Logic level indicator 7400 (CB22407E)

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

Comparator with Transistors (CB6550E)
This circuit was obtained from a Philips documentation from 1968. The transistors can be replaced...
Impedance Adapter (CB11158E)
With this circuit we can use a high impedance source to excite a low impedance output. The input is...
Trigger Schmitt 555 (CB8454E)
Found in a 90s American documentation, this circuit consists of a trigger that generates...