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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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23 views

Relay Switching MCU Hanging/Reset

I am working on samD21 MCU to control the 16 relays. I am also using a circuit to detect the input AC switch status On/OFF (Connected serially to the relays). This is connected through optocoupler ...
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56 views

What can happen to a relay at temperature outside of its spec?

I am building a system for measuring some parameters in a climate chamber. The test runs from -55 to +125°C. I need to switch some signals between multiple devices under test using relays. I want to ...
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3answers
98 views

Is there Mosfets for wires? [on hold]

Mosfets are pretty cool but they are either designed for circuit boards or for breadboard's. Is there a version of a mosfet that can be used for slightly thicker wires than what would be usually ...
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1answer
30 views

Convert a Dusk-to-dawn outlet device to Dawn-To-Dusk?

I recently purchased a Dusk-to-dawn outlet sensor (https://www.amazon.com/dp/B00002NB2X?ref_=pe_2640190_261118450_302_E_DDE_dt_1), but I'm wanting to convert this thing into a Dawn-to-Dusk device ...
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53 views

Looking for a three state relay or switch

I need to control the link between three wires: Nothing touches == State 1 == Light is off Red touches brown == State 2 == Light is on Red touches grey == State 3 == Light blinks A little drawing: ...
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3answers
57 views

how to read this relay diagram

I am a little confused on how this W171Dip-7 relay works. I know 2 is pos 5v and 6 is neg 5v. Looks like the signal from 1/14 will go to 8 / 7 when closed. But i cant tell if 13 is tied to 14 or ...
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34 views

pull-up resistor relay (low trigger)

I'm having issues controlling a single relay module with an arduino. It works fine when its up and running but the relay initially starts triggered until the arduino can send a "high" signal to turn ...
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2answers
40 views

Does only wiring 2 poles of a 3 pole overload relay have any effect?

When wiring a single phase starter, they tend to jumper the overload such that all phases of the overload are used. Now, considering that the overload has 3 separate bimetal strips all connected to ...
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40 views

PIR triggers relay without motion

simulate this circuit – Schematic created using CircuitLab I'm using a HC-SR501 PIR sensor and a 12V relay to switch between green (NO) and red (NC) on a LED strip, everything being powered by ...
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2answers
654 views

Is it OK to use internal pull-down as part of voltage divider?

There is a NUD3160 relay driver on the board that I need to set ON at power-up. According to datasheet, it has internal 100k pull-down and 2V threshold voltage. So, if I add external 910k pull-up to ...
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4answers
71 views

Current booster for relay

I have a DC power source which can provide up to 5V, 50mA (LabJack maximum output current, voltage bus-powered) and I want to power my relay (SDT-S-105LMR2,000) with 5V, 100mA. I have an option to use ...
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19 views

Non-latching relay with timed reset

I have an application that needs a specific type of DIN-mounted relay for switching mains ac (240V) electricity. I'm not sure if it exists, or what it would be called. The application is remote ...
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1answer
94 views

How to control contactors with sequenced time delays

Updated schematic to correctly reflect what I wrote below... I’ve had to add more functionality: Top left: The linear regulator has been replaced by a LM2575-5. This will be the HV variant with a ...
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1answer
46 views

Some help with buzzer schematic and reducing power troughput

I have a water tank with a built in simple 'float switch'. It acts like any other switch. Last year I tried connecting it to a buzzer so that I would know when the tank would be empty. This burnt out ...
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1answer
54 views

Innitially turn off device with relay, Arduino and IR remote

I am suing this code to control relays with Arduino and remote. This code is working fine for my requirements. Only problem is that when electricity goes and come after some time all appliance turned ...
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23 views

Controlling Relays with Arduino and External PSU

I'm on a project in which a number of 5V relays are used. Since I have an LCD connected directly on top of my Mega2560 (via LCD TFT Shield) and it draws significant current from the built-in 5V ...
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1answer
43 views

3.7 720mAh lipo thru TIP120 as a relay — no current?

