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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Reset the raspberry pi with a relay

I'm going to use my Rasp as a GPS tracking and it should be running even if the car is off; however, I don't want run out the car battery. To make it happens I added a battery controller ...
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1answer
31 views

mechanical relay output voltage doesn't change

As a followup to my previous question, where a 2222 npn transistor wasn't beefy enough to handle the load I was putting on it to activate a solenoid valve, I decided to try a mechanical relay board ...
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46 views

Bell Detector with Arduino

I am trying to upgrade our existing bell with my arduino to detect whether the bell is used and to mute the bell. The circuit for the bell runs with 9V AC. In order to minimize the wiring I want to ...
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1answer
14 views

transformer or DC motor returning emf [on hold]

so i using a relay JQC-T73 12VDC the coneection is like [uln2003]-->relay-->230V---->tranformer--->12VAC--rectifier--->12VDC--->12VDCMOTOR.. ok so the problem is when i switched on&off relay ...
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63 views

Keep volts the same but increase the amps in a 60hz 120v AC circuit

I have a over the range microwave with a built in fan for exhausting range fumes below. Would like to add an inline fan to it in the attic that matches the speed of the fan in the microwave but I ...
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1answer
84 views

What type of transistor would be required?

I am trying to turn on a 12V LED, whenever power is applied to a 3.5V LED. I want to use a switch transistor instead of a relay. With the relay, 3.5V+/- on the switch activates 12V passthru; what ...
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1answer
45 views

LED's connected to a relay remain on?

I built a simple project with an Arduino board. I use the board to read analog input values from a rotation sensor (potentiometer), and use the values to determine which SSR relay on a module to turn ...
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2answers
52 views

MAX4544 in plain english

I was looking for a way to simulate a button pressing with an arduino in a black-box circuit I cannot modify (I have no GND), you can see it in my previous question and question. Then, reading this ...
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1answer
56 views

Switching frequency of a solid state relay?

I bought a SainSmart 4 channel solid state relay recently. I am planning to use an Arduino to control some Christmas lights I've put up around my home. My question is: How fast can you switch SSR's on ...
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2answers
53 views

Solid state relay (or equivalent/alternative) to drive 6V DC from a 3.3V micro

I have to open/close two wire from a closed device. I cannot open due to it's under warranty, and the only part that I can open and modify is an external button that connects the two wires. Firstly I ...
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2answers
50 views

dual input temperature comparison circuit

I would like to build a comparator circuit that will compare two varying temperatures and operate a relay to a fan when one is greater than the other, but release the relay if the opposite is true. I ...
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1answer
50 views

Should I use a snubber or solid state relays on a 24 vac circuit?

I'm trying to create a smarter controller for my hydroponic systems. I have an arduino controlling a sainsmart mechanical relay. The load on the relays are 24 VAC orbit sprinkler valves. Everything is ...
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2answers
50 views

Connect 3 switches without dpdt switch

Is it even possible to do such a thing? I am trying to implement home automation at my home, and I have a bunch of these relays. I don't want to need to get dpdt ones, and they are expensive. P.S. I ...
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0answers
28 views

Selecting relay for raspberry pi

I'm currently working on a raspberry pi project.In which i have to control four 30W 0.25A 230V Bulbs(which works using main 230V power supply) using output from GPIO pins.I'm a beginner in ...
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2answers
176 views

Relay not switching immediately from switching power supply to battery backup

WARNING This project as currently described is badly flawed in a number of ways that are liable to lead to complete failure of the equipment. As it is stated that it is intended to be used in a life ...
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0answers
40 views

Double Input “AND Relay”

I am looking for a relay that switches on the single output signal when both of the two input signals are greater than 5V DC. What is the name of these devices?
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0answers
23 views

Analog relay in logisim

I am attempting to create a 4PDT relay in logisim to play with mechanical logic circuits. I am not sure if it is possible to simulate the analog connection of the relay, where signal can flow in ...
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1answer
34 views

Controlling external appliances with a microcontroller by replacing switch with relay

I am working on a custom school project where I want to control a coffee machine's power using a micro-controller. I have never worked with interfacing to external appliances like this before so ...
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0answers
44 views

Relay Matrix PCB

I must design a 2-wire 6x8 relay matrix. The matrix must be used to connect some measurement instrumentation (oscilloscopes, DMMs) to DUT(device under test) pins. 6 rows will be used for 6 ...
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1answer
40 views

What's the purpose of adding a parallel impedance to a relay circuit?

