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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22 views

Supply power for a relay with same source as pump connected to relay

I would like to know if relay will work normally when I supply electric power for the 5V relay with the same source (classical 5V USB charger) as the source for a water pump (3.3~5V) connected to the ...
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1answer
75 views

why relay transmits signal with diode led added to it [closed]

I have a problem with relay. When i want to add a led diode to see that signal from the transmitter is working, my relay it causes that the coil has a transition what cause that a receiver is turning ...
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How to detect if a light bulb is burned out or blown or failed in Arduino [closed]

I have got an assignment to do by my interviewer in Tinkercad where on click of button bulb has to glow if the bulb is failed/blown/burnt then a mini led near button must blink else if bulb is working ...
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2answers
119 views

12V logic control of 3 LEDs

I am building a circuit and am stumped without using many relays to achieve the result. I would appreciate any help I can get. Basically I have 3 different colour LED's in a (push button) some of ...
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1answer
76 views

Form C (SPDT) Relay Failure Modes and Detection

This is a question about the failure modes of an SPDT (i.e. form C) relay. Specifically, I am interested in electromechanical relays for an automotive application. I understand that either contact ...
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2answers
45 views

Can relay source and switching source be the same?

I'm working on a schematic for a power supply system for several linear actuators. I would like to minimize the power supplies needed to run the system. Can the source used to switch a relay be the ...
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5answers
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Why are there three pins in this relay diagram?

I found this diagram on relays from A Guide To How A Relay Works. Why are both 2 and 3 needed? Wouldn't just one be sufficient? I am assuming that when the relay is powered, 1 gets magnetised and ...
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1answer
53 views

Noise from a relay during switching

Is okay to have a load use the same ground as the coil supply of the relay. From my understanding relays do sometimes 'bounce' when switching from N/C to N/O. This inturn can then create some form of ...
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Pass multiple 24V slow-changing binary signals over 3 wires using some multiplexer-demultiplexer [closed]

I need a device which looks very simple. I've expected to just be able to buy it for few dollars, but I was not able to find one. I need to replace multiple 24V wires that can only be on and off with ...
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1answer
61 views

Will this battery bank electrical diagram work as intended?

This diagram is the plan for my van to have a secondary bank of 12 V batteries in the back to run an inverter to power some equipment. Originally my only extra requirement was to make sure the ...
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1answer
96 views

Driving relay coil with 12 V from 24 V source

I'm looking for a solution to drive the coil of a relay (G7L-2A-X DC24). It requires 24 V, which can be reduced to 50% holding voltage after 100 ms. My initial thought was to build a generic buck ...
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2answers
125 views

What manufacturer is this contact?

I have a relay contact, that I am trying to identify. It is from an Audi, who mostly use TE/Tyco, but this is different. It has this marking on it: Which I have tried to replicate here for clarity: ...
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1answer
63 views

Relay does not switch off

I have what I thought was a simple relay circuit but the relay is always on. This is the part of the project that is not working Q5 never switches off. To simplify it further I removed the relay and ...
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5answers
70 views

Latching relay but self resetting (to off) on power off?

I'll try explain my problem: I am trying to make a simple circuit that powers on when a momentary switch is pressed but then stays on until the power source (feeding the lamp) is then removed. I want ...
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3answers
49 views

Using relay instead of L293d

I want to control a dc motor that I have . I don't need any speed or direction control just plain on/off. I was wondering if using a 5v dc relay is better or worse. My only requirement is to have as ...
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1answer
37 views

Need circuit modification for using a PC814 opto coupler to invert relay operation

I have tried every possible way but was not successful for the operation required. When AC Power 220V is fed to the PC814 optocoupler, the relay should turn off. Please suggest modification in ...
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1answer
37 views

DC Power Relay 12V inrush Current

I have a question regarding 12v dc relay circuit design. About 350mA flows through the relay coil from the 12v power supply, so the pmosfet specification was selected as vds -30v, id -2A class. The ...
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2answers
46 views

Should I be concerned about switching power supply to a refrigerator compressor with a standard SPDT relay?

