An A/B battery replacement for the Zenith TransOceanic H-500 radio with filament regulation

KA7OEI built a battery pack to replace the obsolete “A/B” battery for Zenith TransOceanic (ZTO) H-500 and wrote a post on his blog detailing its assembly: There are several things that I decided that this voltage converter should do: Automatically power up and shut down when the radio is turned on and then off Cause […]

Eight Henry inductors from an old “tube” radio receiver

Kenneth takes apart a few old “tube” radio receivers and finds 8 Henry inductors inside, which is several orders of magnitude more then regular inductors we’re accustom to. He proceeds to hook it up to a 10 uF capacitor, and tests the ringing frequency of this LC circuit. This LC pair resonates at 12Hz, which […]