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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35 views

Arduino Relay Alternative [closed]

I am looking for an alternative to this Arduino relay circuit. Mosfet? Any suggestions?
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Atmega 328pu as stand alone

I am used atmega 328pu as stand alone.i used 7805 as regulator. I regulated from 12 VOLT 2 amp smps. When I connect my dc 12 VOLT pump in between 12 VOLT and ground dc motor working fine but Atmega ...
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23 views

activate a relay with two esp8266 -12e pins

I have an esp8266-12e that I want to activate the reset side of a latching relay. The problem is that the 12e only puts out 12mA/pin and the relay needs more than that. I am using a transistor on ...
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186 views

Arduino 5V pump digital pin

I am trying to control a 5V pump with arduino and ultrasonic sensor however i can't make it work with the pump connected to a pin. I saw on the forum that you need transistor or relay but i don't ...
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1answer
42 views

How to set a timer for a function and be able to reset it in the middle of the process?

Hello me and my friend have to do an assignment for school but we need some help. We have to make a LED turn on and of with a button and a relay. But when I press the button the LED should be on for ...
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44 views

5V on HIGH Digital Pins, Only While Using USB Power

So I have a small problem with my Arduino Pro Mini here. May be worth noting that it is a clone, but otherwise this is still some weird functionality. I have done some experimenting so I'll just set ...
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1answer
63 views

ESP8266 reseted due to relay / AC plugged

My Wemos card is reseting for unknown reason. For example, the pump plugged on the relay works fine till 1am and then the pump stop. After a few research I figured out the ESP should reset because all ...
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2answers
191 views

To control the relay switching in nextion using esp32 Microcontroller

I have developed the code to control the relay switching on/off using nextion display and esp32. But whenever I press my dual state button in the nextion display there is some delay and I need to ...
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Noob here.. Need help with a thermostat controlled relay

So After trying several sketches for a LM35 and none working I finally found one that was giving me accurate results. The problem is the code is way over my head. I was able to modify it enough to get ...
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Desmos D1 + Numpad + relay can't put D15 pin on HIGH

So I basically have the following setup: This schema is not %100 accurate, since the tool I used to generate this did not allowed me to express exactly what I wanted, so some clarifications: The CPU ...
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19 views

Help, I want to turn relay constantly on until a difference is detected, but triggered only one instead

Help, I want to use arduino to control relay for electricity, i get data from a sensor and when a value is detected it should be constantly on until another detection triggered again, i can get the ...
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38 views

Driving an enable pin low via arduino

I have the following V regulator, that has an enable pin that i'd like to control via an arduino: https://www.pololu.com/product/2582 I tried using a relay (ELEGOO Relay Module 4 Channel DC 5V with ...
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Use esp-01 relay with Nodemcu possible?

I'm building a simple mobile controlled relay switch. however, I'm out of relay modules, but I do have these esp-01 relays: https://ae01.alicdn.com/kf/HTB1VIKLeJLO8KJjSZFxq6yGEVXaW.jpg I'm wondering ...
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1answer
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srd-05vdc-sl-c and coil operating time

I'm using Arduino UNO to control an imatic relay board with 16 relays model srd-05vdc-sl-c. I use all the relays to control some linear actuators and everything is working fine. My only question is: ...
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62 views

Arduino code does not function when relays are powered

I have a mega arduino, which is supposed to to power 4 relays using 4 touch sensors TTP 223, the relays are 5V coil and 220V. the arduino is powered by a 5 V adapter "mobile phone charger" and it ...
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266 views

Multiple buttons to control relays

Dears, I have a problem that I could not solve for a while, I tried the code below but it did not work. There will be 4 buttons controlling 4 relays but in a way that button one will turn relays 1&...
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Relay LOW makes ESP8266 deny ESP.deepSleep command

ESP8266 reacts as expected when I issue the command: digitalWrite(D2, HIGH); // = OFF ESP.deepSleep(300000000); which switches a relay OFF and enters a deepSleep state. ESP8266 reacts NOT ...
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129 views

Made a light controller for the holidays

I am a new the world of Arduino. I found on YouTube, how to build a light controller (https://www.youtube.com/watch?v=WvG9c84ApFA&t=39s). I follow every step but it doesn't work. Here are some ...
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682 views

Control 5V from ESP8266 Wemos D1 mini

I am making a simple heater with the help of ESP8266 wemos d1 mini. Heaters will use 12V DC power suply and ESP8266 must turn the heater on and off with the help of 5V DC relax. I want to avoid the ...
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170 views

control 3 relays with 1 button

Is there a way to control 3 relays with 1 button? My idea is: There are 3 modes; mode 1 for relay 1, mode 2 for relay 2 and mode 3 for relay 3. With a long press you switch between modes (After 3 ...
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1answer
138 views

Connect 5v 30a relay with Arduino Uno

I have previously connected 5V 10A relay switches to my Arduino. But for my new project I need to use a 5V 30A relay switch with my Arduino. In 10A relay switches, we make connection with Arduino ...
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4answers
87 views

Detect if laptop is on or not?

How would I safely connect an Arduino so that it can detect if a laptop is on or off? The Arduino would be powered separately by a normal USB charger, since it needs to be turned on even when the ...
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1answer
62 views

Adding WiFi to my Arduino Keypad Lock

I'm a really passionate beginner with arduino and electronics and I've built a Keypad lock for my room's door (inside the house). I've used an arduino that activates a motor using a transistor to ...
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1answer
1k views

Timer Countdown to control relay (multiple functions in void loop)

I'm trying to build this project with a simple code. Object is to hit up button to increment minutes or down to decrement minutes then hit start to start countdown, while its counting relay will turn ...
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1answer
87 views

How to code 4 relays to go off in intervals and not in sequence? [closed]

Code : //FOR AEROPONIC SYSTEM WITH ROOM TEMPERATURE AND HUMIDITY SENSOR //AND 4 GROW CHAMBERS WITH DIFFERENT SPRAYING TIME // RELAY CONTROL #define RELAY1_PIN 2 #define RELAY2_PIN 3 #define ...
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1answer
1k views

NodeMCU keeps disconnecting

I have made a home automation system consisting of a NodeMCU, 4 channel relay board running on Blynk and IFTTT. At the moment I'm only controlling a string of fairy lights and two LED strips from it, ...
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1answer
105 views

The current direction for digital output pins

I am new to Arduino. The digital pins can be configured as output (https://www.arduino.cc/en/Tutorial/DigitalPins) for triggering some sensors. I am now setting a digital (output pin), say no. 7,which ...
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1answer
474 views

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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195 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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1answer
78 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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1answer
43 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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1answer
52 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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307 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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232 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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1answer
126 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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5answers
1k 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
610 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
125 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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2answers
103 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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3answers
542 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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155 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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39 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
689 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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76 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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116 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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22 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
2k 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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1answer
68 views

Stuck Arduino Relay?

I am looking for a relay that stays on (NC=Normally Closed), 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
60 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
125 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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