Copyright 2015, 2020 - Alan R. Klase - All rights reserved

Time flies when your having fun:

I sold my house in the deep New Jersey suburbs in 2007, and moved to Jersey City.  The crystal set environment here is quite different.  See:  The City Mouse.  So it's been a while since I built a serious crystal radio.  For a while now, I've had good intentions of building a reproduction of this  WWI Telefunken Crystal set.  This is a good example of a portable communication receiver from 100 years ago.  And, having been designed for short-range communications on the battlefield, it is strictly a medium wave device.  The tuning range is 500 to 2000 KHz, making it much more like a broadcast-band crystal set, than the better know maritime radios of the wireless-telegraph era.

This radio was displayed in the Fort Monmouth museum.....        but now, it's in here, beside the Lost Ark.

This radio is associated with Edwin Armstrong, who's unit in France, 1918, did evaluations of captured equipment..
These  Signal Corps blueprints came from HERE.

This is one of the earliest radio I know of where the designer was smart enough to tap the detector "down" on the tuned circuit.

I didn't feel up to an accurate reproduction, so I'm settling for a similar circuit with a few modern tweaks.

The Breadboard:

If you're going to build anything nearly this complicated, you need to breadboard it first.  I used a piece of 1/4" luan plywood, and a 3/4" base.  I added a wooden stiffener to the top of the front panel.


Performance:  (Keep in mind the signals are strong here.)

Final Build



I've been playing the set into an modified Atwater Kent horn with an sound-powered telephone element as a driver.


Video of my presentation to the New Jersey Antique Radio System

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