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.

Code Practice Oscillator (CB4207E)
Also suitable for use as a noisy alarm, this Morse Code or telegraph practice oscillator was found...
Overtone Oscillator II (CB4585E)
In the figure we show a configuration for a crystal controlled overtone oscillator using a...
Inverter For Multimeters (CB3813E)
Some old analog multimeters use a 22.5 V battery for high resistance measures. These batteries can no...