Editing Multivibrator (section)

==== Output pulse shape ====

The output voltage has a shape that approximates a square waveform. It is considered below for the transistor Q1.

During [[#State 1|State 1]], Q2 base-emitter junction is reverse-biased and capacitor C1 is "unhooked" from ground. The output voltage of the switched-on transistor Q1 changes rapidly from high to low since this low-resistive output is loaded by a high impedance load (the series connected capacitor C1 and the high-resistive base resistor R2).

During [[#State 2|State 2]], Q2 base-emitter junction is forward-biased and capacitor C1 is "hooked" to ground. The output voltage of the switched-off transistor Q1 changes exponentially from low to high since this relatively high resistive output is loaded by a low impedance load (capacitor C1). This is the output voltage of R<sub>1</sub>C<sub>1</sub> integrating circuit.

To approach the needed square waveform, the collector resistors have to be low in resistance. The base resistors have to be low enough to make the transistors saturate in the end of the restoration (R<sub>B</sub> < β.R<sub>C</sub>).