texts: How more efficiently can I write the test bench for a MOD 16 asynchronous counter using JK flip flop?

texts:
//////////**Code for jk flip flop** ////////////

module jkff_behavmodelling(q,q_bar ,clk, reset,j, k);

input wire j,k,clk,reset;

output reg q,q_bar;

always @(posedge clk) begin

  if(reset)

            begin
            q=1'b0;
            q_bar=1'b1;
            end
  else

        begin
            case({j,k})
            {1'b0,1'b0}: begin q=q;q_bar=q_bar; end
            {1'b0,1'b1}: begin q=1'b0;q_bar=1'b1; end
            {1'b1,1'b0}: begin q=1'b1;q_bar=1'b0; end
            {1'b1,1'b1}: begin q=~q; q_bar=~q_bar; end
        endcase
    end
 end
endmodule

////////////////////**code of mod 16 asyn counter**///////////////////////

module mod16asynCounter(q, q_bar, clk, reset, j, k);

output  [3:0] q; output  [3:0] q_bar;

  input clk,reset, j, k ;

 jkff_behavmodelling jk1 (q[0], q_bar[0], clk, reset, j, k);

 jkff_behavmodelling jk2 (q[1], q_bar[1], q[0], reset, j, k);

 jkff_behavmodelling jk3 (q[2], q_bar[2], q[1], reset, j, k);

 jkff_behavmodelling jk4 (q[3], q_bar[3], q[2], reset, j, k);

endmodule

/////////////////**test bench of mod 16 asyn counter**///////////////////

module mod16upc_tb_v;

    // Inputs

    reg clk;        reg reset;  reg j;  reg k;

    // Outputs

    wire [3:0] q;   wire [3:0] q_bar;

    // Instantiate the Unit Under Test (UUT)

    mod16asynCounter uut

(.q(q),.q_bar(q_bar),.clk(clk),.reset(reset),.j(j),.k(k));

    initial begin

        // Initialize Inputs
    clk = 1;    reset = 1;  j = 1;  k = 1;
    // Wait 100 ns for global reset to finish
     #100   j = 1'b1; k = 1'b1;  reset = 0;
     #100   j = 1'b1; k = 1'b1;  reset = 1;
     #100   j = 1'b1; k = 1'b1;  reset = 0;
     #100   j = 1'b1; k = 1'b1;  reset = 1;
     #100   j = 1'b1; k = 1'b1;  reset = 0;
     #100   j = 1'b1; k = 1'b1;  reset = 1;
      #100  j = 1'b1; k = 1'b1;  reset = 0;
      #100  j = 1'b1; k = 1'b1;  reset = 1;
      #100  j = 1'b1; k = 1'b1;  reset = 0;

end
always #50 clk <= ~clk;
endmodule

/////////////////////////////////////////////////////////////////////


texts:
I made a Slayer exciter according to the schematic below.
I have done about everything necessary for it to work such as sanding the bottom of the secondary.
I have 2000 turns on secondary, and 7 on primary. I am powering it with 18V DC.  It is powered from my power supply. I notice on my power supply that no current is being drawn from my supply when I power it.
I have an Arduino in the schematic to play music to it.
At the moment the wire going from the Arduino to the actual primary isn't connected in my actual circuit, while it is shown as so in the actual schematic.
Here's the schematic:


texts:
I'm trying to simplify this circuit but I'm not very sure about what the next step is. Something tells me that I could ignore R5, R6 and R7 and it would be the same but I'm not very sure. Any help would be appreciated, thanks.

Edit: This is my new attempt but I'm not too sure about it.

Edit 2: Latest attempt


texts:
Why are polyfuses so big? I was looking at a 500mA polyfuse, it is in an 0805 package, but there was only one of them - the rest were 1206. I have two questions.

Why so big?
Does anyone make 0603 polyfuses?


texts: How to avoid high current flow through long runs of addressable LED tape without compromizing the data ground

texts:
I'm battling with Addressable LED tape power. I have 12V TM1812 RGB LED tape and want to run the maximum lenght in pixels , which is just over a 1000 pixels. This means the current will be around 40 Amps at 12V. This comes to about 20 meters of strip.

I will ditribute the 12V and GND along the strips by using a bigger cable to reduce voltage drop and heat. But connecting the GND across for the reference of the data signal will give a path for the current to flow through the thin PCB of the strip which I need to avoid.

I'm adding small restistors to reduce noise betweeen the strips for data, but how can I make sure the high current which is driving the LEDs is not passed through the previous strips and goes through the big ( buzz bar ) cable I use to power the strips.

Each strip of 132 pixels  draw just over 5 Amps on 12V.


texts: Why always in communication protocols R/W configuration,Reading is configured by “1” and writing by “0”?

texts: when a microcontroller communicates with another one via one of the communication protocols there is a configuration bit in a control register to choose whether to send(write) or receive(read) this bit in all the communication protocols that I dealt with is configured by setting it to "1" for reading and clearing it for writing..why is that?


texts: Size of resistor connect to positive input of an inverting op-amp (LMH6702)

texts:
I'm building a TTL to fast-NIM converter using an LMH6702 op-amp (datasheet).

Figure 25 on page 13 shows almost exactly the circuit I'm building, with Rt=50ohm, Rg=3.1k and Rf=237. In that drawing they show that the input resistor to the positive input is 25ohm.

I found here several questions related to that resistors, and they were answered that the resistor needs to be on the same size as the input resistors to the negative input, and in that case I need it to be at about 3.1k.

Is that correct?


texts: I'm trying to make a clock pulse generator but when I run the simulation nothing happens

texts:
I am new to using circuit/breadboard simulation apps.  When I run the simulation nothings happens. Here is the original schematic.
Edit: I'm using 74HC00.
Also I learned how to use Virtual Breadboard more, so here is my final submission, sorry for the inconvenience I'm new to this site and to electrical engineering as a whole.
Here is what's supposed to happen:

I'm trying to create clock pulses, One LED should be off while the other is on, the problem is both of them are on.

I tried to measure the voltage on the inputs of the gate 1 and 3.  It's 0, I don't know what's blocking the current.


texts:
Are there crystals that are tolerant of high pressure?

Or do they all have an open space in their case?

A customer wants to use our product in a submarine, immersed in high pressure oil.

I thought we'd be OK using SMD crystals, based on this Wikipedia article and based on reading the reference from the US Dept of the Navy.

Instead, under pressure, the top of the case of the crystal imploded.

(Picture of imploded SMD crystal after high pressure oil immersion test.)

Obviously, there's an air pocket in there.

It was suggested that we pot the crystal in epoxy. But I have some doubts that that would work: The pressure cracked the ceramic body of the SMD crystal; I doubt that epoxy can withstand what ceramic couldn't.

(Can a kind soul with 300 reputation points create a "high pressure" tag and add it to this post, please?)


texts: Make adjustable mosfet constant current source

texts:
I want to modify this circuit below so the current can be trimmed.

The problem is the variations in base-emitter voltage of the NPN transistor. According to datasheets, it is between 0.55V and 0.7V with a collector-emitter current of 2mA. I need to trim the current through the LEDs to 0.35A, using a potentiometer of 100 ohms or greater.

How could I modify this circuit? The supply will be well regulated.

simulate this circuit – Schematic created using CircuitLab

Thanks


texts: Altium Automatically fill Description and Comment with values from parameters

texts:
I have made a full schematic with misplacing description and comment.

Is there a way to automatically make that Comment get filed automatically with Manufacturer Part Number (after having imported the components from the Supplier Search module into schematic) for all components inserted in the schematic ?

Same question for Description to fill with components description .


texts: What is the purpose of combining two differential amplifiers as in the figure below? The first differential amplifier is a single input balanced output and the second differential amplifier is a dual input unbalanced output. What is being achieved here? I understand the purpose of the current mirror.


texts: how to use an npn as a switch between battery and motor?

texts:
I am a noob playing around with nodemcu and esp8266. I am trying to control a motor in an automated air freshener. I had been trying to power the motor with board supply but I gave that idea up when I was unable to manipulate the voltage and current. so now I am trying to just use an npn transistor to close the circuit already in place. There's only the battery and the motor in the circuit. How do I use the npn, considering I am using a nodemcu breakout board?

Also if someone has any idea how to power the motor directly, I am all ears;

Link to motor specs: http://szlh-motor.manufacturer.globalsources.com/si/6008851876220/pdtl/Micro-motor/1146386525/500TB-metal-brush-micro-motor.htm

Battery seems to be 2 AA 1.5v in series.

Apologies and regards in advance for the stupid question.

EDIT: Picture of the motor and battery assembly: https://ibb.co/fnMpic

I would rather not change the soldering of the assembly as I might want to put it back


texts:
I am designing a programmable bench power supply and I want the output voltage and current to be monitored by a microcontroller. The voltage range is 0-20V and the precision that I want it to have is 0.01V. I have read about ADCs in wikipedia and I have combined some formulas that I found on the Internet. This is what I have came up with:

(where n is resolution and Δ is voltage per step)

Most ADCs operate in logic level voltages so I have to use a voltage divider to reduce the output voltage 4 times (so that 20v->5v and 0.01v -> 0.0025v). So I need an ADC with a precision of 0.0025v per step. So with Vmax - Vmin = 5v and Δ = 0.0025v, n = 10.9 , so I need a 12bit ADC. For current, I am planning to use a .1Ω shunt resistor in combination with an opamp with a gain of 10 so that 1a = 1v. The current won't exceed 3A so I don't need a voltage divider. 0.01 A will be 0.01V. If we do the math again, n = 8.9 so I need a 10 bit ADC. Is the way I am calculating it correct or not?


texts: Playing a low res WAV/PCM file using a Basic Stamp II microcontroler speaker

texts:
Is there a way to convert PCM data to PWM impulsion so that I can send it a basic stamp microcontroler in order to play audio on a external speaker ?

(without using an IC)


texts:
Apologies before I dive into the question.  This is the best title I could think of for a more complex question.

Is it possible to have a timer circuit that consumes no power when quiescent?  I mean that the circuit draws no power whatsoever, until a button is pressed momentarily.  The button press might only last 0.1 seconds.  Following the actuation, the timer outputs a 100 mA signal for say 5 seconds.  The timer then reverts to it's quiescent state again.

This is for:-

I have a large posh antique door bell push. I don't want to replace it with some plastic thing from Taiwan.  Unfortunately it's very prone to contact oxidation, so the electrical operation is very erratic.  I want to operate it from batteries only.  Hence I'm looking for zero current drain whilst not operating.  Due to the electrically noisy contacts, I thought of using some form of monostable based pulse stretcher plus capacitor thingie.  Upon pressing the button, the timer would operate a loud electro mechanical ringer, then stop.

This circuit arrangement seems possible to me, but it's realisation remains just out of reach. Perhaps something with relays?  Is this actually possible, or would I be violating some fundamental law of logic?

