All Questions

0
votes
0answers
2 views

Is a PD controller necessary if VBUS is always >5V?

I'm trying to implement a board that will use USB Power Delivery. We want to operate with 20V 5A input. If we know the source will always be at 20V, is it necessary to put a PD controller on the board?...
0
votes
2answers
12 views

What does DC voltage reading from a DMM mean?

When a DMM is set to measure DC voltage, does it display raw voltage readings or voltages averaged over a time interval? An oscilloscope always reads fluctuations in voltage, but a DMM tends to give ...
0
votes
1answer
24 views

Missing pulse detector for low input?

I'm looking to implement a watchdog circuit. Tried the standard "missing pulse detector" schematic such as one from http://www.falstad.com/circuit/e-555missing.html - and it works well when the input ...
1
vote
0answers
14 views

High side mosfet-driver circuit configuration for current bypass

I'm designing a current bypass bms and having trouble switch mosfets between calls When i connect the high side gate drivers and simulate with Proteus the overall voltage appears at the topmost cell ...
1
vote
1answer
40 views

How can an induction motor be “self starting”

I read that all you need to start an induction motor is to apply the AC voltage, and with time the slippage decreases. How does this happen magnetically? If a rotor, connected to a moderate sized ...
0
votes
1answer
26 views

Making QI charging desk

i want to make my desk surface qi charger but i want a large surface so integrating a pd wont work. Can i dissatsemble the charger and add multiple coils to it, or i need to buy several charges and ...
0
votes
0answers
34 views

Controlling An Optical Shutter with Laptop [on hold]

I want to control the light exposure time of a light source using an optical shutter(blocks light beam when closed). My goal is to program the shutter to open for a precise time interval (say 5.25 ...
2
votes
2answers
60 views

Is using the CH340G on a commercial product a horrible idea?

I'm developing a niche product that will be produced at a fairly low volume (low hundreds). I'm using an Atmega uC, and one of the requirements is the ability to be field-flashable by the user. My ...
0
votes
1answer
20 views

Triac control circuit through load

Why is it that in every triac analog dimming circuit I find that the triac triggering circuit is fed through the load and not straight from the mains??
1
vote
0answers
26 views

Bulk header pin wire? [on hold]

Does anyone know where I can find the wire that header pins are made from, or even what its called? Or even what the type of metal would be? I need it in longer lengths, anywhere from a few inches ...
0
votes
0answers
28 views

What could be the issue with this tesla coil? [on hold]

Trying to troubleshoot this tesla coil we made several years ago. It used to work, and then it didn't. What could be wrong / broken? (To test it we're using the same 13w CFL bulb as in the video). ...
0
votes
1answer
29 views

Thin CAT6 cable - RFI problems?

I have got a short length (1m) of standard fat CAT5 shielded cable that runs inside a piece of equipment before the signal exits via a bulkhead connector to a PC. It's the old kind that is a real pain ...
0
votes
0answers
24 views

Washing machine causes noise on PC speaker [on hold]

When ever our washing machine is running, I can hear noise coming out of my PC speaker, the noise is really in sync with the way washing machine spins. I figured this out after a couple of times it ...
-1
votes
0answers
25 views

Which microcontroller for homekit alarm system [on hold]

I have idea to build own PCB for alarm system which should handle following things: GSM (probably via SIM900 or Ai Thinker A6/A7) RFID (most likely external PCB) Keypad (via touch display) Homekit ...
0
votes
2answers
53 views

How come rectifier diode current waveform is not distorted?

Shockley equation is non-linear but without any linearisation effort such as in BJT small signal biasing, half wave rectifier passes almost an undistorted half sine wave. In amplifier we bring the ...
0
votes
0answers
27 views

How to program aliexpress Xilink X-SP6-X9 FPGA? [on hold]

I am new to the world of FPGA's. I just bough a Xilink X-SP6-X9 (Spartan 6) board on aliexpress but I don't know how to program it. I got this one: https://aliexpress.com/item/32665068263.html?spm=...
1
vote
0answers
14 views

EZ430 Chronos wireless on battery vs usb power [on hold]

I have a Texas Instruments EZ430 Chronos watch, and I have an issue regarding the Chronos wireless (or RF) communication on battery power vs USB power. When I put the watch on ACC mode when on ...
3
votes
0answers
64 views

Is this symbol standardised?

