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.

Class A No Distortion Amplifier (CB6124E)
This low distortion circuit was found in a 1964 Electronic Design. The transistor admits...
Optocoupler Code Practice (CB26321E)
This ingenious circuit was found in a 1990s Popular Electronics. The oscillator is a 555 and the...
Crowbar (CB4862E)
This short circuit protection circuit accelerates the blown fuse in case of an output overcurrent. The...