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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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What should be the expected voltage on pin 30 of a starter relay? [migrated]

I was doing some research about how a pin 30 works on a relay and basically it said that this should be wired through a fuse to the battery. I checked the voltage on the relay slot where the starter ...
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Replacement for Airpax Solid State Metering Relay [on hold]

Question: what is a modern equivalent (or near-equivalent) for an Airpax Solid State Metering Relay, specifically model number AMS91 or AMS92? I have a cut sheet from the manufacturer dated April ...
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1answer
70 views

How to join and connect two wires in one connector point professionaly in a high voltage PCB?

Regarding a HV (6KV) PCB design there is a part of the circuitry, related to reed relay connection. I have chosen a HV relay (datasheet) with flying lead connection in order to separate physically ...
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75 views

How to connect these relays together?

I have 4 relays as shown. I have created a small connection flow diagram with these relay.-->shown Is these connection ok for control four relays? Any current/voltage issue come? Any ...
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2answers
40 views

Inrush Current effect on a Relay

I am confused about inrush current for a relay. For example, if I had 12A as the inrush current due to a motor, if the contact rating of a relay is only 6A, does a new relay need to be chosen? As in ...
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2answers
28 views

How to connect a device to ground using negative signal with high impedance

simulate this circuit – Schematic created using CircuitLab I have a device that enables a ground connection when I press a key on a remote control. This negative signal used to control other ...
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2answers
72 views

Cheap alternative to limit inrush current (eg. relay bypassing a fixed resistor or MOSFET)

I'm editing the question because several (great) answers focus on the fact that the LTC3780 module (inside ajustable my power supply) can handle the inrush current (maybe, maybe not). I'm glad to know,...
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“Solder PCB” or “Flying Lead” high voltage connection for a reed relay model?

I'm searching for the HV reed relay solution for channels multiplexing printed board design: V < 6KV, I < 10mA. 8 relays that connect 8 input pins to V or GND (given for an external supply ...
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1answer
38 views

Simple battery backup [closed]

I am experiencing sudden outage in my area from few seconds to a hour or so. I am currently using this circuit. Turning on and off every time for a blackout is just annoying. I just want to cut off ...
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1answer
79 views

Does anyone know what these marine radio pot/switches are or what they do?

I enjoy re-purposing misc items and components to make neat gadgets etc. I have salvaged these two "switches" from an old marine radio. The rods on each click in and click out and rotate in both ...
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Handling Hi voltage and very low current (10 mA) will need to prevent arc and corona effects on my PCB?

I' m following this guide; concretelly 3 and 4 chapters for High Voltage (HV) PCB design: https://www.magazines007.com/pdf/High-Voltage-PCDesign.pdf The fact is that I have read interesting ways to ...
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Connecting Arduino to 10hp 3 phase ac motor?

I want to connect Arduino to 3 phase 10 hp ac motor. I just want basic functionality that is I should be able to turn it on or off using the code. Is it possible to do with 3 phase solid state relay? ...
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2answers
60 views

Looking for reed relays for high voltage commutation

I need to chose a reed relay for connecting a point to high voltage (probably between 7000V:15000V) or to GND signals. System will have 8 channels (pins). Some of 8 pins will be connected to high ...
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1answer
75 views

PNP Transistor Switch for Relay

simulate this circuit – Schematic created using CircuitLab Hi, I have a low battery detection circuit here. When the voltage of the battery goes below 10.5, I have an LED flashing (Uses the ...
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1answer
37 views

Flasher Relay Wiring Diagram Help

This is a diagram for a flashing relay. Normally used for automotive, I'm curious if I can get it to work with my needs. I want to be able to start and continue the flasher with a 12V output, and ...
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1answer
73 views

Why does my non latching relay design not switch back to original state as I expect?

I am using the EE2-12NUL relay and the LL4148 flyback diode. I am controlling the relay with a GPIO pin from an MCU connect to some mosfets. The coil current is 11.7mA for this relay. When not ...
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1answer
30 views

What do relay switching characteristics mean?

