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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1 answer
69 views

Pushbutton firing somewhat randomly

I have a circuit which consists of a pushbutton and 2 relays. The power supply is driven either over USB, where the circuit seems to work fine, or powered by a linear regulator board I've knocked ...
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0 votes
1 answer
47 views

Using Millis instead of delay to reboot relay

I want to reboot relay (turn off , waiting 4 seconds and turn ON) it works perfectly if I use delay(4000), but code is blocked while delay (4 seconds) and I cant start relay 2. How can I use Millis ...
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-1 votes
2 answers
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How to connect a 4 channel relay switch directly to a 5V power source?

When connecting a 4 channel relay to a Arduino Pro mini, there is a noticeable power drain from the board when relays are active. This is clearly visible as the 16x2 LCD dims. I remember reading that ...
3 votes
3 answers
88 views

How to perform multitask using arduino such as update data as well as check condition?

Here data is updated after every 2 seconds. But when the condition is true then the valve and motor process starts and data is updated only after completion of that part (i.e., data is updated after ...
1 vote
2 answers
104 views

Controlling multiple solenoid with relay and Arduino and the process stops after few cycles

I am trying to control 2, 12 V solenoid (externally powered, 12V/1A adaptor) using UNO (externally powered using adaptor) by using 2, 5V relay (connected to 5V and Ground of Arduino board). the ...
2 votes
0 answers
31 views

Can the Blink class be used on a 5v to 240v relay?

I have found the following code and it works fine on a breadboard controlling small LEDs but I want it to work with LED strip lighting with external 240v transformers. We have built the circuit using ...
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1 vote
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49 views

Relay switch problem: Arduino Nano with a 312 PIR sensor

I am working with a 312 PIR sensor with an Arduino Uno Nano. When sensing motion Port 13 goes High for Time_A (10 minutes). If I then press a push button on the Arduino board it takes Port D2 LOW, ...
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-1 votes
1 answer
67 views

Arduino controlled 25A 12V DC relay

I have an air compressor that I often give difficult tasks, where the compressor needs to run longer than it was designed for. So it gets close to overheating, which requires periodically giving the ...
0 votes
1 answer
161 views

NodeMCU with a 5V latching relay - LOW triggers relay

I am going to connect NodeMCU to a latching relay board like tis one (4 channel version): LINK Both MCU board and relay board will be powered from the same 5V voltage regulator. Now I have two ...
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2 votes
1 answer
209 views

Using MAX30100 SpO2 value to turn on LED

max30100 i2c sensor gives heartrate and spo2 reading in serial and also can show values in lcd display. I want to show it's indication via LED. If SpO2 value <94 , it will turn on Red led in ...
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1 vote
2 answers
222 views

Back EMF from Relay causing trigger on INPUT pin

I am wiring up a light show for my pickup truck. I have installed various high power spotlights and light bars into a dedicated relay/fuse box in the engine bay. These relays are wired into a switch ...
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1 vote
0 answers
72 views

Eleminate noise from a Relay in ArduinoFFT

I have built a circuit with an Arduino Nano to measure frequency from my music, it's basically this schema but I changed the code a little bit to fit my needs. My problem is I want to add a Relay (I ...
1 vote
0 answers
190 views

USB and LM7805 both to power Arduino

I have high current usage For my circuit as you can see below (link): I like to power Arduino when it is not connected to PC by USB Connection, So I want to add one external power supply and connect ...
2 votes
1 answer
104 views

Error trying to simulate temperature dynamically

I'm trying to simulate dynamic temperature using a small set of data with ESP32. I've just realized that the relay doesn't change the status if there is some variation of the temperature upper or ...
0 votes
2 answers
148 views

Arduino Uno - Raspberry PI - Float Sensors - Water pumps

I am experimenting with Aquaponics and since I am a software developer I found it "smart" to use arduino/raspberry in order to control the water flow and not simply use a water pump with ...
0 votes
2 answers
302 views

2 way switch with Arduino?

