This two-channel wired intercom was found in the April 1990 issue of Radio Electronics magazine. Maximum cable distance depends on cable thickness.
This oscillator with crystal for overtone operation was found in an old American documentation. The coil...
In the figure we have a basic PLL circuit with the LM567 or equivalent. The circuit is from a 1977...
The A3906 integrated circuit from Allegro MicroSystems (www.allegro.com) consists of a single...