Questions tagged [relay]

A relay is a part that acts like a switch that can be controlled by an Arduino. They usually are powered by sending current through a coil, which moves a piece of metal to touch a contact within it. (Note there are also solid state relays which act more like a transistor.) The moving parts is why some devices make a "clicking" noise when they turn on/off a light or another device attached to it.

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Activating a Relay with Wemos D1

I have a problem similar to these questions: Wemos D1 doesnt drive Relay Wemos D1 is not triggering Relay I got this BC548B transistor from an old apparatus I scratched. The transistor saturation ...
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29 views

Can I use the NodeMCU ESP12 5v pin and control it with a relay?

This question might be a little esoteric, but I cannot find any answer for it. Situation: I want to have more than 8 Analog sensors on a NodeMCU ESP32. Unfortunately due to SPECTACULARLY poor design ...
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58 views

New to arduino, help wiring relay

I am new to arduino and need some help. I just baught light bars for my jeep and wiring harnesses with them, the harnesses come with buttons and I wanted to replace the button and have them controlled ...
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25 views

Esp and blynk app

It is possible to control one relay using Blynk app and also using an atmega? To a better understanding think at a relay that will turn on a fan when you use the blynk app. but when you don;t have the ...
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41 views

LED array flashes once before being lit

I've built this simple Arduino controlled led-array. The Arduino sets a 5v pin on a relay to connect the high current power supply to a led array. However, just before the led array is being fully ...
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32 views

Wemos D1 is not triggering Relay

Update: I realized my relay module was 12V and the current leaving the digitalpin from my Wemos D1R1 is only 3.3V. I bought a 5V relay module that I read in some articles that it could work, but it ...
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52 views

Difference between these two relays (D1 Mini Relay Shield and Single 5V Relay)

I've setup my NodeMCU v3 with this relay and I got this: When using 3V to power the relay, I can hear coil when I turn on the board and I can only turn it on once. Then I can no longer hear the coil, ...
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42 views

How to make a circuit to control a 24V solenoid

I'm new to programming with Arduino and a little rusty with circuitry. I'm trying to control a 24V solenoid with the Arduino mega board. I've done some research into this and I believe I have a code ...
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122 views

Fan regulator control from Arduino

I'm trying to control my ~230 V fan from the Arduino. Can anyone say the best possible ways to design a fan regulator that can be controlled by the Arduino using a low cost design.
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2answers
44 views

Why is my relay not triggering?

I have a 4 channel relay for my Arduino. Here's an image: From what I can tell, it's rated for 5V direct current because of the big 05VDC at the bottom, but please tell me if I'm wrong? If I'm wrong, ...
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2answers
31 views

Can the 'Adafruit Non-Latching Mini Relay FeatherWing' be used with an Arduino microcontroller such as an Arduino Mega 2560?

Can this relay found here: https://www.adafruit.com/product/2895 Be used with an Arduino Mega? The description given seems to specify that you should hook it up to their dedicated 'Featherwing Board'...
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59 views

Arduino and Solenoid Water Valve

I use Arduino UNO and two SPST Relay (Wemos Mini D1 Relay) to make the reverse polarity circuit. I use this circuit to open and close the Solenoid Water Valve (SWV), which work with 9 to 12 volt. The ...
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2answers
140 views

Esp8266 Vin pin

I've read that Vin pin is directly connected to usb cable in esp8266 (which is 5V). I wonder if I can power a relay 5V and a servo motor Sg90 with this pin? And is there any danger of doing that ?
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47 views

L293D with arduino's 5V

I am trying to use L293D with relay to power a 12V DC motor. Can I use arduino's 5V to provide L293D inputs 4 and 8 such as in the drawing? Or do I need to use a separate source, e.g. a power module?
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32 views

Too little current to trigger a relay?

