Voltage Level Detector (CB22135E)

We found this circuit in an English documentation from the 80's. Transistors are general-purpose types.

TTL LS Debouncer (CB16001E)
Two inverters, of the 6 available in a Low-power Schottky 74LS04, are used in this anti-ring...
4-scale millivoltmeter (CB7389E)
Found in Radio Electronics from the 90's, this circuit can be implemented with other operational...
Varistor Modulator (CB21915E)
Taken from a 1956 Raytheon transistor manual, this circuit uses varistors to obtain modulation of a signal...