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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Building the second version of my IoT vehicle control unit (VCU) and want to turn on the ignition using FETS instead of relays

I need to build the "Circuit" block of this schematic. The ignition works when the 48V voltage supply is shorted with the ignition cable. Relays worked fine, but I want to remove all moving ...
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esp8266 occasional resets when controlled relay is energized

I am having trouble with a circuit that I have designed for an esp8266, that controls 4 relays. The MCU is flashed with esphome, and occasionally resets itself, after turning on one of the relays. I ...
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1 vote
1 answer
111 views

First PCB layout but can't validate yet [closed]

I'm learning some basic circuitry with an ESP32 Dev Kit and copied some schematics online to connect the ESP32 to external power, a relay and an input reed switch sensor. My problem is I'm still ...
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4 votes
4 answers
2k views

Two parallel relays for double current

Can I use two relays to increase current rating? I have requirement of 12 A, 240 VAC load, but I have 7 A, 250 VAC relays. Can I add two relays to make 7 A + 7 A, relay which is driven by single input ...
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using LM3915 to switch relay or motor

I am trying to switch either a 12v motor or a relay with the outputs of a LM3915. I have found an answer on this site about using a pnp transistor on the outputs to switch multiple leds. the circuit -...
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2 answers
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ESP MCU, directly drive BT136

I have questions about driving a BT136 TRIAC using a port of ESP8266-NodeMCU-12E. I have tested BT136: if you apply 1.2V from a AA cell between Gate and T2, this result in T1 and T2 conducting for ...
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9 votes
2 answers
411 views

Is this single transistor interface good enough for this relay-control?

I need to turn ON/OFF an 12V 10A SMPS supply by a relay. I want to switch the SMPS via its line input using a microcontroller. I need a normally open non-latching magnetic relay such that the SMPS ...
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1 vote
1 answer
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Is the same overcurrent relay used for both phase-to-phase faults and 3-phase faults?

In MV grid with no distributed generators, 50-51 overcurrent relays are used to detect both phase to phase faults anf 3-phase faults. In Italy, time independent characteristics are used inside these ...
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2 answers
63 views

Control 12V relay by using Arduino [closed]

I have an Arduino Mega, 12V relay module, and 12V external power supply. I want to control relay state (on/off) by using Arduino I/O pins (5V). Is it good idea to use following simple diagram? There ...
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Simplest solution to automatically turning off dash cam when ignition is off, but turn it on with button?

I recently purchased and installed a dash cam in my vehicle (large truck). It requires three connections: ground, constant ~12V, and ignition/accessory ~12V. I have connected the dash cam to ...
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1 answer
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Motor voltage spike

The circuit below is used as a relay in order to cut-off the common ground C- and Motor-. In my system, the m otor driver (Motor+,Motor-) is connected in parallel with the supercapacitors (C+,C-.) ...
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1 answer
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IR remote code amplifier

I am interested in amplifying output mod signal of my tv remote in order to use a higher power led/vcsel. Now, it should be as simple as cutting the emitter led and putting a transistor that would ...
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0 answers
33 views

What causes voltage drop when powering both 8-relay module and DE-10 Nano simultaneously using 5V and 0.84 Amps through a power supply?

I have a robot that have uses DE-10 nano fpga board stacked on top of another pcb board that acts as power distributor to other components such as linear actuator brakes, wheel brakes, spray gun, etc ...
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0 votes
3 answers
79 views

12V DC motor takes substantial amount of current when the direction is reversed

I am working on an underwater ROV. I am running four 12V DC motors using an Arduino Uno and four N-type logic level MOSFETs to control the speed of each motor individually. There are also four 12V ...
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1 vote
1 answer
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Relay system not always working

I've got a project I just put in place and I've run into troubles and it's a little above my knowledge level so I'm looking for some suggestions. Goal: Control a 220vAC pump from 2 locations ...
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Induction from latching relay at AC lines voltage

I am using an AC latching relay in my house to switch the same LED light from three or more places. Somehow the LED lamp seems to be very sensitive to parasitic voltages, because when I engage one of ...
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2 answers
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Switchover delay in my UPS circuit

I previously posted a question regarding my circuit. I was having a delay in my circuit releasing the relay when the power was down. Some people suggested to try out some stuff and I did that but, I ...
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4 answers
61 views

How to connect a bistable valve?

