Micro siren (CB21234E)

This circuit with the LM3909 can be powered with voltages from 3 to 5 V. We found it in a Popular Electronics from the 90s.

CMOS Touch Switch (CB12091E)
This circuit, obtained in a 1983 magazine, can drive loads up to 100 mA if the transistors are...
Monostable LM139 (CB15529E)
It is possible to design a monostable multivibrator around a voltage comparator of the four...
Voltage inverter (CB23691E)
This voltage inverter circuit is from a Radio Eklectronics from October 1965. It was used in...