Questions tagged [relay]

A relay is an electrically controlled switch. Electromechanical relays use an electromagnet to activate mechanical contacts, solid-state relays use semiconductor switches.

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28 views

Can I get power from my Thermostat's AC relay wires?

I have a 2-wire thermostat that activates my baseboard heater when the 2 wires are shorted. I did an experiment closing those two wires with a relay and got that working well with an ESP32 as the ...
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57 views

Adding logic to existing 240 V AC circuit

I have some heating circuitry which runs on 240 V. I need an output from an XOR gate from two points on this circuitry. I was thinking I could do the gate with relays but couldn’t find any relays with ...
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I need some help for my project

I need a favor I was trying to recreate this circuit but apparently for some reason, it doesn't work. The idea behind this project is that when the user makes a phone call from his phone to the phone, ...
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20 views

Can a faulty TVS diode cause power supply problems?

I have no power feeding the mosfet base with positive signal to switch on the relay that powers the ecu. The mosfet is to the top left above Q111. The TVS is the big SMD next to D100. The fault is ...
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48 views

Control 12v relay in series with 3.3v

I would need to control 4 relays (300 mA each) with an esp32. Relay will open and close at the same time so i not need a dedicated control. As I'm not expert I would like to ask you if you can propose ...
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Is it necessary to connect relay contact at voltage zero?

While disconnecting relay contact, it is recommended that the action should be done at or near current zero. As the contact area decreases rapidly, a spark is generated due to high current density. ...
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2answers
37 views

Double powering relay

I have a problem with my circuit and I want some help. I have an input connector connected to a dry sensor. It will send 0 when it's ON. So I made this circuit to protect my CPU. My problem here is ...
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57 views

Do DIN rail mount interface relay modules with a “spare” terminal exist?

I'm currently designing an industrial control panel that I'd like to be as compact as possible, and was looking at interface relays, and was hoping to find a specific feature, but now I'm not sure it ...
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21 views

Wiring up ESP8266 relay (Shelly 2.5) to power receptable

I have several of the Shelly 2.5 relays: https://shelly.cloud/knowledge-base/devices/shelly-25/ I'm trying to wire it up to a power board. The power board has four outlets, so I'll assume I need two ...
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1answer
57 views

Using a UA741 IC as sensor for an existing AA LED

I am trying to know if an air conditioning is ON/OFF (Daikin with only Wired Remote Control). I want to read its LED. The circuit is fed by a simple 17.8 V two wires from the machine. I've read the ...
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42 views

I need direction with part names and/or a diagram

Im suck!!! I have a project with two separate 12v dc connections. I need one to be always on until the second one is activated. When power is there for second 12dc output I need he first one to shut ...
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35 views

Options to control (fast switch) a 12V LED DC with MCU - mosfets vs. relays vs. SSR vs. mosfet relays vs. something else?

(Newbie alert) I have a 12V 3A light that I want to control in a ~12V DC circuit (lead acid battery, stator coil). The light shares a common ground with every other light unit in the circuit. I was ...
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One Channel Relay Board with NRF24 / WiFi connectivity with built in power supply

I have been looking out for a board which has a one channel relay along with some wireless connectivity such as a NRF24 module or a Wemos D1 Mini attached to it aong with a built in power supply. Is ...
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2answers
47 views

Controlling 32 solenoid valves from a single BeagleBone Black

I am trying to control 32 solenoid valves from a single BeagleBone Black. My EE skills are not up to par for this task, but I am learning. In this system, at most one solenoid will be active at any ...
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83 views

Arduino spuriously resets with power draw

I have a simple circuit, pictured below, that uses an Arduino to control two large bidirectional motors via 12V relays. Normally this works a treat, but sometimes the Arduino ends up resetting itself. ...
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94 views

Is there such a thing as a fail-safe, low-power relay?

Background Let's say I have a device. I can't give details, but, like many heat-producing devices, it's intended to be used for a limited period of time, but if left on indefinitely can be very ...
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78 views

Why is this relay circuit with an ESP32 not working?