This is the relay section of a PIR Sensor I have taken apart.: L_FUSED is 240VAC, and the relay is intended to turn on a light bulb from "OUT" (standard edison screw), so it could be incandescent, ...
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1answer
40 views

How to use relay switch

I have a relay switch. Particularly, leone SC5-S-DC6V. I am a noob who wants to use this relay switch. And I don't know how to operate it. Can someone please help me? For now, I just want to use it ...
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1answer
38 views

Problems getting an SSR to turn on

Has anyone had problems getting a solid state relay to work? EDIT: see Spehro Pefhany's answer. Lessons learned: don't accidentally take out current limiting resistor solid state relay rated for ...
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38 views

Design a low-pass RC circuit to eliminate SMPS noise

As per a previous question I've asked - trying to track noise from a circuit. I've built a audio relay switch and the audio path seems to be inducting noise from the relay power supply (shared ...
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1answer
46 views

Increasing the current to a solid-state relay?

I've got two strings of LED Christmas lights that operate at 120 V / 0.04 A (4.8 W). I'd like to connect them to this 5V solid-state relay: Unfortunately, there's one small problem. According to ...
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3answers
125 views

555 monostable circuit - triggering relay

I'm looking for a little help with regards to the logic required for a project I'm looking at undertaking soon. I am looking at creating a 'quickshifter' for my motorbike. The way this will work is ...
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1answer
66 views

Clean DC power supply from a dirty souce

I'm building a guitar pedal which uses a series of relays to switch various signals. The relays are currently being powered by a cheap 5V switchmode supply and the audio path is inducting high ...
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1answer
50 views

3v Relay raspberry

I'm trying to drive a 3v Relay with a schematic like this: Relay is a HWE JRC-21F and transistor is a PN2222A instead of a BC337. This won't work unless I connect 3.3v directly to transistor base, ...
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1answer
71 views

Weird problem when using relays

We have a product which is to do resistance measurement. The simplified schematic is as below. A 50mA DC current flows through the resistor, and we measure the voltage on the resistor's terminals. ...
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2answers
49 views

Refrigerator Relay - Need replacement [closed]

I have a broken Kegerator and need some insight. I'm familiar with electronic circuitry, but far from an expert. Everything (temp display, internal fan, change set temp) appears to be working as it ...
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2answers
47 views

Relay - Datasheet Max DC Voltage

This may seem like a dumb question, but I want to be sure. In the below datasheet, what is the DC voltage the relay can handle? I am assuming it is the ...
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0answers
49 views

How to keep the signals at the pins on a Arduino upon software restart

I have a Arduino board, connected to a relay. When the digital pin on the board is set to HIGH, the relay closes. If the digital pin is LOW, the relay opens. Now that from time to time, I will have ...
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1answer
44 views

Will a tvs diode help my relay with inductive loads?

I am not an EE, so please be gentle! I will obviously get a certified EE to review my design before anyone else touches this so please assume that I know enough to at least be safe with 120VAC and am ...
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2answers
39 views

Building circuit for n-relays using flip flops, is this the best solution?

