The Trekster Crystal Radio
Wednesday, April 8, 2026 at 07:56:43
A “crystal” radio, or an AM radio that works without any kind of power other than that generated by the radio signal itself, is one of the staples of basic electronics. It’s something that’s always fascinated me, and while I’ve never wound one by hand I’ve built a few kits over the years and generally enjoyed them. It’s so named because originally, these would have used a chunk of some natural semiconductor like galena to make the detector - but in a modern sense we use a small crystal of germanium in a 1N34/1N60 type device.
This particular device is sold on a popular auction site, and is offered by the creator. What’s in the box?
Packing material! Just what I wanted. No, not really.
A couple of sheets of instructions, a couple bags of parts, and a PCB.
We have:
Two variable capacitors
A germanium diode of type D9K
An earphone jack
Two screw terminals
An inductor
and, a Resistor.
In the other bag, we have:
Two cut clipleads
A Piezoelectric earpice
Those of you who have been around for a while will recognize that earpiece as the same one included in every Radio Shack kit ever made. There are lost tribes using these as jewelry somewhere.
Also included is this PCB.
The board itself looks nicely made, and uses the copper as part of the inductance for the circuit. The only thing I see right off is the diode is going to be a tight fit with the leads bent down right at the body of the part. That’s not really good for a glass part, and hitting that with heat can cause damage - especially if you’re not careful to get in and out asap.
But, I think it should be ok. We’ll see, I’m going to build this kit within the next few weeks. There will be one more post about the building and testing, stay tuned!
Next part of this series: Coming soon.