30 MHz Amplifier (CB5939E)

This low noise circuit was obtained from a 1980s US RF publication. Transistors used are uncommon today and the gain is 19 dB..

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Carbon Microphone Preamplifier (CB14801E)
Carbon microphones are no longer used in most projects. However, finding one in the scrap metal, it...
Sonic Repellent for Animals (CB13162E)
This circuit produces a strong tone of audio or ultrasound, depending on the values of components C1 and...
Alarm (CB12604E)
This alarm from an old 1978 publication uses PNP transistors and driver and output transformers that are...