Edit:  I'm looking for a simple electrical solution to this with such as relays, capacitors, monostables, e.t.c.  I don't have access to a micro controller development environment, nor any credible C skills.


texts: Can I drive all these FETs from this microcontroller?

texts:
I'm trying to design a driver for a 35x7 flip-dot display I picked up from scrap today. The plan is to put a half bridge at each column and row so at each pixel there's a full bridge. For this display, that means 2*(35+7) = 84 transistors are needed. Because I don't want to actually solder 84 things if I can avoid it, I want to use full H-bridge FET chips, c.f.  the DMHC3025LSD.

The display requires something like 8V to flip the dot which broadly speaking no microcontroller can do so the PFETs in the bridges can't turn off. To solve that problem I've added an inverting N channel level-shifter (using UM6K1Ns and a pullup) to each PFET which has the bonus of being fail-safe by initializing the PFETs to off when powered on.

Here's an abbreviated schematic:

This leads up to the following: The UM6K1Ns have a very tiny gate capacitance, 13pF, and the DMHC3025LSDs are substantially more, 5.4nC. The microcontroller I want to use, the PIC32MZ2048EFM144 has a maximum supply current of 150mA and a pin limit of 15-33mA (pp. 611 of datasheet). Now, I know that gate charge is the product of the gate current and transition time, but I don't know what would happen in this case since I don't know how the uC supplies current. I suspect that each FET would try and draw the maximum allowable and, because there's 84 of them, overload the microcontroller. What I would hope happens would be the the uC would distribute the 150mA and they would all transition slower.

What can I expect to happen in this case?

If this overloads the microcontroller, what can I do to work around it? Is daisy chaining shift registers my only option?


texts: Automatic power selection circuit design and part selection

texts:
I am working on a project that has LIPO battery and a USB as a power inputs. The system should use the battery but if the USB cable is plugged it has to use that as a power source instead of the battery.

The design is mostly based on Adafruit ESP32 feather https://cdn-learn.adafruit.com/assets/assets/000/041/630/original/feather_schem.png?1494449413. If I understand it correctly the MOSFET is turned off if V_USB is < than V_BATT.
I plan to have this board assembled by JLC PCB and both the MOSFETs and the Schottky diode are extended parts. I want to replace them by basic parts to make it cheaper so I'm looking for alternative parts, Are B5819W and AO3400A adequate replacements in this case?


texts:
The circuit below should be taking a 3.3V signal from an MCU on MCU_LS12 and outputting a 12V high-side signal.

The output is always 12V. On scoping the base to the output transistor is not being pulled to ground "enough" - only going 12V then to 11.5V.

What am I missing? Input signal on LS12 is a 3.3V from an MCU, sending in a 50% square wave for testing. Why is Q6 not dropping Q8s base to ground? What can I change? Is it the divider?


texts:
One type of analog display is the oscilloscope. A beam sweeps across the screen and voltage deflects the beam as it goes. The drawback is that it requires an electron tube, with all that that entails.

In my application we want to transmit and receive an ultrasonic pulse and then display that pulse. Obviously, this can be done with an oscilloscope. Ideally we would like to find a much simpler, cheaper device that can display the analog pulse. Is there such a display technology?


texts: RF signal receiver is short distance and unstable. Can antenna sovle this? How?

texts:
I am using a 315MHz RF receiver and transmitter pair, which are connected with Arduino UNO board. The objective is to copy 315MHz RF signal, and replay it back. FYI, the design is very similar with this.

The overall design works already. But, the problem is: the RF receiver must very close to RF signal source when copying (e.g. less than 10cm).

When the distance is more than 15cm, the copied signal is always unstable (e.g. the value of LOW and HIGH vary). When the distance is more than 25cm, the receiver always cannot receive the signal.

How to solve this? Can this solve by software? Maybe add antenna? I do not have such knowledge about antenna.


texts:
Whenever I try to set a certain port to high, then wait some time, then set some other port to high, I get an issue where only the last value would be set.
The code I import via USBASP and avrdude is:

#define F_CPU 1000000UL
#include <avr/io.h>
#include <avr/interrupt.h>
#include <util/delay.h>

int main(void)
{
    DDRD = 0b11111111;
    PORTD = 0b11111110;
    _delay_ms(1000);
    PORTD = 0b11111101;

    while(1)
    {
        ;
    }
}

And that just sets all pin on PORTD to high except PD0, ignoring the second instruction. Moreover, if I replace that piece of code with something like this:

_delay_ms(1000);
DDRD = 0b11111111;
PORTD = 0b11111110;

It does light all the pins on the port with a one second delay. I'm using an ATmega8A and also utterly lost.


texts:
I need something to work as an input for a rotary device. It must be able to rotate continously, accurate to a degree of rotation, and so that any extra full rotation will have no effect on the input, a+360 is the same as a. With no limit of rotations as well.

So I have found no potentiometer that does that. And rotary encoders never have so many levels. I thought about doing it mechanically, and the using something kind of pressure potentiometer like this one https://www.sparkfun.com/products/8678 to transmit any rotation of my mechanical device to the surface of the potentiometer. This is the best I could come with, but if I could find something better, and specially less expensive, it would be great. Is there any standard device to do this?

Thanks in advance.

EDIT: Ok, so found, thank you to the answers, the rotary encoders that seem to be what I'm looking for. My doubt is: what I will be using as the input is the global position of the encoder, the degrees to which it's rotated, and not how it's being rotated, left or right, which is what the incremental that I've seen do. Are there any more types of these things? Or does an incremental one tell you how much it's rotating?


texts:
There're some easy concepts which I don't get exactly in my mind. I'm afraid I've been studying these things for two years of my engineering but they still bother me. Capacitor is one of them. Can someone explain?

What does a capacitor do? Does it store charges? If so, then how does it do?

I have searched it on Google and Yahoo but didn't find any helpful thing there (for me). So I will be glad if I got my problem solved here.

P.S. I hope that the question would not again be an off-topic, as it always does and moreover people don't suggest then where to go. It's a real sad thing.


texts: What natural processes can cause Catastrophic Failure of a Hard Drive?

texts:
My understanding of conventional hard drives is they fail slowly.  Something breaks and skips along the platters and data begins to be corrupted.  I believe this is what the mean-time-between-failures indicates.

Is there a 'natural' way for a drive to be fully useless?  I know there are systematic way to accomplish this (e.g. EM guns).  Ideally I'd like to see statistics on the chances of a drive experience complete failure?


texts:
I have recently began studying processors and am attempting to design my own simple processor in Logisim. I have previously studied the MIPS Assembly Language and am hoping to have my processor work on instructions similar to MIPS.  My instructions are 12-bits in length and my ALU only supports addition and subtraction. My CPU uses a 12-bit instruction RAM and an 8-bit data RAM.

My instruction set so far will only consist of the following 4-bit opcodes, similar to MIPS instructions:

lw    0000
sw    0001
addi  0010
add   0011
sub   0100

My instructions are of the following format:

     [opcode: 4 bits] [rs: 2 bits] [rt: 2 bits] [rd/offset/const: 4 bits]

For example:

addi $t1, $1, 5    ->    0010 1010 0101

I have created the program counter, ALU, 8-bit register, etc. but the one bit I am really lost with is the control unit. I understand that the control unit should take as input the opcode of the instruction, and then output signals to the necessary registers / memories / ALU / etc.

So, how many outputs will my control unit need and what will each output correspond to?


texts: How do I find the voltage across the capacitor?

texts: The circuit which is shown above has no resistance. So there is no time constant. Plus the current source has no resistance in parallel. So I cant convert it into voltage source. Is there any way to find the voltage across the capacitor after 6 seconds?


texts: Setting an oscilloscope to read a noise level

texts: what to set an oscilloscope to when reading a 10 mV noise level on a 12 V power supply output?  Frequency is unimportant.


texts:
I am narrowing the selection of an uC for my project and currently reading the datasheets. One contender is Microchips 'ATSAMC21*' series. Using the parametric selection tool I get following information

In the datasheet it says on p. 2

Up to eight Serial Communication Interfaces (SERCOM), each configurable to operate as either

Does this mean I have eight interfaces as combination of SPI,I2C and UART?
Or like in the table above 6-8 separate interfaces (18 in total)?


texts:
Im using an arduino uno to upload code via TPI to an Attiny10-TSHR on breadboard.
Communicating with the chip works fine and uploading code but it never runs the code.
By dumping the chip memory I can see that i has uploaded the code fine.
But when I upload some simple code to toggle PB0/PB1/PB2, disconnect MCU and restart nothing happens.
I have tried all GPIO is with oscilloscope and multimeter. I use the same VCC/GND when running the program as when i program it.
It's like its stuck in some programming mode or something. Or the binary im uploading is bogus?
Anyone have any idea? This is the code im compiling with Atmel studio for attiny10.
#define F_CPU 12000000UL         /* 12MHz internal oscillator */

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

int main(void)
{
int i;

// PB0 and PB1 outputs
DDRB = (1<<PB0) | (1<<PB1);
// Timer0 in mode 14, fast PWM with ICR0 as top.
// Enable OC0A and OC0B, lower mode bits
TCCR0A = (1<<COM0A1) | (1<<COM0B1) | (1<<WGM01);
// Set top to 1000
ICR0 = 1000;
// Start timer with prescaler 1:8 and set upper mode bits
TCCR0B = (1<<CS01)  | (1<<WGM03) | (1<<WGM02);

while(1)
{
    for (i = 0; i <= 1000; i++)
    {
        OCR0A = i;
        OCR0B = 1000-i;
        _delay_ms(1);
    }
    for (i = 1000; i >= 0; i--)
    {
        OCR0A = i;
        OCR0B = 1000-i;
        _delay_ms(1);
    }
}
}

It outputs the binary;
:100000000AC011C010C00FC00EC00DC00CC00BC084
:100010000AC009C008C011271FBFCFE5D0E0DEBF6E
:10002000CDBF02D039C0ECCF43E041B942EA4EBD6A
:1000300048EE53E053BD42BD4AE14DBD68EE73E06A
:1000400040E050E057BD46BD862F972F841B950B8F
:1000500095BD84BD87EB9BE081509040E9F700C0DF
:1000600000004F5F5F4F493E93E0590759F748EE54
:1000700053E057BD46BD862F972F841B950B95BD2A
:1000800084BD87EB9BE081509040E9F700C0000001
:0C0090004150510B70F7D4CFF894FFCF13
:00000001FF

When I read the flash of the chip it returns;
**NVM lock**
3F00: FF FF
**configuration**
3F40: FF FF
**calibration**
3F80: 7B FF
**device ID**
3FC0: 1E 90 03 FF

