Wattmeter (T1351E)

This circuit is from a February 1949 Radio Electronics magazine. The circuit uses 3 tubes and includes the power supply.

Phase Shift Oscillator (CB20565E)
This low-frequency oscillator was found in a 1963 documentation. Capacitors determine frequency. The...
Liquid Level Detector (CB1309E)
This circuit uses a triac to detect the level of a reservoir, and a sensitive SCR connected to the...
Algebraic Comparator (CB6492E)
Found in a 1964 Electronic Design this circuit compares two signals by providing the inverse of the...