Address decoder using the 74LS138 (CB20537E)

This decoder circuit 3 of 8 was found in a publication for PCs from 1992. The circuits are TTL and must be powered with 5 V.

Reverse polarity protection relay (CB8905E)
This circuit was found in a 90s EDN. It activates a protection relay in case of reversing the...
Output Stage with Transformer (CB12821E)
This is an old traditional class B transistor circuit, using an output transformer to supply power...
Skin Resistance Controlled Oscillator (CB11084E)
This circuit was found in a 1977 publication, but it can be easily assembled, although unijunction...