This transmitter for the 3.5 and 7 MHz ham radio was found in a 1950s Japan publication. No information was given on the coils and the power supply.
The frequency of this oscillator can be set in a range from 5000 to 1. We found it in an old...
This filter was found in Radio Electronics, and its configuration can be applied to any...
The keyboard for this organ is made by small metal plates where the probe touches when in...