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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Wiring a relay for mains power

I want to make a plug that I can turn on and off with a micro controller like a raspberry pi. I picked up one of these http://www.radioshack.com/radioshack-15a-12vdc-125vac-relay/2750031.html And the ...
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1answer
34 views

High Power LED and relay with the same power supply

I'm rebuilding optical printer (the machine which does Super8 to 16mm film blow-up) and designed new electrical circuit for it so I can control it with Arduino (or maybe later with Raspberry Pi). ...
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1answer
43 views

Is there any wearout mechanism for a relay simply from current flowing?

How will the wear of a relay be affected if the current through the relay is brought to zero before the relay is operated? I'm thinking about having a solid state relay in series with 3 mechanical ...
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1answer
21 views

How to make a latching/unlatching relay circuit with 240V converter

I want to make a circuit that at the touch of a button turns on a 12V circuit controlling LED lights, powered from 240VAC. So I need a latch/unlatched relay circuit after a 12V converter, and I've ...
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1answer
50 views

Two flyback diodes in parallel across a relay coil?

I'm using relays that contain a flyback diode internally, so no need to add an external flyback diode. However, I want to provide a place on my PCB to possibly stuff a flyback diode in case I would ...
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1answer
27 views

Relay sla-05vdc-sl-c is not working on arduino uno and nano

At first time, trying to check this relay modules (I got 2 the same) they both worked nice - no problem. But now I am going tu build the temperature controller for old fridge (it is working ...
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36 views

Connecting/disconnecting AC signal via uC

I want to mix up to four AC signals, that may or may not be DC biased, but will always be between -5.6 and +5.6. For that I was going to use a summing amp. (If anyone wants to talk me out of that in ...
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1answer
47 views

Raspberry Pi Intercom, switch using transistor or relay?

I am researching a way of using a Raspberry Pi to act as an Intercom. I already have the intercom system mounted, but it's a very old one and wanna do something to it to be more new technology ...
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42 views

Overriding Mechanical Switch with GPIO

I have a mechanical switch that sends a current (~5Vdc) into one of two wires. simulate this circuit – Schematic created using CircuitLab I would like to add circuitry which can override ...
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0answers
36 views

Can I use a 100-240V AC 5A Time Delay Relay to spread out startup of drives?

My storage enclosure has dual power supplies for failover. Specs for each PSU:100-240VAC 5AMax continuous output power: 250WTotal power on +3.4V & 5.V is 128W mx I need to delay initialization on ...
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1answer
26 views

Relay control of AC motors, handling turn-off kickback

I've been researching how to control a smallish AC-motor using a relay, and more specifically, how to turn an AC motor off using a relay. This is a subject that has been up many times at this site, ...
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1answer
63 views

How to wire many bi-color LEDs to a single power supply, and switch them on/off individually

My goal is to have 13 separate stations, each with a bi-color, common cathode LED (Dialight 606). These LEDs do not require external current limiting resistors. Each LED can be 'On Green', 'On Red', ...
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1answer
58 views

Relay Solution for Controlling Pumps with Arduino

I'm working on a hydroponics project that requires me to run 10 pumps for 15 seconds every 2 minutes. I was able to set this system up by running a relay board off of an Arduino, but the relays were ...
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2answers
22 views

6v switching large load

I'm looking to build a remote firework launcher. I'm using parts from an rc car for the remote, but I need a circuit that can switch a large current (~2-3amps) with 6v. Can I do this with a ...
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1answer
49 views

switching power redundancy

I have a load (LEDs) that draws 36V, 5A. The circuit is made in this way: Power Supply (AC-DC) -> LED Drivers (5 in parallel) -> LEDs (5 strips). What component I need to install if I want to add ...
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2answers
57 views

What kind of a relay do I need? [on hold]

I'm building a home automation unit using arduino. Most of my appliances can be controlled using a 5V 10A relay, but there is one power hungry appliance. Its a 1TON split AC unit which is currently ...
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1answer
36 views

Will a 3-32 VDC input signal relay be damaged (or will work) with a 110 VAC input?

