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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General wiring questions: high power LEDs, relay and microcontroller

I think I understand the Raspbery Pi GPIO pins and most of how this diagram below works, at a high level at least. First question, it's not clear to me exactly how the middle part with the ...
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20 views

Remotely Toggle Relay

A while back I decided I wanted to get into electronics, after which I bought a number of components to get me started, along with the Raspberry Pi and breadboard I already had. I am now wanting to do ...
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237 views

Why would I need a relay between a DC motor and my Arduino?

I was told that I should put a relay between my 5V motor and my Arduino. I asked why, but they didn’t know. Why do I need to separate them with a relay? The motor requires 5V and the Arduino provides ...
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31 views

Controlling Wireless Relay [on hold]

I've been watching some videos recently, and I've really gotten into home automation. What I am hoping to do, is create some really simple switches that allow me to toggle simple electronics around my ...
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32 views

what relay switch to use to control a 1500W 120V 12.5A heating element? [on hold]

I am trying to switch ON and OFF a 1500W camco heating element powered by a 120V GFCI outlet using an Arduino Uno (5V DC). The heating element is being used to heat upto 5 gal of water in a kettle. Is ...
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59 views

Relays and Determining the State of the Relay

This is a set-up for switching our relay and determining the state of the relay. The problem is that if multiple loads (2 or more) are already connected in parallel, the load (which is a light bulb) ...
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101 views

Switch on computer with microcontroller

I'm making a simple microcontroller based circuit to turn on a computer when certain events are triggered. I am interfacing it using the PCs soft power switch pins on the front panel header: There ...
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1answer
40 views

Equivalent sequence/stepper relay to “FINDER - 20.21.9.012.4000”

I am currently looking at this relay: FINDER - 20.21.9.012.4000. Which is step relay, that makes contact AC output active with coil input DC (12V) [which i need]; and disconnects output when coil is ...
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35 views

Finding low-contact resistance relays

I'm trying to find relays with low (<5 mOhm) contact resistance, or ON-resistance. It doesn't seem to be something that's universally specified, and when it is, it seems to always be something like ...
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1answer
31 views

Trigger Relay Only from one specific grounding path?

I have a car wireless door lock system I want to modify. The basic operation is that when the key fob's button is pressed, a light relay is triggered, to flash some of the car's lights, to indicate ...
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403 views

Is there such a thing as a pulse relay?

Is there such a thing as a pulse relay? So that I do not have to supply constant power for it to remain open, instead just pulse it?
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1answer
63 views

How to protect FPGA from relays?

I'm preparing for a project that will interface an FPGA with many 3v relays on its gpio. Additionally, some of the relays will be powered with the same power supply that the FPGA uses. The FPGA will ...
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1answer
132 views

Arduino crashes switching 230V relay OFF

Here is my circuit schematic : I need to power ON/OFF a 230VAC fan using a relay. The relay is powered by a 5V DC power supply. Digital pin on the Arduino board open or close the circuit in PNP as ...
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3answers
52 views

Two sequences in order, one button push

I am inexperienced in the field of electronics and don't yet understand diagrams and things alike, but I have a specific need and would appreciate any help you can provide. I am constructing a ...
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3answers
159 views

Where to put freewheeling diode in relay circuit?

I am building a circuit to lock/unlock a door using a standard electromagnetic door lock (http://www.amazon.com/Seco-Larm-E-941SA-600-Enforcer-Electromagnetic-Holding/dp/B00196YB5Y) and controlling it ...
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3answers
115 views

How do Wi-Fi controlled light switches feed themselves?

There are smart light switches in the market that are Wi-Fi controlled like Plumlife (formerly ube) and Belkin WeMo. I wonder how they control the electricity that they operate on. When I unplug my ...
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82 views

Why doesn't this relay circuit work?

