Crazy Crystal Set

copyright © 2006 by Larry J Solomon


Experimenting with various circuits, and using the Mystery set as a starting base, I wanted to create a receiver with a double-ganged (oder döppelganger) capacitor. This turned out to be not as simple as it first seemed. Simply replacing the two variables with a döppelganger  made the set untunable, because the two rotors are connected together and are inseparable. So, I began tinkering with the circuitry, trying this and that. The circuit that worked best seemed impossible. Indeed, some who see this will probably proclaim it to be impossible. To the contrary, it is not only possible, but a fine performer.

crazy crystal circuitI

I call this weird circuit the Crazy Crystal Set. Notice that there is not a single resistor or fixed capacitor. The astonishing thing is the dead end coil, L2, connected to an antenna but going nowhere! I have never seen such a circuit in print before. However, it works beautifully! Here are some of my photos.

This shot shows the simplicity of the set, the vernier dial, coil, and capacitor.Most of the wiring is under the chassis. The phone jack can be used for high impedance phones or for audio output to magnetic phono (low level) input on a stereo amplifier. Sensitivity and selectivity are both good.

The whole view from the front showing vernier.

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This close-up photo shows the view from the back with the space-wound coil. The crystal diode mount can barely be seen inside the coil. The antenna post is red, and the ground is black The green coil is L2..

Another back view all the way to the front.


This is a view from above. Note the crystal inside the coil.

This view is from the left side.

This is a closeup looking down into the coil, showing how the crystal is mounted.

A fisheye view of the same.