**program**

4000: A0 0C 11 0C 01 0C F0 0C E0 0C D0 0C C0 0C B0 0C
4010: A0 0C 90 0C 80 0C 11 72 F1 FB FC 5E 0D 0E ED FB
4020: DC FB 20 0D 93 0C CE FC 34 0E 14 9B 24 AE E4 DB
4030: 84 EE 35 0E 35 DB 24 DB A4 1E D4 DB 86 EE 37 0E
4040: 04 0E 05 0E 75 DB 64 DB 68 F2 79 F2 48 B1 59 B0
4050: 59 DB 48 DB 78 BE B9 0E 18 05 09 04 9E 7F 00 0C
4060: 00 00 F4 F5 F5 F4 94 E3 39 0E 95 70 95 7F 84 EE
4070: 35 0E 75 DB 64 DB 68 F2 79 F2 48 B1 59 B0 59 DB
4080: 48 DB 78 BE B9 0E 18 05 09 04 9E 7F 00 0C 00 00
4090: 14 05 15 B0 07 7F 4D FC 8F 49 FF FC FF FF FF FF

I see that the printed hex from the chip is "inverted" A0 is 0A etc, is that how it's supposed to be presented?
I've spent about 10 hours on this problem now, ANY ideas would be highly appriciated..
Thanks


texts:
I recently got a new project to work on, an Electrospray Deposition setup. Basically, it consists of a needle that contains a liquid, a electrode and a high voltage source. The needle is positioned at a distance to the electrode and the source is connected to both the needle and electrode. Because the needle is charged by the source, the liquid inside is also charged, up until the moment where the liquid disperses into little droplets. These droplets are then accelerated towards the electrode placed under it.
The source for this is a DC Voltage supply ranging from 5kV to 35kV, which also brings me to my question, how dangerous is it working with this kind of setup and what safety measures should be taken? Once the supply is turned of and the experiment is over, the electrode and needle are still going to be charged, which is why I thought a discharge stick would be necessary, do any of you have experience with this?
I will link the voltage source, which was already bought without my influence and gives me not the best impression if I am honest.
HV350CC/GRA80 is the one I have at my disposal.
https://www.amazing1.com/hv-dc-power-supplies.html
From papers of other setups I figured I'd need about 5-20kV range for my setup, but I'd prefer it to be safe for the whole range. Do any of you have tips on how to choose the resistors for the discharge stick or what other measures to take?


texts: Relationship between speed against armature current/torque in DC shunt motor

texts:
I do not understand why the graph is like this as below when we use flux control method of DC shunt motor
Also, can I change the x-axis of this graph to be armature current instead since equation of motor speed is given by:
and I take y-intercept to be V/kphi, and gradient to be -Ra/kphi
However, if I do that the graph does not make sense, because the slope of gradient should increase when flux decreases from increasing resistance


texts:
I have a USB to TTL Adapter. The Adapter uses the CP2102.
I noticed that the CP2102 seems to derive it's power from the USB V+. My problem is that I need to supply power to the USB. The reason is that I need to drive a NULL USB cable. The transceivers (FT232R) requires 5V. I connected both the 3.3 and 5V and measured the Voltage at the USB and it is 3.3V. My plan is to just jumper the 5V to the USB V+. I don't have a schematic for the USB-TTL adapter. I believe This should work.
Adapter: https://www.amazon.com/HiLetgo-CP2102-Converter-Adapter-Downloader/dp/B00LODGRV8
NULL USB: https://www.amazon.com/FTDI-USB-NMC-2-5M-CABLE-ASSEMBLY-MODEM/dp/B00HKJSSQ2
FT232R Datasheet: https://www.ftdichip.com/Support/Documents/DataSheets/ICs/DS_FT232R.pdf


texts: Finding the voltage and current across a DC diode

texts:
I have a simple question from the electronics course
If the cut in voltage of the diode is 0.7 find the voltage and current across the diode


texts: How does external trigger work in an oscilloscope?

texts:
I'm having hard time to find any easy explanation to understand how triggering and especially external triggering works.

And it is even more confusing when a function generator's SYNC/TTL output is used for that purpose.

It is not easy to illustrate in mind what is happening when using a function generator to external trigger the oscilloscope just by reading a text.

I also tried find if there is similar question which could be a duplicate but I couldn't find.

Is there an easy way to grasp or illustrate the idea behind external trigger?


texts: Tune the track length of a segment but not the entire net in Altium

texts:
I have a differential pair routed like this:

U1 ======> U2 ========> U3

I want to equal the length of the pair between U1 and U2, but Altium always try to equal the entire net length between U1 and U3.

Are there any method to achieve this?


texts:
We're doing a school project where we have to measure weight on a fitness machine.

The user can select how many weight plates to use by moving a rod like shown in the picture.

How would you do it?

We've talked about the following solutions:

a strain gauge measurement unit beneath the stack, be we doubt that it will be robust, and it will be expensive.
an IR distance sensor that counts the spaces between each plate.
inductive proximity sensors
Some kind of electromagnetic solution?


texts: Can a generic 2.4 GHz transceiver be used on an 802.11x network?

texts:
I am prototyping a potential future product, and I am struggling to get my head around the complexities of using Wi-Fi components in it.

I understand that Wi-Fi (or 802.11x) is primarily just a 2.4 GHz signal modulated in a specific way, as is Bluetooth and ZigBee. Is it possible therefore to just use a basic 2.4 GHz transceiver in my project and configure it for the 802.11 protocol rather than having to use some expensive branded one that comes pre determined? Or is it not as simple as that?

I presume in industry, when doing design for large production runs, something similar takes place? Or do they indeed have to use a transceiver that is preconfigured to be Wi-Fi? All the pre-configured components I have found so far seem quite expensive (even when purchased in volume) to make a commercial design viable.

I have looked at devices such as the Lantronix WiPort and the Roving Network WiFly GSX and comparing them to devices such as the Microchip MRF24J40 - is it possible to use a Microchip MRF24J40 and then configure the rest of the hardware and software to enable the device to work on a Wi-Fi network?

For further detail, here is what I want to do at the most basic level:

Part 1: I want to make a patch that contains a small buzzer, an accelerometer, a PIC and a Wi-Fi transceiver that can be stuck to an object. This patch would be able to communicate with "The Cloud" though the users' home Wi-Fi network. When the accelerometer detects movement, the PIC will send a message, via the Wi-Fi link, to a server in the cloud to register that movement along with a time stamp.

Part 2: Through a web interface I want to be able to send a message to the patch setting the buzzer to make a sound next time the accelerometer detects a movement.

I have already made a rudimentary version of the system which works over a 433 MHz RF link and a laptop serial port with a local piece of software running on my laptop. I know how to do the web coding (PHP and MySQL), but it's the replacing the RF link with the Internet that is causing the issue.


texts: Why use the fast Fourier transform for noise reduction instead of a classical electronic filter?

texts:
I'd like to know how to remove environmental noise from a speech recording.

I've made some research and I've noticed that most of the methods proposed use the fast Fourier transform. But why can't you use a classical electronic filter to remove the noise frequencies? Why bothering with doing an FFT?


texts: Two stage Doherty Power Amplifier Voltage Connections

texts: I am using nxp's two stage doherty power amplifier(DPA) A2I20H060N and having trouble discerning the numerous voltage connections to the board. The datasheet is not completely clear on voltages to use for either the peaking nor carriers VGS/VDS connections and was hoping someone could help me decipher it. Here is a link for the datasheet https://www.nxp.com/docs/en/data-sheet/A2I20H060N.pdf


texts:
I am designing a class D amplifier for a pair of bookshelf speakers (Sony SS-MB150H).

I guess inside each speaker there is a crossover for each driver but... am I right to assume that I just need to feed a PWM to the speaker and it will work just fine? Or do I need to put a band pass filter (from 20HZ to 20kHz) on the output of the class D amplifier before feeding it to the speakers?

Thank you so much for your attention!


texts:
A friend wants an automatic headphone controller for his bike. According to the Android spec we should be able to add a bias resistor of 5kohm between mic and ground, short mic to ground for play/pause or short to some resistance for volume up/down.
Play pause works perfectly fine, but I can't get the proper resistance for volume up/down which is a necessary feature. We can't add a stereo potentiometer into the line because of the form factor.
This is our current circuit.

We have attempted replacing R1 and its FET with a potentiometer and button to quickly test other resistances with no luck. We are testing with an iPhone running iOS 14.2 with a lighting to 3.5 mm adapter.
Are we thinking about this all wrong? Any thoughts or advice would be appreciated.


texts: Inner layer routing of LVDS traces in between ground vias

texts:
I have ground vias underneath an ADC on a multi-layer board for thermal relief. I am using inner layers to route the LVDS signals for the ADC. The image shows diff pairs on layer 4, which is in between plane layers. Do the ground vias have any effect on the diff pairs, even though the vias are not connected to layer 4? If so, is the pair at the bottom more susceptible since only one half of the pair is adjacent to ground vias?

Due to space constraints, I cannot avoid routing underneath the ADC region. So what I have done is use routing layers that are farther from the surface layer and that are in between planes. Any suggestions will be appreciated.

I looked up other threads regarding thru vias and diff pair routing rules, but could not find something that addresses this.


texts: What is the best method for placing text on copper?

texts:
I've been wondering what is the best method electrically for placing a text on a copper layer?
I have a full GND polygon on the top layer. Should I just make the text a cutout from the solder mask so it will be on GND potential, or should I make a cutout from the polygon and place the text inside on a floating copper layer? I added a picture of the two method, which is better? Or does it even matter?


texts:
I'm trying to add 4 output of ADA8282 together and create only one analog signal with bandwidth about 6 MHz, I know Op-Amp adder as "How can I add three AC signals?" and "ElectronicTutorial" said. Also someone in "How can I add three AC signals?" called for analog multiplexer and inspired me this:
multiplex at 4xbandwidth of signal, then LPF to 1/4, tada, the answer will be average of all 4.
but these are not reliable need work, design and time, but i want reliable firm timeless solution, exactly an IC that do this for me is it available? and why, if not. Is adding signals are not commonly used?!why? Are everybody uses the Op-Amp method?


texts:
I'm trying to interface a Raspberry Pi with the mini-box OpenUPS. It claims to implement the Smart Battery SMBus specifications.

I can read data from the device using the i2c_smbus_read_word_data() function as defined in the Linux Kernel docs.

So, my basic problem is this: When the device is booted for the first time, and I perform the first read, all the data is messed up. I get negative numbers, and none of it makes sense.

But, if I perform a single byte read, then all following word reads give the correct data.

It's almost as if the byte order is getting messed up in a buffer someplace, and it takes a single byte read to straighten it out. But why doesn't it work the first time?


texts:
Is it possible for this circuit to have two different time constants? One from 0 to 30µs and the other one from 30µs. I tried to calculate the values and I get τ1=20µs and τ2=95/7 µs. They seem quite different so I want someone to confirm or tell me the right way to calculate them.

This is how I did it:

for t=0: S1 in A is closed while in B is open. S2 is open. I tried to find an equivalent circuit formed of a capacitor, a resistance and a voltage source. I got R=10 ohm, C=2µF, V=20V. So τ1 = RC = 10*2µF = 20µs
For t>=30µs: S1 in B is closed and in A is open. S2 is closed. This means that there is no connection between the voltage source and the capacitor. I tried to find an equivalent circuit and I got: R=95/14 ohm, C=2µF V=0V. So τ2 = 95/7 µs.

