PURPOSE: To realize an economical generation of the pulse with a simple constitution by giving the ON/OFF control to the transistor in accordance with the input voltage.

CONSTITUTION: With application of one high-level voltage to input terminal 1, the voltage of power terminal 6 is applied directly to the base of transistor 4 owing to existence of capacitor 3. Thus transistor 4 conducts, and as a result output terminal 7 features a low level. When the potential of terminal 1 becomes zero low-level voltage, the lowers down at the side of resistance 2 of capacitor 3. As a result, the charging current flows through capacitor 3 via resistance 8, and transistor 4 is cut off for this period to turn terminal 7 to a high level. When capacitor 3 is charged, transistor 4 conducts. As a result, the voltage lowers down at terminal 7 to feature a low level. In such way, the pulse can be obtained at terminal 7.