Upon pressing the switch, the circuit generates a pulse whose duration depends on C. The transistors can be BC548 and the power can be between 1 and 6 V. The circuit is from a 1975 publication.
This circuit is from a 90s Popular Electronics. It appears elsewhere on this site. Q1 can be any...
This variable bandpass filter was found in an American 1980s documentation. The power supply must be...
This circuit for analog video signals was found in a 90s 303 Circuits. The used digital switch is...