Now, let's say I already have the capacitor voltage in a period of time (0 - 100µs). How do I calculate the output voltage (Vout(t))? I get two different expressions again...


texts:
Possible Duplicate:
  How could you transfer data over an audio line?

I'm trying to make my Android phone talk to my robot which uses an Atmega8535L chip. The idea is to use the phone's camera as a line follower's sensor (already done) and send information to my robot's wheels.

As of now I have a quite naive idea of how it'll work: I'll use left audio channel as clock and right as data over a simple scavenged audio cable which I'll connect to analog pins (as the audio jack doesn't put out much voltage, the threshold will be low). Since I cannot output digital signal from my Android phone (I think) I'll use some noise as 1 and no noise as 0.

I'd like to use no electronics whatsoever between my phone and my robot... if that's even possible. I've heard about FSK, but it seems complicated, especially the demodulation part.

Is this even feasible without additional electronics?


texts:
I'm working on a device that is connected to 2 serial ports (both TX and RX).The first serial port is connected to a CP2104 USB chip, the second serial port is left open with TX,RX,GND,3V pins.
I want to be able to switch between these 2 ports with some kind of analog switch/multiplexer and a mechanical switch  but I cannot find a way to implement it.
To summarize, the user would select between USB serial or header pin serial. Pseudo-schematic:

The MCU is an ESP8266, which has only one serial port. Whenever I send data via its serial header pins it doesnt receive anything because it is already connected to the CP2104 serial port, and I dont wat to use softwareserial since it is not reliable for WiFi applications.
I did some search and found these analog switches but don't know how to make a circuit with a mechanical switch so that I can change from one serial port to another. Any help or advice is appreciated
=========== EDIT 1 ============
I found a MUX/DEMUX analog switch used for switching between 2 USB(D+,D-) ports. I made a prototype circuit of what I'm trying to achieve with the mechanical slide switch. What do you think?

=========== EDIT 2 ============
Asked another question related to this topic:
Is this analog switch good for UART lines?


texts:
What kind of signal do we have to at the base of a transistor? Is it a current signal or voltage signal? On the other side, what kind of output (amplified) signal do we expect? Is it a current or voltage signal?
They said the output current is current gain times base current, so it seems that they are using current as base signal, but then why do they add a voltage source (AC) to give signal?


texts: A basic level question about grounds in a differential amplifier circuit

texts:
As far as I know, voltage is a defined with respect to a common ground in circuits. So if there is a source and a receiver/amplifier; then they should have a common ground if we want to talk meaningfully about the voltages at any node.

Below illustration showing a differential amplifier used for both single-ended and differential inputs:

I can see in single-ended input case the signal ground of the source is tied to one input of the diff. amplifier. So they share a common ground.

But where is the common ground for the differential input case? Is the source's ground is tied to the ground of the diff. amp? Where is the differential source's ground? Where is the differential amplifier's ground? Can someone draw a more clear example diagram which also shows how and where their grounds are tied?

Edit:

I tried to make the confusion more clear with this illustration below:

We have on the left a differential signalling circuit and it has its own ground GNDA.

We have on the right a differential amplifier and it has its own ground GNDB. Its rails are supplied with +15/-15V wrt GNDB.

Imagine for a moment in time the signal source is outputting +1V and -1V with respect to its own ground GNDA.

One might say here the differential amplifier will take the difference which is +1 - (-1) = 2V and this 2V will be the voltage with respect to GNDB.

Now lets say we measured GNDA = GNDB + 100V.

What does that mean? It doesn't matter or does it?

And here I tried to simulate the situation with LTspice:

It seems if GNDA - GNDB is greater than some voltages the output corrupts.

What is this about?


texts: Timers and internal clock generator on Freescale MCU

texts:
I am using MC9S08AW60A with DEMO9S08AW60E Board (Freescale). I have studied about the timers given with the MCU. I wish to know how exactly to Implement timers by code. The Freescale suite also comes with Processor Expert (a GUI to configure the MCU).

I have written the following code to light-up the LED's in a sequential manner WITHOUT using a DELAY function i.e only by altering/using TIMERS and INTERNAL CLOCK GENERATOR.

//------------CODE BEGINS------------

PTFDD = 0xFF;
TPM1SC = 0x0E;//configures the Timer 1 Status and Control Register
TPM1C2SC = 0x98;//configures the TImer 1 CHANNEL 2 Status and Control Register
ICGC1= 0xE8; //Have altered the ICG with respect to TPM.
ICGC2= 0x8E;
//As you can see i have not altered the ICG in any way.And the same values as above
//(for TPM) i have emulated using the Processor Expert.
for (i=1;i<=8;i++)
  {
    if (i==8) i = 1;
if (i==1) PTFD = 0x01;
if (i==2) PTFD = 0x02;
if (i==3) PTFD = 0x04;
if (i==4) PTFD = 0x08;
if (i==5) PTFD = 0x10;
if (i==6) PTFD = 0x20;
if (i==7) PTFD = 0x40;
}

//----------CODE ENDS-----------------

But all I get:

LEDs are on but very dim, I think they're toggling very quickly. Am I right?
Also, Do I need to change the ICG settings if using TImer?
Also, i have initialized the device with Processor Expert and written the same as code. does it interfere. (i have made sure both represent the same values,else it would have shown me an error.

On the data sheet, refer to page 165 for the timer/PWM and page 129 for Inter Clock Generator.


texts:
Why do so many embedded cameras in computers, etc., prsent a mirror image?  It means anything with writing on it is backwards.
Why is this desirable?


texts: How do you determine the input impedance for an inverting amplifier?

texts:
Essentially I am getting confused trying to do the sums for an op amp with a gain of 10dB and an input impedance of 1kohm.

I worked out that \$\frac{V_{out}}{V_{in}}=-\frac{R_{2}}{R_{1}}\$ because \$V_{+}\$was going to ground, \$=>V_{-}=0\$.

I know that the output impedance of the amplifier itself is very high.

I know that the compensation resistance \$R_{3}=\frac{R_1R_2}{(R_1+R_2)}\$ but I am not certain why.

I had thought the input impedance would be the \$R_1||R_2\$ (or whatever else would go to the node for \$V_-\$ which in this case is just \$R_1\$ and \$R_2\$) but I am doubting myself.

Can anyone clarify what this input impedance is actually referring to?

I should also perhaps add that I am going to construct this for real out of a 741 amplifier so I am trying to figure out what resistances to pick to get my 1000 \$\Omega\$. I can't believe that \$R_2\$ wouldn't matter in this, so if anyone can clarify that, it would be useful.


texts:
My friend asked me this question and I had no answer.

Here is what is proposed :

An amplifier is fed a current of, say 1 Ampere. Let's say it amplifies it to 100 Amperes. The output is so designed with parallel resistances that one of the branches draws 1 Ampere and the other, 99 Amperes.

The 1 Ampere is fed back to the amplifier and is used to power it.

I know a little current will be lost each time so it can't go on forever. But what if the amplifier used five amperes to charge itself?

Is this a feasible idea? Can it happen?

Many thanks in advance.


texts: How to use ADC for battery operated application?

texts: In my application VDDA = ADC Reference voltage and VDD = Microcontroller supply voltage changes due to battery drain form 3 V to 2 V so because of that my adc count not stable so what can I do to make stable?


texts: How can I capture naturally created static electricity so that it won't create a shock when I touch a grounded object

texts:
How can I capture the naturally created static electricity in our bodies, so that it won't create a shock when I touch a grounded object.

I'd like to capture it and store it for future use, maybe wire in an LED, buzzer, or cell phone...


texts: When do I need to use a clock buffer IC?

texts:
I am designing a circuit and PCB for driving 7 DACs from an FPGA. (DAC is AD9762)

Would it be possible to drive the clock inputs on all 7 DACs with a single clock output (from a PLL output pin) of the FPGA? Or is that a recipe for disaster?

It will be a single ended clock with a max. freq. of 125 MHz.

Or should I use a clock buffer to buffer the clock before each DAC clock input?

If so, is this a good clock buffer? (NB3N551)

Is there a better one I can use?

Edit: Sorry, I should have mentioned: All the DACs will be on a 5"x5" PCB connected through a short (few inches) ribbon cable to the FPGA board.

Edit2: If I can rephrase the question: If I can afford the room and cost of the clock buffers, are there any potential negatives? Or would that be the safe way to do this?


texts: Variable power source from an ATX power supply?

texts:
I have an ATX power supply (400W) and I want to use make a variable power source for 3-20V using a LM317.

I know that the 4 pins connectors (like the ones for the IDE devices) are +12V|GND|GND|+5V, is it possible to put in series 2 of the +12V outputs to get 24V?


texts:
Is there any reason why solar and wind farms cannot share the same piece of land?
The number of solar arrays that would have to be omitted to make way for the turbines should be relatively few. The advantages are:

Dual use of the land, (more power per square metre) and you could still graze animals.
Shared use of much of the infrastructure such as transformers, switchgear and cables.
Somewhat more even supply, more chance that the site would be producing something 24/7.
Possibly output would be less weather dependent. I can't say for sure, but sunny days tend to be calm (Summer high pressure weather systems) and cloudy days are windy (Winter weather). This is a generalisation with exceptions and caveats.

There would be downsides, higher capital investment and sunny sites are not necessarily windy and vice versa. However they both are often found on less productive agricultural land, so in that respect vie for similar sites. But on the whole are there any technical disadvantages?


texts: What is this black, marking-less, 6-pin surface mount device?

texts:
Below you can see the device I'm trying to identify:

It is mounted underneath the expression pedal in one of these:

Basically, below the pedal there is a little plunger which gets closer or farther from the device. The end of the plunger which is facing the device is covered in a small amount of white paint.

My best attempt at an educated guess is therefore that the device is some kind of LED+photodiode/phototransistor combo, used to estimate the position of the footpedal.

Unfortunately, the ribbon cable that attaches the small daughterboard to the unit goes straight into a busy section of the main board, which makes it difficult to trace its surrounding circuitry. All of the surrounding circuitry is SMD resistors, capacitors and transistors, so my guess is that this device is analog.

The device has no discernible markings on its top or sides.

Does anyone recognize this? Does this kind of "split package" have a name I can start my search with?


texts: (How) does LM386 allow an input past its negative rail?

texts:
I am confused by the LM386. In the data sheet, multiple examples connect the inverting input directly to ground.

To me, that feels weird. How can the IC amplify if the input goes below GND?
The data sheet goes on: when left unconnected (or AC coupled) either input will float to 12.5 mV. That is certainly not enough to allow for the full 2Vrms output (500 mW into 8 Ohms) at a gain of 20.
Does the LM386 actually allow the input to go past the lower rail? How does it do that? Are the input transistor pairs all in saturation, i.e. \$V_C>V_B\$ ?


texts: What kind of signal processing circuitry do I need to generate a line level output on an Arduino?

texts:
I am trying to create an Arduino based music synthesizer.
How can I safely generate line level output (+/- 2 volts centered at zero, with a frequency range from 20Hz-20KHz) from my Arduino using a minimal number of components?
This is what I imagine the flow will look like, but please correct me if this is wrong.