I need to control a bi-stable valve: Here is the typical wiring provided for such 3 wires type valve: But I don't want to continue to feed it when actually closed or opened which is normaly ...
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1 answer
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Replacing button switching 1.3V with microcontroller

First, sorry, I am a total hardware beginner (and 20 years since I had some electronics classes on the uni). I want to replace a mechanical switch (well two switches…) with something driven by a 3.3v ...
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1 vote
1 answer
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Looking for advice on a 12V relay circuit with ESP32

I've made the below circuit on a custom PCB and it doesn't appear to work as intended. For whatever reason, I'm seeing only ~3.8-4V on the coil pins of the relay rather than the expected 12V needed to ...
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4 votes
3 answers
137 views

How to cut power to an embedded device without damaging it?

I have to build a system that shuts-down an embedded device by cutting off the power supply (in case it stops responding). The device I want to turn off is quite sophisticated (it is a custom PCB ...
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1 vote
1 answer
44 views

Switch stuck in closed position

I'm repairing and old board that had a problem with its power switch, a C&K NE182UEE6AMP DPDT switch for 250V/6A (https://www.ckswitches.com/media/1409/ne18.pdf). I found a replacement and ...
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1 vote
0 answers
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One freewheeling diode for two relays? [duplicate]

I have two separate relays, both with different part numbers and coil inductances. Both are driven with the same 12V 'control signal.' When the control signal is removed, the inductance of both coils ...
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0 answers
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Which type of MOSFET is required to supply enough current to activate the coils?

I am using a NPN-PNP Transistor couple to act as a switch for activating the desired coil of my relay. If the H/L pin is in HIGH state, COIL1 must be supplied with 3.3V and if LOW, COIL2 must be ...
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0 votes
3 answers
91 views

A question of a controlling PSU safely

Is there a type of relay which is AC powered (does not require a DC supply)? Or any solution to the following issue? To simplify the question, inside an enclosure there is an SMPS and a module which ...
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1 vote
6 answers
156 views

RC time delay circuit to trigger relay

I'm trying to design a circuit that uses a momentary switch/push button to turn on an LED, then it turns off after 1 sec if the switch is held in the ON position longer than that. Below is a diagram ...
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2 answers
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Relay does not turn on when using a 2.5A 12V power supply

I have a relay that I am using for a project. The relay datasheet is here. I am using a 12V DC 2.5A power supply to supply power to the relay above, datasheet. From the datasheet, however, I saw that ...
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0 votes
1 answer
54 views

Using High Power Relays to Actuate an AC Motor

I want to remove the need for contactors in a motor application. Currently we are using a 1.5HP (1.1KW) motor and actuating it via a contactor. I have a PCB I am designing and want to use the ...
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0 votes
2 answers
77 views

How can I control firework igniters (e-matches) with an Arduino?

I'm looking to do an arduino based firework show and am wondering how I can find out the specifications of e-matches, and what i'd need to use to control them? Thanks
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0 votes
2 answers
51 views

bi-directional motor using SPDT relay and diodes

I have a bi-directional motor that I am trying to control using an SPDT relay. It is only working in one direction when I remove the circuit for the opposite direction, and it is either shorting or ...
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0 votes
1 answer
44 views

best 5v switch with 3.3v

i have a kobo with a serial port output providing 3.3v when the device is turned on. i want to use it to control a microcontroller 5v board with esp32 on it drawing max 200mA directly from the battery ...
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0 votes
0 answers
66 views

Switching between two circuits with DPDT with minimal current consuming

I am trying to design a system that will be powered by solar panel and 3.7v lithium batteries only. Im not electrical engineer, ...
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2 votes
2 answers
97 views

Can anyone help me with this delay problem in my UPS circuit?

