I want to build a theremin! (any chance of some help?)

[carboncomp]

Hello guys!

I really want to build a theremin as a gift for a friend but, have very little experience of theremin outside of playing about on a Moog Etherwave!

Don't want to just knock up one of these mini kits, so am wondering if there are any good open source projects akin to the moog?

[amptramp]

Here is the page you want to go to:

http://www.theremin.us/

Several different designs for transistor or tube or digital logic designs.

[gcme93]

Great link Ron, I've been toying with the idea too and that easily has the simplest yet most functional looking circuits I've come across.

Quick question that I suppose requires a step more circuit knowledge than I have...





One is set up for AC input, one for 9V, they also have slight differences in the format of the two oscillators but obviously still with one set, one controlled by hand capacitance. Could I get away with a MAX1044 ±9V supply on the AC version (given a few recalculations for the voltage dividers)? I know they produce a high frequency hum which I suspect would cause problems with a tuned circuit, but my thinking is basically that the *first circuit looks nicer for components and tuning purposes...

[cortezthekiller]

The one on this site works great and is quite easy to put together and calibrate:
http://www.theremin.us/101/101.html

Though there is only a pitch antenna and the volume control would be simply adding a pot to the output of the circuit.
2 chips and runs off a single 9v battery for a while (since it uses a 5 volt regulator for the entire circuit).

[LucifersTrip]

I bookmarked these cheapo, easy ones a while ago

http://losaparatos.blogspot.com/search?q=transistor+theremin

http://musformation.com/build_a_photo_theremin_from_only_7_parts/

http://www.bsidebeats.com/and-a-fancy-new-opti-theremin/comment-page-1/

and one from Deadastronaut

http://dl.dropboxusercontent.com/u/7464107/CYNTHIAT.gif

[gcme93]

BASED ON THIS SCHEMATIC:



Art suggests keeping the two chips as far away as possible in his design notes to prevent mutual capacitance. Do you think that these two are too close? If so, would a bit of blank circuit board between them (say another 5 columns of vero) help matters?

Thanks in advance

[duck_arse]

I built a harrison 146 for a mate a while back, didn't know harrison was still designing. the 146 works pretty good, with a bit of tuning.

ahhh, veroboard, the endless possibilities. if you swap sides for IC1 and IC2, and then use IC2 d,e and f instead of a,b and c, you can shove IC2 all the way to the left to get a bit of space in between. for maximum seperation, and if space is not a limitation, I would put IC1 above and IC2 below, and run a few grounded tracks full width between, and maybe yr regulator somewhere thereabouts..

[R.G.]

I did a modified version of the SWTPC theremin circuit on a PCB back in 1997. Had it up at Geofex for a while.

The SWTPC design does have its eccentricities as the theremin site mentions. However, I got it working on a 2" by 7" PCB with whip antennas on each end.

The problem I was solving then was the unavailability of adjustable inductors. I used fixed inductors and variable AM-radio tuner 10-265pF capacitors to set the tuning.

Worked.

[duck_arse]

I went a bit silly with modifying the 146, as I always do. I tried to add overtone-ing tanks, with tuning gangs, just to get some tonal character. I'm not sure it worked all that well, I haven't finished it yet ....

[gcme93]

Good tip about grounded tracks between. I guess at this stage I'll need to work out what it's going in, and boost the size as big as i can

[Schizo910]

Art suggests keeping the two chips as far away as possible in his design notes to prevent mutual capacitance. Do you think that these two are too close? If so, would a bit of blank circuit board between them (say another 5 columns of vero) help matters?

Thanks in advance

I've build this, but there's almost no volume, just a slight and faint sound. Increasing the volume on the amp results in noise...
Any ideas?

[charbot]

A 'real' theremin will have both Pitch and volume circuits  ( = two antenna,  rod and loop)      While the SW- based circuits are ok- and Art Harrisons make for  decent science-fair projects/noise makers... If you want a real instrument that is playable-  I highly suggest checking out the 'Building the EM theremin" article by Bob Moog.   It was published in EM magazine in the 90's and show you how to build what is essentially a Etherwave.   The article should be fairly easy to find online.  I believe it is also posted on the MOOG archives.    You should also visit Thereminworld.com.  There are (well maybe not 'lots' , but several) other builders and threads about theremin construction.    If you like tubes- the Mark Keppinger theremin is pretty nice.   Lots of DIY- documentation there.  There is even a Keppinger- builders yahoo group.  Mark will even help you and answer questions.

[petey twofinger]

+1 ^

i did that vero layout and wasnt thrilled , i can not remember who i ordered it from , but there is a pcb available that i built and we used it . it works very well as a noise maker , but we ended up just getting a korg monotron delay for next to nothing .

[duck_arse]

I like the look of those keppinger coils, but not the price of copper.

[italianguy63]

I was just looking, and Harrison sells the "minimum therimin" in kit form.  The PCB is about $10, individually.  Not much to the build.

[gcme93]

Sorry guys, that really wasn't posted as a tested/complete vero layout and I should have been much clearer about that. I guess it is accurate schematically but I'm still new to layouts and there's probably a few things I needed to factor in that would help it work as intended.

So for others looking at that layout:

Please buy the kit or use that layout as a rough guide rather than a complete solution!

My apologies again to those who invested time/components on an untested layout!

[charbot]

For a Pitch only theremin project, this is probably the best one available:
http://thereminworld.com/Forums/T/29231/my-new-year-gift-to-tw-a-new-theremin-circuit?Page=0

[R.G.]

Just as a note; theremins are inherently RF designs, and the frequencies are up there where circuit traces are significant components in terms of inductance and capacitance, and the signal can and will radiate out of the traces. So layout is critical to getting these things to work right. Don't be discouraged if a simple layout doesn't work as expected - it's all the fancy stuff needed that cannot be shown on a schematic that is getting you.

[Mihkel]

I built Art Harrison's Minimum Theremin over the weekend roughly going by his layout, but using perfboard. Was relatively easy and worked like a treat. It is temperature and location sensitive though, so you might have to recalibrate pretty often. My build was for my brother's birthday, so I'm building another one for myself this weekend.

Here's the first test (yes, I put it in an enclosure and changed the antenna later): http://youtu.be/p5XkTfM05bA

[PRR]

While you can still get Photo-Resistors:

A basic resistor-controlled oscillator (triangle wave) in a box with an LDR on the top will make wild noises when you wave your hand between the box and the light.

I once built a dozen of these and a famous composer scattered them under trees. But my niece can make more musical sounds with hers.