Site Overlay

Simple Blinking LED Circuit

A very simple circuit that you can build to blink or flash LEDs. The circuit is built using transistors, resistors, capacitors, and LEDs. Of course you will need a breadboard, jumper wires, and a power source. The parts list includes:

  • PNP Transistor, P/N 2907A, qty: 2
  • Resistor, value 470 Ohms, qty: 2
  • Resistor, value 100k Ohms, qty: 2
  • Capacitor, 10 uF, qty: 2
  • LED, qty: 2
  • Breadboard
  • Jumper wires

Step 1: Add the Transistors to breadboard

Picture of Add the Transistors

Add the two PNP transistors and the jumper wires from the power BUS to the emitter of each transistor. Because of the way I inserted the two transistors the emitter is on the left side of both transistors.

Step 2: Add the Capacitors

Picture of Add the Capacitors
Picture of Add the Capacitors
Picture of Add the Capacitors

Connect the two capacitors to the circuit. Connect the positive lead of the first capacitor to the collector of second transistor. Next connect the negative lead of the same capacitor to the base of first transistor.

Repeat the above process for the second capacitor. Connect the positive lead of the second capacitor to the collector of transistor 1. Connect the negative lead of the same capacitor to the base of transistor 2.

Step 3: Add the 100K Resistors

Picture of Add the 100K Resistors

Next connect the 100k resistors to the transistors. One lead of the resistor connects to the Base of the transistor, the other lead connects to ground. Do this for both transistors.

Step 4: Add the LEDs

Picture of Add the LEDs
Picture of Add the LEDs

Finally add the two 470 Ohm resistors along with the two LEDs. I added a picture of a transistor to identify the Emitter, Base, and Collector.

Connect one wire of the first resistor to the collector of transistor 1. The the other resistor wire then connects to the positive wire of the first LED. The negative wire of the LED is then connected to ground.

Follow the same steps for the other resistor and LED. Connect one wire of the second resistor to the collector of transistor 2. The the other resistor wire then connects to the positive wire of the second LED. The negative wire of the LED is then connected to ground.

Step 5: Supply Power and Watch the LEDs Blink

Picture of Supply Power and Watch the LEDs Blink

The last step is to supply power and watch the LEDs blink. I used a 9 volt battery and it worked fine.

For fun you can try other capacitor values to change the rate at which the LEDs blink.

Leave a Reply

Your email address will not be published. Required fields are marked *

Copyright © 2019 DIY Projects Arduino Crafts. All Rights Reserved. | Foodoholic by Catch Themes