This high-impedance headphone circuit was found in a 1990s William Sheets. The power is low, but the high input impedance makes it useful for radio applications.
The circuit presented is a game based on an integrated TTL of type 7473. In the figure we have a...
This simple timer with unijunction transistor was found in an old American technical...
This simple oscillator with a photocell was found in a Radio Electronics from January 1965. The...