3-tube receiver 2 (T1603E)

Using known tubes, this receiver was found in a Radio Electronics from 1949. The circuit does not include the power supply.

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...