A relay is an electrically controlled switch. Electromechanical relays use an electromagnet to activate mechanical contacts, solid-state relays use semiconductor switches.

learn more… | top users | synonyms

0
votes
1answer
69 views

Replacing BJTs with power MOSFET

I have 2 x 2N2222 BJTs powering 2 relays of 200mA each. I am using 2 output pins with 500ohm resistors to power the transistors. After powering it the circuit not working well, while replacing the ...
1
vote
2answers
158 views

How to wire this relay (silkscreen in Chinese!)?

I have the following relay and am unsure of how to wire it since the silkscreen is in Chinese :-/ Datasheet. I'm finding the datasheet difficult to interpret, but from playing around with my ...
0
votes
2answers
118 views

Transistor to run relay

In addition to my last post I have more information and details. I want to run 240V Relay (5V Coil) from my AVR chip (ATmega328P). My EMR relay takes up to 200mA on it peak. I have 2N2222 ...
4
votes
3answers
203 views

Is it good practice to parallel relay contacts for increased current capacity?

Say I have a DPDT relay, like T92S7D12-24. The contacts of this relay are rated for 30A, but there are two sets of contacts. Can I parallel the contacts to get an effective 60A relay? Further, could I ...
2
votes
2answers
139 views

Choosing the right Relay for the mission

I am building new project, which I will power up the water tank heater from my smartphone. I have few safety though I want to ask here to get your opinion.. I am going to use AVR to run a relay, that ...
1
vote
1answer
83 views

Choosing a transistor to Relay

I am building new project, which I will power up the water tank heater from my smartphone. I have few safety though I want to ask here to get your opinion. I am going to use AVR to run a relay, that ...
-1
votes
2answers
105 views

How to properly wire 2 CAN transceivers to the same CANH and CANL

I'm attempting to design a system with 2 CAN transceivers, a High speed and Low speed that use the same CANH and CANL lines, like so: I was planning on using 4 MOSFETs or 4 Relays connected to the ...
0
votes
2answers
65 views

Will this relay handle my current and voltage requirements?

I have this relay: SONGLE SRA-24vdc-cl I want to use it to run 240V 11A device. I can see in the datasheet it can be up to 20A (section 7, line 4-5), but the relay is so small and its legs so ...
0
votes
1answer
50 views

How do I wire up this relay?

I'm making this circuit: I've bought an Omron G5LA-1 non-latching SPDT relay. It looks like this (from the datasheet): I'm struggling to figure out how I wire this up though. I believe I need to ...
1
vote
1answer
81 views

Measure on/off pulse of relay (with reversed polarity) with a MCU?

Below I have the following (simplified) circuit: What I want is to measure (monitor) every time the relay switches on and off. The pulse is around 3V and for 32ms. The problem is that the voltage ...
1
vote
2answers
49 views

What means coil inductance (h) for relays?

I'm looking at the data-sheet for a Single Coil Latched Relay. In there, i see the Coil Inductance (ref. value)(H) for Armature ON and OFF column. Specs: Rated ...
0
votes
0answers
52 views

Arduino with GSM shield and relays

I have some machines operated at 240V and would like to remote control them. Some factory customized boards were made and are currently in operation, but they are expensive and I am seeking for lower ...
0
votes
1answer
81 views

Choosing Screw Terminals for connecting Arduino to other components

For connecting a 16 channel relay board to 16 devices running off 24VDC, and for connecting the relay board to Arduino, I am thinking of using screw terminals where one side of the terminals connect ...
0
votes
0answers
39 views

Latch Switch with timer relay

So my basic operation of things are: -A button will be pressed -A timer relay will be triggered and will run a high power motor. -The relay would turn off after a predetermined time. -The button will ...
2
votes
2answers
47 views

Can I use a higher ohm resistance relay?

I'd like to build the circuit detailed here, which calls for a 12V DC 260Ω resistance relay: Looking at some relays, what consequence would using a 400Ω relay have? Would I be able to use one ...
2
votes
2answers
79 views

Relay switching for audio

I'm designing an audio equalizer with the option to relay switch between a solid state and transformer output path. I'm worried that the relay will cause an audible pop on the output as the relay ...
1
vote
2answers
117 views

Why do I need a transistor to control a relay with an arduino, and which one should I get for this circuit?