Sometimes there are these two half-arrow symbols on PCBs and on enclosures. See the images, for examples. Those symbols are often placed near the screws, that are to be unscrewed upon disassembly. ...
1
vote
2answers
45 views

Constant current load circuit? (20 amp)

I'm pretty new to stack exchange and I've only just gotten my basic circuit analysis classes done in college. For my school's solar racing team, I've been tasked with designing a constant current load ...
0
votes
1answer
30 views

Understanding 3ph Transformer Specs

I am looking at a Delta-Wye with 480 on primary and 208/120 on the secondary. The transformer in question is Schneider's EX30T3HCUNLP. I came across this drawing in the spec sheet but I am not sure ...
0
votes
0answers
32 views

Itsy Bitsy M4 Locked

I am tryning to program adafruit Itsy Bitsy M4 Board using Atemel studio 7. I am trying just to program freeRTOS example through Ateml Studio. I have bootloaded the Board properly. When i am trying to ...
3
votes
0answers
44 views

Frequency Divider Analog Circuit issue

I am trying to implement a divide-by-two circuit quoted from the book "Low power CMOS circuits : technology logic design and CAD tools" by Christian Piguet Could anyone advise about the spice error "...
0
votes
1answer
39 views

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

Suppose we have an NMOS transistor with VGS> VT. When VDS is 0, the channel depth is uniform along the transistor. However, when we increase VDS, the channel becames deeper near the source and ...
0
votes
4answers
33 views

Phase control universal motor dimmer

I need to control the speed of a 220v universal motor using arduino and I am thinking to use an atteny85 ic with a phase control circuit (ltv814 to detect zero crosses and moc3052 to drive a triac to ...
1
vote
3answers
89 views

how can homeplug device send ethernet down mains wiring

AFAIK when you wire a patch cable out of 5e, you only need to wire two of the conductors correctly for it to function as a ethernet cablebut you won't get gigabit ethernet. However Homeplug uses ...
10
votes
3answers
409 views

How does an ARM MCU run faster than the external crystal?

So before this I only worked with simple 8 bit Atmel MCUs and I realized on my development board schematics it has only a 12Mhz crystal, yet the MCU operates at up to 100MHz. (I think the default is ...
0
votes
2answers
33 views

Making a wireless lavalier microphone with ESP8266-07

I'd like to make a lavailer microphone and receiver using two ESP8266-07 Wifi modules. I'm using a condenser microphone with it's own preamlifier using 5V. I want to compare my signal with 300kHz ...
0
votes
0answers
14 views

STM32 RTC with HAL libraries

I am working on stm32l053 (nucleo 64) and I want to track time with integrated RTC. Since I am quite new to stm32 development I am using CubeMX and HAL libraries. My problem is that the time is not ...
-1
votes
1answer
51 views

9 volt battery and a 10 watt IR LED [on hold]

I connected a 9V battery to a 10V IR led and the brightness lasts 3 seconds before "dimming" down to a soft glow. How do I maintain the initial brightness? Do I plug in a few AA or do I buy a 30 or ...
0
votes
2answers
39 views

VI component tester not working properly when capacitor is placed parallel with diode

I am trying to repair mainboards with VI component tester. (Such as this device and that device.) I check the characteristic VI curves of the components on the card and identify the defective parts ...
0
votes
0answers
40 views

Complex Boolean Algebra simplification problem [on hold]

Anyone has a solution on how to continue this simplication? \begin{align} X &= \bar R \bar S \bar T \bar u + \ldots \\ &= \bar R \bar S (\bar T\ldots)+ \ldots \end{align} Attempted but don'...
0
votes
2answers
38 views

I2C Communication Between STM32F3 and SSD1306

I am trying to write data to my 128x32 OLED display. I researched it online and found that it has the SSD1306 controller connected to the display. It uses the I2C protocol and it only has 4 pins (VCC, ...
3
votes
4answers
203 views

analysis of BJT PNP type - why they can use voltage divider?

