texts: Cell matching by capacity and resistance

texts:
When matching li-ion cells in a battery pack how do you use both the cell's resistance AND capacity?
I've seen sources mentioning that each parallel group should have about the same capacity, and that cell internal resistances should be "close".
How do we match based on both criteria?
Say I want to build a 3S2P pack with the following li-ion cells (made up values):

A: 2800mAh 50mΩ
B: 2950mAh 80mΩ
C: 2950mAh 100mΩ
D: 3000mAh 90mΩ
E: 3050mAh 70mΩ
F: 3150mAh 20mΩ

Method 1, capacity matching:

Combination
Capacity(mAh)
Equivalent resistance (mΩ)

a+f
5950
14

b+e
6000
37

c+d
5950
47

Method 2, resistance matching:

Combination
Capacity(mAh)
Equivalent resistance (mΩ)

a+d
5800
32

b+e
6000
37

c+f
6100
17

What is the correct way to balance a pack considering both cell values, and how would you match the example cells?


texts: Compatibility and Interoperability Between CAN Standards

texts:
I'm intended to design a CAN system for a automotive scan tool. So, I need to comprise the main CAN standars used nowadays. Searching on the web I found the following options:

ISO 11519-2:1994 – Low-speed CAN transceiver
SAE J2411:2000 – Single-wire CAN transceiver
ISO 11898-2:2003 – High-speed CAN transceiver
ISO 11898-1:2015 - CAN FD transceiver

I know that CAN FD is backward compatible with CAN 2.0, but the phisycal layer of CAN Low-Speed is not, so I need a separeted transceiver to it. My doubt is about Single Wire CAN(SW CAN), Can I use one of the lines of standard ISO 11898-2 (CANH for example) to communicate on a Single Wire CAN bus ?

In the following figure I summarized the idea and the doubt.

So, I would like to know, can I use a regular transceiver (Differential CAN lines), but using just one line, to communicate in a Single Wire bus or is mandatory to have a Single Wire CAN transceiver ?

There is similar question, without answer, that were made in the following post:

Interoperability between regular and single-wire CAN bus


texts: Why isn't current through D2 0 in LTSPICE?

texts:
The current through d2 should b zero as it is reverse biased. Why dosen't ltspice software
show zero current?

-
If I am doing somethin wrong then kindly make correction and tell me what to do to get zero current in both D1 and D2?


texts: Is there a good book that explains the features of electronics with math?

texts:
With differentiation equation, I mean.

I've seen many books which explains it with quality analysis,but now I'm seeking of a book that can explain it with quantity analysis,which means a lot of math.


texts: How to convert R,G,B,W signal to 1 wire in LED strips

texts:
I found this RGBW controller which I really like aesthetically , the only problem is that this only works for LED strips that are 12V with separate R, G, B, W, data lines and the strips I have are the WS2812B which only have 1 data line and are 5V.
The solution I came up with is to place a microcontroller say an ESP with WiFi or an Arduino with WiFi which opens up me controlling the strips via WiFi at the same time with that wall mounted controller.
I already understood how WS2812B strips work with the help of this question. Not to mention the vast libraries available for the chip. My only problem now I don't know what kind of signal/protocol the R,G,B,W data lines are spitting out.

Are they analog / digital?
Where can I read more on it? I'm having a hard time finding the datasheets (probably just my bad googling skills.)


texts: Will this DC UPS with off the shelf components for home network and laptop work?

texts:
I am trying to build a DC UPS to power modem, router which have power requirements of 12V 2A and a laptop which has power requirement of a 20V 3.5A.
I am planning to use a AC to DC SMPS which is capable of 24V 20A which is connected to a solar charge controller via step down (buck) converter (21V ~20A).
A 12V 46AH SLA Battery is connected to the output marked for battery in the charge controller which means it takes care of trickle current and float current to charge the battery.
A modem, router is connected directly to the output marked for connecting DC load in the charge controller. Output is 12V and max 30A current.
In parallel to the modem and router a step up/boost converter is connected to the charge controller. It steps up the voltage to 20V to meet the requirements of a Laptop. Max current for the laptop is 3.5A.
I am more of a software developer than a electrical engineer. I have come up with this design using off the shelf components with the knowledge available to me by means of other DIY DC UPS in Youtube.
I would like to know if this would work? If any flaws in the design or any heating problems that I should anticipate.
edit:
Updated diagram:

Old diagram:

Off the shelf parts listed below
Battery Charger 20A: https://www.amazon.in/gp/product/B07SSS5CKZ/ref=ox_sc_act_title_3?smid=A2VYJQQSTF1WW0&psc=1
Buck Converter 20A: https://www.amazon.in/gp/product/B0837TPK4S/ref=ox_sc_act_title_1?smid=AJT2XDFHXWA1M&psc=1
SMPS 24V 20A: https://www.amazon.in/gp/product/B07LCW6VLS/ref=ox_sc_act_title_2?smid=A1LNY5B2YFX2LR&psc=1
Solar Charge Control: https://www.amazon.in/gp/product/B07TDWVCBW/ref=ox_sc_act_title_4?smid=A2UUB15FGE4DQW&psc=1
Exide 12v 42AH https://www.amazon.in/gp/product/B014H8GDY2/ref=ox_sc_act_title_7?smid=ADKPHPW19MNT3&psc=1
Step up 12V->20V 3.5A https://www.amazon.in/Converter-12V-32V-12V-35V-Adjustable-Voltage/dp/B06ZY7X1X6/ref=sr_1_8?dchild=1&keywords=boost+converter+12v+to+48v+10A&qid=1598674951&sr=8-8


texts: How do I correct this SystemVerilog syntax error?

texts:
I am working to reuse some Arduino code on my Cyclone V GX FPGA using a compiler I have found on GitHub.
https://github.com/dimag0g/nios_duino
However, once I generated the SystemVerilog HDL, I always encounter this syntax error when compiling:

Error (10170): Verilog HDL syntax error at nios_duino_inst.sv(1) near text: "(";  expecting ";". Check for and fix any syntax errors that appear immediately before or at the specified keyword.

The Intel FPGA Knowledge Database contains many articles with specific details on how to resolve this error. Visit the Knowledge Database and search for this specific error message number.
Is there any way I can eliminate this error? I have already tried to move the terminating semicolon to other locations and checked for any missing or additional commas or parenthesis.
For reference, here is the other SV file I am working with, the previous file instantiates this one.


texts: Do switches induce voltage spikes in the AC power grid?

texts:
I know that DC inductive loads create back EMF when turned off and that's why we use a freewheeling diode.
Does this also true for AC inductive loads and AC loads in general?
I know we can't use a diode though.
I've noticed when I turn on and off switches around the house, it affects sensitive electronics.
Is there any solution?


texts: Why Gerber Viewers are slow to display, zoom, and pan?

texts:
My machine has quad core i7 and should have enough ram. I tried different free Gerber viewers. They are slow to zoom or pan. There is always this "lag" feeling.

Does the gerber format contain too much data?
What do you use for Gerber viewing?


texts: How to understanding min/max input values of Schmitt Trigger from datasheet

texts:
I am having some difficultly understanding the values described in this product sheet for the SN74AHCT14 Schmitt Trigger Inverter:

http://www.ti.com/lit/ds/symlink/sn74ahct14.pdf

Given a Vcc of 4.5V, I would like to know the following:

What is the lowest input voltage that would cause the trigger output to switch from low to high output?
What is the highest input voltage that would cause the trigger output to switch from high to low output?

And where can I find this in the product sheet?


texts:
I've just hidden away our entertainment centre electronics including our Infrared controlled DVD Player, Amp and Mac Mini .

I was wondering if there is any IR Remote code for Arduino, that I can use to eventually control the entertainment centre. I plan to write a simple iPhone app, that talks to an Arduino with an Ethernet shield.


texts: I have this light dimmer circuit, when I plug it into the AC, the dimmer works fine but I noticed that the heat in potentiometer is increasing, is there any workaround to fix this problem?


texts:
can you explain me in simple words how does a linear feedback shift register work for generating a code?

Consider for instance this scheme:

If I have understood it correctly, each block is a D Flip Flop whose output bit becomes equal to its input bit after a clock cycle.

So, let's suppose the first sequence of bit equal to 1011

How do we decide this sequence? It is the random sequence which is generated when flip flops are activated?.

At the input of M1 there is 1 + 1 + 1 = 1 (in binary arithmetic). So at the next clock cycle we will have: 1101. At the input of M1 there is 1 + 0 + 1 = 0. So at the next clock cycle we will have 0110 etc.

Which is the number of coded bits we see at the output?
Does it generate a periodic sequence? If yes, how?


texts: ATTINY85 and NRF24L01+ only works with longer vcc/gnd lines on PCB

texts:
So I've been banging my head for a couple weeks on this, but I need some help. I'm trying to build something small and battery powered. I have a handful of ATTiny85's and NRF24L01+'s.

I have breadboarded it using the 3-pin method described on Instructables and it works (I have a Pi set up to simply listen and print out the message and is how I monitor the success of the radio). My next goal is/was to start building out a PCB, then case, etc.

The boards turn out pretty decently (I'm just using single-sided for now) and I've added a 2x4 header for it to plug into on the PCB. But I cannot get the board to work for the life of me plugged into that header.

I have etched about 10 different boards in different configurations, some with ground planes copper fill, some without, decoupling capacitors, ....

This is my latest iteration:

Please note the decoupling caps on the ATTiny85 as well as the 2 (electrolytic and ceramic) on the NRF24L01+.

I found if I add at least 16mm of wire on both the VCC and GND pins to the NRF24L01+ it works... But if I use the shorter (11mm) jumpers on those 2 lines, it doesn't work. I've tried multiple cables/wires/etc, however I get the same voltage when checking the header pins on the NRF24L01+ as I do on the board (3.017vdc). All the other communication lines work fine.

I have a 10 pack from Amazon and plugged various ones into other boards and they all work as expected; I just cannot for the life of me get it to work in a small form package without pulling it away from the board.

I found if I physically place the module where the headers are (with the longer wires attached) it still works. I've even face-planted the antenna and face of the NRF24L01+ into the tiny IC, batteries, and it still fires away.

A few suggestions on other forums/boards have recommended putting the NRF24L01+ away from the board or turning it perpendicular (I tried this and it made no difference). I have seen other people successfully stack these boards on mySensors, here, with an Arduinos, Pis, and Nanos (oh my). So it has to be possible to be on a minimal PCB...

There must be something I'm missing (hopefully something stupid and small); any suggestions would be greatly appreciated.

PCB iterations:

Ground plane Copper fill
no ground plane copper fill
all lines traced to other side (not under board)
jumpers
perf board

TL;DR:

NRF24L01+ transmits only when I use a longer lead for GND and VCC off the PCB.

I used a ground plane copper fill on this one...