I'm looking at getting a SSR-25DA relay (http://www.amazon.com/gp/product/B0087ZTN08/ref=ox_sc_act_title_1?ie=UTF8&psc=1&smid=A1THAZDOWP300U) and using it with a temperature controller that ...
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1answer
63 views

Transformer and a relay in series - but function like in parallel, but not exactly

I've been doing some planning to build a home automation system on top of the existing power infrastructure of my house. The first thing would be making my light switches smart. My original plan is ...
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26 views

contact resistance

AZ2150 is a power relay that is rated for 40A at 240VAC. It has a contact resistance of <20milliohms initially. After use they say that typically the contact resistance will be between 20-100 ...
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1answer
39 views

Most efficient two-way switch relay and/or schottky (or..)

Scenario: On my old military Land Rover I have a three-way pole switch which turns the pilot and tail lights on (top position), or also turns on the headlights (bottom position). Top: Pilot and rear ...
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3answers
86 views

Insufficient current to drive automotive relay?

I'm adding a leisure battery to my van so I can run some stuff with out fear of draining the starter battery. My leisure battery is wired to my starter battery so it can charge from the alternator ...
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1answer
33 views

Implementing a safety lockout through ladder logic

The family fireworks show has become my soon-to-be brother in law's and my "thing" over the last couple of years. We have some ideas to make the show better next year, my part is spinning up some ...
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28 views

Can I use the Omron G6RN relay where reinforced insulation is needed beetween coil input and switched circuit?

I want to use a relay to control 230V power to an electric motor. I'm considering using the Omron G6RN relay: http://datasheet.octopart.com/G6RN-1-DC24-Omron-datasheet-10910301.pdf According to the ...
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1answer
44 views

16 channels relay control with 3.3v pins

I'm going to buy two 16 channels relay boards from Sainsmart : http://www.sainsmart.com/16-channel-12v-relay-module-for-pic-arm-avr-dsp-arduino-msp430-ttl-logic.html I want to control it with a ...
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1answer
23 views

Autoelectrics: Testing components off 12v battery

I'm quite good with mechanics and am just starting to learn more about electrics specifically applicable to automotive. One thing I am still yet to get the grasp of is the way electricity behaves. It ...
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1answer
82 views

Relay or Transistor for DC Resistive Load?

I'm building a circuit that includes a resistive load that I have to switch, which is going to be supplied with ~200 VDC and 0.1 Amps. I've looked at different mechanical relays, and typically they ...
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2answers
67 views

What do these symbols in ac connectors stand for?

I'm trying to use a relay to control my house lights with a electronic circuit. I'm familiar with 5V DC circuits, but I've never played with AC before. My relay has three connections, which I assume ...
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2answers
63 views

What are the differences between an AC and DC coil relay?

If a DC coil was just a coil, it would saturate. If an AC coil was just a coil, the magnetic field would drop to zero at 120 Hz and the relay would chatter. Presumably the designs in some way prevent ...
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32 views

what should the specifications of relay be for the circuit?

I want to use relay to switch the 'live' line of the ac supply. The coils of the relay will be controlled by a microcontroller pin through an optocoupler. The normally closed pin of the relay will be ...
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1answer
64 views

Help with On/Off Flip Flop Switch

I'm still fairly new to electronics and have been teaching myself as a hobby. Currently I'm working on a project that detects a red laser beam, and once detected will turn AC lights OFF if they're ...
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2answers
159 views

SMD vs THR Transistor for Relay

Designing a Relay control from a MCU's GPIO, there are some requirements to take into account. Coil Voltage: 3V Coil Resistance: [36-45]Ohm Relay Voltage: 250Vac // 30Vcc GPIO Voltage: 3V3 Max GPIO ...
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2answers
63 views

Why does my solid state relay not properly power a DC load?

I'm using a T108S02 to try to use a logical signal to turn on or off a small 3V DC toy. I'm not sure of the load current of the toy since my ammeter is not working. When I activate the relay, my toy ...
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27 views

Using Optoisolator to Control a Toy

I'm trying to control Tweet Monkey (http://codefoster.com/tweetmonkey) using a optoisolator. It's a 816S, but it looks like the specs are identical to the more popular PC817. I have an Intel Edison on ...
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3answers
85 views

Why do designers use a series diode and zener for coil suppression rather than just a zener?

