Experiment 7 - The monostable Multivibrator III

How does the capacitance of the capacitor influence the time required for the multivibrator, before it falls back to a stable state?

Take a look at the circuit shown. You have replaced the capacitor C1 by a capacitor with a capacity of 10 μF.

Circuit of a monostable multivibrator. (Enlarge)

Circuit diagram of a monostable multivibrator.

Now the multivibrator switches to a much shorter time period back into the stable state.

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

T = R₂C₁ × 0.693

Now you can place the values...

T = 100,000 Ω × 0.00001 F × 0.693 = ca. 0.7 sec.

(Want to know where this formula comes from? See experiment 25.)

Contrast this with the switching time T from the experiment 5 (capacitor C1 = 100 uF)...

T = 100,000 Ω × 0.00010 F × 0.693 = ca. 7 sec.

From the formula you can see that also the resistor R2 influences the switching time. However, you are not free to choose any resistance. This you investigate in experiment 26.

Now you discuss the third and last multivibrator...