Code:

#define CE_PIN 3
#define CSN_PIN 3 //Since we are using 3 pin configuration we will use same pin for both CE and CSN

#include "RF24.h" // https://tmrh20.github.io/RF24/

RF24 radio(CE_PIN, CSN_PIN);

void setup() {
  radio.begin();

  radio.setPALevel(RF24_PA_MAX);
  radio.setDataRate(RF24_1MBPS);
  radio.setChannel(0x76);
  radio.openWritingPipe(0xF0F0F0F0E1);

  delay(1000);

  const char text[] = "Starting up!!!!!!!!!!!!!!!!!!!!";
  radio.write(&text, sizeof(text));
}

void loop(void){
  const char text[] = "Hello World Hello World. 123456";
  radio.write(&text, sizeof(text));

  delay(1000);
}


texts: What is the practical difference between watts and VA (volt-amps)?

texts: I have seen one inverter rated at 300W, and another at 300VA. What is the practical difference between them, if any?


texts: What are the difference between a P(Protection) Conductor and an E(Earthing) conductor.They combined make a PE conductor(Protective Earthing), but what are the difference between them separate?


texts:
I've just opened the top of my XPA-2 amplifier and had a huge surprise: it seems like almost ALL of the caps are leaking from the bottom. Not just the main PSU caps, but smaller ones on PSU PCB and also on amp PCBs look suspicious. It seems like smaller caps are glued to the pcb, like a kind of silicone or rubber to the touch, although it is really just a thin layer. I really can't say if that is glue or leaked electrolyte.

Just a few of the mian PSU caps are a bit bulged on top, but no other that I can see without dismounting the whole thing. I really can't see how they are seated, since I have no view of their bottom.

Even jumpers seem "rusted"!!! Funny thing is, the 2 "rusted" jumpers are on each of the 2 amp PCBs and are in perfect symmetry to each other. Thought maybe originally they had some kind of insulation and got damaged during assembly, but it is unlikely.

This unit has never been exposed to any kind of excessive heat. It has been, however, under my receiver for about one yr, but there is over an inch between them, and amp case or top was never hot.

This amp powers a pair of Philharmonic 3's and sound is absolutely perfect. No difference or complain at all, high or low volume.

I bought this unit precisely 3 yrs ago, so it is still under warranty. However, I am far from USA right now, and shipping a package this size would cost a loooooot of money.

I work with electronics and I have never seen all caps bad like this, except during cap plague, which I believe is finished and on equipment exposed to excessive heat. What do you think, have you seen something like this before?

Do you agree they have leaked?? Could some of that be actually glue?

I want to hear your opinion before getting to Emotiva.

http://s24.postimg.org/9oqvo3olx/IMG_1446.jpg
http://s24.postimg.org/hk1f2wy8l/IMG_1447.jpg
http://s24.postimg.org/3zan3sifp/IMG_1448.jpg
http://s24.postimg.org/fn4oyc7kl/IMG_1449.jpg
http://s24.postimg.org/6be1nn5n9/IMG_1450.jpg
http://s24.postimg.org/ibzhodd1x/IMG_1452.jpg
http://s24.postimg.org/w4ihxqt79/IMG_1453.jpg
http://s24.postimg.org/vvkx7tget/IMG_1454.jpg
http://s24.postimg.org/51pf02qmt/IMG_1455.jpg
http://s24.postimg.org/uzt163w45/IMG_1457.jpg
http://s24.postimg.org/d4nlbeb85/IMG_1459.jpg
http://s24.postimg.org/ps7y1nfit/IMG_1460.jpg
http://s24.postimg.org/5wgjzunv9/IMG_1461.jpg
http://s24.postimg.org/4rmhuh1ed/IMG_1462.jpg
http://s24.postimg.org/4iox4jolx/IMG_1463.jpg
http://s24.postimg.org/x9h5gv51x/IMG_1464.jpg
http://s24.postimg.org/bzy4jre51/IMG_1465.jpg
http://s24.postimg.org/zfg1p3xw5/IMG_1466.jpg
http://s24.postimg.org/b0cf1sod1/IMG_1467.jpg
http://s24.postimg.org/u7zjye6ol/IMG_1468.jpg
http://s24.postimg.org/6jk234a51/IMG_1469.jpg
http://s24.postimg.org/dvpi8nsd1/IMG_1470.jpg

*Sorry, can't get those images to work!!


texts:
Is it possible to parallel two power transformers of different step down ratios? The transformers have the same MVA rating, but a different impedance. If done, what will be the circulating current?

RATINGS ARE :

TRANSFORMER 1:

16/20 MVA
33 kV / 6.6 kV
DYn11 = 8 % / 10 %

TRANSFORMER 2:

16/20 MVA
11 kV / 6.6 kV
YnD11 = 5.66 % / 7.07 %


texts: How are high voltage power lines earthed?

texts:
Most high voltage power lines run on a delta configuration with three phases and no neutral. Now if there isn’t any neutral (due to the nature of it being a delta system) then how can the power line be effectively earthed?
In other words, as far as I know, if you measure line to earth voltage you will find exactly the line voltage (as if earth is 0v), or do you?
When searching for earthed delta configurations I have found two ways, one called “centre tap” and the other one “two-leg tap” which are illustrated below:

Are any of these methods employed in high voltage lines? If so, that won’t guarantee that that you’ll get the line to earth voltage equal to that of the line voltage on all phases.
The question is then, how exactly are high voltage (delta) lines earthed?


texts: how to configure RN xv 171 module for UART communication?

texts: Heyy, I am using the RN xv 171 module along with stm32f4 discovery board. I wish to communicate with the module over uart from the board. However, the module is either mute or echoing the messages sent over UART. I have done the configuration to be done in the ad-hoc mode, as given in the user manual. I would like to know if any other configuration changes are required? Thanks in advance.


texts: Determining the beam frequency & EM-component that is emitted from the human eye (supposedly)

texts:
I am interested of determining how much truth there is in a persons claims that our eyes emit a beam that can be detected by a device that he has built and patented.

The person who invented the device is Colin A Ross (MD), a doctor specialized in trauma and its treatments.

In a nutshell the doctor says that the feeling that we sometimes get, when someone is looking at us, comes from the fact that our brain emits an EM field through the eyes.

The patent for the device that he has built has the patent number US 7806527 B2. A document describing the patent can be found here:
http://www.rossenergysystems.com/Downloads/Patent_7806527-Electromagnetic-Beam-Detection-System.pdf

A demonstration of the device is shown in the video at the bottom of this article:
http://blogs.dallasobserver.com/unfairpark/2008/08/colin_ross_has_an_eyebeam_of_e.php

The question I wanted to ask is: is it possible to determine from the patent what frequency the beam is and what EM-component the device reacts to?

For example, whether the beam detector reacts to the magnetic component or the electric component?

But the purported frequency is more of interest.

Best regards,

JJ

Edit: thank you all who have responded so far. I agree with stevenh on the fishyness of the demonstration video and the confirmation bias that likely is the reason for the belief in the eye beam (we may in fact often feel that we are being looked at even when nobody is around us, but some people may forget these occurences).

Thank you "Fake Name" for your interesting clarification on this issue.


texts: ESD ratings of diodes and bipolar transistors

texts:
While it's easy to find ESD ratings for ICs (bipolar, CMOS, and any mix) and to some extent for MOS transistors (for the inherent reasons), I don't find ESD rating for many common diodes (left apart TVS and Zener devices, given their use).

Let's say I'm looking for ESD rating of an S1J or S1M diode: no manufacturer seems to detail it. Is it because being massive, high-voltage parts (operating up to 1kV DC) they already are over an "interesting" value?

Again, if I look for the same rating of a BAS21 part, just a 250V diode, I can't find it from common suppliers.

Even going down to an humble BC847 bipolar NPN, no details on ESD rating, looking in a few data sheets.

If any of these parts is handled wrong, or connected to the outside port of a device, could easily come in contact with dangerous voltages.
I'd like to know more on these ratings and why they aren't listed.


texts:
I work on a DALI lighting system for home usage and I design all DALI devices from scratch. In this system, also a sensor module will be implemented. Since it will draw only a negligible current (app. 4 mA), I thought it would be convenient to use DALI interface itself to power this device. Commercial products usually offer this feature, but I couldn't find any details on how exactly does it work.

Just to clarify, DALI logic levels are 9.5 - 22.5 V for HIGH level and -4.5 - 4.5 V for LOW level.

So what I need is some basic idea or schematic of circuit I can use to turn DALI interface into some sort of power supply.


texts: PCB,DIY USB Mobile Phone Charger. Shield to GND?

texts:
Little project using a step down converter that steps down 13v from a car battery to 5v 3A. I have added Decoupling capacitors and so on to the 5v line for filtering(Probably gone overkill) but im wondering if i should  connect the USB Shield to ground directly or connect it using a ferrite bead from Shield to ground?.Or maybe shield to gnd using resistor ?or does not even matter ?

Also as this is only a charger and not doing any data do i need to add ESD Suppressors ESD Protection ?  (USBLC6-2 TVS )

mouser.com/ProductDetail/STMicroelectronics/USBLC6-2SC6/?qs=po45yt2pPpu%2FhNIlwQdTlg%3D%3D


texts: Padding/impedance matching of a phono input

texts:
My old stereo amp got coffee spilled on it.  I replaced it with the latest model from the same manufacturer.

I am an old-world person, and prefer simple approaches - i.e., radio buttons to select from multiple RCA inputs.  My whole system is built around that.  The problem is the new amp doesn't have 3 RCA inputs: it has two RCA line-ins, plus a phono input.  The phono is, of course, low level and equalized to offset the treble-heavy output of the phono cartridge.

I would like to use the phono input for another of line-in since it, too, has an unbalanced RCA jack input.

Most of my experience is with professional audio where 0 dBm is fixed as the nominal level; the line is balanced; and there is no odd EQ at work.  In that case, matching the high-level source to the low-level input could be cleaned up with an H-pad of resistors alone.

I can hack something out, but does anyone know of a stylized/standard approach to using the low-level and equalized RCA phono input so it can (for example) be used as an input for unbalanced line-level sources?  This looks to me like it would be a T-pad with a capacitor or two to get the equalization right in addition to reducing the input level?


texts: ic to drive either one pwm signal or another

texts:
I have an existing RC circuit for a toy truck. Obviously it already has its own mC to receive the antenna signal and output a PWM signal to a motor driver IC.

I want to be able to ALSO control this motor driver IC from an ESP8266 but I would like to do so in a non-invasive/non-permanent manner, ie I would want to be able to simply remove my ESP8266 at some time and the RC truck will still be functional as if it was stock.

I would like to only introduce/add an IC that would allow me to choose between which PWM signal to use to drive the motor driver IC.