Generate a sine wave tone using a DAC (I'm doing this already using
MCP4725)
Level shift the signal -2.5 volts and lower gain
To perform level shifting I think I need to generate a negative 5 volts
to supply to a dual supply op amp, but I'm not sure if this is
correct

There is a lot of confusing/mixed information on line level requirements. I hooked up the output jack of my macbook pro to an oscilloscope and generated a square wave. It looks like the macbook pro puts out -2 to 2 volts, so I think this is where my target output voltage should be.

Edit:
My target output voltage is 1.25VRMS, since I am using a QSC PLX3602 amplifier with an input sensitivity of 1.25VRMS.

Some questions:

How many milliamps do I need to be able to source for line level
Given that I am going to be outputting square waves (which can
sometimes damage speakers), is there anything I should keep in mind?
I am planning on matching my amplifiers RMS wattage rating with the
speakers RMS rating. Do square waves produce higher current than RMS?
Can anyone recommend a schematic or components I can use to
accomplish the signal conditioning needed to do this safely/without
damaging audio equipment?


texts:
I have some arcade machines which I build custom Linux PCs for. They all have 15khz monitors in them so I do some funky Linux stuff to output (what I think is) a correct signal to drive them.

This is the spec of the display:

                    Arcade CGA
                      640x240
    Horizontal                Vertical

Scan Frequency: 15.725 KHz   Scan Frequency: 60.018 Hz
Scan Period: 63.6 µSec       Scan Period: 16.7 mSec
Active Video: 50.0 µSec      Active Video: 15.3 mSec
Video Delay: 11.9 µSec       Video Delay:  1.2 mSec
Sync Pulse: 4.7 µSec         Sync Pulse:  0.2 mSec
Resolution: 640              Resolution: 240
Clock Freq: 7.16 MHz

However, I run the game at 640x480. To do this I use a XFree86 Modeline, specifically this one:

Modeline "640x480" 12.324 640 648 706 784 480 483 489 524 interlace -Hsync -Vsync

If you're not familiar with modelines this is what the numbers mean, they translate to this:

Horizontal:
    Width: 640
    Sync start: 648
    Sync end: 706
    Sync total: 784

Vertical:
    Height: 480
    Sync start: 483
    Sync end: 489
    Sync total: 524

Pixel clock: 12.324MHz

Based on these numbers I can do some calculations to see what frequency the display is being driven at:

(12.324*1000000)/784 = 15719hz = 15.719kHz (horizontal refresh)
(12.324*1000000/(784*524) = 29.99Hz (vertical refresh)

Since this display needs to be run at 60Hz, I interlace the signal (interlace option in the modeline), which I understand effectively doubles the vertical refresh rate.

Based on the specs, does this output signal seem safe? Is there a better modeline I could use?


texts: How can I use my SMD Arduino to program a separate DIP ATmega328?

texts:
I have an arduino with a surface mounted (SMD) microcontroller:

I know how to use a DIP arduino as a programmer for a DIP ATmega328. It's easy --you just pop your microcontroller in the holder.

However, with a surface-mount Arduino, there's no obvious. Desoldering the microcontroller is one way, but that's icky and destructive.

Can I use this Arduino as a programmer for a DIP ATmega328 without mortally damaging the board? If so, how?


texts:
I have a MOSFET that I'm trying to identify the manufacturer of. I know it's an IRF520N, but it doesn't behave the same as an IOR IRF520N, so I'd like to find the actual manufacturer's data sheet.
The unknown one is the one on the left.


texts: How do I write and upload a LED blink program on a PIC (pic16f59)?

texts:
I have a PIC16F59 and I want to get started with it by writing a blinking LED program. I am using HI-TECH C for the PIC10/12/16 MCU Family and the PICkit3 and MPLAB X as my IDE. Here is my attempted code which is supposed to turn on all LEDs on port B.

#include <stdio.h>
#include <stdlib.h>
#include <htc.h>

int main(int argc, char** argv)
{
    while (1)
    {
        // Put delay code here
        PORTB=1;
        // Put delay code here
    }
    return (EXIT_SUCCESS);
}

The program compiles fine. However, when uploading the hex file using the PICkit3 I get this error message:

Program operation of Program Memory failed
Address 0x0, read expected 0x25

What I am I doing wrong? Are there any configuration settings that I am not aware of?


texts: How to use TA1 of P1.6 without also using it on P1.2 on MSP430F1101

texts:
I have been struggling for a lot of time now, training to use the pwm function on pin 1.6 of the microcontroller. For P1SEL=BIT2, it is correctly using TA1 on P1.2, but for P1SEL=BIT6 it is not using P1.6. I have tired other combinations too, it only works(as far as I know) P1SEL=0xF4, but that also uses P1.2...
I hope I was somewhat clear in my explanation.
EDIT1: I used Proteus 8 for simulation and IAR Embedded Workbench IDE as IDE
#include "msp430f1101.h"

typedef unsigned char u8;
typedef unsigned int u16;

u8 pwm_preffered_idx(const u16 frecv)
{
  if(frecv < 2)
  {
    return ID_0;
  }
  if(frecv < 4)
  {
    return ID_1;
  }
  if(frecv < 7)
  {
    return ID_2;
  }
  else
  {
    return ID_3;
  }
}

u8 pwm_preffered_idx_div(const u16 frecv)
{
  if(frecv < 2)
  {
    return 1;
  }
  if(frecv < 4)
  {
    return 2;
  }
  if(frecv < 7)
  {
    return 4;
  }
  else
  {
    return 8;
  }
}

void pwm(const u16 frecv,const u8 fu, const u8 pin)
{
  P1DIR=0;
  P1SEL= ~BIT2;
  TACCR0=800000/(frecv*pwm_preffered_idx_div(frecv)) - 1;
  TACCR1=((TACCR0+1) * (100-fu))/100;
  TACTL=( TASSEL_2 | pwm_preffered_idx(frecv) | MC_1 ); //SMCLK | DIV/1 | Up mode
  TACCTL1=OUTMOD_3; //Set/reset
}

int main( void )
{
  // Stop watchdog timer to prevent time out reset
  WDTCTL = WDTPW + WDTHOLD;

  pwm(1000, 10, 12);

  while(1);
  return 0;
}


texts: Problem with 74HC76, silly mistake or possible fake?

texts:
I am a hobbyist and have been buying a few cheap ICs on AliExpress to play around with at home.  I know that there is some risk involved in buying these but I seem to have had mostly good luck so far.  A couple months back I received a batch of ICs that were definitely fake because they didn't have any coherent output.  When I contacted the seller they didn't reply and it was too late for me to initiate a dispute.  So now I try and sanity check what I receive right away.

Right now I am having a problem when testing some SN74HC76s (JK flip-flops).  I have a bench power supply with current limiting and when set at 5V, 20mA it just dumps all the current out of ground.  I've verified this with a DMM.  I don't think this is normal for this chip, is it?  The datasheet doesn't seem to indicate this.  Neither Q nor ~Q are going high.  I am hoping that you guys can sanity check my hookup to make sure I'm setting it up properly.  No matter what the reason for it failing to work I just want to understand why.  If it is a fake, I'd like to get better at realizing it sooner.  Thanks for any help.

Here's the datasheet


texts: So I have a 5 volt supply on a pcb and I have been asked to add another component to it, this component takes a strict 1.8 volts only. I would like to know types of methods I could use to perform the voltage drop with limited space and heat sensitivity.


texts:
For a project, I am connecting the output ports of a 74AC04E hex inverter to bnc ports.

Something could be (but not necessarily) be plugged in at one or more ports at a given time.

Should the ports have pull-up:s / pull-down:s or could they be left floating?


texts: Wirelessly connect 5" resistive touch screen to computer

texts:
Figured out display, just need to transmit touch signals wirelessly.

What I have is a 5" monitor with a USB touch overlay connected to my laptop with a USB cable.

I've done quite a bit of research and found solutions only for analog sticks, keyboards and mouse; but none for touch.

What I'm understanding is a micro-controller and a BLE module is needed. Only thing left would be the code.

Since the analog input is already converted to digital and outputs that data via USB what can I do to transmit that data wirelessly?

Also the computer recognizes this device as a USB mouse


texts: ESP8266-12E unstable WiFi connection (Need feedback)

texts:
i have made a small circuit using ESP-12E here is how my circuit looks like:

Here i have kept in mind that wifi connection should be stable, still i am not able to get the stable WiFi connection. Reason is still unknown to me.

I kept the WiFi antena without below ground plane. So it won't create disturbance in WiFi signal.
I kept the capacitor as close as possible to VCC, but its far from ground, not sure how i could make it close to that.
No complex component is near the ESP8266 chip on the board.

Not sure what is making it unstable. Any suggestions how can i improve its stability in this circuit design.
Thank you!


texts:
In an assignment, I need to find the settling Time of the ADC Input Circuit time to reach 1/4 of the LSB.

The ADC has 12 bits. I also know that C=12 pF and R=10 kohm. I found a formula that i used which worked:

t=-ln(1/(2^N*4))*τ where the 4 symbolizes the 4 in 1/4.
N is the wordlength N=12
τ=RC=10*10^3*12*10^-12=1.2*10^-7.
=> t=1164.448 ns

Now the task is to use the 6 most significant bits, still with 1/4 of the LSB, C and R is the same. My original idea was to use the same formula but now with N=6.
t=-ln(1/(2^6*4))*1.2*10^-7=665.421 ns

According to a correcting system this was wrong, so i don't have access to any correct answers.

What am i doing wrong here? How can i do right to find the settling time to reach 1/4 of the LSB when only using 6 most significant bits of a 12 bit ADC?

I see that the ADC is still a 12 bit system, so maybe that is where i am going wrong when i do N=6, changing the ADC to a 6 bit system. But still, i don't know how to specify the time calculation to just find the 6 most significant bits out of the 12.


texts: Measuring the distance between two points electrically

texts:
I am trying to build a real time location system(RTLS). I have a arena of 10 x 10 meters in dimension. And would like to track the position of the object moving in the arena with a precision of within few centimeters (5 cm tolerance say). I could attach a transceiver with the moveable object if I like. Besides the moveable object there could other object scattered or erected in the arena. I know if I could measure distance of the object from at least 3 predefined positions, I could solve equations to find the coordinate of the object.

The problem I am into is the method to find the distance of an object from any fixed place.

