Automatic LED flasher projects using PC817 optocoupler

Automatic LED flasher projects using PC817 optocoupler

Simple LED flasher circuit using PC817 optocoupler


An optocoupler, also called an optoisolator, photo-coupler, and optical isolator, is a type of semiconductor device that allows electrical signals to be transmitted between two isolated circuits using light.

Here we will present another application in which automatic LED flasher circuit using PC817 IC project.

Here is a PC817-based circuit for you - an LED flasher circuit diagram So here is the step-by-step guide to making this Automatic flashing LED circuit.

Circuit Diagram

optocoupler pc817 flesher circuit diagram

LED Flasher Circuit using PC817

Circuit Components

  1. 12volt power supply [See Buy Click Amazon]
  2. 100uf,25vdc polarized capacitor(01pc) [See Buy Click Amazon]
  3. 1K Ohm Resistor (01pc) [See Buy Click Amazon]
  4. 5.6K Ohm Resistor (01pc) [See Buy Click Amazon]
  5. 3mm LED (01pc) [See Buy Click Amazon]
  6. PC817 optocoupler (01pc) [See Buy Click Amazon]

Working of the Circuit :

  1. First time collect all the required components.
  2. Connect pin 1 of PC817 IC to Resistor(R1) and Capacitor(C1) positive Figure-1
  3. Connect pin 2 of PC817 IC to the ground and Resistor(R2)terminal. show Figure-1
  4. Connect pin 3 of PC817 IC to Capacitor (C1) Negative and Resistor(R2) terminal
  5. Connect pin 4 of PC817 IC to the LED Negative terminal.
  6. The power supply(12vdc) connects to the Resistor (R1) and LED Positive terminal.
  7. Connect the power supply in the circuit.
  8. when you connect the power supply to the circuit, it flashes the LED.
  9. If that doesn't work, check the connections again. Also, make sure the battery is properly connected to the circuit and power is reaching the circuit components.

PC817 IC pin diagram

PC817 Optocoupler IC(Integrated Circuit)

PC817 Photocoupler has a transistor that is controlled based on light (photon). So this IC basically has an IR (infrared) LED and a photo-transistor inside it. When the IR LED is powered the light from it falls on the transistor and it conducts. The arrangement and pinouts of the IR LED and the photo-transistor are shown below.

PC817 Internal Connection Diagram

PC817 Optocoupler Pin Configuration

This IC includes 4 pins 2 input pins, and 2 output pins each pin and its functionality is discussed below

  1. Pin1 (Anode): Anode pin of the IR LED. Connected to logic input
  2. Pin2 (Cathode): Cathode pin of the IR LED. Connected to ground
  3. Pin3 (Collector): Collector pin of the Transistor. Provides logical output
  4. Pin4 (Emitter): Emitter pin of transistor. Connected to Ground

Features and Specifications

  1. Input Diode Forward Voltage: 1.25V
  2. Collector-Emitter Voltage: 80V (max)
  3. Collector Current: 50mA (max)
  4. Cut-off frequency: 80 kHz
  5. Rise Time: 18us
  6. Fall Time: 18us


  1. I/O isolation for MCUs (Micro Controller Units)
  2. Noise suppression in switching circuits
  3. Signal transmission between circuits of different potentials and impedances
  4. AC/DC Power control
  5. For Transmission of Signal
  6. Noise Coupling Circuits

Read Also:

Frequently Asked Questions:
what is PC817 optocoupler?

An optocoupler (also called optoisolator) is a semiconductor device that allows an electrical signal to be transmitted between two isolated circuits.

What is the type of optocoupler?

An optocoupler or optoisolator consists of a light emitter, the LED, and a light-sensitive receiver which can be a single photo-diode, photo-transistor, photo-resistor, photo-SCR, or a photo-TRIAC

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