Logic level indicator 7400 (CB22407E)

In the figure we have a simple logic level indicator for TTL circuits or powered by 5 V.

20 W Amplifier 2SC492 (CB18907E)
This amplifier was found in a Japanese publication in 1972. Transistors are uncommon today, and...
12V Transformerless Power Supply (CB14961E)
The current of this source is 200 mA at the most, and the output depends on the zener that may...
Playback amplifier (CB7335E)
Found in Mallory documentation from 1968 this circuit uses an integrated circuit from that time. The...