555 and 556 Timer Circuits

The 556 is a 14 pin dual version of the 8 pin 555 timer IC

555 / 556 Timer Pin Diagram

• • Astable - producing a square wave

  • Monostable - producing a single pulse when triggered

  • Bistable - a simple memory which can be set and reset

  • Buffer - an inverting buffer (Schmitt trigger)

Supply voltage 4.5V - 16V

Note for low voltage below 4.5V you need to use the CMOS version LMC555 IC (1.5V - 12V)

Output of 555/556

The output of a standard 555 or 556 can sink and source up to 200mA.

555 Timer Modes Explained