This receiver was found in a 1924 book by Gernsback. The circuit uses three tubes and is powered by 3 batteries of different voltages, common at the time.
This circuit was found in an old publication about transistors. The circuit can be used to drive...
Using a symmetrical source this circuit reverses the rotation of a small motor through light...
This circuit was found in a 2005 Linear Technology documentation. The circuit is based on LTC4213...