I need to control a coffee machine plugged into a wall outlet using a relay connected to an arduino. Apparently I need to connect a transistor to the relay. Why? Is it because the arduino can't supply ...
0
votes
0answers
60 views

Relay needed for an input ot 0.15 V

sorry about the question but I'm a beginner here. I have a very low DC voltage of 0.15V and I want to use a relay with in a simple circuit to light a LED. I'm learning in how to build circuits. So ...
2
votes
1answer
109 views

I need to replace this button in this circuit board with a relay

I have a circuit board with a button in it (the clear white button pictured below is the one I'm targeting). I need to somehow remove the button from the circuit and put a relay in it's place. I'm ...
3
votes
2answers
386 views

How to go about turning on/off a coffee machine with an Arduino?

I have a coffee machine that has one button. When this button is pressed, the coffee machine will do its thing and automatically shut off after a certain period of time. I need to use a signal from ...
4
votes
3answers
189 views

|Solved| PIC16F628A Resetting after relay turned off

I am having problems with controlling a relay with load on it. I am using PIC16F628A. The problem is following: The relay has load. At first it is off. When the microcontroller's output is on, the ...
0
votes
4answers
85 views

Problem with relay current requirement and how to increase current in DC circuit?

What is the minimum current required to run a relay of 5 V (part: RWH-SH-105D). Will the relay run with 5V DC and 0.8mA current (my inputs)? If it does not work, then please suggest methods to run the ...
1
vote
2answers
46 views

Relay max current

I'm building a magnetic stirrer. I wanted to add a heated bed and I've been looking at peltiers as a heat source. To control the temperature I've identified the "WH7016K", a Chinese-made temperature ...
0
votes
2answers
91 views

How to interface 3 serial devices to AT89S52 microcontroller?

I have to interface GSM, GPS and RFID to one microcontroller (Atmel AT89S52). The GSM and GPS can be switched using relay but I can't find a solution about RFID.
0
votes
1answer
41 views

SSR function con control panel

I'm new in electronics and would like to build an electric brewery with an electronic control panel. I found on www.instructables.com one control panel and is described as in following image. Could ...
2
votes
2answers
199 views

Transformer coils in series, switching for 12/24V. EMF killing my circuit?

I'm making a little linear PSU for my lab. Based on the good ol' LM338K. I fried one last night and I'm still trying to figure out why. I think it might be EMF from my transformer. I have a ...
9
votes
5answers
735 views

Why don't relays incorporate flyback diodes?

Warning: this may be an extremely naive question (if so, please enlighten me). Many applications of relays require a flyback diode to protect against inductive voltage. I'm unable to find any relay ...
6
votes
3answers
1k views

Why is there a diode connected in parallel to a relay coil?

In most electrical circuits with a relay, a diode is connected in parallel to the coil of the relay. Why? Is it always a good practice?
0
votes
0answers
73 views

Driving SPDT relay using PIC18F2580

I’m working on driving a relay i.e. the Omron G5Q-1A with a PIC18F2580 using a Darlington transistor array specifically the ULN2803A. I’m utilising the ULN2803A as I need to drive more than one relay ...
3
votes
2answers
100 views

How can I multiplex my oscilloscope probes?

Let's say that I'm tasked with the job of measuring the propagation delay of each inverter in a 7404 hex inverter. I've got a pulse generator, a power supply, and an oscilloscope with two probes, so ...
0
votes
2answers
104 views

Any negatives using a Triac to transmit square wave?

I want to use a TRIAC as a switch to open a gate to transfer a 9600 baud rate square wave (for a uart communication between two avrs). Currently I'm using dc relay, but I'd like to use the Triac to ...
0
votes
1answer
60 views

How can I test for a closed circuit without adding excessive resistance? [closed]

I have one speaker and two audio inputs. One of the inputs is powered by a 12VDC circuit; I want to switch the speaker to this input only when this 12V circuit is closed. If I add a double-throw relay ...
1
vote
1answer
118 views

Can a single power supply control multiple relays?

