T ube driver (T452E)

This stage was suggested by MIT documentation from the 1940s. The circuit uses well known tubes at the time and is powered by a voltage of 250 V.

Sound Activated Relay (CB5989E)
This circuit makes use of a low impedance microphone. The relay is according to the supply voltage...
Low Power Astable Multivibrator (MSB037E)
The astable multivibrator shown by figura 1 has a very low current drain and can be powered from 6...
Output stage with the AC117 (CB4278E)
This step is also suitable for the AC188k and SK3004 transistors and was found in a 1980s...