I would like that if the ESP8266 is not present it use the existing mC PWM signal, ie use the existing mC signal by default and if the ESP8266 is present I can choose from the ESP8266 which PWM signal to send to the motor driver IC.

thanks in advance for your help!

simulate this circuit – Schematic created using CircuitLab


texts: Error with reference to scalar wire 'reset' is not a legal reg or variable lvalue

texts:
I'm getting an error in Verilog with an input parameter it's not recognized as a legal reg or a variable lvalue. I had the same problem with the output in the module however it was fixed by labeling it as a reg. It's the only error in my code and it occurs only at the input reset variable in the always block.

module lasersystem(input clk, input reset, output reg click
     );

reg [1:0] next_state = 2'b00;
localparam off = 2'b00, start = 2'b01, on = 2'b10;
reg [32:0] counter;

always @ (clk)
begin
case (next_state)

off: if (clk == 0) begin
        next_state = off;
        reset = 1;
        counter = 32'd0;
        click = 0;
        end

      else if (clk == 1) begin
        next_state = start;
        reset = 1;
        counter = 32'd0;
        click = 0;
        end

start: if (clk == 1) begin
          reset = 0;
          click = 0;
          counter = 32'd0;
          next_state = on;
        end

         else begin
          next_state = on;
          reset = 0;
          counter = 32'd0;
          click = 0;
         end

on: if (clk == 1) begin
        reset = 0;
        click = 1;
        if (counter == 32'd249999999) begin
            next_state = off;
        end
        else if (counter != 32'd249999999)
            next_state = on;
    end

default: next_state = off;
endcase
end

always @ (posedge clk) begin
case (reset)
    1: if (next_state == off) while (counter > 32'd0 && counter <     32'd250000000) counter = counter - 32'd1;

    0: if (next_state == on) while (counter > 32'd0 && counter < 32'd250000000) counter = counter + 32'd1;

default: counter = 32'd0;
endcase
end
endmodule

Why does this happen?


texts: Does this exist: instrument that measures voltage at many points on a pcb?

texts: I'm imagining an instrument that has many very sharp and fine needles. Sharp enough to pierce soldermask and fine enough not create any shorts. You then lower this device onto your board and it measures the voltage at each needle point and displays it on the computer with a cool graphic.


texts: 8 bit addressable latch at 3.3V with open drain output

texts:
I need to drive 40 leds from a 5V power source. These leds are controlled from a raspberry and I was thinking to use 5 TPIC6B259 but I need a logic level shifting from 3.3 to 5 V for the input of TPIC6B259. I was looking a 3.3V device similar to the TPIC6B259 but I didn't find anything: only addressable latch without power mos (ex 74HC259). Adding 40 power mos is not convenient. Is it possible that the TPIC6B259 is the only addressable latch with power output?
Can you please suggest me other solutions?
Since the 3.3 power is sourced from raspberry I need a low power addressable latch followed by an open drain mosfet to drive (at 5V) the loads.

Thanks
Fabio


texts: Trying to reverse engineer a simple circuit

texts:
My only experience with electronics is a bit of playing around with an Arduino starter's kit, but nevertheless I decided to buy a cheap little remote control car and figure out how it works and see if I can connect the antenna to my Arduino and make it do stuff... but that turned out to be harder than I expected.
There's one wire connected to the antenna, then this circuit connects to the two motors, but I've been unable to figure out how the actual circuit works. I thought maybe I would learn something by connecting a wire from the antenna to my Arduino and reading the analog values, but they were all over the place so either I did that wrong or it's the wrong thing to do.
So basically, I'd appreciate any tips or hints on how I can figure out how the antenna works and how to use that.
Here's a picture of both sides of the board.


texts:
I am going to build the inductor in the figure above.  I have a ferrite core with a relative permeability of about 70.  Based on ARRL formulas, I have plenty of core length to separate the two coils along the length of the core.

Should the coils be such that the shorter, 23 uH, coil is wrapped on top of the longer, 470 uH, coil, or should they both be wound on the core itself separately, given that they should be magnetically coupled?

In connecting the coils at the point where C1 joins them I take it that the coils should be wound in the same direction on the core, and if wound from left to right (regardless of being on top of one another or not) that the right most end of L1 Primary should be connected to the left most end of L1 Secondary, based on the dotted terminals in the figure.

This is for a radio project wherein this inductor is part of a tuned circuit to receive in the AM band.  Given that I am not sure about the relative permeability of the core (it was purchased from an eBay supplier who gave a Russian figure of the relative permeability of M400NN for which I have not found a translation) I will measure the resulting inductance with the aid of a 50 ohm signal generator and a scope.

Thanks in advance for any answers and advice.


texts: What's a good way to reduce the output from a 9V battery to the 1.8V to 5V required by an ATmega328 controller? The context is a small robotics platform with low power requirements (very slow movement).


texts:
I want to connect an AD7626 with a Zynq FPGA or a Kintex.  Which bank should I choose?
Let say the for case

Chosen Zynq FPGA has only HR bank
Kintex has HR and HP bank.

How should I choose a bank for both of these cases? What are the things one should look at in the ADC datasheet when an FPGA needs to be connected? How should one choose an FPGA bank in this case? Does this depend on the supply voltage for the ADC?
From different forums I understood I should check if the DC characteristics of the LVDS input and output of the ADC are within the range specified in the FPGA datasheet, but could not find how to choose a bank.
##Details of ADC are as follows##

Differential Output Voltage, VOD 245 to 454mV
Common-Mode Output Voltage, VOCM 9802 to 1375mV
Differential Input Voltage, VID 100 to 650 mV
Common-Mode Input Voltage, VICM 800 to 1575 mV


texts: Odd millivolt readings on UT61E multimeter

texts:
I've just bought a Uni-T UT61E multimeter. The purpose of the purchase was to measure voltage in the uV-mV area.

When I start the multimeter (without even attaching the probes) it outputs random readings (see attached photos).

Is my multimeter broken or is there something I've missed (like configuring it?)


texts: Mosfet: gate voltage 0 but still led strip on

texts:
LED strip: DC, 4W

Mosfet: IRF740 (datasheet)

To Do: Use wall socket (AC) to run DC led strip and also turn it on/off with MOSFET and arduino.

AC to DC is done with rectifier and transformer. So this part is excluded from the diagram.

Circuit Diagram

simulate this circuit – Schematic created using CircuitLab

When I send a LOW signal to Gate, the led strip is still faintly on. I have read about why does this happen(stackexchange link)

What I was wondering is how can I stop this? Will a diode help? Is a MOSFET driver what it needs? Or should I increase the load (a pretty bad hack)?

I know the mosfet in use is not a TTL but the mosfet does turn on at low gate voltages (1.5~2V). I am able to fade the led strip but could not get it to completely turn off using the MOSFET.

Also, not sure if this is a concern or not, but the supply voltage (24v) decreases to 18v when the MOSFET is turned 'off'.

Any help is appreciated. Thank you.


texts: Is there a way to make an op amp circuit using only RLC and op amps that would make V0 = V1-4V'1 -3V''1 -5V2 possible? Assuming that V1 and V2 are independent sources and considering that the prime indicates derivative with respect to time. I have tried to use 1 op amp and connect RLC in series with V1 source but then I would have to derive V0. I have tried other ways and tried to solve with two op amps but still couldn't figure out the design. Sorry for the bad English and apologies if the question seems trivial; I have just learned circuits.


texts:
I have built a PCB using this schematic used to charge a small wireless device.

This schematic is based on this Texas Instruments evaluation module: https://www.ti.com/lit/ug/slvu928c/slvu928c.pdf?ts=1594940372649
On top of what ti offers, I have thrown in a microcontroller to record the digital signals (LEDA, LEDB, LEDC)
This board is going to be a raspberry pi 4 shield and I am going to use the i2c bus of the atmega328p to send information about the digital signals mentioned above.
I am still learning electronics and I am debating whether I should have connected the analog and digital grounds on the board. Right now the grounds are separated, one going to GND and one to GND (picture 2 raspberry pi schematic)
The problem I am getting is that I get weird voltages on the board.
Here are some examples of voltmeter measurements:

5V source - GND = 5V
5V source - AGND = 2.6V
TLV70033 3V3 output - GND = 1.96V
TLV70033 3V3 output - AGND = -0.48V
ATMEGA328p 3v3 input - AGND = -0.48V
TLV70033 EN output - AGND = 3V

Here's a link if you want to look at the actual board. Go at REV1
Here's a list of questions I have:

Why is there a voltage drop on 3v3 output (was looking for 3.3V but now <2)
Why do I get negative voltage between ATMEGA328p 3v3 in and AGND?
What does BSS138 do in each case? (Q2/Q3)
What does DTC114 do? (Q1)
What is the purpose of ground separation and how is it done correctly?


texts:
I got a buck converter from Amazon. This- https://www.amazon.com/MCIGICM-step-down-Converter-3-0-40V-1-5-35V/dp/B06XZ1DKF2
Now it's soldered onto a custom PCB I designed. I'm supplying it with 12V and the output is set to 5V. Total power in and out of the system is about 9W.
As soon as I start pulling power from the chip, it emits a horrible screeching sound, something in the high 10kHz range. That makes sense because it might be noise from the inductor, but here's the kicker: If I desolder the same buck convertor and instead of soldering it directly to the board, attach it using jumper wires; the sound disappears. I can also duplicate this problem with the exact same results with all the buck converters I received and it's breaking my mind a little
Any clue why? I'd like to have the chip soldered on and not floating in the air.  Any suggestions on how to get out of this mess?


texts: In order to avoid solder bridges during reflow, What is the minimum pad-to-pad spacing?

texts:
With regard to DFM, I am wondering if there is no risk of solder bridge during reflow as long as there is a soldermask web between the pads?
Soldermask clearance(2 mils*2) + soldermask web(4 mils) = 8 mils
Is it 8mil the minimum pad-to-pad spacing to avoid solder bridges?
If so, how about soldermask-defined pad, still 8 mils?

Thanks!


texts: Do amount of Joule mean the quantity of surges or power of one surge?

texts:
There is such specification as amount of Joule for power strips.
What exactly do they mean, the quantity of surges it can withstand (in other words longevity of a strip) or how powerful a single surge can be?


texts: What kind of cable does a function generator use?

texts:
I picked up an Agilent 33120A function generator used (yay!) and I need to buy the cable that attaches the output to the circuit. Problem is, I'm not sure what kind of cable it is.

So, I guess I have two questions:

Does anyone know the name for this type of connector/cable?
Once I know the name, I'll probably try to buy it on e-bay since I'm a student and kind of strapped for cash. Is that OK, or will a cheap cable be a problem?


texts: ULN2803 - do i need COM(VSUP) for relays ?

texts:
I'm building a relay board with SRD-03VDC-SL-C relays and an ULN2803 Darlington transistor array. As I am a beginner I don't understand the purpose of the COM pin?
In the datasheet VSUP (Coil Supply Voltage) is rated from 12 V to 100 V, since I'm working with 3V3 will this be an issue?


texts: According the the following link, a minimum of 4800W is drawn from an electric stove when all burners are turned on: http://www.ehow.com/how-does_5179441_many-watts-electric-stove-use_.html. I'm just wondering how a stove achieves this? Are they not limited to approximately 1800W like other power outlets are?


texts: Measuring analog voltage from multiple differential input causes voltage fluctuation

texts:
As shown above i am using a micro controller's differential input to measure the analog voltage. When the the micro controller measures the voltage on the input pins there is a voltage fluctuation along with a voltage drop on each of the analog inputs.
What could the possible reasons be for this.The above diagram is not the final design and I need to scale it up for multiple controller. A design limitation prevents me from using buffer based solutions to the issue, even impedance matching cannot be done.
Any suggestion would be greatly helpful.
Thanks in advance.


texts: In a DC motor, how is it that field flux can stay constant despite a changing load?

texts:
According to my research, field flux depends on motor current in a series configuration, and depends on armature voltage in shunt configuration. Since motor current and voltage change with varying loads, how is it that we can keep a constant field flux?

