With its low part count this easy build timer project makes a good introduction to electronics. The timer uses a resistor capacitor network to provide a time delay of between 1 second and 40 seconds, which is set by the PCB mount variable resistor. When the button is pressed the LED changes from red to green, then at the end of the time interval it turns red.
This kit contains:
- 1 x 2AA battery holder
- 1 x 47ohm resistor
- 2 x 10Kohm resistors
- 1 x 1Mohm potentiometer
- 1 x 1000uF capacitor, electrolytic
- 1 x BC558 PNP transistors
- 1 x tri-colour LED
- 1 x PCB mount switch
- 1 x easy build timer PCB
PCB dimensions: 54mm x 26mm.
Requires x2 AA batteries, available separately.
Click here to download build instructions 
Note: Schools will receive a more detailed set of teaching notes on a CDROM.
