This powerful transmitter for the 27 MHz band was found in a Japanese publication from 1961. The circuit is powered by battery and has the details of the coils given next to the diagram.
This circuit of a 1978 American publication monitors a telephone line by triggering a relay. The...
This interesting FET-tester circuit was obtained from an old American documentation. The bipolar...
This old VHF TV booster that also serves FM was found in Radio Electronics magazine from April...