This sensitive 4-tube, battery-powered receiver was found in a 1949 Radio Electronics. The circuitry was wired in crystal earphones.
The circuit presented consists precisely of an oscillator (multivibrator) that takes advantage of the 4...
The critical components of this project from a 1978 publication are the transformers, which can be...
This circuit can switch signals in the 3.5 to 30 MHz band. We found it in a QST magazine from the...