I have a 12 VDC refrigerator compressor that is powered by either a battery or an AC-DC converter. Currently, I manually switch power sources whenever I need to. What I would like to do is set it up ...
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2answers
91 views

ULN2003 relay driver

I designed a Raspberry Pi shield PCB. There are 6 relays on the board and a ULN2003 relay driver to control these relays. The BCM pins to the relay driver are marked in yellow below. When two relays ...
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1answer
58 views

Doubts regarding relays

I post this question asking for advice. I am working on a personal project for my garden and I want to automatize a water supply system, more specifically a 1/2 HP water pump and a motor. Both work ...
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1answer
75 views

Fan speed control using three relays

I'm trying to control the speed of a 12V(0.14A max current) fan using three relays. It should have four states which are turned off, low speed, medium speed and high speed. What's the correct wiring ...
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0answers
73 views

Trying to automate a drill

I’m very desperate to solve this problem so any advice is greatly appreciated. I got a deal on a 9A corded drill and took it apart today after testing to make sure it has enough power to do what I ...
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1answer
125 views

Why is my latch circuit not toggling?

While I am waiting on some parts I made this circuit in a simulator. When S1 is pressed it should toggle the relay K1 and latch in that state, turning on the other LED. When I press the switch, though,...
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1answer
54 views

I want to control 24V relay with NVIDIA Jetson

I have NVIDIA Jetson Nano Developer. I want to control a 24V relay with Jetson pins but I am undecided on which method to use. (Transistor, MOSFET) The other thing to know is that Jetson pins work at ...
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2answers
76 views

Optocoupler relay driver - Help needed

I build the following circuit found in some websites, and the relay is on without applying any voltage to the optocoupler. These are the details: The relay's coil resistance is 720R. As soon as I ...
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0answers
24 views

Adding LED lights to old F150 ('90)

I want to add auxiliary LED backup lights to my old F150 and strip LED lights inside the camper shell. I want them to be switched when the ignition is in ACC or RUN position. I want the AUX backup ...
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2answers
94 views

Reverse voltage spike protection on high-side of a (coiled) relay without flyback diode

Post-answer edit: as pictured in the question, the circuit would burn the MCU. While the original question was about how deal with reverse current coming out of the JD1912 relay, I ended up building ...
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2answers
76 views

Replace 5V relay module with 3.3V relay

I'm working on an electronics project that was using an Arduino to drive a 5V relay module specified here. The relay switches a 240V AC (upto) 10A load. I have now moved to using an ESP32 which uses 3....
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40 views

ADW1205HLW latching relay heating issue

I want to take the advantage of latching relay to remove power dissipation from the circuit. I am also using ADW1205HLW dual latching coil relay but faces an issue of heating even after set or reset ...
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2answers
74 views

24V Bridge Rectified Relay Circuit blowing L7805 & PIC18F

I've got a circuit which is powered using a 24VAC transformer fed into a KBU606G full bridge rectifier to generate 24VDC. Originally there was a 470uF smoothing capacitor, however I was unaware that ...
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1answer
69 views

Can One Flyback Diode be used for multiple relays controlled by the same switch?

I am working on a project where several 12V relays need to be controlled by the same push-button switch, essentially running the relays in parallel. I wondering whether relays configured in this way ...
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2answers
69 views

No stock anywhere - relay driver [closed]

I used this relay driver in a design, but there is no stock anywhere as far as I can find. I have been looking for similar alternatives, but it seems to be hard to find anything similar even (not ...
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1answer
82 views

Sub-miniature signal relay (normally closed SPDT) getting stuck due to arcing

I have a 24V motor which is driven bi-directionally with PWM using DRV8873 H-Bridge motor controller. The circuit looks as follows: For normally driving the motor in either of the direction, I switch ...
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1answer
29 views

DPDT (110V) with memory

I have one switch that should control two power lines (A and B) with lamps. ...
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3answers
138 views

Why can't I route USB lines through a relay?

