1947 Two-Tube Regen for Junior

1947NovPSWhile this project from the November 1947 issue of Popular Science is ostensibly a Christmas present for Junior, the text of the construction article reveals that Mom and Dad might have an ulterior motive:  “Everyone in the family will enjoy this little two-tube headphone set.  Junior can listen to all the programs especially meant for him, and Pop and Mom will escape the nerve-shattering tommy guns and thundering herds.”

The set is a two-tube regenerative receiver for the broadcast band, using a 12J7GT detector with a 12J5GT serving as audio amplifier.

It’s an AC/DC set, meaning that Junior should probably make sure he doesn’t use it close to the water pipes. It appears to be electrically isolated from the chasis, and as long as capacitor C8 doesn’t short out, the headphones will be isolated from the AC line.

To tame the regenerative receiver, and keep Junior from becoming a squeal hound, the controls are preset, and tuning is accomplished with three or four trimmer capacitors set to local stations, and a switch is used to pick the station.

No external ground is used (probably to keep the AC-DC set from blowing a fuse or zapping Junior). The article notes that an outdoor antenna is desirable but not absolutely necessary.

 

1947NovPSschematic


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