Questions tagged [relay]

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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4-layer PCB with VCC and GND inner planes with high current

I have a 4-layer PCB with GND and power planes and on the top and bottom layers I have 220 VAC with 10 A currents. I have many questions about every part of this board but the most important ones are: ...
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4 votes
2 answers
175 views

Relay contacts temporarily have resistance after closing

The relays that I am using are JS1-12V-F. The relays are being used on a testing apparatus to automatically test PCB components for accuracy. When powered off for a long time (> 3 minutes), the ...
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Making my coffee maker smarter

I'm planning to add a WiFi-enabled relay (Shelly 1) to my coffee maker for some fun home automation. In this case, the coffee maker has a tactile switch labeled "brew now". I understand the ...
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Latching relay circuit design

I am designing a circuit to control a latching relay through an MCU. I got this circuit from one of the application notes. I want to run my K153A-D012P-1BT latching relay. What are the changes I need ...
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I'm struggling to understand the meaning of the ports 11, 12, and 14 for the Relay Socket for the G2R-1-T- 5VDC [closed]

I want to add a relay system into an ORC (Organic Rankie Cycle) by adding a relay between the national instrument and the value. The issue I'm having is that I don't understand the ports A1, A2, 11, ...
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How does a charging station stop a charge with EV connected? [closed]

I'm trying to control a charging station with a Raspberry Pi. The software is almost finished but there is something missing in the electrical architecture of my CS. The EV is connected to the CS with ...
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Stacking 12 V relays [duplicate]

If I use two 35 A relays to power 1-2 solenoids does it make my current capability 70 A on a 12 V system? I have a variation of different solenoid applications that range from as low as 17 A to as ...
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Data acquisition at 100V [closed]

Here is a very basic system level drawing of our system: In operation 2 out of 50 systems have reported the relays being welded. I have been trying to recreate a scenario where this will happen in ...
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Keep having to replace 5 V relay - fridge thermostat replacement

I'm using this circuit to replace the thermostat in a small mini fridge. In the fridge, I took the white and black wires, attached them to the NO and COM ends of the relay, and have the Arduino open ...
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1 vote
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Current Spike when charger plugged in?

Here is the rough set up of the system: Relays used 1-1393277-4 (https://www.farnell.com/datasheets/2243264.pdf ). The way the set up works is when the battery is turned on, there is a micro (not ...
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Disconnect mains voltage when voltage or frequency is out of spec [closed]

I am designing a panel that needs to disconnect single phase mains when the frequency or voltage is higher/lower than specified values. I plan to disconnect both live and neutral via a DPDT relay. The ...
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What's the purpose of the form b in 4a1b relay?

This relay AHER4191 has contact arrangement 4formA + 1formB. I know the 4formA (pin 9~12 pin 1~4) are for L1/L2/L3/N lines but don't quite understand in which scenario the 1formB (pin5, 8) may be used?...
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How to operate a relay (24 VDC 8 mA) from a 4-20mA signal?

I have a PLC that can output a 24 VDC, 4-20 mA signal, but it cannot be turned off - the lowest it can go is 4 mA. I found a relay (J104D2C24VDC.20S, 24VDC, 0.20W) that per the datasheet operates at ...
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4 answers
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Control two or more channel relay using a single signal pin from an Arduino [closed]

I would like control a four-channel relay using a single signal pin from an Arduino. Is there any way to do it? Using external components, is this possible with any PWM pins or something else?
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Relay module input giving off voltage

I have a 12 V relay module, as pictured below (not this exact image, the relay has 12 V logic, not 5 V as in the picture.) I am getting a voltage reading from the signal, it's floating around 12.2 V ...
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1 vote
2 answers
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Is signal point in a relay isolated from power points?

