Busy Line Indicator (CB18711E)

This busy line indicator is very simple, serving for analog lines. The supply is made by two batteries and the transistors admit equivalents.

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Electronic Repellent (CB16654E)
This simple oscillator is yet another of the many versions of sonic insect repellent that we find...
4 to 20 MHz XTAL Oscillator (CB12705E)
The circuit in the figure operates at frequencies from 4 to 20 MHz and also uses a common junction FET...
Decade Counter (CB24584E)
This TTL counter was found in the April 1979 issue of Radio Electronics magazine. The circuit is...