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.

SCR High Power Control (CB12248E)
This circuit is from a 1980 publication. In it we have a half-wave power control in which the SCR...
Low Input Current Fast Adder (CB14126E)
We found this circuit in the 1994 Linear Applications Handbook from National Semiconductor. The...
Sound level meter (CB8225E)
This sound intensity meter was found in a 90s Elektor. The circuit uses an integrated device from...