PS This is ignoring slight drops in field flux due to armature reaction.


texts: Does leaving a cell phone on charge all the time weaken the battery, and why?

texts:
If I leave my cell phone with the charger plugged in all the time, would this weaken the batter, and why? I've heard that you should only charge the cell phone when you receive a 'battery low' message and leave it off the charger at other times?

The cell phone has got a Li-Ion battery.


texts: Making an obstruction avoiding device without microcontroller

texts:
I want to make a toy device which spins to the left whenever there is an obstruction in front of it, without any microcontroller. Can anybody please check whether my approach in building the device is correct or not [let's assume we are driving our device in a bright room with uniform lighting]? Any tips or suggestions for improvement (if it is correct) will also be appreciated.

My approach is to use two DC motors as the rear wheels of the device. Attach an LDR to the front of the device  and connect it to the left motor. Now both the motors are connected to a power supply. When the power supply is switched on and no obstruction is in front of the toy, both the motors will be moving at approximately same speed since the LDR will be in exposure to light and its resistance will be negligible, because of which the toy will run straight. Now when there is some obstruction in front of the device, the amount of light falling on the LDR will decrease, which will imply a rise in resistance of the LDR. Thus the velocity of the left motor will decrease, while the velocity of the right motor will be moreorless constant. So the device will spin to the left.

The circuit diagram corresponding to my argument is provided in the link below. I will post the mechanical simulation of the device shortly (within 2 hours from now).


texts: How to log Fixed-size Array with Mentor Modelsim/Questa in a tcl with add wave *

texts:
I have Fixed-size Array in port Out but my wildcard doesn't include them and I didn't find anything in the manual.

add wave -noupdate -radix  hexadecimal {/tb/DUT/*}

How can I include them using a tcl command?

Tools/Wildcard filter:


texts: NMOS transistor: how does its structure relate to two interconnecting diode?

texts:
There is a popular idea that structure of NMOS transistor could be viewed as the inter-connecting diode across their PN junction. Therefore, when operating NMOS, you always want to keep the Source and Bulk connect to lowest possible voltage to keep the diode reverse-biased.

I understand that if you have PN junction, then it will be a diode.  But I can't visualize at which region below forms a diode, and I can't see why you need to keep diode reverse-biased so that the transistor is functional. Can someone please draw the diode on the following diagram and explain?


texts: DC motor doesn't start until PWM duty cycle exceeds threshold but continues to run when duty cycle reduced below threshold

texts:
I'm using a DC gear motor (from this kit, plastic gears) driven by a L298N module controlled by a STM32 BluePill. The motor voltage supplied to the L298N is 9V from a variable voltage AC adapter with a max current of 1A. The STM32 is powered from USB. The STM32 and L298N share a ground circuit.
I'm using a PWM signal from the STM32 to the Motor A Enable pin of the L298N to control the voltage applied to the motor. The Input 1/2 pins are driven correctly to rotate the motor in one direction.
When I start with a low duty cycle to produce a low voltage, the motor does not start turning and simply makes a high pitched whining noise. As I increase the duty cycle and thus voltage, the whining noise increases in pitch and eventually at a specific duty cycle the motor will suddenly start turning at quite a high speed. Once it's turning, if I reduce the duty cycle below that threshold, the motor will continue turning albeit at a slower speed. If I reduce it further, the speed of the motor becomes uneven and eventually stops and the whining noise resumes.
I don't understand what's happening here. Am I not controlling it correctly? Is the torque produced by the motor at low voltage not high enough to overcome the friction of the gears and inertia of the motor?
Motor specs:

Operating Voltage: 3-6V DC
Reduction ratio: 1:48
When the voltage is 6V:

No-load current: 200mA
No-load speed: 200±10%rpm

When the voltage is 3V:

No-load current: 150mA
No-load speed: 90±10%rpm


texts: What is "Saturated CTR" of an optocoupler?

texts:
For example, in the datasheet of 4n27: .

So what is saturated and what is non-saturated CTR?


texts: How to connect a MEMS Microphone Breakout - INMP401 to a RN-52 bluetooth module?

texts:
I intended to use a  INMP401  (MEMS MIC) to capture audio and stream it via bluetooth using an RN-52 bluetooth module (RN-52). The RN-52 has inputs for differential +- signals.

The INMP outputs single channel audio peak to peak at approximately 200mV. I presumed that connecting this to the L+ input of the RN-52 via a 47nF capacitor and connecting the L- of the RN-52 to ground would allow me to capture audio. However the audio I receive is highly distorted and noisy.

I have tried to recreate the circuit shown here:

This however still remains unusable. Any advice on how to get the two devices connected effectively would be greatly appreciated. TIA.


texts: How to choose a transistor for amplification

texts:
I've been trying to find information on choosing an NPN transistor but everything I've found seems to apply to saturated transistors only. I'm basically trying to amplify the current given from a 3mm audio headphone jack to a useful level. Knowing the voltage and current required for the load at the collector, plus the voltage and current supplied to the base how can I determine from a spec sheet if a transistor is suitable?

Also, am I correct in thinking that the voltage supplied by the audio source will need to be at least 0.6V?

EDIT: For the sake of an example let's say the load is a bunch of LED's totaling 9V and 800mA. Obviously with an appropriate power source. I'm still researching the current and voltage of the audio signal but for this example let's say it's 0.3V and 5mA.


texts: How to program a microcontroller via USB using JTAG?

texts:
I have some hard time understanding JTAG for programming.
I have an mcu that can only be programmed via JTAG.
What are some easy chips to start with in order to program an mcu via JTAG? I suppose I d need a chip (mentionned in the previous sentence) in order to convert the serial data received via usb to the "JTAG-equivalent"?

I am trying to program this mcu: TM4C1294 cortex M4, which can only be programmed via JTAG.

EDIT: a lot of you guys are talking about an FTDI2232 chip. But how would you wire an FTDI chip to the mcu? I mean the ftdi chip does (as far as I know a conversion to TTL and that s it). So you would then have all your data on the TX and RX pins. But with JTAG you need a TDI,TDO, TCK and a TMS pin. So I think you need another chip to do the conversion. No?


texts: What are the typical qualification norms for assembly line workers?

texts:
My question seems OFF-TOPIC, but I do believe there might be people here(at electronics_stackEx) who know the answer. And I really don't know a better place to post this.

Here Goes the question:
What kind of education qualification do electronics assembly line workers possess?

I don't know the nature of this kind of work.


texts:
Below is the circuit in question.

Good evening,

I'm working on a problem that requires me to graph voltage at point A between -10 ns and 120 ns. I know that we must factor in wave reflections that happen during that time. My problem is, I am not sure how to proceed when more than one load is present. Would it make sense to isolate both "halves" of the circuit, make two bounce diagrams, and "sum" the two?

I've calculated \$\tau_1 = \dfrac{5}{2 \cdot 10^8} = 25\ ns\$ and
  \$\tau_2 = \dfrac{12}{3 \cdot 10^8} = 40\ ns\$.
Would it be valid to assume that the reflection coeffient of the "right side" doesn't account for the left side?

i.e. \$P_{L1} = \dfrac{Z_{L1}-Z_{01}}{Z_L+Z_{01}}\$

Additional info: At \$t = 0s\$, the voltage source goes from 2V to 6V. The transmission speeds of the lines are \$2 \cdot 10^8\ m/s\$ and \$3 \cdot 10^8\ m/s\$. Lines are lossless.


texts: Clamping Voltage without disturbing the power supply

texts:
I am using a circuit similar to the following, to clamp the input to my microcontroller to around 5 volts:

How do I make sure that the (5V) power supply is not disturbed and stays regulated.

I am using linear regulator to maintain 5V from 12 volts supply.


texts:
I got three UFO / Saucer LEDs from China. According to the seller on ebay they are produced by Ranpo, but the LEDs are as unbranded as it gets. They are also, according to the seller, 30W - but the LED itself is silent on that as well.

Anyway, the LEDs get somewhat hot. I measured 52C on the top "golden" area. Is that too hot, or is it fine for this wattage?


texts:
I have heard from here that if you put 1 turn of wire around your house, you can hear music all around inside your house. It doesen't tell me very much on all of the components etc. to drive but I am assuming that you have to have an amplifier on the receiver and the transmitter. To simulate, before actually performing the experiment, I wrapped 1 turn of wire around a cardboard box. For the transmitter, I found a stereo system, which can produce a very loud sound. The only problem is because it acts as a short, I can only turn it up to a certain volume. For the receiver, I just hooked up a speaker to a coil, and I heard a faint sound. I know with the scale of a large house, I will need some time of amplifier. How would I set up the circuit for amplifying the low signal sound found on the coil. Would this be possible with a TL082CP op-amp and if so, how would I set up the circuit? Also does anybody know of any better way of transmitting the sound through it or is the stereo fine for the setup around my house?

Also, I came across a very strange thing when I found a head-set and put one ear-piece in the magnetic field. I heard the audio out of the other. I had nothing connected up to the jack and it seems impossible for this to happen with a stereo head-set. Why is this happening?


texts: Can this part of the slayer exciter circuit be disconnected?

texts:
Basic Slayer Exciter

The rest of the circuit makes sense, however I am wondering if this wire can be disconnected from the circuit. If a charge is being accumulated at the "275", where it will ultimately discharge as an arc, why is it necessary to connect this wire? Would it be unnecessary if it was an AC current source?


texts: Is it good to ground the polygon plane on the routing layer?

texts:
For my final project I have to measure multiple signals up to 10MHz with a TMS320F2809 processor which is clocked at 100MHz.

I have the following layer stackup:

Top Signal
Ground
Signal
Signal
Source
Bottom Signal

On the signal layers do I have to put a polygon plane? Is it a good idea to connect to the ground? Will it act as a capacitor between the trace and the ground polygon?

According the following description on the top and bottom layer should be routed only low frequency. Which range is low frequency)(1Hz up to ?)? I tried to follow that description, but when two IC was within 1cm range I routed on the layer where the ICs are.


texts: Driving BLDC motor directly from Generator

texts:
There are affordable BLDC motors up to 200kW. The Controllers, however, are double in price and the AC-DC inverters breach the 4 zeroes price scale.

Q1: Could one BLDC act as a Generator for spinning another, without any electronic components in between (no pulse correction AC->DC->PWM conversion etc.)?

Q2: Can BLDC motor be driven with a sine-wave rather than a square-wave?