Trying to ignite an RC glow plug using an Arduino Nano and TIP120 as the relay per the typical circuit -- using a separate 3.7 lipo 720mAh w/o the circuit ignites the plug (actually its twice what the ...
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1answer
44 views

Protection against a circuit being closed too long or failing closed

I'm prototyping a device that allows me to electronically open my front door, which it accomplishes by using a relay to close an existing circuit in my house. All I know about this circuit is that it ...
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81 views

Easiest way to short 50 pairs of wires together

I have a serial keyboard that has 24 pins and works via one of the top 11 pins shorting to one of the bottom 13 pins when you press a button (top and bottom membranes touch) and this is picked up by ...
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1answer
51 views

Alternatives to a sliding switch and relay?

There is a sliding switch on my board to select two different cases. A key like this: From sparkfun.com You know its equivalent schamtic is as below: From sparkfun.com I am designing ...
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5answers
209 views

Why not use actual switches instead of Relays

Relays are expensive and have limited lifetime. Choosing a proper relay for a particular application is also important. In other words relays require a bit more of everything when compared to a simple ...
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29 views

Triac design for switching load to resistive heater

I'm designing a triac-based relay circuit to switch ac mains on-off to a resistive heater. The app note (AN-3004) for the opto isolator I am using, the MOC3061, suggests using a gate resistor value ...
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41 views

AC to terminal block relays

How can I use one power cable to connect to 4 relays in parallel? So for example, I have one power cable and I want to turn on 3 radiators out for 4. This is my screenshot of the circuit. Terminal ...
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3answers
110 views

“Break-delay-make” relay?

I'm new to relays and still learning terminology. "Make before break" and "break before make" both make sense to me. Is there such a thing, or a specific term for "break before make" relay that can ...
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37 views

Electro-mechanical relay durability curve

For general-purpose electro-mechanical relays, it is often mentioned in datasheets the number of cycles under various categories of load (AC1, AC15, DC1, DC13 etc.). For example, the following image: ...
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89 views

Darlington array: How to output desired voltage at uln2803a driver colectors?

Someone suggested this driver array to get the current I need: datasheet I also need a 12V signal and about a current of 100mA in order to control a relay coil. My 12V signal would come from a logic ...
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1answer
66 views

Switching between 2 24V 30A power sources

I am trying to make a changeover switch. The current at full load which the switch needs to handle is 30A. I looked into automotive relays, but I believe they are not rated for continuous use. I also ...
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3answers
41 views

How calculate and chose the right BJT that comands a relay

I was projecting a simple circuit that, from a digital OUTPUT from an Arduino zero (3.3 V) switch on a BJT that is connected to a relay. The base of the BJT must have a current of about 5mA or less. ...
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1answer
78 views

Help me understand my campervan split charge relay

I am new to the world of electronics, but keen to learn. The below all relates to the 12 V circuit of my van. I have picked up a campervan which has a second "leisure" battery which powers items in ...
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2answers
75 views

To what pins of the relay do I need to connect a device to be able to control that device ? NO or NC? Why?

I am very bad at electrical things, as I don't understand much of electrical engineering. I was tasked to design a software that will take some inputs, randomize them and give some outputs to some ...
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49 views

How is an NPN relay switch circuit analysed?

So I came across this good article: https://www.electronics-tutorials.ws/blog/relay-switch-circuit.html It gave me a good insight into the different transistor-relay switching circuits. But ...
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1answer
56 views

Problem with voltage comparator with relay

I'm making a circuit to alternate its input, depending on the voltage that's feeding the system. I used a voltage comparator with a transistor and a relay to do this: The simulation works pretty well,...
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1answer
44 views

What contacts do the numbers on this DPDT relay refer to?