Objective: A device to prevent automatic restart of a motor (or pump) after power failure. Background: It is well known that aquarium fish are curious and will explore items in the tank. In the ...
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1answer
52 views

Driving a linear actuator from a home automation system

I am not exactly an expert into electrical engineering. I have a Linak LA12 IC linear actuator, and am trying to drive the motor from two outputs on my home automation system. The home automation ...
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1answer
132 views

How to detect that my apartment door buzzer is being pressed

I want to detect the button presses of my apartment's door buzzer. This is the button in the building lobby which, when pressed, plays a ringing/door bell sound in my apartment to alert me that ...
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1answer
112 views

How to supply 2 different voltages to a circuit every 2 minutes

For executing a (stress) test scenario, I need to simulate the following behavior on my circuit: for 2 minutes, deliver 11V to the circuit for 2 minutes, deliver 14V to the circuit for 2 minutes, ...
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2answers
101 views

Turn on an LED when power is lost with a relay

A friend of mine has just finished his race car but is having fan issues. What I want to help him do is setup an LED that turns on when the fans have lost power. Often the fuse blows. I would assume ...
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1answer
41 views

Raspberry Pi high voltage supply soft-off circuit

After looking at various designs for a "software" controllable power off circuit for a Raspberry Pi computer I decided none of them fit my need so I designed my own. Before I commit it to a PCB for ...
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3answers
168 views

How do I get a digital signal from a switch?

I want to essentially drive a relay using a switch. For eg: If the switch (AC Voltage : 220v, 50Hz) is switched on, it sends a digital signal to the relay to switch off.
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165 views

limit switches to control motor direction

I am trying to use two limit switches and two DPDT relays to control the direction of the motor. When the power is applied the motor should rotate one direction (direction for this question isn't ...
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2answers
117 views

Two relays for DRL on a car

I am trying to make a circuit for my newly installed DRL (Day running lights), what I am trying to do is have the DRL run all the time, turn off when using high beam, dimmed when headlights are on. I ...
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76 views

Insufficient Power when using one power source vs two [duplicate]

So I've been working on a wireless remote relay switch using several components and have struck a break wall. The issue I'm having is that the D0 siginal output triggers the relay but only at short ...
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99 views

Control relay from Bluetooth on ATtiny85

I know someone else has made a Bluetooth transmitter to a relay so i wanted to ask a few questions about it being possible? I am an almost newbie at electronics but i do know a few things, so first of ...
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83 views

How to increase current output of a multiplexer for activating a relay

I want to make a multiplexer for my project which needs 24v dc to operate. I am using an OR Gate IC for generating an output. My 4 gate inputs are connected to 6V battery power and I am getting a 6V ...
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78 views

How can I amplify cellphone's vibrator signal to switch my home electricity on or off?

I need to connect my Samsung s1 cellphone to my home's lights when I am away. I realised that I can use my cellphones' vibrator signal when I call my "Home" cellphone number. I know that the mentioned ...
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1answer
67 views

voltage regulators destroyed — protection diode needed?

I have the following basic circuit: As I was flipping the button to turn the relay on and off, I noticed sparking from the voltage meter, and it eventually caught fire, releasing the magic smoke ...
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2answers
78 views

How do I active the relays on this relay bank?

I purchased 2 "Mechanical Relay Board, 8 gang, 10A 220VAC, 24VAC 30ma coil" relay banks that I am trying to control from a raspberry Pi. To do this I've built out 2 595 shift registers and I'm using ...
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110 views

Minimum permissable load for a relay

I understand the purpose of the minimum permissible load (for contact wetting) but I want to know the relationship between the voltage and the current. For instance, the above table states that the ...
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3answers
98 views

What are UL Contact Ratings in a Relay Datasheet?