I am thinking of using a 5v relay switch to isolate some 6V solenoids and a motor from my arduino circuit. Can I use my 6V adaptor to also power the relay and use digital output of arduino to signal ...
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Switch on when voltage detected

I'm adding a Google Home Mini to an antique floor radio. I don't want to toss the original components, so I'm planning on wiring the speaker to the Google Mini and want to add lights that come on in ...
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VAC/VDC Control input voltage in Solid state relay

I have been trying to understand the datasheet of solid state relays from different manufacturers and I was not much familiar with solid state relays. A confusion arose when I came to see the control ...
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1 vote
1 answer
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Driving 3 V relay with ESP32 and transistor

I am trying to drive a 3 V relay with an ESP32 by using a BCP56 transistor, based on several guides that I have found online. Below is my design for this purpose, but it does not trigger the relay. ...
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Circuit to turn relay on/off based on button press

I'm using a CPU case to enclose a diy project and I'm looking to see if I can turn the main circuits power supply on using the on/off switch in the front panel of the case. The button needs a circuit ...
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Driving relay using attiny48

I'm making a circuit which contains 6 relais. The circuit is powered by battery (2xAA alkaline in series). I'm about to submit my fourth iteration for a small test production batch, but the last 3 had ...
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Is an SSR better than a electro-mechanical relay?

To solve signal cleanliness issues in a system where I have to very accurately measure pressure I am thinking of employing a relay switch to operate an air pump which I am currently operating through ...
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How do I (can I) replace the relay in this circuit with a transistor?

Background I have the following circuit and it has been working for years. Please note that the circuit drawing may not match the real circuit exactly, but it is just a diagram to attempt to get my ...
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RFP30N06LE question on current

I have a RFP30N06LE. I currently have it controlling a 5 V relay via a pin on my ESP-01, however I'm only ever driving/sinking 24 V. The MOSFET has a range up to 30 V, so is the relay redundant, i.e:...
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What kind of switch to use for output power in a variable bench power supply

I am some what new to electronics. I have been designing a variable bench power supply from an ATX. I want to add two output power switches: One to the low current low voltage variable output rail (...
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1 vote
1 answer
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Replacement relay - slightly different specs

I have an old kitchen range hood whose lighting suddenly stopped working. With my limited knowledge and capabilities in this field, I was able to access the PCB just to see that the power relay is ...
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3 answers
66 views

Discharge lithium ion battery to a specific state of charge

I am trying to make a circuit to discharge a 4s battery pack to 30% state of charge to ship it safely. I will be doing this from time to time and would like to discharge the packs rapidly (around an ...
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5 votes
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Does a relay with a capacitive load still require a MOV?

I was planning to install this Metal-Oxide Varistor (MOV) across a relay switch. But after I read about the use of MOVs for switches here, it seems to me that MOVs are useful only if the load is ...
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5 votes
2 answers
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Is a flyback diode required for this relay?

Regarding the relay RL1 input side below, I know that the flyback diode D1 below prevents high voltage spike at the collector of the Q1 during switch off: The relay RL2 above is magnetized by the ...
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1 answer
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Problems driving a relay: ESP-01 via I2C bus controlling PCF8574 to activate a Songle Relay

In the past, I've been able to drive a relay using a 2n2222a via a GPIO pin given the same schematic with PCF removed. However, once I introduce the PCF8574, it doesn't work. I have read that I ...
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6 votes
3 answers
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Is there an easy way to detect when a DC current flows, then close a path?

A wire has two states - 20A DC flowing or no current. Is there a simple device/relay that can let 20A flow through it and close a switch? The device must keep a path open when no current flows. It ...
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How can I safely connect 230V AC to this relay?

I have this high inrush relay (type G5RL-1A-E-HR.) Page 5 of the datasheet only mentions pin names from the bottom. The relay will switch on/off AC side of an SMPS. There is no polarity mentioned for ...
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4 votes
2 answers
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Will this method theoretically reduce inrush current during relay turn on?

When a relay is connected to a purely capacitive load and an AC supply voltage is turned on, it will experience inrush current. Since the potential difference of an AC voltage can be represented by $$...
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Injecting a UART TX output signal to an audio input pin, without messing up the audio?

Oddball design question: I have a pin that's used for audio input (allowing up to 12Vpp AC), and for testing/utility purposes I'd also like to be able to use this pin for a reliable UART TX output as ...
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0 votes
1 answer
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How can I control a 5HP single phase motor with an Arduino UNO?

