PURPOSE: To obtain a high-precision delay circuit featuring a simple constitution by giving the by-pass to the fluctuation of the waveheight value of the input pulse via the diode and constant voltage diode and thus cutting the upper part of the waveheight value.

CONSTITUTION: Constant voltage diode 11 is connected to the power source via resistance 12 in order to give a constant reference voltage to the base of transistor Tr8. Capacitor 5 is charged with the pulse input supplied to terminal 1. And the output pulse is generated when the terminal voltage of capacitor 5 reaches the prescribed reference voltage. Here the fluctuation of the waveheight value of the input pulse, if any, is by-passed by diode 11 and via diode 13 to cut the upper part of the waveform. As a result, capacitor 5 can be charged with a constant charging pulse to always secure a constant delay time. In such way, a high-precision delay circuit can be obtained with a simple constitution.