These UL contact ratings are listed in the datasheet for a Tyco relay: T90 Series, 30A PCB Relay. (Note: the link will ask you to download the PDF, as do most Tyco PDF links) The contact life is ...
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65 views

Standard Relay vs SSR vs TRIAC for Switching CFLs

I'm confused weather I should go for a standard electromechanical relay (EMR) or a sold state relay (SSR) to switch CFLs @ 220V with 100W max load. This is for a commercial product with the following ...
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2answers
72 views

Actuating a relay (either 5V or 12V) with 3V

I am trying to figure out how I can actuate a high amperage 12V relay with only the batteries I have on board. Basically the idea is here to have a 3.7V lithium cell, a momentary switch to actuate ...
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176 views

SC2272-M4 Behaviour when using relay SRD-05VDC-SL-C 5V DC

I'm currently encountering a problem when using a relay switch with a 5v receiver. When using the same receiver with a row of LEDS it works flawlessly. I've noticed that the relay keeps making the ...
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63 views

Connecting common of relay with main cable of 240VAC

I trying to control my turntable switch with Arduino. This is a toggle switch with 3 wires one wire is for CW rotation the other one is for CCW and the other cable is main with 240VAC. I am using this ...
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1answer
176 views

SRD-05VDC-SL-C 5V DC relay not working with XY-DJM-5V

I'm just a beginner and need some assistance. below is a diagram of a 4CH reciever which works fine with some leds and it reports 5V positive on Data0 when holding channel 0 on the transmitter. What's ...
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54 views

PSC motor driver circut using relay

I am working on a project in which i need to connect Permanent Split Capacitor(PSC) AC motor using relays as shown in the below block diag fig 1. I want to rotate it in both CW and CCW direction. It ...
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43 views

How to use LM56 to switch on/off a 2kW heater

I have an oil heater at 220V/2000W so lets say 10A. I was thinking of creating a circuit to switch the oil heater on/off with a LM56 (http://www.ti.com/product/lm56). Is it possible using a relay or ...
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1answer
39 views

Remote Wireless 4CH Switch On/Off - Data PIN Network Cable

Planning Stage I'm in the planning stages of making a wireless on/off switch that will basically cut off pin 6 on a network cable. I know little about electronics and I've attempted to learn as much ...
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2answers
130 views

Timed LED circuit with ATX PSU, help

I want to make a circuit that turns on and off the light (LED) of a given time (eg. on 9 pm and off 6 am). I also want it to be adjustable. My idea about the design: I will be using an ATX computer ...
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1answer
97 views

Switching a relay through a wireless connection

I want to create a circuit which will wirelessly drive a relay. I only have a little experience with Arduino. I know what peripherals I need, but I don't know what micro-controller to use. I made a ...
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2answers
185 views

Power switch with slow control signal

I am trying to switch on and off a circuit that draws about 0.8 amp at 12 V. The obvious choice is to set a MOSFET. The problem is that the control signal (the one that goes on the gate of the MOSFET) ...
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3answers
79 views

SPDT Relay with 8Pin

I needed a SPDT relay with 240Vac so I bought this relay from Maplin http://www.maplin.co.uk/p/15a240vac-spdt-miniature-relay-n07aw But I am heaving problem to wire this relay because it has 8 pins ...
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68 views

Control automotive AC switch via TPS voltage

The A/C compressor is engaged via a single wire that comes from the 'A/C' button on the dash board. I want the A/C button to disengage when the throttle is at 50%. The throttle position sensor (TPS) ...
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75 views

Controlling a bank of relays

I have a project that requires me to control a set of relays (up-to 24 of them). The current setup is using Wago Speedway 767 field-bus modules. I'm just ramping up so I have to either figure out how ...
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1answer
72 views

Contact arcing, how to avoid?

Recently my water heater's thermostat failed. It's just a simple mechanical one, with a piece of metal that "pops" and connects or disconnects the heating element. I would guess that what made it ...
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4answers
130 views

Triple pole triple throw relay

I have a turntable which rotates cw and ccw. This turntable is rotated by AC synchronous motor of 230V. I want to be able to rotate the turntable with Arduino. For this reason I need to control the ...
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3answers
539 views

Thermistor control of peltier voltage with Arduino (for DSLR chill box project)

I am mildly familiar with electronics, mostly from playing around with electronics kits as a kid. That was a long time ago, though, maybe as much as 20 years ago. I am currently working on a cold or ...