Galactic Ham Theremin Device (VIDEO/AUDIO ADDED)

[pryde]

Inspired by guitarmageddon's theremin build I came up with this one using the paul in the lab vero. This one is quite special as it was a real father and son project. He is 9 and I am teaching him everything I can (including how to solder and build cool stuff). Watching him pick out components and complete some soldering is just awesome 

First, the misspelling of "Theremin" (used an a) wasn't noticed until after etching (sorry Mr. Theremin). If this were a customer build I would have started over but I can live with it.

HAM was the first chimp launched into sub-orbital space. Hero or helpless guinea pig? You decide. Anyway, it makes spacey-weird sounds as you know so we like the name/design a lot 

This thing is VERY finicky. On the test-rig with antenna hooked up remote to a nearby enclosure it was working/sounding great. With the circuit boxed (using the enclosure as the areal) it isn't working as well and the oscillation seams "dirty" like there is an overdrive hooked up to it? I isolated grounding and the circuit (wood block underneath) and played with wire positioning and it helps but still not what it was. Going to have to keep messing with it.

Might be my power setup/wiring. Using the battery gives better/cleaner results than the power supply. Anyway here we go.

   

[bcalla]

Awesome father/son project!  Please update the thread if you can resolve the problems.  I plan to build one of these soon.

[cooder]

Very cool indeed! Great stuff, great teamwork!

[brejna]

Great one! I really like it!

[selfdestroyer]

This came out awesome. That etch looks great and the fact you got to pass some knowledge to your son is inspiring. My father used to do the same thing with me and I am appreciative even now as a grown ass man. I still remember the little tips and tricks hes taught me.. it sticks with you for sure.

Cody

[pryde]

Awesome father/son project!  Please update the thread if you can resolve the problems.  I plan to build one of these soon.

Will do. It does sound pretty good but I remember it being cleaner sounding on the test rig. I may remove the circuit and re-test just to see if the enclosure/areal is the issue.

[Guitarmageddon]

Came out looking great!
I found that different settings were required between battery and PS. I think I added a little extra resistance between the DC jack and board to sag the PS voltage a bit to better match my batteries.
Can't really advise you about the aerial, being RF controlled, it definitely makes lead dress and circuit placement relevant though. Mine wasn't neat- for once that may have been advantageous!

[pryde]

Picking up local radio station really loudly as well so that is always going on in background as well. Maybe i will try shielding the output lead also.

[TGP39]

Just love everything about this.

Steve

[Cortexturizer]

fantastic! can only imagine how your son must feel, the accomplishment, the bug...get em while they're young!

[hoodoo]

Very cool all round. 

[nzCdog]

Haha!  love the name, great build, what a lot of fun right there

[jimilee]

Very nice, great fun building with your kids.


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[nieradka]

Im not familiar with the design, but I think the problems you are having could be related to the following:

I dont think using the case as the antenna is the best idea, the floor is closer than you are, so its going to be a nightmare to tune.
Most theremin designs need a good connection to an earth ground to work correctly, Im not sure how that is happening here.

To oversimplify, basically you have two AM radio transmitters, and your capacitance to the antenna is the tuning cap for one of them. The two signals are subtracted from each other and produce a sine wave in the audible range.

[pryde]

Im not familiar with the design, but I think the problems you are having could be related to the following:

I dont think using the case as the antenna is the best idea, the floor is closer than you are, so its going to be a nightmare to tune.
Most theremin designs need a good connection to an earth ground to work correctly, Im not sure how that is happening here.

To oversimplify, basically you have two AM radio transmitters, and your capacitance to the antenna is the tuning cap for one of them. The two signals are subtracted from each other and produce a sine wave in the audible range.

The ground is normal coming through the standard power supply. The entire circuit is isolated from the enclosure. There is no ground continuity to the enclosure itself. The antenna wire coming from the circuit is the only thing connected to the enclosure itself. Not sure if this is the best way but others have done it like this with no reported ill effects so???