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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How to protect P-MOSFET from excessive gate voltage

I would like to build a DIY solid state relay for my car to enable some circuits (less than 1A current absorption) only when the accessories are powered up (independently from engine on or off). I ...
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1answer
56 views

Solid state relay operation without transistor

I have this solid state relay, it's specify that it can run at 5v/16mA. I just want to make my board as simple as possible, so i've been thinking to remove transistor. Is that safe for GPIO/PORT or ...
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0answers
35 views

Relay Question (Jet-Ski based) [on hold]

I need to create a switch that works along with the factory kill switch on a Yamaha Waverunner with an aftermarket MSD ignition. Reason, if forgot to switch manual switch, battery loses charge and ...
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2answers
41 views

Opinion on design changes for Latch circuit

So just to give some background I've designed a circuit to suit the following task. 12V DC Motor moving a carriage up and down a column 2 'End stop' magnets, active-low hall effect sensor attached ...
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2answers
38 views

How to unlatch relay with relay?

I have problems with unlatching relay with relay.. Schematics below: simulate this circuit – Schematic created using CircuitLab The purpose for this is to light on car sidelights when ...
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0answers
43 views

Arduino I/O Shield relay won't switch [migrated]

I have an Arduino Uno and the I/O Shield wired up and I'm trying to switch (i.e. engage) a relay on the I/O Shield, but nothing seems to be working. I've identified the input pins correctly and am ...
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0answers
27 views

Protection relay coordination

I have a question in regard to following 66kV/11kV substation single line diagram: Long story short, the question is how different the coordination procedure would be if feeder no. 1's impedance is ...
0
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1answer
57 views

What Type Of Switch Is only on for a second [duplicate]

I am looking for what type of switch is only only for a split second (1 second max) even when held. Basically: Press and hold button-->LED only on for a split second and back off even though I am ...
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3answers
64 views

Electronically, how to control this 5v arduino-style relay board from a PC serial port

I have the following relay board (pictured below), and to activate any of the relays, you simply connect one of the IN1-IN8 pins to ground. Easy. The current going between gnd and INx is negligible, ...
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2answers
22 views

Connecting multiple input devices to 8 channel relay board

I have an 8 channel relay board (here's a link to the actual product (http://smile.amazon.com/dp/B00KT0E1RY/ref=sr_ph?ie=UTF8&qid=1463753455&sr=1&keywords=smakn+8+channel). I understand ...
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1answer
62 views

How to use arduino nano to switch an 230V AC motor on/off?

I want to switch on and off an 230V AC motor with a relay what is controlled by an arduino nano. The on time and off time would be able to set by a 3-position slider switch. So would be 3 different ...
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0answers
27 views

Switch time for Q-series relays

Im working on a project where I have to read the pulses at a relay contact(FC/BC). The problem is the relay can change from FC to BC and vice versa at any point of time. Every 32ms I read the contacts ...
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1answer
108 views

Relay Feedback Problem

I am a computer science student working on a project for my Diploma and I am building a DIY PDU, I thought building something would be a lot funner then programming a website like 90% of the class ...
2
votes
2answers
75 views

I am having an issue with relays sticking

I use a DL205 PLC with a Do more CPU. This drives SPDT relays to control 90 degree motor operated valves. The valves are apollo motor actuated, which advertises 0.74amp starting/locked rotor current. ...
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2answers
31 views

Door lock relay needs higher amperage - what relay to use?