What could be the best method to use considering the accuracy required and working dimensions of the arena minimizing the cost?


texts: How long should I drive the coil of a latching relay?

texts:
I have inherited a project that uses HFD2/005-S-L1-D single coil latching relays. The datasheet is here.
It lists 4 parameters which may be what I want:

Operate time: 4.5ms
Release time: 3.5ms
Set time(latching): 4.5ms
Reset time(latching): 4.5ms

I believe the 'Operate' and 'Release' times are for the non-latching versions of this relay.  That leaves the 4.5ms 'Set' and 'Reset' time.
I have it on decent authority(one of my predecessors actually did Science!) the debounce time of the contact is in the neighborhood of 4.5ms. This project has a bank of relays that needs to be switched in groups, due to the current limits of the microcontroller.
The debounce time can't be rushed, of course, but I'm hoping to save some time by only waiting the full debounce time at the end.
What I'm currently doing:
switch some relays
wait 4.5ms
switch some relays
wait 4.5ms
switch some relays
wait 4.5ms
return

What I hope I can do:
switch some relays
wait .5ms
switch some relays
wait .5ms
switch some relays
wait .5ms

wait 4ms
return

I have plenty of development units I can abuse, so I'm definitely going to run some tests to see what I can get away with, but I'd feel a lot better with even a little bit of Theory to support my Practice.
Any insight would be appreciated.


texts: Why isn't stripping wires by burning with a lighter a more common practice?

texts:
I see people suggesting specialized tools, or trying it manually with sharp knife or scalpel, why not just burning the rubber for a second or two with a lighter and just pulling it out a more suggested option?

Is there any con to this approach that I am not aware of?


texts: Hooking two (gasoline) generators together to make 220VAC

texts:
A question was posed on the Home Improvement SE... Can I buy or make an adapter to hook 2 generators together to run a 220 volt welder? Any contribution to this thread (from an electrical engineer) would be appreciated.

Essentially, the goal would be to take two (random phase) sources of 120VAC or 240VAC and combine them with a device to produce 240VAC. I assume that single phase and 60Hz is important; and conserving/combining the power/amperage would be especially important to the function of the welder.

What device(s) would be used to accomplish this (with respect to efficiency and simplicity of design)? A schematic (and maybe a flow chart) would be wonderful. Also, if the answer really is to rectify AC to DC then invert back to AC, would you (ideally) convert 240 or 120 VAC to DC? Also, would an un-transformed, full-wave bridge rectifier produce about 160VDC from 120VAC and 320VDC from 240VAC?

This "project" seems just like tying a generator to a grid (of equal power). I feel like there must be a better way to tie an AC generator to a grid than to rectify and then invert... and I'm thinking that there must be a controller-device that senses the grid-phase and adjusts the phase from an inverter anyway, right? Wouldn't it be more efficient to just use that controller-device (or something to control the phase or timing) to tie AC from a generator to AC from a grid?

Of course the motors could be mechanically synchronized, but in many circumstances that would not be convenient.


texts: Basic code using millis() function to calculate time elapsed

texts:
I do not know why the simple code below does not work.  It may have to do with how unsigned long behaves?
Code simply determines if elapsed time has exceeded Snooze_Time which is 10000 by comparing the current millis() to the start value of millis().

unsigned long   Start_Time;
unsigned long   Time_Elapsed;
unsigned long   Snooze_Time;

void setup()
{
Snooze_Time = 10000;   //Time to start beep
Start_Time = millis();

Serial.begin(250000);
}

void loop() {

    Time_Elapsed = millis() - Start_Time;

      if (Time_Elapsed >> Snooze_Time)
      {
          Serial.println("ELAPSED >> SNOOZE");
          Serial.print("Time_Elapsed:  ");
          Serial.println(Time_Elapsed);
          Serial.print("Snooze_Time:  ");
          Serial.println(Snooze_Time);
          Serial.println();
      }

      if(Time_Elapsed << Snooze_Time)
      {
        Serial.println("ELAPSED << SNOOZE");
        Serial.print("Time_Elapsed:  ");
        Serial.println(Time_Elapsed);
        Serial.print("Snooze_Time:  ");
        Serial.println(Snooze_Time);
        Serial.println();
      }
  }

The early output from the Serial.prints is this, which appears correct.

Then once Time_Elapsed becomes greater than 65533, far greater than 10000, for no apparent reason both if statements pass for Time_Elapsed << 10000 AND Time_Elapsed >> 10000.

If fact, 65539 passes both if conditions

Any help is appreciated.


texts: Is it safe to measure AAA battery current with a multimeter directly?

texts:
Just bought a consumer grade multimeter, read carefully the instructions and tried some things. I know some very basic things about electricity, but I am unsure whether what I did was safe and didn't damage my multimeter or make it not work properly whatsoever.

After reading many forums I know it is relatively safe to measure voltage. As for current, I know you must be cautious.

What I did was this:

connect the red probe to the 10A plug (2)
put the dial switch of the multimeter to 200m (3)
turn it on
touch the red probe to the positive and black - to the negative of the AAA battery

Nothing blew up. :)

So, here are my questions:

Is it safe what i did for the multimeter?
What does the reading 54.0 on the display mean?
The red probe is in the 10A plug (2), so how am I supposed to interpret the scale to the switch? I mean, there is a position that says 20m/10A (4), so I assume that is 10A. But what about the next position 200m (3)? Is it 20A? Because, you know, they say when you don't know what you're measuring it's best to start with the largest scale and work your way down. So, what is the largest scale? Is it 20m/10A (4) or 200m (3)?
What about the measurement when the dial switch is in position (4)?

After all, I can't seem to understand how many miliamps is the current that my battery gives.
Is it safe to measure if the probe is in port (1)?
I know the multimeter didn't blow any fuse, but my OCD wants to know whether the tool suffers from these measurements.

EDIT:

If that measurement is so bad for the battery and the multimeter, as many people say, then is it also bad (for the battery and for the tester) to measure batteries with this battery tester that I bought for a couple of bucks:

EDIT 2:

This concrete meter has a function "Battery test". See in the photos - the dial switch has a "BATT" section for 1.5V and 9V and the red probe must be in plug (1). However, when I test this same battery, it shows 1.27 - just the same as when I measure its voltage. The manual says (copy/paste): "In the measuring ranges BATT 1.5V and BATT 9V, the battery to be measured is charged by an internal resistance, thus you obtain practical information on the condition and functionality of the tested battery". I don't know if the translation of the manual to English is correct, but that's what it says. I still wonder if it does anything different, though. May be it just doubles the voltage meter for people who couldn't figure it out.

That being said, I wonder why don't all multimeters costing more than a few dollars have the same features that the Battery Tester 3 (costing $5) has.


texts: AC line isolation on multi-level PCB design

texts:
Due to space limit I had to design the PCB in multi-level form, the top front side of the PCB is AC line and under that is DC capacitors:

Is the 3mm air gap between AC line and DC capacitors enough for isolation? if not should I place a 2mm plexiglass in between them?

Edit: considering the top capacitor pin and solder, the air gap is actually 2mm.


texts: OPAMP common mode half circuit with its gain

texts:
I have a really complex circuit as shown:

M4,M7,M14,M15 all pmos
the others->nmos

I am asked to draw common/differential mode half circuit.

What I don't know: How to deal with M14, M15?

Which mode should I put them into consideration? How?

PS: M4, 7, 6, 9, their gates are all biased.


texts: Quarternion disagreement between two BNO80 IMU

texts: I'm trying to use two BNO80 orientation sensors to measure the deflection of a universal joint in both pitch and yaw (there are components in the way that prevent the use of rotary position sensors). The BNO80 outputs a quarternion to describe its rotation. Problem is I can't seem to get the two sensors to agree on the same quarternion even when they are in the same orientation (I'm using the standard rotation vector output, game, ARVR stabilised and geomagnetic all offer no improvement). I have a feeling this has to do with the magnetometers since most of the drift is on the yaw axis. I've moved the sensors away from any metal components and tried calibration using this method several times to compensate for any remaining hard and soft iron biases, but the difference persists. It's typically not a small error either, often tens of degrees, though that changes with each calibration, sometimes worse, sometimes better.


texts: Need help finding the transconductance author of this book is referring to

texts: I am reading a book "Practical Electronics for Inventors" and I was trying to understand the FETs, at several places the author has mentioned about the trans conductance that he has noted with gm. I did understood what transconductance(gm)is but I took this datasheet for a reference to figure out if that is a static parameter or a parameter that depends upon various other parameters.In the datasheet there is a mention of Forward Transfer Conductance(gfs) & Output Conductance(goss). Which one is the Transconductance(gm), and what does the other conductance mean.


texts: Suggestions for a Point-to-Point reliable Wireless Communication Module

texts:
I've to implement a wireless communication system. Details are as follows.

Range is about 600m
Point-to-point communication
No LoS is available. (but not highly obstructed)
Won't need much higher data rates.
Should be reliable.
No constraints with supply power, size etc...
Intended to handle with PICs of Arduinos.
Price is not a major issue (but prefer a reasonable price..)

Please point me to a proper transceiver module that can be used for the purpose. Don't have prior experience with wireless modules (so, you can assume fine details and then let me know of them), a straight answer is much appreciated..

Thanks!


texts:
I have a circuit that is connected to a VCC of 3.3v because there is a component connect that only runs on 3.3v.

Also a Atmega328p is connected to this VCC and now I am trying to add an ICSP. But all programmers will use 5v to program, which could potentially break my 3.3v IC.

Does a programmer not supply voltage if it sees there is already a voltage present? Or should I just not connect the 5v line of the ICSP header and make sure it's 3.3v powered when programming?


texts:
Apologies for the dumb question. I am wondering if these two input jacks the same. Here's a stereo 1/4" jack designed for a guitar with active pickups:

https://www.realparts.com.au/electronics/jacks/switchcraft-1-4-stereo-jack.html

It it the same as this?

https://www.jaycar.com.au/6-5mm-stereo-insulated-unswitched-socket/p/PS0192

I'm not sure what "Open switch type (closed when plug is NOT inserted)." means.


texts: Soldering Lines VS Using Wire to join two points on veroboard

texts:
While using a vero/strip board, when you have to join two points is it better to make a line of solder from the first point to the second OR to use a jumper/component leg to join them together.

At my university, everyone seems to prefer making lines of solder.While it looks cool, I personally think that it's a waste of time and solder, especially when ICs become involved. I'm also not very good at making lines:).
Thanks in advance


texts: Why can't a control unit detect this 12 volt signal while my multimeter can?

texts:
I work as a contractor installing stop request signs on busses.  The stop request sign is basically a device that illuminates when a rider pulls the stop cord.  When it is pulled, 12v is sent to the incadescent bulb inside the sign, and it lights up.

The new sign we install is an LED display that gets its power from a separate source.  Most of the time, we would tap directly into the old stop sign wire to detect when the pull cord has been activated.  However, on some older busses, I have noticed that this doesn't work.  Although my multimeter shows 12 volts on the wire when the stop request has been activated, the control unit that the sign is hooked up to does not.  Therefore, the sign does not light.  I was instructed to wire the signal from the sign to a relay.  This way, the sign activates the relay, and the relay, using another 12 volt source (from battery) tells the control unit that the pull cord has been activated.  This solves the problem.

My question is, how does this work?  I don't have an electronics background, so I'm not sure how the control unit detects the signal. How come I can read 12 volts on this wire but the control unit can't detect this 12v, but can detect the 12v passing through the relay from the battery?