I am looking for HV realys (3kV) and found a supplier for that. Now they offer relays with different switching characteristics: "No Load" "Make & Break" "Make only" "Carry only" On the web page ...
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1answer
62 views

Switch AC contactor with an ESP-12s - will this circuit work?

I'm trying to make an ESP-12s control 2 relays to switch an AC contactor. I made this schematic in Altium and posted to ask if it will work. The 2 DC power supplies (3.3V and 5V) are isolated.
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1answer
36 views

Voltage drop on relay coil while driving relay using Darlington Arrays

I am using Wemos D1 mini and trying to use ULN2083A Darlington Arrays to drive SRD-05VDC-SL-C relay. The relay does work properly when the circuit is connected as attached schematic. The Darlington ...
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2answers
42 views

MOSFET Controled Relay Problem

As a way to power-on/-off a circuit load, a MCU is used to drive a relay through two MOSFETs. The problem is, when the MCU GPIO output is measured 0-volt, the relay could stay connected. Can anybody ...
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2answers
80 views

Why SSRs for heaters?

In the context of building PID controllers for very large heater systems (ovens, kilns, etc.) nearly all the designs I encounter use an SSR to switch the load, a choice I don't understand. The power ...
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3answers
87 views

Which Pin is NC, NO, COM in this relay module [closed]

Above is an image of a relay module but the problem is the pin name is written in the chinese language so it is difficult for me to figure out the name of the all 3 pins. So, Please clarify which pin ...
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1answer
45 views

Understanding relay contact ratings

The "ice cube" relay in question is allen bradley's 700-HC series. I was browsing through the spec sheet looking at the electrical data to make sure that the relay has the proper voltage/current ...
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0answers
25 views

Transistor to disconnect Ethernet connection [migrated]

An old notebook I found in the basement always tries to boot from the network as I start it. Unfortunately I've forgotten the BIOS password. I figured out that one USB port delivers power until ...
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2answers
101 views

What is the common name for this seal-in relay?

I'm trying to build a hysteresis water pump system with 2 water level switches. Please see the diagram and explanation of this setup I've taken off the web: The first switch (L) is set at the minimum ...
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1answer
59 views

USB VCC powered relay

Sorry for the dumb question, but my electronic skills are even lower than basic level. I need to switch on a relay when PC turns on. I made a simple scheme on the run, but I'm afraid it isn't good ...
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1answer
53 views

Why do protective relays have a delay?

6I am a software engineer with a small amount of experience in electrical engineering that has been tasked with designing an embedded OS for a IDMT relay (uni project). However, I don't understand ...
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1answer
122 views

Why this relay in ciruit become hot? [closed]

I have relay circuit which is controlled by a micro controller (as shown) here relay ON or OFF by allowing phase voltage. load circuit of relay is an inductive load(motor) the problem is, after ...
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1answer
94 views

How to connect snubber across this circuit?

I have a relay controlled by micro controller as shown. Here AC 230v phase will flowing through relay to an inductive load . where in my circuit place a snubber circuit to protect when inductive ...
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I have two inputs which are switching between 12V and a GND. I want to have a wire where I always have 12V and one with where I always have GND

As in the title. Assumptions : The inputs are switching at the same time. If one is 12V the other is GND and vice versa. I have tried coming with a solution on my own : using an OR port (diodes) to ...
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1answer
40 views

IR Remote with 4 buttons timer

So I was wondering how it would be possible to design an IR remote that consists of four buttons for each channel powered by a battery. How would I be able set something like this: The receiver will ...
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1answer
43 views

Safe to drive 24V leds directly via 2SK2049 MOS-FET?

I have built a simple automatic switch that synchronizes IKEA LED strip with the main light in the room, eliminating the need to switch multiple switches in the evening. Currently it works like this: ...
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4answers
101 views

How to overcome over-current in a circuit?