I want to make this circuit, to convert a toggle switch to a momentary switch: I'll be using a 5V power source & relay, rather than 12v (with a higher μF capacitor). Is it possible to use the ...
0
votes
1answer
107 views

Convert mechanical relay to solid state relay

I've been searching forums for a while trying to figure out exactly how to do this. I want the same functionality that a mechanical relay does. When the "coils" are de-energized, I want the 'heel' ...
0
votes
1answer
76 views

Raspberry pi with direct relay

I have a very back to basics question. I've been using a 5v relay with the raspberry pi. The relay trigger is connected directly to an output pin and the other side is connected to the ground of the ...
1
vote
1answer
73 views

What is the simplest way to toggle a relay with analog feedback?

I've been playing with electronics for a long time, but am fairly new to digital electronics, including using Fritzing, so apologizes in advance for that. I'm attempting a fairly basic ...
0
votes
0answers
19 views

residual current relay modeling

I'm trying to model a residual current relay on simscape(MATLAB), but I'm having trouble finding related circuits on the internet. Can someone suggest some links or etc.? General residual current ...
1
vote
1answer
175 views

On/off Circuit with an AVR and a push button

Here is maybe a difficult question I mind asking but here we are, I need to do a Power On/Power Off switch with an attiny 2313 and a push button, the code is ok, but I want this "switch" to power on ...
2
votes
1answer
88 views

Arduino powered relay behaving oddly

I bought a spark fun inventors kit in order to learn about arduino. I am attempting to complete circuit 13 http://dlnmh9ip6v2uc.cloudfront.net/datasheets/Kits/SFE03-0012-SIK.Guide-300dpi-01.pdf . It ...
1
vote
2answers
130 views

Direct connecting 5v relay interface board to usb

I'm absolutely noob in electronics but I have this relay and I want to connect it to USB. When PC switches on usb VCC has +5v. Can I connect USB VCC to Relay Board "VCC" and "IN" wires to open relay ...
1
vote
4answers
107 views

Check if electrical current exists in high voltage

I'm thinking about a simple home automation project, containing a Rasberry Pi, a Sainsmart SPDT Relay, I would like to switch the state of a ordinary bulb (ON , OFF) using both the relay and the old ...
0
votes
1answer
50 views

Relays for Logic - Current and debouncing?

Im just doing a little project for fun using relays to build logic circuits, and just have a few "thinking outloud" type questions... 1) Any contacts that can make a loop back to the power supply ...
0
votes
1answer
149 views

Is LNK304 not suitable to drive a 12V relay?

I am designing the 12V/120mA DC power supply using LNK304 IC. Using that operate the 12V relay. Initially it was working. After that ON and OFF certain time. Suddenly Relay was not working. Then ...
0
votes
2answers
400 views

How to understand the functions of a Therm-O-Disc 12S20 H24V?

I am an electrical novice and have a Therm-O-Disc 12S20 H24V (original image) relay that I'm attempting to understand. The only meaningful documentation I've been able to find is this, 12S, 14S, ...
2
votes
1answer
78 views

Alternative to TPST Shift Registers?

So I'm building a musical sequencer that uses a shift register to close relays and pass the discharge pins of three 555 timers through a manual switch and potentiometer (acting as a variable resistor) ...
5
votes
3answers
212 views

Problem Switching Relay with Transistor from Microcontroller

This is my first time posting here, so hopefully I'm doing it correctly. I've build a circuit which uses a USB-connected FTDI-UMFT240XA. ...
1
vote
2answers
85 views

Microprocessor Power Relay

Beginning Electrical Engineering student here and had a basic question. I am researching microprocessor based relays and came upon the SEL-351 relay for differential over current. Looking at the spec ...
2
votes
1answer
112 views

Recommended voltage/current for dry contact input?

What would be a reasonable value for voltage and max current to used in conjunction with a remote dry contact output so that it can return to my MCU (through isolator)? I plan on using this input for ...
1
vote
1answer
98 views

Will the relay break if the disconnected end voltage is too high

I'm trying to create a simple overvoltage protection circuit. In brief, there are times when my mains voltage goes well over 250V (normally 220) and I want to switch off the whole thing connected to ...
0
votes
1answer
91 views

Connecting a Switch to a Relay [closed]

I am trying to connect 2 motor boats with a relay to a switch. I received a drawing, but I am not understanding how the wires connect into the illuminated switch. Here is the switch and the drawing. ...