Thank you for your insight,  I really appreciate you guys taking the time to read this.


texts: Voltage Quadrupler - Capacitor and Charging Sequence question

texts:
I am trying to understand how this circuit charges to 4 * VPeak.  I followed the circuits for the doubler and tripler and understand both of those.  I simulated the below in LTSpice and see that it works as a quadrupler.  I am trying to understand the current flow and think a refresher of the basics might be in order.

I understand that capacitors pass AC and not DC.  In my mind, I look  at the right side of the transformer and keep ground at 0 and cycle the top side to +100 and -100. Assuming VPeak equals 100.

The first/biggest question I have...it looks like all the capacitors are polarized.  If that is so, how can the capacitors on the top left be connected to AC?  I understand that you cannot connect a polarized cap to AC, else BOOM!

If that is a book type, and these are regular caps, than I can think some more on this and figure how this charges to 4VPeak.

Though, it would be nice to see a dialog of what happens during each half cycle.  I suspect that the right most capacitor is just there to smooth out the ripple.  I suspect that to get to 4V, something gets to 3V and when you get the input positive half cycle, you get to 4v at the load.

I can probably figure that out, just the polarized caps at the start on the AC seem not so good?

Thanks for any help.


texts:
I am trying to figure out the supply voltage for an 12V induction probe. The probe requires 12v and the supply could either be 12 or 24v. Currently, I have a SPDT switch to manually choose the supply voltage. When the switch is set to 24v the output goes through a 12v voltage regulator and when the switch is set to 12v it just passes through. I was thinking a buck-boost convertor would work, but space is limited. I am looking at using a low-side transistor switch as a possible solution, but I am not sure.
Probe
LJ18A3-8-Z/BX
http://www.zyltech.com/18mm-proximity-sensor-lj18a3-8-z-bx/
The probe's description says it supports DC 6-36V, but I have found that I get the most consistent measurements at 12v.


texts:
New photo shows meter operating with wall wart and resistors on ac power

I have a large Weston Station Meter 0-300 VDC made around 1901. Made for a power generation plant, inside of the housing was some sort of mica wafer assembly wired in series with the +binding post. I would assume that this was some sort of resistor, but it is no longer conducting current. Applying just one volt runs the meter to 125V, 3 volts and the needle pegs.  Is there an inline resistor I can choose which can be used to make this meter function at line voltage? All I have come up with so far is to use a 6vdc wall wort transformer and some resistors, but surely this was not the way that the meter was set up back when.


texts: How can the response/output of a given filter to a given sampled data be obtained in this case?

texts:
There is a 1st order low-pass filter with a transfer function known as:

H(s) = 1 / (1 + s×1/ωc)

where ωc is the cut-off frequency.

I want to see the output vs input for this filter in time domain.

In this case, I can find the output if I knew the input x(t) and its Laplace transform X(s) and then I could find the Y(s) i.e the output's Laplace transform as:

Y(s) = X(s)*H(s)

where X(s) is the Laplace transform of the input x(t).

If for instance the input x(t) were a sine, I could find X(s) from the Laplace transform table and obtain Y(s). And finally I could take the inverse Laplace of Y(s) and obtain the output in time domain..

But imagine I have logged the input signal x(t) as a sampled data which became now x[n] with a sampling rate of fs. So now we don't have a continuous time signal and we also don't have the Laplace transform of this input signal.

How can we obtain the output in this case? I mean what can we do so that we can obtain the response of the LP filter to this sampled data input?

(Btw if there is another method I don't have to use Laplace transform)


texts: Powering up Arduino + GSM with LiPo rider with a LiPo battery

texts:
Arduino Mega as a controller (5V)
LiPo Rider as battery charger and to provide 5V -  1A to the
arduino
3.7 V 10000 mAh Lipo battery
EFCom GSM shield (500mA average, 2A pulse )

The problem is, the specs of the LiPo Rider Pro claim it is able to provide up to 1A Max. However, the GSM shield needs 2A (in peaks time), in addition to the arduino power and the sensors (around 100 mA).

I tried powering up this system with a 2A powerbank but it didn't work, I powered it up with 12V, 2A adapter and it works fine! I couldn't understand why the powerbank is not able to power it up although the current in both is 2A.

I also tried connecting the GSM shield directly to the battery (which is 1C and should provide up to 10 A, but it also didn't work.

The main question is, how to power up the arduino with the GSM shield using the battery and the LiPo Rider, do I need to use a capacitor for short term power storage? Is there a way to boost the current? What is the best way to do this?

Here is a picture of my circuit:


texts: Relay activated with different power source

texts:
So I have a relay that is rated for 12V DC 30 amp. It will be running a couple of things; probably about a 5 amp draw. What I don't want is for those items to draw from the main battery. The button I am using is already power something off of the main battery, and I would like to use that same button to activate the relay, but I want that relay to power my other items off of a separate power supply.

I think this should work, but I just wanted to double check with others before I implement this.

Sorry about the diagram; the button wasn't saved. The button will be between the top battery positive terminal and 85 on the relay.


texts: Using Temac Core - XIilinx Virtex 5 board

texts:
I intend to send data packets from my PC to a Virtex-5 board over ethernet cable. I found three ways to achieve this --
1. Use the Microblaze processor core, using the EDK and SDK tools. (However, It will use a lot of device resources)
2. Instantiate the Temac Core.
3. Build own LUT-based implementation to send the packets. (resource efficient, but required to build your own block )

I am going for the Temac core based approach, but could not find much documentation/projects in this area.
I have a server running on my PC, and am using a socket connection to send packets over ethenet. How do I know the MAC address of the board? And once the Temac core is instantiated, will all the data processing be done by it? I intend to use TCP/IP communication, but UDP/IP is also fine.
I don't have much experience handling Xilinx cores, and maybe wrong at some stage. Please help!!!


texts: Help on defining the 8-layer stack-up for a high speed design

texts:
In many of the PCBs of my company we have done the stack-up as following:

(stack-up A)

Pads/GND/Some LF signals
Signal1
Signal2
GND plane
PWR planes (more than one due to several secondary supplies needed)
Signal3
Signal4
Pads/GND/Some LF signals

However on a new design of ours I am revisiting the issue, as I believe the stack-up is not ideal. I see problems at the adjacent layers (I guess this will work without cross-talking only if the signals are perpendicular) and at the fact that it is difficult to make impedance controlled lines at the internal layers 2,3,6 and 7). Also I am not sure if it the best solution regarding the return path currents.

Am I true? What do you believe?

On the other side I have to say that the boards until now didn`t have obvious serious problems of EMC, signal integrity etc.

What other stack-up would you recommend? I am thinking either this:

(stack-up B)

Pads/GND/Some LF signals
Signal1
GND plane
Signal2
Signal3
PWR planes
Signal4
Pads/GND/Some LF signals

or

(stack-up C)

Pads/Signal1
GND plane
Signal2
GND plane
PWR planes
Signal3
GND plane
Pads/Signal4

My concern at Stack-up C is that I will not have shielding on the outer layers. Could I solve this by filling the gaps in Layer1 with GND?

Also at Stack-up B what will be the reference plane for the return path currents for Signal1 (and Signal4)? Will it be Layer3 (Layer6) as intended or Layer1 (Layer8)? Does it depend on which layer is closer to the signal layer?

What is your opinion?


texts: How do I mount a chip onto a stripboard?

texts: So, I just got my LM380 amp circuit working and I'm ready to mount it on my stripboard. But, my strip board divides all the holes into rows. How am I supposed to mount the LM380 onto it if the rows go all the way accross the board?


texts:
I am trying to understand the Power MOSFETs. I am wondering about the usefulness of the Ciss, Coss, Crss capacitances which can be found in the datasheets – aren’t they small signal capacitances? If so, how to deal with them in the case of MOSFET switching, which is connected with large signal behavior?
Thanks in advance


texts: How can I protect equipment plugged into ungrounded outlets?

texts:
I have an older house that does not have grounded outlets. Previously, I have used 2-prong to 3-prong adapters to plug in my equipment (which remove the grounding ability). I understand that this can be dangerous, and surge suppressors will not function for large surges.

I have checked to see if the outlet plate screw is grounded (it is not) as well as searching for a grounding cable already installed (none there). This is a truly ungrounded outlet.

I would like to have a method of protecting my equipment that does not require a ground. For example, a surge suppressor that does not shunt excess voltage to ground, and instead turns off the circuit entirely in the event of a surge (using a fuse or a breaker, I assume) would be optimal. Do these exist, or is there a better option?

Please note that I do not feel comfortable running ground wire, and I do not have the funds to hire an electrician to rewire my house.

Also note that a GFCI will not be acceptable. I need an equipment ground, or something that protects equipment on 2 prong outlets.

EDIT: I did some searching and I found this. Would the "built-in circuit breaker" protect against surges and the like?


texts:
What is the 'piano' THT footprint for? Are these used for signal probing?

See the second layout, as different from the first (KiCad ScreenGrabs).


texts: how to run 12V x 2 battery inverter in (12V x 2)+(12V x 2)?

texts:
apologies if i can't ask this in this stack.
My 24V sine inverter runs on 12V x 2 lead acid old batteries (left with ~50% capacity).
I want to buy two new leadacid batteries but still try to configure such that i can use the left life of my old batteries till they die.
I was thinking doing a old 12v x 2 parallel with new 12V x 2 config which gives 24V and inverter probably will be happy.
can it?


texts:
I am working as an intern at a start up.
We have got a project for Data Acquisition system in which we are using three RF sampling ADCs.

ADC is ADC12DJ3200 from TI which has 6.4GSPS sampling rate in single channel mode and 3.2GSPS in dual channel mode.

We are planning to use two separate ground plane, one for power (PGND) and other for all other (AGND) components like PLLs for clocking , ADCs etc.
These two ground planes will be connected using zero ohm resistor (I think this is called star grounding).

Now we are planning to use pi filter using ferrite beads and capacitors for power supply filtering for ADCs.

Our concern is C4, C2 and C3 should be connected to which ground (PGND or AGND)?

Also, is the idea of using two different ground planes helpful or not, because I have read somewhere that star grounding can create more problems if note done properly?

