Experiment 11 - The Monoflop with 555

With a NE555 you able to build a monostable multivibrator monoflop or one-shot. Find out how here, and what you need to be aware of.

Consider to the circuit shown. You surely recognize the basic circuit from the Experiment 8.

Circuit diagram monoflop with NE555.

Once you push the pushbutton switch S1, the LED2 lights up. After a switching time T of approximately 2.5 seconds, LED2 goes out and LED1 lights up again.

Circuit monoflop with NE555. (Enlarge)

Signals of the monoflop.

In fact, you can calculate the approximate switching time T...

T = 1.1 × R₂C₁

   = 1.1 × 22,000 Ω × 0.0001 F = 2.4 sec

What happens if you press the push-button switch repeatedly?