I have a relay switch that operates at 10 A and 120 V connected to a DC motor that runs at 18 A and 36 V. Will the relay switch burn out? If so, how can I protect the relay switch?
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2answers
158 views

Why this circuit may consume some extra current?

I have this transistor circuit with relay. Here the transistor input is connected to the GPIO pin of the micro controller. According to whether this relay is ON or OFF, then phase voltage is passed (...
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2answers
82 views

What is the purpose of the relay in this circuit?

I have tinkered with relays while building small projects with microcontrollers in the past. Usually I use them to switch higher amperage circuits off or on. I recently purchased this horn and this ...
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2answers
100 views

Parasitic drain - What type of relay is this?

I am having issues with my car in that my electric window circuit appears to be taking .2A when the car is off. I have access to the wiring diagram for this circuit and there is a relay (T13) before ...
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6answers
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Is there a kind of relay that consumes power only when switching?

The relay must stay in its state. When an electrical impulse is sent to it, it should switch its state and should maintain its status. So I am really curious about it. Is there such a thing for ...
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1answer
44 views

MCB with electronic trigger-off [closed]

How can I design a system that gives the functionality of an MCB (overload protection, operates in an AC circuit) with an electronic trigger-off. So that once the device is in ON state, it should be ...
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0answers
27 views

Relay F. Bv. 153e

This is an old relay from a Hitachi electron microscope vacuum gauges power supply. Is there another equivalent version available? I have located an Omron F. Bv 153b but there are too many pins. Mine ...
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28 views

4 Wire Thermostat for Two Separate Heaters

Is there any reason why I cannot use a 4 wire thermostat (Honeywell T410B, DPST) to control two separate heaters (they are fairly close to each other)? The contacts are each(?) rated for 22 A and let'...
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0answers
29 views

Switching between high voltage power sources [duplicate]

I need to get an LED to switch on once the voltage across a capacitor goes above 40V. It must then remain on from 40V to the maximum voltage reached by the capacitor which is currently 1200V. The ...
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1answer
31 views

TENS spike smoothing when using a relay

I'm currently messing around with a TENS unit and would like to block/unblock the signal from reaching the muscle (Alterations to the TENS unit circuitry aren't possible). The unit uses a 2 mm jack ...
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3answers
70 views

What is the safest way to trigger an output?

I need to trip a 12V output with a signal. In other words, I will send a signal through the output of my microcontroller and ...
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1answer
70 views

i need a circuit to kiss NO contacts no matter how long you hold the button [closed]

I am working on a license camera at a gated community and the nvr is holding the gate up to long. the lowest setting is 5s but I need it to be 1 sec. I looking for a made relay or a circuit to build ...
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2answers
54 views

Relay Driver with 24VDC Relay… Zener diode?

I am part of a physics project group, and we are trying to design a relay driver. Our Relay is rated at 24VDC (it is a Tyco Electronics 1432826-1). What zener diode (or regular diode if that would ...
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0answers
41 views

controlling central heating/cooling unit with relays, thermostat

I am working on a thermostat project for a heating/cooling system in the house. The original plan involved having three relays (like this one: https://wiki.wemos.cc/products:d1_mini_shields:...
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1answer
43 views

Relay or Transistor as low DC switch

I am working on a project for a watering controller where I would need to turn on or off an solenoid valve (electric valve), my first thought would be to use a relay, but I know relays are good for ...
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3answers
59 views

Breakdown Voltage of relay contacts in series

I am working on a module that allows a small internal-combustion engine to be shut down remotely. These small gasoline-powered motors are of various makes and models and all have magneto ignition ...
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2answers
105 views

Power drop on AC-DC converter due to relay

A uController circuit is powered with an AC-DC converter. This circuit in turn acts on some relays to turn on and off some loads. We have two bi-stable relays and another simple relay (Omron G5DN-1A) ....
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1answer
73 views

Phototransistor relay circuit

I don't quite understand this type of circuit: When light strikes Q1 (phototransistor), if the light is intense enough, Q1 is turned on, then current flows into the base of Q2 which also turns Q2 on, ...