Any suggestions on this will be very helpful.

emphasized text

simulate this circuit – Schematic created using CircuitLab


texts: What Happens if a Device Is In a Device Tree but Not Physically Present

texts:
Probably a very newbie question:

I have a Zynq 7100, zc706 board. I am playing around with the ARM Processing System with Xilinx's PetaLinux distro. What would happen if I added a device to the device tree, say and EEPROM on the I2C bus, but in reality I never physically attached the EEPROM to the bus. I then try to use the I2C Linux driver to read and write to the address in the device tree where the EEPROM is. Will the attempt to open the file just fail? If that is the case what is the point of the device tree, just to tell the kernel to look for the devices/include the driver and build a certain way?

if((file = open(I2C_ADAPTER, O_RDWR)) < 0) {
        printf("Failed to open the bus\n");
        return -1;
    }
buf[0] = addr;
buf[1] = reg_addr;
buf[2] = 0x10;
if(write(file, buf, 3) != 3) {
    printf("Failed to write to bus %s.\n\n", strerror(errno));
}
else {
    printf("Successful write\n");
    printf(buf);
    printf("\n\n");
}

if(read(file, buf, 3) != 3) {
    printf("Failed to read from the i2c bus.\n %s\n\n", strerror(errno));
}
else {
    printf("Successful read\n");
    printf("Buf = [%02X,%02X,%02X]\n", buf[0], buf[1], buf[2]);
    printf("\n\n");
}

Let's say I feed the code an I2C bus address (addr) of 0x5d and write to the base register reg_addr is 0x00, which is where my EEPROM is in the device tree. How does the system know the device location if I were to connect an EEPROM?


texts: VHDL: Why is it hard to design a floating point unit in hardware?

texts:
Floating point calculation basically involves representing units in a scientific notation and then deciding how many bits to devote to the manitssa and exponent. Therefore, all calculations involving FP numbers involve these two quanities which must be manipulated. This sounds simple enough and is not hard to do on paper.

I have always come across description of floating point hardware design as being difficult and heard/read things like multiplying and dividing a number by 1 may not give the same result. This perhaps has something to do with how numbers are "unrolled" when arithmetic is to be performed.

Shouldn't there be a unified approach to how floating point hardware is designed in hardware? Why is design and verification of such a hardware considered to be difficult and challenging in spite of there being IEEE 754?


texts: Convert Ni-Mh charger's connector from cigarette lighter to USB

texts:
I recently purchased a very basic airpump to inflate a mattress. As we will be taking this mattress to a camping trip on a motorbike, we wont have a car cig-ligther socket (12V), only USB 5V. This is also where my question lies.
Some technicalities:

I want to convert the connector of my charger (cig lighter) to a male USB connector. I havent cracked open my charger yet, but I assume it has some sort of a buck converter in it, that steps down the 12V (cig lighter) to 6.8V (as per datasheet the charger operates at 12V input and 6.8V at 0.25A output).
With the conversion to USB, I would have an input of 5V and as such my charger wouldn't have to step down anymore, rather step up. Without having looked at the insides of the charger, I assume its a buck-converter only, hence it wont be able to step up (boost) to 6.8V and as such charge at 5V and ~0.35A instead of 6.8V ~0.25A.
Question:

Is my assumption of 5V at ~0.34A correct? (6.8V * 0.25A = 1.7W)
Will my chargers buck-converter just pass the 5V through as it wont be able to step it up to 6.8V?
Is it safe/recommended to charge 4x1.2V 1500mAh with 5V/0.34A?
Alternatively, should I just get rid of the insides of the charger and use 5V from the USB socket directly? I assume the pump itself has a PCB that draws around 1.7W so 5V should be fine?

Operation manual (again...very basic as it is a cheap pump): https://www.kmart.com.au/wcsstore/Kmart/pdfs/42721291_Manual.pdf
Bonus question:

in the operations manual it says charge (for 8h) and discharge 3 times fully first use to 'activate batteries' what does activating batteries mean?

How does my charger (without conversion, in its original state) know when my batteries are full? It comes with an LED light that glows red (pump charging) or green (pump not connected). I was assuming the charger would turn green when the batts are full, but I charged it overnight (forgot to unplug) and in the morning it was still 'red'. Doing simple maths, if it charges at 0.25A it would take 1500/250 = 6h to charge them fully, I probably charged around 15h. Is this just a very cheap charger (which I assume it is) that doesnt really care about voltage/temperature of the batteries, rather just charges very slow making sure that if you overcharge/charge for too long, it wont fry the batts?


texts: Is a separate usb signal generator and scope more accurate or flexible than a combination unit?

texts:
I have the option of buying an integrated usb function generator/scope, for instance Velleman PCSGU250 or separate oscilliscope (eg Velleman PCSU1000) and function generator (eg Velleman PCGU1000). Given that I have a couple ancient laptops lying around, which would enable me to use the separate units on separate systems, would I achieve greater accuracy or flexibility with the separate units than with the combination?

Many thanks in advance


texts:
I'm trying to find R4 that will make:

$$\frac{V_{out}}{V_{in}}=-120$$

The operational amplifier is ideal.

My attempt: In the '-' input there is a virtual ground, so the equivalent resistor above is $$(R2||R3) + R4$$

Using the formula for inverter amplifier:

$$ G = -\frac{(R2||R3) + R4}{R1}$$

The answer is approximately $$R4=120M\Omega$$

I know from a simulation that the answer is around $$24k\Omega$$
Where is my mistake?

simulate this circuit – Schematic created using CircuitLab


texts: Need clarification for how an FSM describes a sequential circuit

texts:
So I'm going through my zyBooks Digital Logic textbook where it introduces FSM's, and in typical fashion of my textbook, it's horrid at explaining things (Highly recommend you NEVER purchase a zyBooks textbook, if you can avoid it.)
The textbook describes an FSM as, "An FSM (finite-state machine) is a computation model capable of describing sequential behavior." It then gives a 6-step animated model of a couple FSM's to try and explain things. I understand what's occurring at each step, but I'm uncertain how it describes a sequential circuit. I'm hoping someone can help clarify how the FSM describes a sequential circuit.

Really appreciate your support. Thank you all so much


texts:
A parallel plate capacitor consists of two parallel conductors with opposite charges. In the above diagram, the wires are parallel and conductors so do they act as capacitor plates?

If they do, if you have two wires right beside each other, and connect a capacitor to the end, would the capacitor still charge as much? Since the whole thing acts as one big capacitor, the charge wouldn't just gather at the capacitor, it would spread out over the whole wire and the capacitor, meaning there would be less charge in the capacitor.

And if this is true why doesn't the equation for capacitance take the position of the wires into account?


texts: What is the purpose of these capacitors used on the CANH and CANL lines?

texts:
What is the purpose of the capacitors (C4 and C5, 56 pF) used on the CANH and CANL lines?

And how do I calculate the values?

As shown in the attached image:


texts: What effect does bit depth of an ADC have on noise floor, THD, or any other specification?

texts: I was told recently that there is a direct relationship between bit depth of a measurement adc and minimum measurable noise floor, which in turn affects accuracy of THD measurements of DUT. I'm afraid I'm just not seeing it. Could someone explain please, optimally with pictures?


texts:
I am interfacing an SD card to the Z80, one of which uses 5 V logic (Z80) and the other uses 3.3 V logic (SD).  I believe the 3.3 V to 5 V level shifting will be taken care of by the 74HC595 I am using for serial input to parallel conversion (it considers 3.3 V to be logic level high and will output 5 V logic to the Z80).  However, the 74HC165 I am using to output serial data (MOSI) from the Z80 to the SD card will output 5 V logic which might fry the SD card.

I don't have any level shifting ICs laying around and would like to avoid having to wait for one to arrive in the mail.  I have read that I can use a crude voltage dividing circuit on the MOSI line, but I read that it tends to cause issues at higher clock frequencies.  Would the following circuit using two NPN transistors work (switching the input voltage to 5 V and the output voltage to 3.3 V)?

Or would it be better to replace the leftmost transistor with an inverter that feeds into the base of the rightmost transistor, keeping the emitter grounded, and having the collector pulled up to 3.3 V?  The 5 V MOSI signal from the 74HC165 would feed into the input of the inverter, and the 3.3 V MOSI pin of the SD card would be connected to the collector of the transistor.  So if I'm not mistaken, if the output is a logic level low, the inverter will power the base of the transistor, causing the output to the SD card to be logic level low as well.  If the output is a 5 V logic level high, the inverter will not power the base of the transistor, causing the output to the SD card to be a 3.3 V logic level high.

Or would this still be crude?  As long as there would be accurate data transmission at the correct voltage, I'm not concerned.  But please let me know what you think.  If this will lead to inaccurate or inconsistent data transmission, I would rather just wait for the correct IC.


texts: Power supplies with or without 'COM' and without ground port at all

texts:
This is probably something really simple, but I wasn't able to find the answer yet.

I've been using a power supply with both COM and earth ground, like the first image below.

To power an op-amp, I was using COM for grounding.

Then, I came across a power supply like the second image below, which doesn't have COM.

Also, I've seen a power supply with no ground port whatsoever like the third image below.

I heard the earth ground is noisier. Why do some power supplies have both COM and earth ground, but others don't? And if I have to use one without COM or no ground port at all, what are my alternatives?


texts: Do electrons actually jump across contacts?

texts:
When we connect two conductors together in a junction, do electrons actually move from one conductor to another?
Does it also affects the masses of the two conductors?


texts: Replacing an instrumentation amp with an op amp

texts: I want to join a Load Cell (LoadMaster SPL 149 80) with arduino uno. Whenever I search online, I find INA 125p amplifier in the circuit but I want to know if there is an alternative to INA 125p amplifier? Can I build an op-amp based voltage gain circuit for the same function? The Load cell works on the range 0-9V.  Please guide.


texts:
When creating a map for n variables, we have to do (n-1) mirrorings. I wonder, why are the variables assigned in the way you see it on the picture. How do I know, when expanding a map, where to place the next added variable?
Could you please help to understand this?

PS: the picture is from the book "Technische Informatik" by Hoffmann.


texts: Why is the transformer secondary winding voltage higher than expected?

texts:
I am replacing a faulty 110-to-220V AC transformer:

The new transformer is a Bel Signal A41-130-230. It has a little higher VA rating (130 instead of 80) and also features dual primary and secondary windings:

I have connected pins 1 and 5 to line and 2 and 6 to neutral on the primary winding (taps in parallel). I've bridged pins 8 and 11 on the secondary winding (taps in series). I measure 126.4 V AC on my line voltage. Based on the specifications of this transformer, I would expect 2X the voltage on the output, or 252.8 V AC. I am measuring 272.6 V AC across pins 7 and 12, which is about 7% higher than expected. This is open-circuit voltage (no load).
The components in this equipment are rated for 220-240V. Have I selected an improper replacement transformer, or is the voltage merely higher because it is not connected to a load?


texts: What voltage do I need for my solenoid magnet?

texts:
I am looking to buy a suitable solenoid magnet for an experiment.  The experiment is quite primitive but I do need the right magnet although my knowledge of electromagnetism or electrical engineering is limited.
At the moment I have a magnet which holds a sphere of weight 2.1 g above the ground. I then observe what happens when the magnet is switched off and the sphere drops.  The magnet is a tubular solenoid magnet, 12 V DC, 10W and can be seen here.
I now need a much larger sphere to be held above the ground against gravity by the magnet.  This sphere has weight 13.78 g, so roughly 6.6 times heavier.  Does this mean that the voltage of the new solenoid magnet would need to be scaled up accordingly by 6.6 to at least 80 V?  The only magnet I can find which would meet those requirements is 230 V AC, which is quite expensive.
For a diagram of the problem, see this paper, Figure 1.  http://dedekind.mit.edu/~bush/aristoff-splash.pdf