This unusual circuit from a Popular Electronics of the 90s uses LED indicators, operating as a bridge. The components used are common. It is based on the tuning of the signal by a PLL.
This circuit produces a IR beam with a frequency adjusted by the 100k pot. The circuit can be used in...
This voice scrambler and descrambler circuit was found in a Radio Electronics from July 1963....
This transistor source was found in a 1990 documentation. 2N3055 transistors must be equipped with...