I know that Li-ion needs some kind of Constant Current-Constant Voltage charger type so I was wondering how can I build such a system?
Is there any way to know the state of charge of the battery without an advanced measuring equipment?
Would a pump be more convenient than a solenoid valve, to let the water flow down?
The challenge here comes from the fact that the valve or pump requires 12V, while to power the Arduino board, it needs only 5V (through the USB). How can I rectify these voltages?
Can I connect a valve/pump directly to an Arduino or do I need extra power from the batteries?

The questions might sound confusing because I'm not an expert in the field, and if it does, please let me know and I will try to add more details. I would appreciate any advice on how to make such a system and what extra components do I need.


texts: What is the use of R5, C4, C2, R6, R5, D1 in the below amplitude modulation circuit?

texts:
the project is taken from this website for my college project

http://www.instructables.com/id/Modulating-Audio-on-a-LED/

I think I have figured out function of few components but still need confirmation on below points.

I think that the C2 is used to block DC current due to Vcc is it correct. also I made a assumption that the audio input creates the signal which can be allowed through this C2.
The diode will allow forward current but no backward current but what is the need and what will happen if i remove it?
Also they said if I will be using electrect microphone as input then R6 is required but in case I use mono audio cable with pc as input then it is not required, but why ?
why is both the output wires from the audio amplifier block is connected across the R3, I hope the transistor circuit in LED modulator block is used as potential divider mode.
what's the use of R4 and what will happen if I remove it?
What's the use of R5, and C4?

In the website they have used a simple receiver to receive the modulated light with solar panel with speaker but can i use the same circuit below as a receiver but instead of audio input put a photo diode and instead of LED put a small speaker or earphone? specially i was thinking of using earphone


texts: Which terminal do I hook the panel ground wire to on my VFD?

texts: Have the TECO 7300CV - 220v single phase in, 220v three phase out. The manual clearly shows the motor ground connection going to the "PE" terminal but it does not show the source / panel ground connection. There is another "PE" terminal but I'm hesitant to hook to this on account of all the horror stories I'm reading about misconnections and smoking units. I'm also weary because I know there's a 120v potential between my panel ground and each 220v leg, whereas there is no potential between ground and one of the legs on the 120v input VFD's - but does this matter? Should I connect to the other "PE" terminal? Also, there is no chassis ground screw on the VFD, or anything labeled "ground" for that matter.


texts: How to replace bulb with LED in a PWM circuit (car)?

texts:
I want to replace a light bulb in a Peugeot 308 SW with a LED. The bulb works (lights) normally, but the LED blinks. I thought they are controlling the bulb in alternative current but my digital voltmeter shows 9V on DC scale.

And no. It is not a blinking LED (I also thought it was). I have tried it with a battery and works perfectly. The blink must come from the dimming system - yes, the car dims the lights instead of suddenly turning them off.

I have tried also to use a diode and a capacitor to convert from AC to DC but it is not working. Maybe they are suing an open collector circuit?

My guess is that they control the bulb in DC pulses (PWM), and the circuit is an open collector.


texts:
Today I updated my KiCad by installing new version over the previous one.
Afterwars I created a new project, added schematic symbols, associated them to footprints and generated netlist.
Now when I'm trying to read netlist in Pcbnew I get errors about missing TO-220-3_Vertical footprint. This footprint was available in the previous version of KiCad and should be in the default github library.

What is going on? Am I doing something wrong?

The full error is:

Error: Component “U1” footprint “TO-220-3_Vertical” was not found in any libraries in the footprint library table.
Error: Cannot add new symbol “U1:/5B6DC52C” due to missing footprint “Package_TO_SOT_THT:TO-220-3_Vertical”.

When I was assigning footprints to symbols I could see correct footprints in the preview window.


texts: Analog Led Audio Spectrum Analyzer Simulation

texts:
I am having a bit of trouble trying to simulate a variation(different frequency ranges/gain for the BP filters) of this project: https://makezine.com/projects/audio-spectrum-analyzer/
I am not too experience in simulation so I am not too sure what I'm missing to get the simulation to work. I'm using multisim. Here is one of the bandpass filters that has the frequency ranges of 20-250hz. Also what exactly is the purpose of c3 and r5? I circled them.
All help appreciated thanks!

https://imgur.com/vz1HMbQ


texts: Reduce power consumption and schedule power on and off with RTC module?

texts:
I work on an Arduino based beehive scale project.

My circuit is wired and it works perfectly (measure temperature, humidity, weight every day at 6 AM, 2 PM and 10 PM and sends it to the server by GSM module) while powered by 5 V and 3 A.

My goal is to power everything with 12 V battery pack which will last for at least 1 year. The circuit consumes about 20-30 mA (it is because Arduino is turned on, sensors work all day long, GSM module is an active whole day, etc.) and about 150 mA while GSM is sending a message (few seconds).

I was looking for the best way to solve my problem and found this guy:

DS3231 RTC Module will probably be the best choice. Arduino watchdog timer is very inaccurate and consumes more power than the RTC module.

My questions are:

How can I program a DS3231 RTC module to power on Arduino at a specific time and wait for Arduino to tell him when to power off or be turned on for example 5 minutes until the server gets all the measurements? How long will the RTC module's battery (CR2302) last in my case? Is Arduino's watchdog timer in combination with Arduino's sleep mode a better and easier solution to fix that?

PS. Now Arduino works all day long and delay is specifying time when it will send measurements to server.


texts: microchip pic18f: What is the difference between a POR/BOR and other resets

texts:
I found similar questions on the internet. some answered that all resets re-initialize the SFR. I don't know if this was tested or concluded. I'm so confused because  at http://microchip.wikidot.com/8bit:mclr they state that:

  When an external MCLR reset occurs, the program counter will be reset to the top of the program execution or memory location 0x00 which is the start of all program memory. MCLR resets will not re-initialize all internal functions like a Power On Reset (POR) or Brown-Out Reset (BOR) style reset. It can be considered a hardware means to activate a software reset.

Also in microchip slides (RESET causes and effects) http://ww1.microchip.com/downloads/en/DeviceDoc/reset.pdf

  An MCLR reset will not change the state of any general purpose RAM locations, but some of the special function registers will be initialized. This applies to most types of reset, and the initialized state of the special function registers are specified in the applicable data sheet.

In the datasheet, (pic18f45k22) the legend found under the description of the SFR states that the initialization values are after a POR. look for example at TRISA register.

  -n = Value at POR

Why did they state that it's "Value at POR" not "Value at any Reset"
on the other hand, some registers such as the OSCCON2 define 2 initialization states.

  -n/n = Value at POR and BOR/Value at all other Resets

also in the same datasheet section 4.7 Reset state of registers:

  Some registers are unaffected by a Reset. Their status is unknown on POR and unchanged by all other Resets. All other registers are forced to a “Reset state” depending on the type of Reset that occurred.

What does that mean!?

also in the same dataheet:

  Table 5-2 describes the Reset states for all of the Special Function Registers. The table identifies differences between Power-On Reset (POR)/Brown-Out Reset (BOR) and all other Resets, (i.e., Master Clear, WDT Resets, STKFUL, STKUNF, etc.). Additionally, the table identifies register bits that are changed when the device receives a wake-up from WDT or other interrupts.

Well, table 5-2 has only the "values at POR/BOR". How can I know the value at other resets!?
I find this confusing. So are all SFR initialized to the values in the table after any reset... For example, will an MCLR reset cause the TRISA register to initialize to 0xFF or will it remain unchanged?

Thanks a lot


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