I'm trying to build a circuit for n relays, each relay should hold it's state (ie latched). My first Idea was to use decoders, but clearly this was a bad option, since the state of the relays won't ...
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2answers
99 views

Activate a buzzer when power goes off

I am totally new to electronics so I would like to have your help. The project I would like to build is very simple but yet I don't know the name of the parts that I have to use. So, I would like to ...
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2answers
33 views

Wiring CanaKit Relay and Southco EM-05 Electronic Lock

I am attempting to wire this relay http://www.canakit.com/4-port-usb-relay-controller.html to this lock http://www.southco.com/en-us/em-05. I have done some work with Arduinos before, but I am not an ...
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1answer
53 views

Explain operation of solid-state relay

Link for Datasheet: http://www.ixysic.com/home/pdfs.nsf/www/CPC1230N.pdf/$file/CPC1230N.pdf This is the relay I am using in my circuit, but I am not getting how it connects/disconnects and flow of ...
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2answers
58 views

What is the purpose of using only the coil of a relay?

In these two examples: http://www.electronicecircuits.com/electronic-circuits/cd4060-timer-circuit-1-minute-to-2-hours/comment-page-4#comment-48679 http://www.zen22142.zen.co.uk/ronj/24hs.html A relay ...
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4answers
146 views

Relay alternatives that are silent and support 500mA+

What can I use as a silent "general-purpose" relay alternative? There are various scenarios where I will need a relay-like device that allows me to control one circuit with a separate isolated ...
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3answers
122 views

Audio Signal Switching - “DPDT switch vs. 4066”

I've got a signal coming from an electric guitar and I need to switch it. Basically it's a distortion circuit. I need to switch between the distortion and clean (directly connected to the output) My ...
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1answer
123 views

Controlling multiple relays with Arduino

I've tested controlling single 24VDC relay with Arduino by using external power source to power the relay. Now I've set up a board to control several of these relays, but noticed that the Arduino ...
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2answers
31 views

What things to think about when selecting a relay for controlling small valves?

We are creating a novelty drink dispenser that controls a set of 8 pumps with a Siemens Simatic Step7 1200 PLC. The decision to use this PLC was based on our need to have a very stable prototype. Now ...
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1answer
44 views

What kind of time delay switch to choose to reverse motor for just a couple of seconds

I would like to know the following: I have a motor driving a lead screw which transports a part either up or down. When going down and something comes in the way a switch gets triggered by the ...
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0answers
54 views

Audio via transistors

Is it possible to push an audio stream through transistors or a DPST relay? I'm using Arduino to do selection between two audio sources and two destinations, and I've completed the first part which ...
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2answers
80 views

Troubleshooting circuit in make Electronics Book (Experiment 8) [closed]

I created the same circuit as in Experiment 8 of make Electronics book but cannot get it to work in the same way as described in the experiment. When I connect the circuit to the power source and ...
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1answer
37 views

Relay circuit for circulator pump and actuators

I need help designing/wiring a circuit for thermostatic relays, which control electrothermic actuators. Basically I have 4 actuators and thermostatic relays, which pretty much is just a 12vDC ...
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1answer
106 views

Normally closed SSR won't work with grounding out a magneto's primary to ground

I've been trying to find a device that will ground out a magneto's coil (primary kill wire) in a normally closed state without using a mechanical relay because I want my circuit to be all solid state. ...
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1answer
66 views

Use Arduino for switch a 12v powered remote control

I've a remote control powered by a 12v battery. I need to switch a button using arduino, can I use directly the digital pin without any relay or transistor? Thanks in advance
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2answers
95 views

Circuit seems to lack something

http://www.electronicecircuits.com/electronic-circuits/cd4060-timer-circuit-1-minute-to-2-hours I've replicated the circuit in the given link but \$D_2\$ in my circuit doesn't work at all. Also, the ...
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2answers
70 views

Using DPST Relay to control AC Load

Below is the functional schematic that I am planning to use to control an AC load (air conditioner in this example with max current draw of 32A). Since I am still relatively new to mains power and ...
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1answer
47 views

Mains into a relay?

Will hot/live go into NO and neutral into COM, to switch over 200v? Can someone explain please. I saw in some places it says natural into NO but what into com?