Hey I'm working on a home automation system where I can replace one of my 2 way switches to an Arduino Or node MCU controlled one but I want to avoid normal relays because as of what I know they can ...
1 vote
0 answers
221 views

HC-05 bluetooth module short range

I have started learning about arduino and just bought a bluetooth module, HC-05. From where i bought, it says it has range of approx.10 meters. I made hc-05 connection with arduino in below described ...
1 vote
1 answer
125 views

NodeMCU and relay with VIN power

Have read a lot of different things online, and I just ain't sure yet. I'm trying to hook up a NodeMCU to control some relays. And want to power the NodeMCU by the VIN pin. Anyone know if this setup ...
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1 vote
1 answer
149 views

Digital pins are no longer outputting enough to click a relay

I've been working on a project for awhile now, and I ran into a problem a week ago I couldn't solve. I'm using an Arduino uno R3. My project involves the use of 4 relays triggered by the digital pins. ...
3 votes
1 answer
126 views

Reproduce simulated temperature data with Arduino

I'm starting a test using Arduino to reproduce a set of temperature values in water each three hours and need some help with it. I will use two ds18b20 sensors to control two thermostats connected to ...
2 votes
1 answer
56 views

Arduino changing output based on wire voltage

I’m new to arduino and I want to build myself smart switch that can be turned of both manualy and via wifi, is there any way to change position of relay based on if another wire is live or not? Im ...
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1 vote
1 answer
295 views

Control DC motor in both directions with two relays

I am using an Arduino and two relays to control 12V DC motor. I need to rotate the motor in both directions. For the first trials it worked fine. Finally one next switching fried my Arduino. I think ...
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2 votes
1 answer
205 views

digitalRead() function of Arduino doesn't read Input value sent by sensor after detecting the object

I'm trying to turn ON the LED(inbuilt/PIN13) when photoelectric proximity sensor(12v) senses any object. Sensor is connected on pin 2. Assigned pin 2 as INPUT, I've got a 12v spdt relay for switching. ...
1 vote
1 answer
366 views

Driving 5V relay with ESP-01

I'm trying to drive a 5V relay with 3.3V ESP-01 with schematic below. I programmed the ESP to start a portal through which I can derive the relay by triggering GPIO-0 & GPIO-2. However when I ...
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0 votes
1 answer
66 views

How to close humidity sensor at specific humidity

I am using dht humidity and temperature sensor on arduino and i would like to add relay and buzzer on the system. What I would like to do is to close it via buzzer and on 65% humidity run buzzer. The ...
1 vote
0 answers
295 views

I'm desperate and need help with MFRC522 (stops working randomly)

I've made a light switcher that switches lights on for 15s after a correct tag is presented, and also when door is opened for 6 seconds (its for outside) so i can see a keyhole after leaving for a ...
1 vote
1 answer
68 views

Help with NodeMCU based smart switch

The project I'm planning is to use a NodeMCU at each electrical board in house to control lights and fans via relays. Each MCU will communicate via MQTT over WiFi to a Raspberry Pi 4 from where I can ...
1 vote
0 answers
25 views

error ph meter cant show the data [duplicate]

im using ph meter DFROBOT v1.0 at i compiled the code from the DFROBOT web this is the code * # This sample code is used to test the pH meter V1.0. # Editor : YouYou # Ver : 1.0 # Product: ...
1 vote
0 answers
44 views

Peculiar relay behavior from POST

I am trying to toggle on/off between two separate HTTP request. One submit button to turn it on, and another separate submit button to turn it off. I expect the device to launch in the off/low 0V ...
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0 votes
2 answers
95 views

Turn on relay for amount of time by continuous input

I have a project having two input status first the input is not continuous the output buzzer relay will be on for 10 seconds and then turned off or it can be off directly by push button the second ...
0 votes
2 answers
142 views

How to use a push button & transistor as a kickstarter for power supply?

My goal is to save energy, and I intend to do so by powering a chip with itself, and cut power whenever unnecessary. The best image I can have is of a startled monkey who jumps on the branch, screams ...
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-1 votes
1 answer
769 views

Can i connect in pin of relay module to Analog pins of arduino instead of digital pin?

Im a complete beginner Im making a project using relay modules and arduino. but all the digital pins of my arduino are filled. I wanted to ask if i can use the analog pins to connect my relay module ...
2 votes
1 answer
1k views

Which relay module to buy and what is the difference between 1 channel and 2 channel relay boards

I wanted to d a simple circuit using Arduino to control the lights in my house. But i do not know which relay module to use my house runs on standard 220v ac. Can anyone tell me weather this relay ...
0 votes
1 answer
81 views

How to stop the relay after it is getting on and let the sensor get the result

I want to provide a delay in the following iteration reading so that the sensor can read the condition after the pump starts. void loop() { //-------------Fungsi Read sensor----------- // ...
2 votes
1 answer
86 views

