Experiment 15 - The astable Multivibrator using NOT Gates
An astable multivibrator can also be build using logic gates.
Often NOT gates are used.
In the circuit shown, you use the NOT gates of a
Circuit of an astable multivibrator of NOT gates.
Circuit diagram of an astable multivibrator of NOT gates.
If you connect the battery, the LED begins to flash.
The oscillation period t is determined
by the capacitor C1 and resistor R2.
You calculate t with the formula...
t = R1C1 × 2.2
This circuit is often used in test environments
because it is simple to set up.
However, there are some disadvantages...
For practical circuits,
the calculated oscillation period deviates sometimes strongly
from the real oscillation period.
For long oscillation periods, the input of the first NOT gate needs
to be protected by a resistor.
This makes it even more difficult
to determine the oscillation period.
Occasionally the oscillation fails to start.
The next circuit prevents these problems...