This interesting 1924 triode tube receiver was found in a documentation by Gernsback. Observe supply voltages. Coils are for tuned wavebands.
What this circuit does is to stretch a pulse, increasing its duration. The integrated circuit is...
This circuit is designed to measure very weak currents, in the order of picoamperes. We found it...
Found in an American documentation from the 90s, this circuit uses small low voltage lamps (6 to...