1-Ttube reflex receiver (T1555E)

This one-tube circuit is equivalent to the previous one. We find it in a 1924 book by Gernsback, Power is made by batteries.

Symmetric Tracking Type Power Supply 78xx (CB15160E)
This circuit is from the SGS manual of linear integrated circuits of 1982. The L78xx is equivalent to...
Instrumentation amplifier (CB20685E)
This low displacement circuit was found in American documentation from the 90s. Operational...
Liquid Level Control (CB5311E)
The purpose of this circuit is to maintain the liquid level of a reservoir between two values...