Logic level indicator 7400 (CB22407E)

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

Surge Protector (CB18721E)
This circuit acts on a relay disconnecting the load when the input voltage exceeds the set limit....
Capacitive discharge ignition (CB23698E)
We found this circuit in a Radio Electronics from February 1966. The circuit uses SCR to control an...
20 dB amplifier 741 (CB15057E)
This is the traditional configuration of an inverter amplifier with 100 voltage gain and...