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February 5, 2017 - And now for something different

A project log for The Cardboard Computer - IO is my name

My goal is a 4-bit CPU using recycled cardboard substrate and Diode Transistor Logic. This is an educational platform for me.

dr-cockroachDr. Cockroach 02/06/2017 at 00:125 Comments

Just dug out something from my junk box of parts that I almost forgot about.

I used to be very active with crystal radios and one day I wanted to see if I could make my own variable capacitor. Using two soda cans, a cardboard ( what else ) loo tube , electrical tape and a plastic tube, I was able to come up with this. Wired up with a crystal radio set it tunes quite nicely on the mw broadcast band here in the U.S.

Hope this gives everyone a smile :-)

Discussions

Ted Yapo wrote 02/08/2017 at 21:00 point

Nice!

I've been meaning to try to 3D print some radio parts - coil forms that change distance with a lever to control feedback in a very simple regen.  I wonder if you could make some variable capacitor parts that just need to be covered with foil?

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Dr. Cockroach wrote 02/08/2017 at 21:33 point

Hi there Ted, I think that something like the Crosley Radio book style condensers ( yes it is an older word ) would work out well for a regen set. I have not messed with my regen for over a year. The coils are just simple toilet paper tubes and loose coupled much as your lever. I could give making something a like a book style a try.

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Dr. Cockroach wrote 02/08/2017 at 21:33 point

Hi there Ted, I think that something like the Crosley Radio book style condensers ( yes it is an older word ) would work out well for a regen set. I have not messed with my regen for over a year. The coils are just simple toilet paper tubes and loose coupled much as your lever. I could give making something a like a book style a try.

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Eric Hertz wrote 02/06/2017 at 09:10 point

Hmmm, if I need to replace that trimmer-cap on my PC/XT mobo, maybe this is the way to do it :)

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Dr. Cockroach wrote 02/06/2017 at 09:45 point

:-D

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