This primitive solar radio was found in a Gernsback publication from 1960. The transistor is made of germanium of the time and the earphone is magnetic with high impedance.
This circuit with two HT2030s powers 6 LEDs in a decorative flashing system. The circuit is from...
The regulator for TTL source is from the SGS linear integrated circuits manual. The integrated circuit...
The SCR sector of this circuit can be powered by high voltage AC and instead of the LEDs we can...