I understand the use of the Zener but what I don't understand is one topology uses two components, but why can't the other topology be used ? simulate this circuit – Schematic created ...
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2answers
67 views

Relays in series to handle initial short circuit

I'm trying to design a circuit to turn on and off an electrical 230V 1A 1-phase motor using a relay. I'd like to design it such that if the user inadvertedly short circuits the output, the relay is ...
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2answers
95 views

How to drive relay using uln2003 [closed]

I am designing a IR base home light control. for this i use 6 relays and i try to driver it through uln2003. I connect the GND and COM wire with 12 volt power supply and input pins are connect to ...
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3answers
63 views

Starting the 5.5kva Kipor diesel generator from a distance

How can I start my kipor 5.5kva diesel engine generator from a distance of about 30m? I would like to avoid going outside my house to access the ignition key panel but just start from the comfort of ...
2
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2answers
48 views

Relay Isolation

I have read on many websites to use a separate power supply for relay only. But I've few questions. Can I use some component instead of using a separate power supply ? Or what would really the problem ...
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2answers
50 views

Confusing relay rating [closed]

I have this relay and the ratings are quite confusing - 10A 30v and 10A 28v, I'm confused as to why there are two. Could anyone please explain it to me. Thank you
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88 views

Need a switching device. Should it be a relay?

I am trying to build a system where first i would charge the battery (3.7V,40A), and then discharge it through a high wattage Resistor. For this purpose i will be connecting a power supply (15V-50A) ...
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3answers
70 views

How to avoid Relay buzzing noise? (LDR dependent)

I have the following circuit where I'm switching a relay based on whether it's day or night. I made a voltage divider using a pot and an LDR, which leads to the NPN transistor. So when it's dark the ...
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21 views

Vakind 4 Channel Relay Contacts not closing

I have a Vakind 5V 4 channel opto-isolated relay breakout (http://www.sainsmart.com/4-channel-5v-relay-module-for-pic-arm-avr-dsp-arduino-msp430-ttl-logic.html) An Arduino Mega2560 is driving the ...
3
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3answers
266 views

Determine adequate speed of flyback diode for a relay

I have already looked at this question which looked like it would provide the answer: How to choose a flyback diode for a relay? But it didn't, so I also checked out these: ...
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0answers
35 views

Actuate a 12 v relay with audio signal

I was trying to actuate a 12 v ready when my phone rings through the audio 3.5 jack; knowing that when it rings the volt is raised from 0 to .7 volts. and I need to protect the phone from the circuit ...
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3answers
75 views

Solid state relay doesn't turn off

I am trying to build a custom light setup for my computer desk. I want to use the scroll lock LED signal to control a pair of 12 volt DC CCFL lights run off the same inverter. The problem is when I ...
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1answer
60 views

Reed relay driving motor getting stuck

So, for a project I'm using a light sensor to switch on a relay which drives a motor, as seen in the pic below Q1 is 2N2222A NPN transistor, Q2 is an NPN phototransistor, R1 is a 100k pot The ...
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1answer
56 views

Need advice on my simple solar powered lighting system

I'm building a simple circuit in which a solar panel will charge a 12 V battery during the day and then switch over to battery power during at night to light up a few bulbs. I'm using an LDR which ...
3
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2answers
86 views

Is a flyback diode necessary when no sensitive chips are used?

I have had a look through all the information available about flyback or snubber diodes in a relay system and was hoping to confirm if one is necessary in my circuit or not. All the info about why a ...
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3answers
131 views

Relay Spike at Vdd

I have a problem with voltage suppression at the time of relay switching. I use a transformerless ac to 12v dc conversion circuit similar to (I use 12V zener and 470uf capacitor) : ![enter image ...
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1answer
58 views

Switching 12V/6A with an AVR - MOSFET or relay or both?

I want to control the 12V heating of an oxygen sensor with an ATmega328P. It draws about 6A when switched on when it is cold and about 1.5A at the operating temperature of 350°C. It is powered with a ...