I am asking this because I've run a small test on two 800kV/200W motors (connected back-to-back).
By spinning the 1st-one with a drill at ~100Hz, I was able to observe smooth sine wave in its output (1.2V RMS, 0.3A, this is on a single phase).
Once connected, the 2nd motor was shaking badly and barely reaching 1Hz.

Unless I was running a test well beyond the minimal voltage, an answer to Q1 seems to be "NO"?


texts:
I have a strain gauge mounted in a voltage divider as in the image below:

simulate this circuit – Schematic created using CircuitLab
where \$R_{g}\$ is the resistance of the strain gauge when it is not strained (120 \$\Omega\$), \$R\$ is a 1200 \$\Omega\$ resistor, \$V_{app}\$ is the voltage applied on the voltage divider (1.1 V) and \$V_{meas}\$ is the voltage measured with a lock-in amplifier.
When the strain gauge is not strained, \$V_{meas}= V_{1} = \frac{R_{g}}{R+R_{g}}*V_{app} = 0.1 V\$
How to calculate \$V_{meas}\$ when the strain gauge is strained?
This is a shortened version of my question. The original formulation is hidden behind the spoiler.

 The strain across the strain gauge is \$x = \frac{1}{GF} * \frac{\Delta R_{g}}{Rg}\$ (eq. 2) where GF is the gauge factor. I am not certain how to express \$x\$ as a function of \$V_{meas}\$. So far, I used the following method:
 when the strain gauge is strained, eq. 1 becomes: \$V_{meas} = V_{2} = \frac{R_{g}+\Delta R_{g}}{R+R_{g}+\Delta R_{g}}*V_{app}\$.
 From there I get \$\frac{\Delta R_{g}}{R} = - \frac{R}{\Delta R_{g}} * \frac{V_{2}}{V_{2}-V_{app}} - 1\$ (eq. 3).
 By inserting eq. 3 in eq. 2, I have \$x = - \frac{1}{GF} * (\frac{R}{\Delta R_{g}} * \frac{V_{2}}{V_{2}-V_{app}} + 1)\$ (eq. 4).
 Using eq. 1, I get \$\frac{R}{R_{g}} = \frac{V_{app}-V_{1}}{V_{1}}\$ and inserting this equation in eq. 4:
 \$x = - \frac{1}{GF} * (\frac{V_{app}-V_{1}}{V_{1}} * \frac{V_{2}}{V_{2}-V_{app}} + 1)\$.
 Knowing the values of \$V_{app}\$ and \$V_{1}\$, I obtain: \$x = - \frac{1}{GF} * (10*\frac{V_{2}}{V_{2}-1.1} + 1)\$ where \$V_{2}\$ is the voltage measured with the lock-in amplifier when the strain gauge is strained.
 Could someone confirm these equations? Thank you!


texts:
I got an external crystal for a MCU ( tm4c1233h6pm).

I use the NX-16MHZ from NDK, in the datasheet, the recommend cap charge for the crystal are 2 cap of 10 pF for a 16 Mhz crystal.

My question is that I used 0603 package for the caps in the first iteration, but if I change to a smaller package like 0402 can it leads to problem?


texts: Recreate "Voltage gain vs Frequency" graph of Op-Amp in LT Spice

texts:
I am trying to recreate the "Voltage gain vs Frequency" graph of the LT1037 Op-Amp in LT Spice. According to the datasheet page 6 the graph looks like this: -

Trying to recreate this in LT Spice gives me a graph, that doesn't match the graph above: -

As you can see, the gain is not as high, and graph starts to roll off at a higher frequency. I would like to know why the two graphs doesn't match at all. I believe it has something to do with the resistor values, but I have a feeling that I'm missing some key understanding - such as a wrong circuit design.


texts: Installing a limit switch to a small winch

texts: I need help with installing a limit switch to a small dc winch that has remote controls. I need to stop the winch from going one direction while allowing it to still function in opposite direction. I've included the schematic that came with winch.


texts:
I'm in need of a circuit that can be used both for driving a BJT (NPN & PNP).

The devices will only be "small" devices in TO92 packages that don't dissipate too much power so the requirements for max. voltage and current are not high.

+/-20mA max.

In order to drive the circuit I have a DAC which is capable to output voltage of +/- 10V 24bit resolution.

The source should look like a current source with high Z. Any suggestions?


texts: Can you please review my pcb design? Is it safe?

texts:
I've created 2 layer relay board dealing with high voltage 220V AC and 5V DC simultaneously.

Is it sustainable or safe PCB, if I sell to end user? Is there any chance of problem may occur after some months like fire, accidentally stop working etc.?

Because I pass on-board 5V dc line above/below or parallel with the ac live line & neutral line.

Figure 1. Schematic. (Click for full size view.)

Figure 2. Board topside view.

Figure 3. Board topside-only view.


texts:
I am trying to interface a Texas Instruments (TI) 16-bit ADC to a TI Piccolo microcontroller (MCU) via a serial communication interface (SCI). The ADC block diagram shows 3 connections for this; a Data Out, a SCLK, and a CS.

The Piccolo MCU has an SCIRX and SCITX connection for SCI interfacing. The CS connection I am sure I can take from any GPIO (right?). My main question is what do I hook up to the ADC SCLK input? The only clock outputs from the MCU that I can see are the SPICLK outputs, but thats a different interface.

Please advice.

-D


texts: Writing to register on I2C device, returns device busy

texts:
I am trying to write data to a register on an I2C chip from the Raspberry Pi, when I use i2cdetect I get UU, which I understand is an error.

sudo i2cdetect -y 1

   0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f

00:          -- -- -- -- -- -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- UU
70: -- -- -- -- -- -- -- --

When I try to use SMbus python module to write to the desired register I get the following error:

bus.write_byte_data(DEVICE_ADDRESS, CONTROL_REG, CON_VAL)
IOError: [Errno 16] Device or resource busy

Are there any usual reasons for this or things to try?


texts:
I'm a software engineer who has recently become very interested in hardware. I'm very novice so I apologize ahead of time for any dumb mistakes or misunderstandings I have. This might also be a broad question but I've seemed to be a little lost and could use some direction.

My main project I've been working on is a wearable bluetooth hid controller. As of right now I have been able to connect an attiny85 to an HM-10 bluetooth module to send HID bluetooth commands to my phone using a breadboard.

Now though I want to move from a breadboard and through-hole components to a PCB and surface mount components to try to reduce size and cost. Up until now things have been pretty straightforward thanks mostly due to ( what seems to me ) the bluetooth module abstracting the interaction with the bluetooth chip.

I've been looking at using either a TI cc2541 or a Nordic nRF51822 as a standalone bluetooth chip to put on a PCB in place of using either of these on a module.

Looking at the module it looks like there is more going on then just status leds so I assume that I cant just expect to throw this chip on a PCB with the same connections as I have on the module.

How can I find out what components I need to work directly with the chip rather than the module? Is there a document provided by the manufacturer that lists what other components are required and a schematic as well?


texts:
I have a setup that demands that I use all my I/O's on my Arduino Uno R3 board - including the serial pins 0 and 1.

So I've initialized those pins as inputs, but when I make a reading on pin 0 it reads high although it's not connected to anything. My multimeter tells me 4.8V steadily on the pin all the time.

All my other pins I've not initialized any serial communication, and I've tried running the board on a battery (so no computer connection).

I have Adafruit's Waveshield connected to it, but as far as I'm concerned it shouldn't interfere with pin 0 in any way.

I've made a simple drawing showing the concept of what I'm doing. It's all there is to it, just the size of 12 buttons and 12 lamps. In order to get enough I/O's, I had to implement an IO expander (mcp23016) on the I2C bus, but it's the same principle as on the drawing.

So when I have everything hooked up, all seems to be good except for the pin 0 on the Arduino board. All other readings (both on the Arduino and the expander) works fine.
The weird thing is: when I measure voltage on pin 0, it gives me 4.8V; on pin 1 it gives me 1V and on the other pins it gives me 0V. So something is obviously different from the serial pins.

Are there any internal pull ups or downs on them or could it be the many 10k resistors I use? Do they need to be smaller or bigger perhaps?

Perhaps it's just a bad soldering, but I've been checking for hours and hours and I really can't see any issue on the hardware part.


texts:
I took this motor from a cordless drill and I would like to power up directly from a power supply and not from the battery. The datasheet says the stall current draw is 70/85 Amps (I'm not sure wich model I have).

So do I need an 14.4V power supply capable of giving up to 85 Amps or am I missing something? Is there some kind of a workaround that can be done here?

Thanks


texts:
When you find out that a chip you were interested in is obsolete, and no longer made, how do you figure out which chips have replaced it?

I've been having great fun getting hands-on experience with different chips in the 74xx series: plugging them each into a breadboard with a microprocessor, and making a sample project with each.

As I look down the list of 74xx chips, it's clear that some of them have not been made in ages, because they've been completely obsoleted by more recent chips and concepts.

I want to explore the current set of commonly-used parts. If a chip has been replaced by something that gets the job done better, I want to play with that new thing. How would you figure out what that thing is?

For example, the 74116 chip sounds interesting. A simple, no-frills latch? I can see uses for that. But clearly, something better has come along, because as best I can tell, no one makes that chip any more. What's a good way to figure out what has replaced it?


texts: Bricked STM32 with Read Out Protection Level 1, can't disable it

texts:
So I was testing the boot option bytes of my Nucleo32 STM32G431KB board and somehow my Nucleo board is in Read Out Protection level 1. STLink Utility is unable to revert it, I get the error "Read/Write protected zone for bank 1 can't be reduced".

These are the only lines of code I had in main():
//STCubeIDE autogenerated code...
HAL_FLASH_Unlock();
HAL_FLASH_OB_Unlock();
FLASH->OPTR|=(1<<27);
SET_BIT(FLASH->CR, FLASH_CR_OPTSTRT);
HAL_FLASH_OB_Launch();
HAL_FLASH_Lock();
while(1)
{
}
//STCubeIDE autogenerated code...

I also tried to bypass the STLink and try if I could communicate directly to IC's bootloader using a FTDI driver and writing raw bytes to UART, because there is a command to revert the ROP, but I had no reply from the chip.


texts: How can I interface with RPi-Camera to FPGA?

texts:
I want to interface with RPi-Camera to my FPGA bord.

As you can see,  http://www.wvshare.com/product/RPi-Camera-B.htm

This camera has a 15pin-ffc cable. But I can't get a ffc cable's interface information of RPi-Camera.

Does anyone knows each pin's infomations of 15pins-ffc?
Also does anyone knows the reference site or resference things to interface RPi-Camera with FPGA?


texts: How to find how many Amperes does a equipment use?

texts:
In the specification of this miner https://www.asicminervalue.com/miners/bitmain/antminer-s9j-14-5th it says it uses 1350W power with 12V electricity. I like to know how can I find how many Amperes this machine uses?

In general I like to know with a electricity supply around 380V and 150A how many of these machines can be run?


texts:
I'm trying to bias an op amp, I'm reading this document for reference.