I try to use this relay with a Arduino Mega. I connected with jumper cables 5V pin to DC+, GND to DC- and Digital Pin 13 (because its a lucky number) to IN. The power LED from the relay is lighting ...
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1answer
93 views

Normally-Open opto-coupler board

I'm looking for a Normally-Open optocoupler board for arduino. I need to control power of a device (DC 12v, 500mA). I tried to use TLP281 board, which works, except that it inverts the output: device ...
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30 views

Rfid stops scanning after wrong card scanned

My Rfid reader stops scanning cards after scanning the wrong rfid card. It doesn't scan it anymore after turning off the relay. *It turns on the relay if my rfid card is the right one #include <...
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1answer
49 views

12 V relay using Arduino [closed]

I want to control a 12 V relay using an Arduino 5 V signal, but due to some unknown reason the relay does not work. I am using a BC548 transistor as a switch for relay. Please suggest where I go wrong....
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21 views

Voltage to keep my board safe

I have recently made a home automation system using node mcu and relay module and i am powering both together using my 5V ,2A dc adapter and i am scared that if I'll keep using it for very long hours ...
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3answers
112 views

How to initialize digital output pin as low

I need to define a pin as output for relay module but when i do it in setup section, relay is activated (low - 0) automatically then i deactivated immediately with coding digitalWrite(pin, 1) but this ...
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0answers
31 views

Stuck Arduino Relay?

I am looking for a relay which stays on/NC (Normally Open), and when I send a new signal switches to off/NO (Normally Open). So the relay doesn't consume any power while being in a specific position. ...
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1answer
53 views

Do all pins of Arduino Uno output 5V?

I am currently working on a project which uses PIR motion sensor and 5V relay. Since you might be familiar that both the motion sensor and the relay requires a 5V connection. My problem is, I don't ...
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2answers
92 views

What is the state of Arduino pins when the arduino is unpowered?

I'm building a control box to provide logical control of power outlets. I'm using a 4 channel 5V optically isolated relay system to control 4 separate outlets. To use optical isolation you connect ...
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1answer
63 views

Replace mechanical switch with electrical switch or relay

I have a remote controller for a portable heater, and working on a small project to be able to control the fan on/off from an arduino with Bluetooh HM-10 module. I thought a solenoid might work by ...
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1answer
41 views

How do I use a 5v/120v relay that is not mounted on a board [closed]

I bought an arduino kit, and it came with, amongst other things, a 5v relay to control 120-220v. The relay is only that, there is only the 5 pin relay, and it's not on a board on which one can ...
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1answer
54 views

Failsafe Arduino

I want to read an RFID tag using an Arduino, which controls some relais. This is easy. For me the more complex part is to build it fault-tolerant. So I thought I could use the watchdog. The tricky ...
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1answer
147 views

5V 10A 4 channel relay to 2 lights15W light in series in 220V AC supply

I am trying to setup my first relay module with live environment. I have attached the relay module image below. Which I am using to control 4 devices in my switch board as follows: Fan (working ...
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2answers
189 views

Is it okay to short IN and GND pins of relay module with controller ground? [closed]

I have this relay module that is attached to an ESP8266 (Wemos D1 Mini). Currently, I operate the relay by shorting the IN and GND pins to ground (relay module uses low state to energize) with a ...
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0answers
45 views

Garbage output/ not running at start up nodemcu

I have a nodemcu acting as a thermostat home office. The wall heating element is controlled with a solid state relay on D2. If i have it connected, I cannot program the board from the arduino ide. I ...
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1answer
25 views

Relay 24 V appliance [closed]

I want to use a switch and an Arduino to "power" a 24 V DC appliance and I am not really sure what relay to use for this. So I need the relay to be able to switch it on and off, but I have not really ...
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0answers
218 views

Wemos D1 mini with relay shield (why does D1 not operate relay but D5 does)?

I connect gnd>gnd, 5v>5v and d1>d1 - nothing works with relay blink code I change connection to d5 on wemos (still d1 on relay) and it works fine with code change to d5 Any ideas, as at present I ...
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1answer
78 views

Digital Input using a button doesn't work properly when using it to control a relay

I'm trying to control a relay both via Bluetooth and using a switch. The problem is that, when the LED is off, I can turn it on with the switch but then if I turn off the switch the relay will stay on....
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1answer
226 views

nodemcu esp8266 does not boot up when 5V pin is connected as a VIN source

Whenever I boot up the esp8266 or flash code via usb ,I have to remove vin pin otherwise it does not boot up. If I remove vin pin then flash and boot up happens and then i am able connect vin with 5 ...
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1answer
75 views

