This sensitive 4-tube, battery-powered receiver was found in a 1949 Radio Electronics. The circuitry was wired in crystal earphones.
We found this circuit in an old documentation, but it is still current, being able to feed sets of...
This circuit was obtained in a 1977 magazine, but it can still be easily assembled, as the...
This circuit was found in a 90s American documentation. The circuit uses an LED that can be of a...