Metronome using operational (CB22060E)

We found this circuit in an English publication. The transistor can be BC549, and the power supply can be between 5 and 9 V.

RMS Current Meter (CB5363E)
This circuit is from a 2005 Linear Technology application manual. The circuit uses a commercial...
Overtemperature Alarm (CB12156E)
We found this circuit in an English publication from 1982. The power MOSFET can be of any type and the...
Integrated Intercom (CB16336E)
We found this circuit in a 1982 documentation. An intercom to be good must be sensitive and have...