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.

Phototransistor Currente Control (3) (CB14641E)
The current of this circuit is determined by a PNP transistor. The circuit is suggested by Texas...
Treble Control (CB21293E)
This passive circuit was found in old American documentation. It can be added to any amplifier input...
90 W Amplifier (CB14272E)
This circuit was suggested by National Semiconductor in its Linear Application Handbook. The...