Transistor Schmitt trigger (CB7801E)

Found in Popular Electronics, this configuration can be powered by voltages from 6 to 12 V. Transistors are common types today.

Simple Night Switch 2 (CB4563E)
This circuit was obtained from a 1977 magazine, but can still be mounted using BC548 for TR1 and...
Audio Line Amplifier (CB4769E)
We found this circuit in a European publication from the 1990s. Transistors are still common types...
Operational with 1 A output (CB25183E)
The figure shows how to add a Darlington stage to an operational amplifier in order to obtain a...