I have set up a circuit as described in the picture. The circuit works so far, the ESP switches all relays and switches on the circuits. The problem is that as soon as I connect the motor, which is ...
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4answers
55 views

Single pole triple throw analog passthrough

I have a circuit that will simulate a device. The device in question normally communicates by adding/removing resistance from a generated signal, the source of the signal will then measure the voltage ...
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36 views

how wire a 24 vac normally closed float switch to a relay to turn power on and off to a 120 vac clothes washer [migrated]

Hi: In over my head just by being here so thanks in advance for your patience and help. My goal is use a 24 vac float switch (which sets in an overflow pan) to interrupt a 120 vac circuit that runs a ...
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3answers
56 views

Help with SP3T relay (on-off-on)

I don't really know electronics, so please excuse my lack of probably even basic knowledge Ive modified a guitar, with SP3T/DP3T switches, which connect guitar pickups in different configurations (...
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96 views

5 V relay connected to Arduino

I have a 5 V relay module connected to WeMos D1 board. The load is a small electric cooker. The code turns on and off the relay every 5s for testing purposes. digitalWrite(pin,HIGH); delay(5000); ...
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2answers
87 views

PCB designing consideration of high speed (0.5 Hz) relay load switching

Can this design cause any problems? I'm planning on switching 75W (220V) loads with this relays. I'm using 10 such relays and terminals (HB9500M). Note that it's highly unlikely all of the relays to ...
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Can I use a Sonoff 4CHRPRO3 to switch 10V DC

I need a DIN Rail 4 Channel Relay controllable over IP. It needs to switch a 10V DC control signals. I found the Sonoff 4CHRPRO3 which seems to fit my requirements and also it is low cost (It has only ...
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1answer
47 views

Switching 12V vehicle headlights with Arduino / Mosfet combination

Ground level noob here, started to tinker with electronics at the beginning of this year after I couldn't get any electronics shop in my town replace my bike's gauge cluster SMD LEDs. I learned few ...
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41 views

Help fixing a power switch

While disassembling a Sega Saturn to clean it, I removed this power switch: I needed to separate the top grey button (1 in the image) from the rest of the switch. After verifying with a multimeter ...
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250 views

Relay flyback protection

Is this the correct way to put a diode for flyback voltage protection to protect the infrared heater? And do I need to put a flyback protection for the Arduino pin or Vcc?
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41 views

How to toggle relay with single push-button

I believe there is a simple circuit, that uses a single non latching push button (1 or more pole possible?) to toggle 12V relay. 1 press - ON state, another press - OFF state and so on. I can't find ...
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1answer
19 views

AQW610EAH-PhotoMos Relay

Can we apply voltage across 1 and 2 pins to control normally closed (N.C) and to pins 3 and 4 for normally open (N.O) at the same time in AQW610EAH ICs (pin diagram of that IC above)? Or only one N.C ...
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31 views

Raspberry Pi Single-channel relay with 6 pins pinout decipher needed

I've got this single-channel relay for my Raspberry Pi. The relay has 6 pins instead of the usual 3, more over out of the box there was a jumper connecting 2nd and 3rd pin (I'm counting pins from top ...
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2answers
85 views

Mechanical relay circuit schematic and PCB. What is wrong here?

I built a relay that closes when a GPIO gives a GND signal. I have tested the circuit with a breadboard and it works with the same components (except breadboard uses THD diode and PCB uses SMD), but ...
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40 views

Relay module and DC motor not working

I there, I've got this code running on an ESP8266 ...
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1answer
28 views

Switching 2 momentary outputs sequentially with one momentary input… how?

so I have two buttons I need to trigger momentarily with a relay for each, the triggering needs to be done with a foot pedal that has a NO and a NC state with each press of the pedal it needs to ...
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239 views

Understanding driving a relay with a transistor

For an embedded application, I'd like to drive a relay using a transistor. At the moment I'm experimenting with a BC547, but only because I've still got some of them lying around. The transistor I am ...
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2answers
57 views

