This old 1967 audio preamp uses germanium transistors. It was found in Japanese documentation at the time and has a gain of 70 dB, being powered by p V. The input sensitivity is only 12 mV.
This circuit was obtained in a 1977 magazine, but it can still be easily assembled, as the...
This intercom for the 27 MHz band was found in a recent English documentation, working with a...
This relay shield circuit for old computers was found in January 1983 Radio Electronics magazine. The...