I am trying to build an UPS for my laptop. My laptop doesn’t have a battery and battery port is damaged, only way I can power my laptop is from the DC port. But the problem is where I live power ...
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0 votes
1 answer
58 views

How to reverse voltage 12-24VDC to use a peltier element for heating and cooling

I'd like to use a standard peltier element as a heater and a cooler. The specs should be something around 12VDC, 30W. Electromechanical relays are not an option, the peltier should be used to regulate ...
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1 vote
2 answers
90 views

Switch off 2 power supplies using a single switch in a feedback loop

We have setup a solar stairwell project at home, using LED and salvaged batteries and this is what it looks like: However it may look, the circuit can be oversimplified to: simulate this circuit &...
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2 votes
2 answers
53 views

How to replace an 8-pin relay with a 10-pin relay?

I've been trying to reproduce the results of some experiments included in the Make: Electronics book by Charles Platt where 8-pin relays are used. The thing is that I haven't found DPDT 9V 8-pin relay ...
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0 votes
1 answer
46 views

6V to 220V relay switch

I want to control the coil of a relay using 6V input to turn on a relay which will activate a 220V device. Is there a relay that works for this application?
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0 votes
1 answer
73 views

How to control a 12V relay from variable voltage source of a LED?

I'm new to electronics and need your help. I have retrofitted a Chromecast to my car and have powered it using a cigarette lighter power adapter to USB. Currently the power adapter is hidden and ...
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-3 votes
1 answer
60 views

Problem with using 8 channel 433mhz 12 v relay module to control an overhead crane [closed]

I have recently tried to retrofit an existing overhead crane with a 8 channel 433mhz 12 v relay module with a receiver and a transmitter I bought online. My existing crane already has a button pendant ...
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2 votes
2 answers
85 views

Battery switching relay problems

I have relay that I'm using to switch between two batteries, if Battery 1 is on charge then it uses that, if not Battery 2. After 15 months it's stopped working. May I ask for suggestions on how to ...
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0 votes
2 answers
86 views

What PWM frequency should be used for a solid state relay (SSR)

I am planning to use an SSR (see product here) to PID control the temperature of a heat bath. According to the SSR40-DA the response time is < 10ms so I would go for a PWM frequency that is well ...
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1 vote
0 answers
27 views

Upstream pressure on solenoid valve

Does a solenoid valve consume more current when the pressure in the connected pipes is more than normal?
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1 vote
0 answers
54 views

What is the life cycle of a cheap mechanical relay

What roughly is the range of switching cycles that a cheap relay like the standard China ones for RPI and Arduino should withstand before breaking? I assume it not to be higher than 50 - 100k. The ...
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0 votes
3 answers
74 views

DPDT relay datasheet

I'm looking for a 5 V relay, low current (Arduino)- DPDT and I found chinese one - RY5W-K in Aliexpress I'm trying to understand the pinout schematic: where is the ...
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1 vote
2 answers
64 views

Running a 220V siren with a digital clock

I'm trying to run a 220V siren from a digital clock that, upon reaching the set time, outputs 7.5V for about 2 seconds then stops. Now, I don't understand much about relays, but I did a little ...
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1 vote
3 answers
75 views

How does the most effective circuit control multiple contacts with a rotary switch?

I will create an electrical circuit to turn on the LCD in 2 ways, namely through the microcontroller and through the header pin. If I rotate the rotary switch to the left then all LCD pins are ...
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0 votes
1 answer
31 views

High Voltage DC Motor (AC rectification) Relay, Current Limiting, and Smoothing Capacitor

Looking at controlling a HVDC motor like so - Type DC781 (2) LSG Operates on 6 - 220 VDC 84 ohm terminal - terminal resistance No load speed of 8000 RPM @ 220 VDC - 100 mA Stall current at 220 VDC: 2....
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  • 5
0 votes
2 answers
117 views

230V AC Relay won't switch off

I have been trying to control the grid circuit (Germany, 230V, controls 3 50W compact florescent bulbs) using a relay and Arduino Nano 5v pin. It usually works as expected, however sometimes it sticks ...
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0 votes
0 answers
37 views

Activate two path from one relay

I have to make a modification for a device in the field, that has only one NO relay that can be triggered. Now, there are two connectors, where on one, the GND needs to be deactivated and on the other,...
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0 votes
1 answer
66 views

Make before break relays

Are Make-Before-Break relays still a thing? I have a 12v DC system I would like to switch between power supplies in such a way that the device being powered does not lose power. Sorry, NOT BETWEEN ...
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