Charging lithium batteries while supplying power to load

So, the problem is that I want to charge (with 19.5v laptop charger) 4s config lithium batteries while at the same time supplying power to the load (In my case, portable speakers, but also want to use ...
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1answer
61 views

Transformer synchronization

I am reading a book about transformers and I am confused by the following paragraph about synchronization check: When the transformer trips or is taken out of service, the primary and secondary ...
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3answers
81 views

Safety of immersion water heater

I would like to build a sous-vide circularor, using a PID-controlled immersion heater. I've read that as the product wears out, there might be some electricity leakages, so I would like to make the ...
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31 views

Relay: wetting contacts before using sub-wetting current

I'm considering using small signal relay for my application since I need to switch shunt resistors to measure currents from 1uA to 10mA (two shunts) with voltages from 0V to 5V. Now, it's clear for me ...
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2answers
26 views

PCB Trace Width : Common (LINE) Trace for 2 Relays

I am designing a simple switch controlled relay board. On board I have two 5Vdc 10Amp Sugar Cube Relays which will receive 230Vac from Terminal block connector and will be controlled with 5Vdc input ...
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48 views

Did I use Diodes and the Relays correctly in my Circuit Design?

I'm a beginner and recently started a project where I build my own portable bluetooth speakers. I already have a rough layout of the whole thing. I basically want to power a 2x50 Watt Amplifier with ...
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2answers
32 views

Control 12v DC motor with arduino and two relays in both directions

I am using an Arduino and two relays to control 12V DC motor in both directions. For the first trials it worked fine. Finally, my Arduino was fried on another direction swtich. I think there is ...
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1answer
107 views

How to power WeMos D1 Mini without USB?

The title does not tell the entire story. I have successfully powered my WeMos by supplying 5vdc to the 5v pin. My power source is 12v battery so I am using a buck converter to drop the voltage to 5v. ...
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1answer
34 views

battery low voltage cut off breaker (manually reset)

First off, I am aware that premade devices like this exist however I have been unable to find any that fit my exact needs which are as follows. 0 power draw when in the off state Minimal voltage drop ...
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50 views

Suppressing noise and ESD from relay into microcontroller

I'd like to read from a relay on a CNC machine with a microcontroller running at 3.3V, the wire will be 1-1.5m twisted pair from the micro to the relay and screwed in to a terminal. There's a lot of ...
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36 views

How to get desired current on output of relay's module

I'm building automatic garden watering system using Arduino Uno 5V relay module - this one https://www.amazon.co.uk/2-channel-trigger-module-JQC-3FF-S-Z-RBTMKR/dp/B01NAJ67ML, here are technical ...
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36 views

Is powering the Nuvoton N76E003 with just the UART0 pins legitimate?

I bought an 8 channel USB/UART controlled relay board from banggood.com: https://www.banggood.com/2-in-1-DC-5V-8Channel-USB-Serial-Port-Relay-Module-UART-RS232-TTL-Switch-Board-CH340-for-Windows-Linux-...
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90 views

Why does Arduino get damaged when used in this relay circuit?

I am controlling a heating element using microcontroller development board (https://store.arduino.cc/arduino-nano?queryID=a777b4d5d5a1040ab95d2450172b4ef2) using the following circuit. It worked fine ...
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49 views

Switching 230V load once every second

So I build a binary clock with led's as outputs. And now it has been suggest to me, that I should make it bigger and use lightbulbs instead of led's. At first I thought I would just use relays, but ...
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1answer
36 views

manual reset relay

I am looking to get some help on something. I am trying to set up a system for our CMM's at work. The machine will crash itself if the air pressure is drained too slowly, but if you shut it off fast ...
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2answers
59 views

Surge protection in power supply

I am building an RS485/modbus controlled device for sensing AC current and switching on/off AC loads. The schematic is given below. 5V DC power for the device and RS485 bus connection are provided ...
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4answers
352 views

Normally Closed Latch Relay

Are there any relays that essentially have the same logic as an SR Latch? Specifically I need one that will latch when power is lost to the coil and then require a separate signal to reset or "...

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