Fuse Test (CB22165E)

This circuit is from an old documentation, but perfectly current. In place of the battery, 2 or 4 small cells can be used.

Two-tone oscillator (CB9071E)
This circuit was found in a 1965 Radio Shack documentation. The transistors are from that time....
Laboratory Power Supply (CB17304E)
This is a typical source of the time (1989) using the well-known regulator integrated circuit 723....
Power Voltage Follower (CB13226E)
The integrated circuits used in this circuit are from the 70s and are therefore no longer common in...