PURPOSE: To avoid the discontinuation of oscillation of an astable multivibrator by supplying the DC power supply voltage to said multivibrator via a diode connected forward to the power supply input side of a transistor at one side.

CONSTITUTION: The DC power supply +VCC is supplied to a transistor TRQ1 via a resistance R1 as well as to a TRQ2 via a diode D3 respectively. Therefore the emitter voltage of the TRQ2 is varied forcibly by an amount equivalent to the forward voltage drop of the D3. As a result, it is avoided that both TRQ1 and Q2 are turned on at a time. This avoids the discontinuation of oscillations of an astable multivibrator.