I’m new to electronics, could someone please list the contacts that belong to each number. e.g. COM1, COM2, NO1 etc. It’s a Taiss/JTX-2C, MK2P-I DPDT Power Relay with Plug-in Terminal Socket Base, DC ...
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53 views

RC Snubber for Air Conditioner SSR

I have a window/Wall AC 2 Ton (240V X 15A = 3600W) I'm trying to control it via SSR to use Central AC thermostat board on it which is working good on fan level and all but I need a relay to switch the ...
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1answer
27 views

Multi valued Relay Ratings

I am not much experienced using relays. Earlier I used any relay with any setup just for the purpose of building something. But now I wish to make efficient and safer projects. For that purpose I was ...
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26 views

Switch gear & protection - Problem

I'm a B.tech student currently in my 4th year. I was learning Switch gear and protection and suddenly I came across a numerical problem while trying to solve it, I'm having a small doubt as: Is ...
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1answer
36 views

Relay coil inductance variations vs. temperature

How does relay (something like this https://www.hobbytronics.co.uk/datasheets/songle-12v-relay.pdf) coil inductance changes with increasing/decreasing temperature? And how can we calculate the new ...
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2answers
99 views

High-current analog switch

I'm looking for an SPST analog switch (or alternative device) capable of handling >=150mA (5VDC) across its switch, controllable by a logic-high signal. I've been looking on digikey, and haven't had ...
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1answer
73 views

How to short two points(2 wires) without using relay

I have made a circuit with ESP8266 which triggers a relay. Actually, I want to bypass a button which is on a 3rd electronic device, which is a closed box with a very complex circuit. I have soldered ...
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1answer
86 views

arduino resets when switching on relay

Good day everyone I have the Atmega328P-AU on a PCB (Controller IC used in arduino nano). I have made the connections as shown in the arduino website for bootloading and uploading the code. This part ...
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2answers
96 views

Can I use this DPDT relay with this circuit? If so, which wires connect to what terminals?

I'm following this tutorial to wire an automatic chicken coop door. The DPDT relay they're using is different to my relay so I'm finding it difficult to understand which wires connect to where. I'm ...
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3answers
99 views

Do unused relay pins help with heat dissipation?

I have been using DPDT relays to control high-current loads (~15 A at 240 Vrms) though I am only using them in a SPST, NO fashion; that is, the load is disconnected when the coil is de-energized, and ...
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1answer
45 views

Switch that change its state with a signal of some seconds

I'm making an IoT project for a friend, but I need some tips: I want to use an old mouse sensor and convert it to a movement sensor (just for a door) and if it's activated, a second device (an esp8266)...
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1answer
79 views

Switching 400V motor with 5V

I'am trying to make an automatic irrigation system using an Arduino, a moisture meter and a water pump. The issue is that I can't figure out whether there is some relay/contactor type component that ...
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3answers
72 views

Problem with a relay decoupling voltage

I made a simple circuit to alternate its output between two inputs: a photovoltaic panel and a 12V DC voltage source. The schematic: The step source represents the photovoltaic panel and the two ...
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0answers
23 views

PLC Ladder Logic using LRXSW

I'm working on a project for a summer internship and was hoping for some assistance with PLC Ladder Logic. I have been trying for the last couple of days to program the PLC to do what I want but have ...
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2answers
73 views

Motor with two endstops using limit switches

I have a circuit where two limit-switches to be wired with motors to do the following functionality. It is to be used in a remotely placed device so that the intervention of microcontroller on the ...
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2answers
42 views

Hedge relay current capacity with additional wiring

I ordered several OMRON “ice cube” 110 VAC relays, contacts rated for 10A (LY2NJ). When I inspected them under a microscope I noticed the contact wires are AWG 24. The rest of my setup uses AWG 18. My ...
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1answer
58 views

Simplest latching circuit with press-ON hold-OFF button that can cut power when Raspberry Pi halts

So I'm making a battery-powered Raspberry Pi project, and it would be ideal if it could cut off power to the Raspberry Pi after the Raspberry Pi shuts down. It would also be ideal if the power for ...
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2answers
58 views

Coil Voltage Rating of Relay

I have seen many relays with same current and voltage rating (like 10A 230VAC or 5A 30V ) but the coil rating (I am not sure, I am using the right word) are different. Some are 5V some are 12V and so ...