Relays just switch ON and OFF on delay(), not on millis()

I use fuzzy logic for the running time of relays, but the relays just switch ON and OFF at the interval of the delay() I put at the end of loop. This is my code: void loop () { ph = -180/100.0; ...
0 votes
1 answer
101 views

Remove a sudden pulse on pin d3 of nodemcu when powering it up [duplicate]

I am using node mcu and a 2 channel relay connected to the motor via pin d3. When I power on the circuit, it shoots a pulse to the relay and i think it will damage the motor. Please suggest me how to ...
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1 vote
2 answers
200 views

controlling 2 sensor and 3 pump using millis

i make a 3 pump for output and im using millis for it, i want to stop if rach the intervalm now in my code its still looping not realy stop for it thx int pump1 = 5;//pin D5 int pump2 = 6;//pin D6 int ...
1 vote
2 answers
44 views

Module that can both detect Voltage (12V) and Control current [closed]

I need a module for ARDUINO that can both detect Voltage (12V) and Control current between 2 pins (12V), like a relay on another device I have found relay modules to control pins and another module ...
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2 votes
2 answers
936 views

Connect 5V relay to ESP32 WROVER B board

I need to use a ESP32 WROVER B based MCU board with a standard (cheap) one-channel 5 V relay (e.g. to switch on a mains-power appliance). Attempted removal of excess solder around the headers ...
2 votes
3 answers
218 views

Digital pin output voltage drops when driving a relay

I'm trying to trigger eight different 5 V relays using an Arduino Atmega 2560. The relays (70Ω coil) are powered by an external 5 V source, and I'm trying to trigger them through a driving stage which ...
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0 votes
2 answers
404 views

Can I control solid state relay directly from arduino digital pin?

I want to switch on/off some AC device using solid state Omron G3MB relay I know that for magnetic relay there should be transistor and flyback diode, but what about SSR? Can I connect it directly to ...
  • 111
3 votes
1 answer
383 views

Ultrasonic Sensor(HC-SR04) recording random distance

I am am trying to make a code which automatically controls relay on basis of ultrasonic sensor measurements. I am using a nodeMCU as a microcontroller rather than an arduino. The relay and the ...
1 vote
1 answer
99 views

How do I control a conveyor to start and stop in same location using optical rotary encoder

I am a complete novice at arduino. I just want to know if this is possible before I start investing in components. I need to start and stop a chain drive conveyor {can't slip} powered by a 12 volt ...
4 votes
1 answer
274 views

Detect 2 wire thermostat output

I have a 2 wire thermostat. R is +24VAC, W is Heater. I have no Ground wire (C), and I cannot open the thermostat. When the heater goes on, the thermostat internal relay gets powered and connects R ...
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1 vote
0 answers
126 views

XH-M131 Photoresistor Relay Module NC position

I have purchased XH-M131 Photoresistor Relay Module to automatically light my outdoor yard at sunset and turn it off at sunrise. I'ts working as it is supposed to, However, if I power off the relay, ...
2 votes
1 answer
141 views

Relay starts trigger about 6 times when connecting arduino to laptop

I have a fairly simple code to turn a relay on-off every 2 seconds When i attach the USB of the arduino Uno to the laptop, it goes into a frenzy and the relay triggers on off for 6 times within 3-4 ...
1 vote
1 answer
36 views

Sequencing air pistons proble - Help please?

I am a beginner trying to activate 2 sets of 3 air pistons sequentially by going through the YouTube Tutorials... Help, please, pretty please?? :-) There are 3 sets of 2 pistons, each set working in ...
0 votes
2 answers
2k views

What is the proper wiring for relay module?

I want to know the recommended wiring for relay. I am setting it up as NO. Where should I connect the relay, the hot wire or the ground wire? Where should I connect the wire going to bulb, NO or C ...
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-2 votes
1 answer
121 views

Most Efficient & Cost Effective Home Automation Setup

I managed to build a system using Wemos D1 R1 connected to my website to retrieve data to power on or off a 5V relay. Now I would like to expand the project to control all my house outlet. Assuming I ...
1 vote
2 answers
3k views

Controling 5V relay with Wemos D1 R1

I would like to control a 5V relay with Wemos D1 R1 module through webserver. I'm using the following modules: Tongling 5vdc Relay Wemos D1 R1 I'm using the following schematic: and here is the ...

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