Hi everyone, I try to understand why some books used in a voltage divider to find the Base Voltage? or maybe the right question is HOW they can use voltage divider if there is base current? what I ...
0
votes
0answers
26 views

What’s the disadvantage for solving 5 variable Kmap using overlay and reflection method? [on hold]

As far as I know solving kmap using Gray code is widely used but is there any disadvantage in it?
0
votes
2answers
35 views

Power rating of a UPS

I find it odd that manufacturers specify power rating of Uninterruptible Power Supplies (UPS) in VA instead of Watts since VA doesn't tell you how big of a load the UPS can supply. A case in point is ...
0
votes
1answer
28 views

GAN FET gate current requirement

I'm looking for advice in making sure the FET driver I've chosen is capable of driving the FETs I've chosen with turn on time as low as possible. I'm going to use the LMG1210 and EPC2020 with 12V ...
0
votes
1answer
48 views

CPU architecture

im very new to CPU architecture! I wanted to ask, what is the Data memory component in the image below, is it writing/reading to and from RAM or Cache? And also what is the sign extend used for? I ...
5
votes
4answers
243 views

Is there a down side to setting the sampling time of a SAR ADC as long as possible?

In configuring the sampling time for the internal ADC of a micro-controller (STM32F446RE) to sample the output of a current sensor connected to a PWM controlled motor, the sampling is triggered at ...
0
votes
1answer
52 views

What is the cost of converting 12V (lead acid battery) to 220V and back again to power 12V appliances?

I have a small house measuring ~ 8m x 4.5m. It is in Indonesia and power outages are expected daily. Probably the daily power outage is on average less than half-an-hour, but sometimes the outage can ...
12
votes
6answers
2k views

Placing bypass capacitors after VCC reaches the IC

I have a question about bypass capacitors and their possible placements. I am designing what I hope to be a double sided PCB, which has the VCC and the vast majority of the data lines on one side, ...
0
votes
3answers
77 views

Short Circuit Question

I know that static electricity can damage components, even if it does not destroy them or “break them” studies and tests have shown that it could decrease performance even a little if no noticeable ...
1
vote
0answers
15 views

Questions on types K Map [on hold]

What's the disadvantage of Overlay K Map vs the Reflection K Map and vice versa and what's the differences between these two
1
vote
1answer
43 views

Linear Regulation Concept Confusion

I was watching one of Jacob Baker's videos (http://cmosedu.com/videos/f10/ece5472/lec1_ece5472_video/lec1_ece5472_video.html) At minute 19:30, he explains the concept behind linear regulation: His ...
0
votes
3answers
59 views

int functions with no return statement

In a course I am taking on embedded systems, I program LPC1768s which are based on ARM using C. The main functions are always of int return type. However, there ...
0
votes
0answers
16 views

Interfacing with tft lcd(ILI9225) via SPI

As an exercise, I'm trying to make a driver for ILI9225 TFT LCD using SPI. (This one https://www.amazon.com/HiLetgo-ILI9225-176x220-Support-Arduino/dp/B00LSG5HI0) I consulted a datasheet of ILI9225 ...
5
votes
1answer
356 views

An overseas company is making a machine for me and they need to know whether I want 1,2 or 3 phase and what voltage

I'm in Quebec and the company making the machine is in China. The machine is an industrial sized T-Shirt sublimation machine that does two sided printing. So there's a large heated plate that is ...
1
vote
1answer
33 views

General open license PCB GPS antenna

Is there a basic passive GPS reference antenna design that would be considered fair-use or "free to use" that can be placed on a PCB as a strip antenna or patch antenna? I'm looking not to violate ...
0
votes
1answer
30 views

Low power 100MHz sinusoidal modulation laser driver [on hold]

I am looking for a low powered laser driver which can modulate pulses at 100MHz sinusoidal. Is this possible, something that you have come across or possible to custom design. I am looking for ...
0
votes
0answers
20 views

Which power supply choose for lineal actuators?

I have two actuators each of them with the following characteristics: 16 inch, 12v, load 750 N, travel speed 10mm / s, duty cycle 25% BUT Current Draw is not specified, and I have no access to the ...
0
votes
0answers
11 views

How do you properly install backup power delivery? [migrated]

I have a backup power bank made of an inverter and car batteries. It charges when the grid power is on and turns on when the grid power turns off. However, my "electrician" repurposed the grounding ...

15 30 50 per page