Simple Blinking LED Circuit


One of the most common electronics starter projects is the Simple Blinking / Flashing LED Circuit. You can find references to this project and diagrams on many websites. I have created a simple BOM (Bill of Materials) that you can get here at Digi-Key to build this circuit. Below is a simple schematic I have built using Digi-Key’s Scheme-it tool. (Values calculated using a 9VDC power supply or battery.)


Desc P/N QTY
PNP Transistors PN2907A-APCT-ND Qty 2
Resistor 300 Ohms 300QBK-ND Qty 2
Resistor 100k Ohms 100KQBK-ND Qty 2
Cap 10 uF 732-8820-1-ND Qty 2
LED C503B-GCN-CY0C0791-ND Qty 2

Here is a Cart image that has the above components in it for your convience.

Some notes for this circuit.

  • Changing the Capacitor Values will change the speed at which the LEDs blink.
  • If you change the LEDs in this circuit you will need to calculate the value of R2 & R3.

If you need here are some of the prototype products used in this build.
imageBreadboard 1597-1268-ND
imageJumper Wires BKWK-3-ND
image9V Battery P687-ND
image9V Battery Leads 36-232-ND