I'm reading along and it makes perfect sense until section "How to Select Component Values:"

They want to amplify a signal with amplitude of 1V going from 2V to 1V to put it on 0-5V swing.

The gain needs to be -5 but then they introduce "operating point" and never define it.

They say operating point can be set to either (2V, 0V) or (1V, 5V.)

What do those pairs even mean? I stared at the document for good 20 minutes, still can't understand that it means.


texts:
In Altium Designer I see in PCB Inspector (Workspace Panel) both Track and Trace objects.

In my opinion Track is standard Altium object (conductive path between pads), then what is Trace, and what's the difference?


texts: Converting the value of Vrms to A/sqrt(Hz)

texts:
I am taking data by passing the current of the source through a 1 Ohm resistor and measuring the voltage over the resistor with a SRS-SR760 FFT spectrum analyzer. SRS-SR760 FFT giving me values in Vrms (nVrms, uVrms, pVrms) but I want to convert this in A/sqrt(Hz), I know Ohm law giving us V = I R, in my case it should be Vrms = Arms 1 Ohm (because I am using 1 Ohm resistor). But I don't have any idea that how I bring
Vrms --?(to)--> Arms/sqrt(Hz)
Can anyone help me to guide that /sqrt(Hz)?

Thanks


texts: Synthesize VHDL into discrete TTL integrated circuits

texts:
I've got a small project in VHDL (fully working in a Xilinx FPGA) and I would like to implement it using an old-school printed circuit board and discrete TTL integrated circuits, in the spirit of projects such as TTL Clock, for educational / entertaining purposes.

Which (preferrably free software / open source) tools can help me in this project? Suggestions capable of minimizing the number of chips (not necessarily the number of gates!) and generating the PCB layout are very welcome, too.


texts: Output resistance of a multistage BJT amplifier

texts:
In the amplifier shown:

To calculate the output resistance, this equation is used:

I understand that the R5/(B+1) comes from resistance reflection, but why do they not take the resistance in the collector of Q7, which I expected to be in parallel with R5, into consideration?


texts: Can a voltage divider circuit be used before regulator to reduce heat?

texts:
For a project of mine I need to step down 12V to 5V and also 5V to 3.3V. However, I don't have any heat sinks for my voltage regulators. From the equation below, if I reduce the difference between the input voltage and output voltage of the regulator, I can reduce the power dissipation.

If I use a voltage divider to step down 12V to 6V and then use the 6V as the input of the regulator, would that then decrease the heat significantly, or does the heat still generated but at the divider?

Sorry for the noob question, it is my first time messing with power supply other than the 5V.

EDIT: forgot equation for reference

Power = (Vin - Vout) x Iout


texts: I am interfacing Compact Flash with LPC1343. Which is better- 16 bit data and 3 bit addressing or 8 bit data and 8 bit addressing? Anyone please suggest.


texts: Multiplexing, Animation, Bitmap coding on MCU. How to do it right?

texts:
I have been recently getting into programming and micro controllers.
I found myself that i don't really know how to do multiplexing, animation, easily displaying pictures on LED display.
I have been looking for some code examples,  but most of the articles I found, where about the hardware and the software was not even mentioned, the code examples are usually poorly commented and on a platform i don't know (I'm using TI MSP430 MCUs) and the operating theory of the software is never explained.

I'm assuming this is because a lot of MCU beginner come from a software background, and they need more explanation on the hardware.

My question is: How to implement Multiplexing, animation,bitmaps nicely.
How should it be done?
What is the theory of the software for these applications?

Any comments, link to articles, book, etc... are very much appreciated.

Also I have to stress that I have done it, and it's working, but i think my codes for it looks horrible, it would be impossible to manage in a larger program and there should be a better way to do it.
But anyway here are two videos of multiplexing projects:
http://www.youtube.com/user/undeadtreat/videos


texts:
I found some FM transmitter circuits with the MAX2606 VCO.

Example:

Can I replace R1 with the DAC output from an AVR microcontroller? Or can I connect the DAC directly to Pin 3 of the MAX2606?


texts: I want to read the 14V PWM signal on Attiny85 running an Arduino IDE. It is a control signal sent from the car's PCM to the cooling fan.  The frequency of thes signal is 120Hz while the duty cycle is changing from 0 to 100%.  As I understand, I have two main options: 1) use a resistive voltage divider and a capacitor to form a low pass filter, and reading the signal as an analog voltage; 2) a resistive voltage divider and some sketch that will measure the duty cycle.  Which solution is better? Regarding the RC filter, what must be the cutoff frequency?  The speed of the response is not so important.


texts:
I know this question has been asked quite a few times on this site. The closest one i could find is: make-9v-ups-for-router-with-tp4056-and-mt3608.
While there are UPS systems designed for routers, in my country, they literally cost more than the router. I am just trying to see if I can learn anything from trying to put together my own UPS system.
Problem: I have a 12V 1.5A Nokia router. During our daily power cuts (my apartment backup kicks-in in about 5s to at most 1min) my router decides to give up on life and doom me to the internet black hole.
I just need to have a UPS system to ensure uninterrupted internet during the switch over from mains to apartment backup.
This is what I have so far (with my amateur reasoning of it):

My router comes with a 12V 1.5A DC adapter that I am planning to replace with a 12V 2A DC adapter. Connected to this would be a 2S1P Li-Ion 18650 batteries (Samsung make) that will be charged through a 2S BMS board (TP5100). The output from this backup has to go through a XL6009E1 to meet the 12V supply required by my router.
I plan to setup the Li-Ion batteries in series using Nickel strips and with glass fuses rated at 2A each. I wanted the backup to kick in only once the mains went out and so I have got a IRF9520 P-MOSFET along with 1N5408 diodes (the only ones I could get my hands on) for switching the power supply and for reverse voltage protection.
Along with these, I got a couple of pull down resistors (100K), capacitors (4.7μF 25V Electrolytic capacitors) and a heat sink for a TO 220 package.
Will this circuit work to charge my batteries and provide power to the router and then successfully switch to backup for those precious few seconds when the mains cut out?
I just want to make sure I don't burn the house down or something.


texts: TP4056-42 Without battery temperature sensor

texts: I would like to create an integrated circuit with the IC TP4056-42 but without the battery temperature sensor. The datasheet speaks that when we do not use temperature sensor we must ground the pin 1 TEMP. In some circuits on the internet the TEMP pin has a resistor connected to the VCC. But the datasheet does not say anything about it, I wonder if the circuit below is correct.


texts: Using a multimeter to measure the current of a microprocessor

texts:
OK. I'm pretty sure my inexperience is going to show here. I had the task of finding out how much current a microprocessor was drawing. I was going to measure, with a multimeter, between the point after the power (using a AC to DC 5V) and ground. I didn't break the circuit and the microprocessor started smoking at the red probe. Damn.. was I shorting out the point after the power when I did this? But since it is current and not voltage, it shouldn't be. Does anyone have an explanation for why the microprocessor started smoking? Sorry, this description may be vague.

Back to my original task, I used a power supply to measure how much current the microprocessor was drawing. Is there any alternative way to measure the current without a power supply?

Thanks.... OTL


texts: Transimpedance AMP, Active HPF, phototdiode (updated)

texts:
The original post is here Transimpedance AMP, Active HPF, phototransistor

I decided to change back to a photodiode instead of a phototransistor since I have used one for a similar experiment in the past. I also took the suggestion to remove the feedback capacitor.

In this setup I am using a VISHAY BPW34. Should the Rf be good enough for good readings? And is non inverting high pass good enough to pass only 995Hz frequency and amplify the signal? Should this setup work in terms of op amp and output?


texts:
I'm trying to salvage a Samsung LTN154AT07 LCD from a laptop.
I've ordered an MT6820-B rev.3 universal LVDS driver and a 5A step-down module (XL4005), and I think I have a decent grasp of how everything goes together (there's already an inverter on my LCD). I'm following this tutorial: http://sites.google.com/site/lcd4hobby/lcd-tft-as-pc-monitor

The problem that I am having is with the 30-pin cable. I found the pin diagram for the monitor, and also the pinout on the MT6820-B, but the abbreviations for the outputs/inputs are completely different on each. I was hoping that perhaps someone might be able to help match them up so I don't fry the monitor. Once I know what goes where, I can rewire the 30 pin cable. Even if someone can help match up some of the wires it would be a great help.

The image below shows the LTN154AT07 LCD pin assignment on the left, and the MT6820-B controller on the right.

Here is a link to the LTN154AT07 monitor's booklet in case there is some info missing from my image:
http://www.beyondinfinite.com/lcd/Library/Samsung/LTN154AT07.pdf

*edit: here it is in question form:

I am trying to connect the controller on the right to the monitor on the left with a 30-pin LVDS cable. Can someone please help me decipher which pins from the monitor go to which pins on the controller card?

Thanks in advance for any assistance!

Cheers,

-Gabriel


texts:
I'm trying to repair a broken baby monitor and found an interesting looking part. It looks like an thermocouple but I'm not sure. Do you have any ideas?

See board picture.


texts: LM2596 buck converter overheats converting 36DC -> 5DC at 600mA

texts:
In my circuit I'm using an assembled LM2596 converter module (those which are like $2 on ebay). The input voltage is 26V AC (current 140mA), which is rectified (making it ~36 peak DC), and feeds the buck converter. The output is 5V DC, 600mA. All seem to be within reasonable ranges for the converter, but it overheats pretty fast to the point I can't touch it anymore. And if left overnight for testing, it burns out. Both the LM2596 chip and the 330 induction heat up; the inductor seems to be hotter.

So far I tried to drop the voltage at the converter by inserting the capacitor (up to 100mF, non-polarized) into the AC circuit for capacitive resistance. This drops the input voltage to ~9V but the capacitor itself overheats really fast. I also tried with different modules, and they all do the same.

My questions here:

Is it normal?
If yes, what could I do?  Is it reasonable to chain the converters, like using the first buck to drop something like 36 -> 20, and then the next one to drop 20 -> 5? Any side effects, besides the cost of two converters? Or is it more effective to put them in parallel?

Edit: photo of the module. The dark chip says LM2596 -ADJ:

Conclusion: I have tried a bigger capacitor (2200uF), a different inductor, and a heatsink. Nothing worked, except stacking regulators.


texts: Heat-shrink for electrical insulation of a metal hinge

texts:
I have a metal door hinge which is part of a trap for a Physics experiment (measuring 'g' by free fall). I want to cover the hinge so that it is electrically insulated. I was thinking of using heat-shrink to do this.
The hinges is 65mm wide.

Is heat-shrink a good idea or is there a better way to do insulate the metal hinge?

Also, do I need heat-shrink tubing of 130mm diameter of shrink ratio 2:1?

When working the magnet holds the hinge up and then the ball bearing hits the hinge and breaks the circuit connection between the hinge and the horizontal metal. Breaking the circuit will stop the timer which starts when the ball is released by an electromagnet. So the time to fall is measured.

Any help would be greatly appreciated.