I have a door lock that requires 12VDC 750mA to get it to unlock, then it drops to 350mA to keep it open. My door controller has a max load of 500mA, so it won't work connected directly to the door ...
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3answers
49 views

Properties of relays [closed]

i know how a relay works, my question is this. i have a load that needs to be turned off and on remotely. The piece of equipment is 220volts at 30 amps. is there such a thing as being able to use a ...
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2answers
46 views

Doorbell to buzzer with relay and AC to AC transformer

I have the following buzzer and want to use it with a switch by the door. Would the following configuration let this work or are there crucial parts missing? simulate this circuit – ...
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0answers
32 views

How do I simulate a latching relays in LT spice

Here is my requirement. I have a dual coil latching relay. I am giving a pulse voltage to one coil to close the contact and stay contact until second coil is energized with another pulse. Is there a ...
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0answers
31 views

Arduino Uno's RX and TX lights not blinking. Unable to upload sketches! [migrated]

When arduino starts up, RX TX lights doesn't blink. Only the PIN 13 and Green light turns on. Pin 13 light blinks thrice before getting stable. RX TX lights are not blinking at all. I am not able to ...
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3answers
59 views

interchangeable operation of two electric motors without PLC

I have two motors that drive an air compressor. I have a pressure switch to turn the motors on/off. The sequence I want is: when pressure switch turns ON - motor 1 starts, when pressure switch ...
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2answers
45 views

Interfacing microcontroller with external circuit - detect LED and simulate and detect button press

This is my first question on here. I am good at programming but am a little stuck when it comes to electronics and connecting two circuits together. I would like to interface a spa controller with 3 ...
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2answers
31 views

Low amp/volt relay for microphone switching

Its that time of year when I revisit one of my old projects and try to improve it. Currently I have a small 12v PA system that has a microphone and I've added an 3.5mm auxiliary input to play music ...
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1answer
60 views

Relay control using Ardiuno Mega [closed]

How many relays can I drive using Ardiuno MEGA board without overloading the microcontroller?
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1answer
35 views

capacitance calculations

I am trying to calculate what size capacitor I need to energize a small relay coil for 5 to 8 seconds while the supplied voltage is removed momentarily . My supply voltage is 12 VDC, Relay coil draws ...
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2answers
27 views

Connectors: Relay to Heater

Simple project: Swap the on-off switch on a coffee-maker with a relay. The relay is rated to be safe for wall power. The coffee-pot can take it, obviously. But the old crimp-on connectors that the ...
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1answer
49 views

PIR Sensor University Project

I'm working on a project to use PIR sensor to save on electricity bill in a university, almost a fresh graduate in Electronics Eng. Load is Fluorescent tubes 44w each via ballast,there will be ...
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2answers
40 views

Circuit todelay RS-232 TX pin closure after device power up

We have two devices connected via a cable, an ARM based computer on one side and a sensor on the other. This cable carries an RS232 TX, RX, and ground. In addition there is 28V provided from the ...
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6answers
6k views

Why are there so many relays used in a car, instead of transistors?

Recently I did some work on my car electric circuits. I see many relays are used in car circuits. These relays are used for simple switching, and I wonder why these circuits are based on relays and ...
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1answer
48 views

relay coil issue

i've been googling my way through a problem and now i am stuck and haven't found an answer. So here is what I am trying to do. i have 24vdc connected to the positive side of the coil on a relay and ...
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0answers
32 views

Relay module not working

I bought this relay module and I tried connecting it to my raspberry pi. I attached the Vcc (one next to the inputs) to the 5v rail of the pi and gnd to gnd. I attached the input pins to various gpio ...
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1answer
42 views

Relay circuit with off switch

I've been searching for a similar circuit and only found latching relays with two momentary switches for on and off. I don't know if this circuit has a specific name or not, and since I am a complete ...
2
votes
1answer
40 views

Which diode configuration do I need for this solid state relay?

I want to add snubber or supression protection diodes for a solid state relay. Here is the diagram without the diodes: And this is the SSR I'm going to use: ...
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2answers
60 views

Cut off low voltage lithium battery?

Working on a portable boombox powered by four 18650 Panasonic NCR 3400 mAh cells in series. I bought a PCB and I have a small 4s balance charger. The PCB will be secondary if anything fails and cuts ...
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3answers
122 views

How can I implement a solid state relay in LTSpice?