I need to connect two phones with USB-B Micro ports through a relay. I need the relay because I need to control when the phones are connected. I made two USB-B Micro cables with wires on one end. One ...
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2answers
64 views

How to connect a load to a relay

I know the conventional way of wiring up a relay would be Option 1. However, I have seen Option 2 on the famous source of info (Google images). Is there anything wrong with Option 2 when it comes to ...
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3answers
436 views

Relay protection circuit

I came across a relay circuit that uses two diodes and a capacitor. I know the diode across the coil (D1) is a flyback diode and that capacitor (C1) is a filter capacitor. What is diode D2 for?
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1answer
96 views

How to modify this circuit so that the second LED turns off completely?

Circuit simulation is here There are two parts to this circuit. The first part is a switch that is either floating or grounded, controlling a large number of relays via pnp transistors. (Many relays ...
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1answer
77 views

ESP12E : GPIO01 & GPIO02 Usage

I'm making a circuit for driving Relays, LED's from push button and few other functionalities from ESP12E module. for which I'm using simple Transistor driving circuits as shown in image. In this I'm ...
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1answer
90 views

Which relay do I need for 240V input and 5V output?

I am putting together a PIR system and need a relay with 240V 13A, UK mains, input and a 3.3V output to go to a Raspberry Pi. The Raspberry Pi needs to listen for the presence of the mains PIR device. ...
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1answer
51 views

What is the initial input used in a NOR gate for a reset-set latch?

What happens the moment the reset-set latch is switched on?
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1answer
29 views

ESP32 driving 3x 5V Relays sending hi/low power at bootup

I want to try and understand why the Relays get a "pulse" or hi/low signal to all the Relay pins after a POWER on boot. Normally this wouldn't be an issue for a light or other powered device ...
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2answers
94 views

Can I switch a 5V relay shield high straight from the power supply?

2I've bought a smoke alarm with a relay for my 3D printer. If the smoke alarm detects smoke it switches its internal relay. With this I thought I could switch off the printer. The thing is that after ...
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2answers
72 views

NOR gate implemented with 2 relays, schematic with 2 NOR gates with feedback loop

You have two NOR gates here, on the left side highlighted in yellow and on the right hand side highlighted in pink. Each NOR gate is implemented using two relays. In the yellow NOR gate, what is the ...
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3answers
600 views

Current surge protection for relay contacts when closing

Here's a simplified diagram of a circuit I have: simulate this circuit – Schematic created using CircuitLab The battery is 24V. The relay is rated at 8A. My load draws 2A maximum. The ...
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2answers
97 views

Opamp delay off circuit check (updated)

I have a relay that I want to have a 3 second delay switch off from when a pressure switch (normally open) returns to the open state. When the pressure is below a certain level the pressure switch ...
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2answers
62 views

Understanding battery capacity measurement circuit [closed]

I came across this battery capacity circuit on the internet and it seems interesting and useful. So I would like to build it myself. However, I don't fully understand the working of some of its parts ...
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4answers
1k views

Why a low pass filter across relay contacts instead of a high pass filter?

I have found a snubber, it is a low pass filter. It doesn't make sense to have a low pass filter across the contact. I would consider transients such as arcing to be high frequency; therefore, a high ...
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2answers
82 views

Why won't this mechanical relay close NO contacts

I am trying to close the normally open (NO) mechanical relay contacts using the circuit below. . The mechanical relay is Panasonic Relay. I notice that when I give the high command for my GPIO I do ...
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1answer
128 views

Help understanding a motor control circuit for a lathe

I have a lathe with a 1.5 hp 220VAC motor, built in the late 1980s in Taiwan. For lathes of this vintage, a "normal" motor control circuit consists of a couple switches (for forward/reverse),...

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