Newbie question - Biltong Box Project [closed]

I am a newbie to electronics, but I do have experience working with electrical wiring in the UK, so I am comfortable working with 240V reasonably safely. I have also built a camper including all the ...
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1answer
113 views

Using mills() in place of delay() on relays not getting solid switch over

I know I should post some code that maybe cleaner but really I am just in need of a answer to a problem I seem to run into a lot when using mills() in place of delay(), whilst making a Christmas light ...
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2answers
89 views

Voltage Regulator getting too hot

I have an Arduino mega that is being used to control relays and ultrasonic sensors. The relays that I am using is a 4 DPDT Signal Relay Module Model: D-256 Series and the other is a 4 channel Single ...
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1answer
632 views

Arduino UNO + ESP8266 WiFi Relay by LC Technology

I have Arduino Uno, and recently obtained ESP8266 WiFi Relay by LC Technology. I tried to look up some information about that on the net, but all the answers / suggested solution didn't work for me. ...
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1answer
144 views

esp8266 + octocoupler relay: WDT reset when using AC current

I'm trying to switch on bulb via 4 channel 5V optocoupler relay controller from ESP8266 using WIFI Access point. All my connections looking fine and i can able to connect WIFI SoftAP and send signal ...
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1answer
234 views

Shift register with relay board behaving erratically

I have a nodemcu connected to a shift register(https://www.amazon.de/gp/product/B07CHBYR7Z) to control an 8 channel relay board (https://www.amazon.de/Elegoo-Relaismodul-Optokoppler-Arduino-Raspberry/...
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2answers
71 views

8relay module asks more than specs

I have a 8 relay module that should use not more than 20 mA per relay. Altough when measuring it asks around 70. If I use 6 relays, that would be more than an Arduino Mega can give. (I already lost 1 ...
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1answer
146 views

Frequent ON OFF in SSR

I am working on a project on Arduino OLED MAX6675 thermocouple and SSR for my oven. My problem is when my SSR goes in LOW or HIGH state it turn ON and OFF several times before going to permanent HIGH ...
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1answer
67 views

Are these relays connected correctly?

I currently have limited electronics experience. I am planning to use mains power through relays for climate control, so considering the risk, I would like to check to see if these relays are ...
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1answer
81 views

How to detect when intercom is ringing?

For my apartment, I need to check when intercom is ringing and call an API in that case. I was thinking about using an AC input / DC output relay, since the buzzer signal is an AC signal. Is there an ...
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2answers
299 views

shift register 74HC595 enable specific pin

Its driving me crazy for some couple of days now and i don't get the answer. I'm busy to setup a irrigation system with a shift register 74HC595 and a 8 channel relay board. I see a lot of sketches ...
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0answers
48 views

Project: Relay is ticking, but not actually switching [closed]

I'm trying to make an automatic planter for herbs etc. I finally got everything 3D printed and wired together. But for some reason, the relay I'm using refuses to switch or enable certain connections. ...
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0answers
72 views

Correct wiring?

I'm doing some Home automation and am currently trying to automate my intercom system. My overall aim is to be able to detect when someone has pressed the buzzer and then to be able to open the door ...
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3answers
126 views

Monitoring the state of AC relay, design considerations

I want to use a sensor and relay as a safety device to allow/deny power to an AC mains-powered electrical unit. If the wall power is disconnected I loose the state of the relay which is stored in a ...
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1answer
255 views

Relay Module for water pump [closed]

I want to switch on/off my water pump by using arduino nano, I have 2 channel relay module. Is this module safe for controlling pump? Specifications pump: power = 746 watt (1HP) single phase, voltage =...
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3answers
820 views

Push button control of multiple relays

I'm new to arduinos and have not been able to find/create a working bit of code for my project. I'd like to control several different relays (standard 5v optical relays) with push buttons. I want one ...
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1answer
650 views

Problems with NodeMCU and Relay

I've connected the MCU to a cheap chinese 24/12v to 5v car phone charger and hooked some wires to a relay.When I try to program doesn't matter if the pin is set to high or low , as soon as I touch the ...