I am able to switch ON and OFF 1.5 HP single phase motor (current rating of 8A) using a relay with a rating of 10A, 250VAC (SRD-05VDC-SL-C.) What can be used to connect a 5HP single-phase motor (28A ...
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Looking for an automatic switch to keep my two solar systems completely separate? [duplicate]

Here is a picture of my Queensland, Australian setup. My 4kW off-grid system needs to be completely separate from the house 3kW solar system, and also cannot touch the Energex meter box at all, ...
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0 votes
1 answer
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Compact relay banks [closed]

I'd like to switch about 20-30 audio signals. By "audio", I mean non-DC that is low-voltage (<5V peak) and low-current (<50mA peak). I'd like this switching to occupy the smallest ...
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1 vote
1 answer
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Looking for a simple circuit to switch power to IR LED's at night (2A @ 12 volts)

I'm looking for a simple and cheap way to switch power to a few hi-current IR led's at night. So some sort of photo detector and a solid-state or traditional relay. Unless there's a single-component ...
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0 votes
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AQH3223 vs AQH3213

I would like to know what the difference between the AQH3223 relay and the AQH3213 is? I know the AQH3213 is zero-cross, but I would like to understand for sure what that is. Can I use one of these ...
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2 votes
2 answers
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Control AC load via relay with DC trigger?

The headlight of my motorcycle is AC powered via stator. I want to switch between Hi/Low beam using a single pole double throw (SPDT) NC relay. Power to pin 30 (AC) Ground to pin 85 (?) Trigger to pin ...
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-2 votes
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Relays or MOSFETs

I’m making a circuit with peltier modules, a relay H-bridge and an Arduino. The system takes input from user of desired temperature. There is a temperature sensor placed on the peltier and the system ...
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1 vote
1 answer
86 views

Prevent power-on for some time after last power-off

Given is the load that cannot be turned on immediately after the power gone off. This is a High-pressure sodium lamp, which needs cooling down for 5-10 minutes before the next ignition, otherwise it ...
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Is it safe to PWM control a consumer smart plug or smart switch?

I was looking at a project that controls the speed of a normal off-the-shelf AC-powered house fan by plugging it up through a consumer smart plug (specifically, the Kasa ones, if that matters) and ...
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1 answer
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Is there a way to predict the VDC rating of a relay in function of its VAC rating?

I need a 36VDC 20A DPDT (c.f. answer to some other question I had) - resistive load mostly -, but can't find any. I have found candidate relays though, that have been tested at 28VDC 20A, 470VAC 20A, ...
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4 answers
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How to detect welded contacts of a redundant relay? (for reliable high-current e-Stop)

I want to switch ON/OFF a load with an e-Stop backup - the issue is that the load is 20ADC. So the load is switched by a suitable relay (SPST-NO), which is itself controlled by the ON/OFF switch in ...
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Best practice power on/off switching with small switch in power electronic

I am developing an industrial project as an amateur but I have no experience in power electronics. I want to add an on/off button to a PCB design with 12-36V operating voltage and 3A load current. The ...
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2 answers
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Load independent LED flasher DIY advice

I found a product that does something very similar to what I'm trying to DIY. The product purposefully combines a load independent digital flasher relay and electronic push-button controls. Depending ...
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Selection of voltage transformer and current transformer for protection in substation

having a 66/11 kV substation, how does one know which voltage transformer and current transformer to use? They secondary side would be connected to a distance relay for monitoring. I know they need to ...
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2 answers
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Installing a relay and its ratings

I'm planning to install this DC input relay called G5RL-1A-E-HR-5DC at the line of an SMPS supply. The SMSP will sink nominal AC line current of less than 1A but its inrush is 45A at cold start. The ...
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1 vote
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Germanium vs. silicon

I am using a 12 volt relay to operate an AC electric water valve (120 volts.) The problem is that the circuit worked well at first. I placed 2 germanium diodes across the relay terminals to protect ...
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