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.

| Clique na imagem para ampliar |

Multicrystal Probe Oscillator (CB18294E)
We found this circuit in a 1956 documentation from Sylvania. The circuit is for bench testing and...
Sensitive Metal Detector (CB23754E)
This circuit was found in the Radio Electronics magazine of July 19666. The search coils are the...
Low Pass Filter 741 (CB19644E)
This circuit allows only signals with frequencies below the calculated value to pass. The formulas for...