Hotrodded Gakken Mini

Posted: 11/5/2008 11:45:36 AM
jlane72t

From: New England

Joined: 11/5/2008

Heya all ethernauts,

I do realize as a first time poster I should really be in the 'newbie' forum, but I'm really much more of a lurker than regular participant and thought this was a more appropriate location for content.

Anyway, I recently bought myself one of those Gakken "kits". Right away decided I needed to rehouse it into a less toy-like case.

After cannibalizing an antenna from an old radio, and sifting through various packrat "extra parts" boxes (I'm sure y'all can relate) for a spare tricycle handgrip, momentary switch, A/V cable, and ground wire from a light fixture...cobbled this together into a cigar box.

Rather than look strange standing there holding a strip of aluminum foil, the wire around the grip does the grounding, and the momentary switch not only can provide a wild intermittancy effect but keeps the batteries from draining when I am done playing with it (since the on/off switch is buried in the box). The upgraded antenna gives me at least a foot of playable range. The whole thing closes up nice and tight and clean into itself.

Just a post to show what can be done with it if you employ some creativity (and a Dremel)!

Closed box (http://img509.imageshack.us/my.php?image=thereminclosedoq3.jpg)
Handgrip (http://img360.imageshack.us/my.php?image=theremingripjw0.jpg)
Ready to play (http://img511.imageshack.us/my.php?image=thereminantennalf5.jpg)
Interior (http://img83.imageshack.us/my.php?image=theremininsideux1.jpg)
Posted: 11/5/2008 2:42:05 PM
omhoge

From: New York, NY

Joined: 2/13/2005

Welcome to ThereminWorld jlane72t!

Thanks so much for sharing these mod-s, the Gakken Mini has been very popular here.
Posted: 11/5/2008 6:10:25 PM
GordonC

From: Croxley Green, Hertfordshire, UK

Joined: 10/5/2005

Excellent! You've got an articulation regulator. I didn't manage to find such a nice switch for mine (http://flickr.com/photos/8666613@N04/1756172850/sizes/o/). :-( But they're a good addition. Eri uses one on her gakken mini in this mySpace video (http://vids.myspace.com/index.cfm?fuseaction=vids.channel&ChannelID=1000684457).

(I use mine on my etherwave. yT (http://www.youtube.com/watch?v=oEEE2hwJRDQ))

Man From Uranus has a great big one built into the top of his hat.

[img]http://manfromuranus.com/res/photos/TATE_MUSIC_LOW_30_thumb.jpg[/img]
- view full size (http://manfromuranus.com/photos.htm&photocat_id=&photo_offset=40)

Another thing you can do with a Dremel and a theremin is add a fuse-wire propellor then introduce it into the pitch field for ultra-fast frequency modulation.
Posted: 11/5/2008 6:35:31 PM
jlane72t

From: New England

Joined: 11/5/2008

Neat! Funny how folks would just come up with something like that independently.

My design isn't as audibly smooth as yours...since it's primarily intended as a power on/off, it's linked into the battery wires...so when the whole thing turns off and on there's a little 'blip'. I suppose I could adjust the system so the on/off's controlled by a different switch somewheres and this'll cut into the output wiring...hmmm something to think about.
Posted: 11/5/2008 7:19:08 PM
GordonC

From: Croxley Green, Hertfordshire, UK

Joined: 10/5/2005

Mine wasn't an independent discovery. I learned about it from http://www.peterpringle.com/ondes2.html. Apparently it predates the volume loop in theremin development.
Posted: 11/14/2008 9:51:41 AM
jlane72t

From: New England

Joined: 11/5/2008

So I've modified the setup so there's now a pushbutton on/off mounted on the box, and the momentary switch in the handle is wired into the output jack to make it a proper 'articulation regulator'.

I'm having an issue where when I let off the switch to mute, it doesn't fully mute but just cuts the volume by about 3/4. I replaced the switch and that wasn't it.
I've tried wiring the switch in the following formats:
1. as a break in the signal wire
2. as a break in the ground wire
3. with both the signal and ground wires directly connected to the output jack on their respective lugs, but with the switch additionally connecting the ground lug TO the signal lug
The first two give the non-muting problem, the third did nothing (that one was a shot in the dark).

Any ideas? Is it possible that the problem is that I'm using vintage-style guitar wire, with the old-fashioned push-back cloth wraps, and there's some signal radiating out and bleeding through?

As you can probably tell, I am a freshman student at the "Trial & Error Technical Institute".
Posted: 11/14/2008 10:01:13 AM
jlane72t

From: New England

Joined: 11/5/2008

Now that I'm looking at Gordon's picture again, would it be easier for me to scrap the whole idea of having the 'articulation regulator' hardwired into the theremin itself and just build an external plug-in version? I have plenty of cheap guitar cables and 1/4" adapters laying around.

I guess the main question with that would be if I connected the ground wire within the (external) cable to my 'human contact' ground on the handle, would it still serve to improve the theremin's performance?
Posted: 11/14/2008 1:53:13 PM
GordonC

From: Croxley Green, Hertfordshire, UK

Joined: 10/5/2005

Mine is wired as a break in the signal wire.

I'm not an electrician either, but it seems to me that if there's some current leaking through that the switch is not making a clean break - perhaps there's some conductive gunk on the contacts, or a thin strand of solder from one side of the break to the other.

Re: grounding. Try it and see. You can always ground the theremin to something else - bare metal on a radiator, for instance.

Posted: 11/14/2008 2:07:25 PM
jlane72t

From: New England

Joined: 11/5/2008

Yes, that was my thought about the switch too...so I bought a new switch and put it in, and the same thing was still happening. So I'm pretty sure it's not the switch.

Today's attempt will take a lesson from you and build it externally. Headed to the workbench!
Posted: 11/14/2008 3:53:59 PM
jlane72t

From: New England

Joined: 11/5/2008

Okay, plenty of workbench time and it got bizarre. I basically swapped out everything...the wiring, the antenna, the output jack, the switch, the instrument cable...and nothing stopped the background noise.

And then I discovered....that I could still hear that noise...when the theremin wasn't even plugged into the amp! Something in the electronics is broadcasting out enough of a signal that the endplug on the instrument cable picks it up, even when it's a foot away. So I don't see how there's any way to deal with that, even if I dipped the entire box in a super-insulating coating, the endjack still goes into the output jack and would pick up the radiant noise. PPppppbbbhhhhh!

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