I want a specified DC input voltage or above input voltage of a solid state relay to activate it. I want 3V or above DC input to turn on the relay's output switch. Here is the simple diagram: Is ...
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1answer
30 views

Questions about a relay controlled AC fan setup

I need to switch an AC fan by a DAQ board's analog output. Here is the setup in my mind for the moment: The DAC of the data-acquisiton board can output 0 to 10V DC and can deliver max 5mA current. ...
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2answers
56 views

Help choosing a relay for pump control

I'm building my first arduino project, and I could use some help building up the relay portion. My goal is to control a water pump that's running at 110V, 3/4hp, rated at 9A, and measured to run at ...
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2answers
41 views

12 volt switched by 5 volt

I have an issue with 12 volt DC LEDs installed on a 5 volt DC circuit. Switching must be performed as close to instantaneous as possible. So I searched around but nothing would do what I need. I ...
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0answers
18 views

What type relay should I use?

I want to close a switch with a pulse, stay closed until I send another pulse from a different circuit. Would form-A duel coil latching relay work?
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1answer
34 views

Good choice for a flyback diode [closed]

I have a relay with following ratings: coil voltage 3V coil turn on voltage 2.1 I have looked at IN4007 but they are available in bulk quantities only. Can anyone suggest any other diode?
0
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1answer
50 views

home automation with arduino, raspberry using externally powered relay board

I have a plan to put together small home automation system. For now I was just playing with smaller parts like single type of sensors at once etc... I would like to ask for opinion & check of my ...
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0answers
36 views

Amp troubleshooting with clicking relais

Im having some trouble with my old Realistic amplifier. Out of nothing, my speakers started to make a repetitive (about once a second) full in and out movement of the cone, producing a deep bass ...
3
votes
4answers
505 views

Why are my reed relays releasing 10x faster than spec?

I have Magnecraft W171DIP-25 reed relays (datasheet). They are DPST relays with a built-in coil suppressor (according to datasheet). Their listed response time is 1 ms, and, following the logic of ...
-2
votes
1answer
64 views

Help choosing component values for a relay delay circuit

I want to build a circuit that controls a relay with the following specifications: the relay should turn on and stay on for ~60 seconds after the button is pushed the relay should stay on as long as ...
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2answers
66 views

Is hobby relay adequate for air conditioner automation with microprocessor

I'd like to use a Beaglebone Black(3.3v Logic) plus a 3.3V to 5V logic level shifter(74HC125) to control an opto-isloated Songle Relay that has the following specs: Rated Resistive load: 10A ...
0
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2answers
42 views

Built-in air conditioner timer switch wiring

I'm not sure if this is specific to this model only, but I was unable to find any standard wiring schematics for this type of switch. This is for a Haier HPAC9M air conditioner unit. I want to ...
0
votes
1answer
20 views

TQ2-L2-5V latching relay

I'm using a 2 coil latching relay named TQ2-L2-5V. I came to know that, 2 coil latching relays have two modes 1.SET and 2.RESET. I want know, what happens in SET and RESET modes, in my case, in SET ...
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1answer
44 views

Switching circuit or relay [closed]

I'm new here and don't know much more about electronics.I need a switch/relay that help me off DC line when AC (grid) line is available and automatically turn on when AC (grid) line is not available. ...
0
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1answer
66 views

Relay driver from microcontroller

I have put together the following circuit to drive some 12V pumps from a micro-controller using a ULN2003, but it has a few issues. First issue is that the relays click in immediately. I want the ...
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1answer
33 views

Can I cable this relay to my regulator?

I have to control a temperature, with a 3.5 kW under 230 V AC resistor. I have a regulator with this OUT : 4 A / 240 V AC. I found this relay to commute my circuit. My question is : can I use it ? ...
2
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1answer
61 views

How well do relays handle brief overcurrents?

Unlike solid-state devices, relays often (in my limited experience) do not come with maximum peak current draw, only maximum continuous current draws. In general, how well do relays take pulses of ...