ARTE
BELLEZA Y BIENESTAR
ARTESANÍA
CULTURA E HISTORIA
ENTRETENIMIENTO
MEDIO AMBIENTE
COMIDA Y BEBIDAS
INGENIERÍA INVERSA
CIENCIAS
DEPORTES
TECNOLOGÍA
TECNOLOGÍA VESTIBLE
Using Relays — SIK Circuit 13
Ed

Creado por

Ed

17. marzo 2026FI
101
0
0
0
0

Using Relays — SIK Circuit 13

Control a relay with a transistor to switch between two LEDs. Learn about electromechanical switching, SPDT relays, Normally Open vs Normally Closed contacts, and flyback protection.

Instrucciones

1

Parts & Introduction

A relay is an electrically-operated mechanical switch. A small current energizes a coil that physically moves a contact arm, switching a separate circuit. Relays can control high-power devices (motors, lights, appliances) from low-power Arduino signals. This experiment uses an SPDT (Single Pole Double Throw) relay to alternate between two LEDs.

Parts Needed

  • 1x Arduino Uno + USB cable
  • 1x Breadboard
  • 1x SPDT Relay
  • 1x NPN Transistor (P2N2222A)
  • 1x Diode (1N4148)
  • 2x LEDs (different colors)
  • 2x 330Ω Resistors
  • 14x Jumper Wires

Materiales para este paso:

SparkFun Inventor's Kit - V3.2SparkFun Inventor's Kit - V3.21 kit

Herramientas necesarias:

Ordenador con el IDE de ArduinoOrdenador con el IDE de Arduino
2

Hardware Hookup

Wiring Instructions

Transistor + Relay Coil
  1. Connect transistor Base through 330Ω resistor to Arduino Digital Pin 2.
  2. Connect transistor Emitter to GND.
  3. Connect one side of the relay coil to transistor Collector.
  4. Connect other side of relay coil to 5V.
  5. Flyback Diode: Band (cathode) to 5V, anode to Collector.
Relay Contacts + LEDs
  1. Connect relay COMMON through a 330Ω resistor to 5V.
  2. Connect relay NC (Normally Closed) to LED 1 positive leg.
  3. Connect relay NO (Normally Open) to LED 2 positive leg.
  4. Connect both LED negative legs to GND.

Materiales para este paso:

Relé SPDTRelé SPDT1 pieza
Placa de pruebasPlaca de pruebas1 pieza
Cables de puenteCables de puente8 piezas
3

Arduino Code

Open the Arduino IDE and upload the following sketch to your Arduino board.

relay.inoarduino
/*
SparkFun Inventor's Kit
Example sketch 13 — RELAYS

Use a transistor to drive a relay, alternating two LEDs.

Hardware connections:
  Transistor BASE through 330 ohm resistor to digital pin 2
  Transistor EMITTER to GND
  Relay coil: one side to COLLECTOR, other to 5V
  Flyback diode: band to 5V, anode to COLLECTOR
  Relay COMMON through 330 ohm to 5V
  Relay NC to LED 1 positive, Relay NO to LED 2 positive
  Both LED negatives to GND

This code is completely free for any use.
*/

const int relayPin = 2;
const int timeDelay = 1000;

void setup()
{
  pinMode(relayPin, OUTPUT);
}

void loop()
{
  digitalWrite(relayPin, HIGH);  // Relay on (COM connects to NO)
  delay(timeDelay);

  digitalWrite(relayPin, LOW);   // Relay off (COM connects to NC)
  delay(timeDelay);
}

Materiales para este paso:

Arduino Uno R3Arduino Uno R31 pieza

Herramientas necesarias:

Ordenador con el IDE de ArduinoOrdenador con el IDE de Arduino
4

Test & Experiment

What You Should See

You should hear the relay clicking, and see the two LEDs alternating — one on, one off — switching every second.

Troubleshooting

  • LEDs not lighting: Check LED polarity — longer leg is positive.
  • No clicking sound: The transistor or coil circuit isn't working. Verify transistor orientation and coil connections.
  • Relay not making good contact: The SIK relay is designed for soldering, not breadboarding. Press it firmly to ensure all pins contact.
  • Confusion: Don't mix up the TMP36 temperature sensor with the transistor!

Experiments to Try

  • Replace the LEDs with a motor on the NO contact — use the relay as a motor on/off switch.
  • Use a button to control when the relay toggles.
  • Add variable delay to create morse code patterns.

Materiales

9
  • 1
    SparkFun Inventor's Kit - V3.210% de comisión
    1 kit
    €95.47
  • 2
    Placa de pruebas
    1 pieza
    1 vendor sell this, none ship to you yet
    Marcador de posición
  • 2
    Cables de puente
    8 piezas
    3 vendors sell this, none ship to you yet
    Marcador de posición
  • 3
    Arduino Uno R3
    1 pieza
    1 vendor sell this, none ship to you yet
    Marcador de posición
  • Relé SPDT
    1 pieza
    Marcador de posición
  • Transistor NPN
    1 pieza
    Marcador de posición
  • Diodo
    1 pieza
    Marcador de posición
  • LED de 5 mm
    2 piezas
    1 vendor sell this, none ship to you yet
    Marcador de posición
  • Resistencia de 330 ohmios
    2 piezas
    Marcador de posición

Herramientas requeridas

1
Total estimado
Lo que compró quien lo hizo. Los materiales sin precio se consiguen donde tú los compres.
€95.47

CC0 Dominio público

Este Blueprint se publica bajo CC0. Eres libre de copiar, modificar, distribuir y usar este trabajo para cualquier propósito, sin pedir permiso.

Apoya al Maker comprando productos a través de su Blueprint, donde gana una Comisión del Maker establecida por los vendedores, o crea una nueva iteración de este Blueprint e inclúyela como conexión en tu propio Blueprint para compartir ingresos.

Discusión

(0)

Iniciar sesión para unirte a la discusión

Cargando comentarios...