Thanks.


texts: Large differences between datasheets for the same part number

texts:
I'm working with the MIC4605-2 half-bridge MOSFET gate driver. The chip was originally made by Micrel. Microchip has acquired Micrel and took over their product line, including the MIC4605-2.
There's now 2 datasheets for the same part:
The original one from Micrel.
The newer one from Microchip.
There's some large differences between them regarding voltage on the HS node.
Micrel:

Microchip:

Going from -1V continuous and -5 repetitive transient in the Micrel version to -0.3V continuous and -0.7V repetitive transient for Microchip.
Those differences have serious design implications. How can there be such a big difference for the same part? Which version should be trusted?


texts: Programming ATMEGA1284p on internal 8MHz without caps

texts:
I'm trying to burn a bootloader on a standalone ATMEGA1284P without using caps or an external 16MHz crystal, just with a 100nF cap between GND and 3.3V VCC. I am using this bootloader from maniacbug.
I am using the 8MHz bootloader from maniacbug.
I am burning the bootloader using an Arduino Uno, as described here using ArduinoIDE.
I've screened some related ressoruces already that could not help me:
External oscillator or caps not required
Built-in 8MHz crystal can be used
Internal 8MHz clock needs to be selected first.
I think Nick Gammon also provides a bootloader but it is much more difficult to understand than the documentation of maniacbug.
I've double checked my wiring, it is correct, can you eventually help me in trying out the bootloader from Nick Gammon?
EDIT: I have also checked the MightyCore bootloader on 2 of my boards. It definitely supports internal RC oscillator.


texts: I am trying to generate a triangle oscillator > 40 KHz and Vp = 2 V using these two ICs. So far, I only get a flat line when testing on Proteus. I'd really appreciate some help with the expressions I should use for this configuration. Am I missing something? Thanks in advance.


texts:
I got 23 meter of leds strip with 3 power supply which have a share ground to an Arduino.
The Arduino can run perfectly the leds, I have shielded the cable from the arduino to the connector and I have no issues at this point.

When I connect my DSLR via HDMI (shielded cable ) and  AC adaptor ( china made ), some leds start to flicker, and if I put the power cord closer, they flicker more.

I wonder if I just need to buy a better AC adaptor ( takes time ) or by sharing the DC ground of the camera, the flicker will go away ( I am afraid of damaging the camera and leds by doing that ).

One other solution that came up on my mind is to get a shielded sleeve to protect my leds from the power cord.

Any better idea?


texts: Are dependent resistor values possible in Xyce?

texts: I need my resistor to be a function of a node voltage in order to simulate a battery. I can do this is ngspice by setting R=2*v(1), for example. Is this possible in Xyce (or is there a workaround)?


texts: Is it safe to connect lithium protection circuit to positive terminal of the battery?

texts:
I'm designing a lithium battery powered circuit, and want to include a battery protection circuit (e.g. DW01, but the question is applicable to other chips as well). All example circuits I can find on the internet place the control MOSFETs at the negative terminal of the battery. However, I want to have them at the positive terminal of the battery. I can't think of any reason why this wouldn't work, but I also can't find any reference on the internet showing it done this way, so I am afraid there is something I didn't think of. Usually I'd just try it out, but I don't really feel like blowing up a lithium battery ;)

To be clear, the (badly paint-modified) circuit I want to use looks something like this:


texts: Voltage generator and resistor in series

texts:
I'm following a course about electrical engineering at university and I have a question about an example the professor made: he said that if we were to take an ideal voltage generator and connect it in series with a resistor, the voltage measured between the free end of the resistor and the free end of the generator would be V = E + RI where E is the voltage imposed by the generator, R is the resistance of the resistor and I the current that flows trough the resistor.

What I don't understand is the reason why when I try this at home with a 220ohm resistor and a 9V battery, the voltage V is equal to E with the resistor having no effect on the voltage but only on the current the battery manages to output. Why does this happen?


texts:
To find the potential difference between the points A and B:
On applying KVL between A and B, why we do not consider the voltage drop across the 10ohm resistor?


texts: Why is earth used for ground? Literally earth?

texts:
I never considered earth to be particularly conductive. It's just dirt, after all.

However, I've seen "earth ground" conductive stakes driven into the ground in order for electricity to be grounded, because it will find its way down there.

However, it never made sense to me why earth would even provide such an effect: why electricity would bother to flow to dirt out of all the conductive goodness inside the circuit?

What characteristics of earth/electricity makes the current flow right into the ground?


texts: Prevent voltage to drop under threshold in solar panel

texts:
This is a solar charger for my smartphone built with two panels wich I want to keep attached all day long with the phone turned on.
When the sun is going away, voltage output starts to go under 5V and my smartphone repeatedly turns on the display to alert of power disconnection  wasting battery charge for a long time.
Under a certain voltage (< 4.7V) finally smatphone accepts disconnection and stops turning on the display.
Is there a way to disconnect the circuit if voltage drops down a certain threshold or better to keep voltage up until it's not possile anymore?


texts: Generate Square Wave with Fast Rise Time for Testing

texts:
I'm looking to economically generate a 1-2 GHz (configurable) Square Wave with a rise time of 200ps (or faster) to test the performance of various active scope probe designs. I don't need to be able to alter things such as duty cycle or power, however it would be ideal if the output was at least -10 dBm (71 mV RMS) across the frequency range. No modulation is needed beyond a simple periodic square wave.
Does anyone know of some economical off-the shelf equipment or evaluation board which would meet this need?


texts: How much of a surface mount PIN diode is semiconductor?

texts:
The problem: manufacturers provide a lot of information on the operation and characteristics of the devices, but not on what's inside.

I'm trying to incorporate the effects of a surface mount PIN diode in a full wave electromagnetic simulation. The only problem is that there is a portion of doped and undoped silicon in the diode, only I don't know how much.

It's apparent that the pads on the device packaging will likely dominate the interactions due to the diode, but the simulation is for a sensitive device so if possible I'd like to include all electrically active components.

Are there any experts out there who know roughly how much of these surface mount devices are doped / undoped semiconductor compared to the packaging? (the specific diode in this case is the SOD-882 from the SMP 1322 series, Skyworks)

Thanks in advance.


texts: Effective impedance calculation for noise removal from supply

texts:
I am working on single supply Op-Amp amplifier, referring to this post. While calculating the value of the capacitor C2, as to pass all the noise from the supply to the ground. I am unable to understand the logic behind the calculation. If there is noise on the 5V supply, it will pass through R1 and then pass to the ground via C2 capacitor.

If R1 & R2 are 10K ohm, then how the effective impedance will act as 5K ohm for the noise. Thus to reduce the noise up to 20 Hz, the value of the capacitor taken should be min 1.6uF. (I am NOT able to understand why parallel combination of 10K ohm resistor should be done, which equals to 5K ohm).
If the C3 capacitor is not present will the amplifier will amplify DC voltage as well as ac signal?
For calculating the value of C1, as to allow min freq of 5Hz should pass, how is the value of resistance should be calculated? How the resistors R1, R2 & R3 should be involved (I am clueless about it).
Same thing for C3, for passing frequencies from 5Hz onward.

I am looking for how to start thinking about the questions, in logical & step-by-step manner.

Original post by Analog Devices is here.


texts: Identify these components for bluetooth speaker

texts:
I am wanting to make my own DIY bluetooth speaker (first time electronics project) and I have found several good Youtube videos on the topic. However when it comes to finding the actual parts, I am struggling.

Many videos give different parts and I'm unsure of which would go together and if they are even compatible.

I like the design of THIS speaker in particular since there are few components that go into the build, however I cannot identify them and the Youtuber does not list their parts, just a link to their own page to sell the kit that is no longer functional.

I wondered if anybody could identify the specific part names/numbers?

I understand that they are as follows:

Bluetooth & amplifier chip
18650 Li-Ion battery
Protection circuit (I have seen micro-USB input boards with protection on them, but am unsure if this is the same thing or whether this is simply protecting against surges during charging etc)
Step-up module
2x 5W speakers
Capacitor
Micro-USB charger board

I have attached a screenshot of the video with all parts laid out


texts:
This question might seem very basic, but it will help me a lot if someone can answer it from the basics!

I have just finished my first year at college and there was a course on digital design, where we studied the fundamentals of digital systems and also implemented various circuits using ICs in the lab.

When we saw the IC in class, we just focussed on the circuit inside the IC - how everything is connected and what logic gates/ FFs are used. But while implementing circuits in lab, I saw that there were 2 power pins also, on each IC.

Why do they need power pins? Like, all that is present in the IC is a few logic gates (even FFs are logic gates at a very fundamental level) right? Logic gates do not require power when we have to use them right?


texts:
I am having the follow solenoid valves : 2W-320-32, which is marked to work on 24V, but seems like they open on 12V as well, so I am wondering :

What would happen in long terms if I am powering solenoid valve which is marked to work on 24V with 12V source ?


texts: Near field intensity in terms of antenna thickness

texts:
I've been told that the near field created by a thin wire "antenna" goes to infinity in a neighborhood of the antenna as the wire gets thinner and thinner.
However, I'm not able to find any tables or graphs of this fact. Could anyone provide a reference where I could check some values?


texts: Peltier Module TEC1-12706 draws only 2.7A. Is it normal or my unit is defective?

texts:
I had recently ordered a TEC1-12706 Peltier module from amazon. I tested the module as soon as I recieved with a 1.2V Ni-Cd to make sure its working and also to make sure of the hot and cold sides. I purchased it for a small mini cooler project.So, attached the Peltier module to a CPU heat sink with fan and the cold side with a small aluminium block and added the necessary insulation etc. and I was able to cool down a small beaker of boiled hot water to ice cold, though it didn't freeze.I ran the unit for like 45 minutes. The unit was powered with a 12.61V-2400mAh (3 Cell Li-ion ICR18650-24E) pack. The initial current draw was around 3.8A but quickly dropped to 2.6-2-7A and remained stable.Tried bumping up the voltage to 14V and current draw increased to 4.3A but reduced it back since I didn't was to ruin the module. So, is it normal for the device to run at just 2.7A current draw ? because most people on the internet who brought 12706 say the current draw is 4A and above at 12V.

Update: Guys finally I managed to get my issue fixed. the current draw of 6A is infact for Vmax. At 12V the initial current draw of 3.8-4A is okay. I finally managed to get ice. Got a 30ml aluminium cylindrical vessel containing hot water at 60C in my mini cooler to ice in 15minutes!:)..The main issue was the cheap thermal paste I had used initially that I brought for just $0.95.So, purchased another brand ZP Heatsink Compound $3 thermal paste(Thermal conductivity:1.22W/m.k& Thermal Resistance:0.201C-in2/w),removed my old paste and applied this to both hot and cold side.Everything is working awesome.Never thought a bad thermal paste could cause this much bad performance."Gotta change the thermal paste on my i7 too or its gonna fry too!!:rolleyes:"


texts: Cannot permute invalid or irregular data

texts:
I am trying to run a simple simulation for an NFC (Near Field Communication) system using a mutual inductor component to connect two coils. I have written a simple formula for the coupling factor k (\$k\$), of which distance dist (\$\mathrm{dist}\$) is a variable.

k = u0*n1*n2*pi*d1*d1*d2*d2/(2*sqrt((Lread*Ltag)*((dist*dist)+(d2*d2))**3))

i.e.
$$
k = \frac{u_0\cdot n_1\cdot n_2\cdot\pi\cdot d_1^2\cdot d_2^2}{2\sqrt{L_\mathrm{read}\cdot L_\mathrm{tag}\cdot(\mathrm{dist}^2+d_2^2)^3}}
$$
Now, my problem is that when I simulate the system (Transient) and applly dist as a swept variable, I see that from the Data Display Window that the number of points for dist is 'irregular'.

