Wattmeter (T1351E)

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

Solid state relay (CB8861E)
This circuit, which can act as a shield, was found in a 1969 documentation. The circuit uses...
Crystal Oscillator (CB19356E)
This oscillator can generate signals from 100 kHz to more than 50 MHz depending on the crystal used...
1 kHz injector (CB19587E)
This simple multivibrator circuit generates a 1 kHz signal rich in harmonics. The circuit is from...