As a result of this, I cannot do a plot_vs() function.  For example, I cannot plot plot_vs(Uout,dist).

I am not very familiar with Advanced Design System, and so I need some help on what I might be doing wrong.

I'll appreciate your help. Thanks!


texts: LTSpice - Opamp Buffer Input Impedance Measurement

texts:
I tried measuring the input impedance of Opamp LT1128 Buffer using LTSpice. And from the simulation then maximum impedance is showing only 20k.
This particular opamp has 300MEG common mode input resistance, 20K differential mode input resistance and 5pF input capacitance. Coupled with the fact that the opamp is configured in a unity gain follower configuration, shouldn't the input impedance of this opamp measure in Mega Ohms?


texts:
I am trying to design a variable frequency Op-amp astable which works ranging from 0 to 2kHz. I found an useful lead which I attached below.

According to the reference, the frequency can be calculated using the following formula:

Where C=C1 and R=VR1

My question is: How can I adjust that circuit to make it work from 0 to 2kHz?
Also, I am planning to use a TL072 instead of LM324.

Reference: http://www.learnabout-electronics.org/Oscillators/osc42.php


texts:
A colleague and I had the idea to build Conway's Game of Life in a large 8x8' form factor using a 50x50 grid of RGB LEDs (RGB so that the grid can be re-purposed in the future). The idea is to build this thing in 4x4' sub modules (25x25 LED arrays) that can be driven separately and then arranged in whatever orientation. We were trying to come up with some details as to what we'd need to drive this kind of rig, and was hoping someone could offer some suggestions or steer us away from bad ideas.

Some of the big questions that we have right now for building one of these sub modules are:

Will some standard 5mm, 20mA RGB LEDs be bright enough to light up a 2"x2" cell with a thin diffusion layer on it?
If we connect the LEDs in a grid and drive them one row at a time we would need 25x3 control lines for the RGB anode, and 25 lines for the GNDs. In this case, if an entire row was on the theoretical max current draw would be 20mA x 3 diodes x 25 LEDs = 1.5A. Is this a valid assumption? Would it make sense to use shift register such as the MC74HC595 to drive the individual LEDs and then use another shift register to drive FETs or similar to drive the high current common ground? Or vise versa for common anode LEDs?
What kind of micro would we need to drive this? The plan is to do the processing on an laptop and then just send each frame we want to display serially to an arduino or similar to then drive the shift registers.

The budget we have in mind is ~$400/ sub unit. Let me know what you guys think about feasibility.


texts:
I would like to build an RFID-Zapper from the scratch (not based on a camera flash).

Since it is working with a high voltage, I prefer to ask first.

Does this look OK to you?

The capacitor is 330µF, handling 300V, the source is 150VDC and the coil is a self-wound coil, measuring 4.5 x 8 cm, insulated copper wire, 1mm thick, 5 windings.

Question

Can I plug the source directly at 150V to the capacitor or should I increase it slowly?
How can I know the time of discharge of the capacitor?
Will the coil generate a strong enough EMP to destroy the transponder?
Would it be possible for a second version of the RFID-Zapper to charge this HV capacitor with a low voltage battery?


texts: How to calculate thevenin's voltage for this circuit?

texts:
simulate this circuit – Schematic created using CircuitLab
How to calculate the Thevenin's voltage for this circuit? I am supposed to get 12.5V but I am getting 8.5V.
I tried it using KCL with node at R1.
When I did the KCL formula, considering V1 as voltage at R1, I got the equation as 2 - (V1/10k) + ((5 - V1)/10k) = 0.
This is the equation i got.. Is it right? Could anyone guide me as to how to solve and get to the right answer?


texts: How ac coupling in scopes does not give you a phase shift? Or does it?

texts:
For what i know, filtering something always gives some amount of phase shift.

So how do oscilloscopes with ac coupling don't have that?
Do they correct in software? If so, how they used to do it at the time of analog scopes?


texts: Op Amp LM324 Different Source + and -, + and Ground

texts:
I have an issue with Op Amp LM324.

First, I supply with this, and everything is work like op amp. I have output twice than input.

simulate this circuit – Schematic created using CircuitLab

But, when I use different source, the output is equal with input.

simulate this circuit

Then I change the schematic. Output has twice than input.

simulate this circuit

Does Op Amp need supply + and -, and cannot be + and ground? Thanks for your answer.

EDIT QUESTION AFTER 4 HOURS

Sorry it was my mistake. I didnot draw correctly.

Oke, let me clear this. This wiring has output 6 Volt.

simulate this circuit

Why this one has output that same with input?

simulate this circuit


texts:
I am trying to make a use of AD5612 DAC. It has a serial interface and I can not fully understand how to properly drive it. Given that I will be using only one DAC in normal operating mode with ADDR pin set to ground, my first 8 bit frame should be 00011 110, following by the second frame with 00 00 [D9:D6], and the third frame with [D5:D0]XX.

In particular, there are several questions:

Do I have to provide SERIAL BUS ADDRESS BYTE (frame 1) every time I want a new sample to be converted, or the frame 1 is only written on the power up?
Given the 10bit DAC, what should be the 2 LSB bits of frame 3?
When is the new sample available on the DAC ouput?
What's the purpose of the read mode, since I know the content of the register any way?

Here's the clock sequence for reference:


texts: Why am I getting negative voltage on MOSFET gate?

texts:
MOSFET circuit:

I have the following MOSFET circuit to current limit battery charging from an alternator. The alternator is currently not connected.
I'm using a DC-DC boost converter to provide 25V from the battery.

Gate voltage is between 0-25V.

Battery voltage is 12.6V.

Vgs is therefore ~ -13 to 13V.

simulate this circuit – Schematic created using CircuitLab

Driver circuit:

Explanation:

Q23 with pull-up provides 0-25V signal
Q26 / Q25 provides voltage follower (current source, 0-25V)
Q24 provides faster rise time

Oscilloscope:

When the driver circuit drains the gate (connects the gate to ground), the battery voltage spikes high (~25V), and the gate voltage spikes negative (~12V).

CH1: 5V MCU signal
CH2: SIGALT
CH3: Actual gate voltage
CH4: BAT

In the following I added a 5ohm between circuit ground and actual ground, as well as 10 ohm between 25V and Q24 (Q24 failed after 10 minutes of operation, presumably due to overcurrent). This has virtually eliminated negative gate voltage, but did not fix positive voltage spikes on BAT.

CH3: Vs

Math (purple): Vg-Vs

Vgs is ranging between -4V to 13.6V, which is well within operating margins of max +/- 20V.

Note: frequency measurement is incorrectly shown as 930kHz. When downscaling horizontally, it correctly shows ~19.2kHz.

Question:

Why am I getting the negative spike on SIGALT and positive spike on BAT? Introducing D21 seems to have reduced the problem, but not eliminated it. Is there a problem with my driver circuit?
Is it a problem to have a 25V spike for ~1us? If the frequency is 20kHz, this would mean the voltage is 25V for 20ms per 1 second? That sounds rather undesirable.
Can I simulate the problem in LTspice? It doesn't appear in my simulation. I'd like to experiment with various solutions to reduce the problem.


texts: Most accurate, available way to control a stepper motor with python

texts: I am doing a project where I am controlling a nema 17 stepper motor with a raspberry pi 3b. The raspberry pi is controlling the motor through a pyqt5 gui (python 3 is the language). I am using tb6600 drivers set to 1/32 microstep for breakout. My question is, what is the most accurate and efficient way I can control this motor (part of the novelty is not writing the script in C)? Right now I am just getting down low and dirty by using the rpi.gpio library and time.sleep() to pulse the tb6600. I have thought about using the pyqt qthread sleep functions and also applying rpi.gpio pwm to the tb6600. Accuracy is most important. Suggestions from experience?


texts:
I know the 'nominal' voltage of 110/115/120 is both based on Vrms and that stability @ any of those levels is pretty much a fairy tail.

I also know that most rectifiers will output ~130-150V after re-assembling the waveform & filling a comditioning cap.

What I'm not 100% sure on, and don't really feel like digging out my soldering iron & finding a few diodes to test it today, is the peak-to-peak voltage of the 110VAC 'hot' line.


texts: How to turn an electromagnet on and off?

texts:
I need to control an electromagnet as follows:

I need to switch it on/off every T seconds, where T is around 1 second.
I need to be able to change that time, using something like a potentiometer.

Which components do I need?

Please take into mind that I don't have much electronic knowledge (learning physics in school, including electromagnetism).


texts: Battery nominal voltage - can you confirm my understanding?

texts:
I am trying to understand why we can simply just calculate the usable energy that a battery has by multiplying the capacity and the nominal voltage.

Since the capacity  (available electrical charge) in a battery depends on the drawn current (unlike in a capacitor), we can't actually know what energy is in the battery because we don't know the nominal current at which the capacity was set. So in order to really know how much energy we can get from a battery, we have to measure/calculate it for every possible load.

Here is my thinking and please correct me where i am wrong:

1

Most simple way of modeling a battery is with a simple internal resistance. Internal resistance does not affect the battery capacity because the charge is conserved. Constant current draw can be modeled by an ideal current source.

2

With a current-source as a load, the current is independent of the
voltage of the battery (at least when the battery operates in its
operating voltage)
Power drawn from the battery in this model does depend on the voltage.
Available electrical charge at the certain current draw linearly falls with time.

3

For a LiOn battery, we usually see a graph like this - how the voltage depends on left-over capacity. This capacity does kinda relate to how much electrical charge is left in the battery in the form of ions, but it has mainly to do where we define the usefulness of the battery.  We defined the charge/capacity to be 0 when the voltage falls to 3V and for it to be at e.g. 2000mAh, when the voltage is at 4.2V. In reality however, there is more charge in the battery if we further drain the battery under 3V or charge it above 4.2, but it's either unusable (voltage too low), unsafe or it damages the battery in some way.

4 My doubt about the meaning of the nominal voltage

The energy received can be calculated with integrating Voltage and Current through time OR with integrating the Voltage through electrical charge.

The energy is represented by the surface under this graph. Nominal voltage is defined to be at the point, where the surface can simply be calculated with a simple multiplication instead of integration.


texts: I would like to use 2 momentary switches to controle a water pump (start stop). When you press start the pump should run until I press stop or there is a power outage. The pump should also be off when the power is back on again until I press start. What type of relay should I use and how should I wire it?