Simple Theremin suggestion?

[mathflan]

Hi,

I want to build an simple theremin.
Do you have suggestions for that.

Thanks.

[Giaime]

Try this:
http://home.att.net/~theremin1/100/minimum.html

I don't have built it yet, but I will probably...

[Paul Perry (Frostwave)]

And here's a 'less than minimum' theremin, using a LDR and two transistors:
http://www.geocities.com/SoHo/Lofts/8713/optotheremin.html

Plus the obligatory 555 based optical:
http://www.fataltourist.com/articles.asp?id=4

I expect to see reports of these in two hours from now.. get cracking!

[KORGULL]

A few projects here:http://www.oldtemecula.com/theremin/
I'm in the middle of building the "RS Ultimate 2." There's also some add-on boards you can build to expand it's capabilities. There are sound samples posted and all electronic parts can be found at Radio Shack.

[Giaime]

Wow! Those looks cool (and simpler)!

[mathflan]

finally I'am building this theremin :



It use 4 IF transformer


The URL is :

http://www.siliconchip.com.au/cms/A_103277/article.html

AND this URL (It's a modified version)

http://www.thereminworld.com/silicon_chip_theremin_modifications.html

I just want to know if it's a good theremin, what do you think about that?

Thanks

[Paul Perry (Frostwave)]

I couldn't get the Silicon Chip theremin to work satisfactorily. Neither did two other people I know.
But, other people are happy witht it!!
The designer (John Clarke) is a known "good analog designer".

Certainly, it is a b*stard to tune. :x
Thanks for pointing to the mods, Mathflan!! Maybe I should have another shot now!

I'm very keen to hear how you get on with it.

[inverseroom]

I really like the PAiA Theremax.  It was easy to build, hard to set up, and sounds really good.

[KORGULL]

I built the Silicon Chip theremin. It is tricky to tune and very temperamental. I was having one problem while initially tuning it where the sound would almost completely cut out then come on again. I might have a bad IF can, I'm still not 100% sure of the cause though.
Finally got it (the sound) to stay on and tuned reasonably well.
Sometimes the volume pot will affect the operation of the circuit (the pitch) while I'm touching it (no knob on shaft).
The volume plate doesn't have much of a usable range.  I think using a large loop antennae instead of the plate might improve the range.
I haven't tried any mods for it yet. There used to be a bunch at maxiespages.com, but it was off-line last I checked. I will look into your link tonight mathflan, thanks.
Overall, I'd say:
1) it is definitely worth building-the cost is low enough.
2) It is not the most musical theremin you can get. The tone and the pitch/vol control are not exactly top notch.
3) for sound FX and weird/eerie noises it is great and alot of fun. I run it through an old Digitech delay pedal (through two keyboard amps)and occasionally switch on an EA tremolo and can get some very haunting sounds - from an abandoned attic to an alien spacecraft. I want to build a fuzz for it - my guitar distortions take out too much of the low end rumble.
With the dry sound and some fast hand vibrato you can totally nail the haunted house/ghost type sound effects from old movies and T.V./radio shows.

[Paul Perry (Frostwave)]

I built the Silicon Chip theremin. It is tricky to tune and very temperamental. I was having one problem while initially tuning it where the sound would almost completely cut out then come on again. I might have a bad IF can, I'm still not 100% sure of the cause though.

It isn't a bad IF can :wink: What is probably happening, is interaction between one of the two hetrodyning oscilators (that generate the pitch) and the other RF oscillator that does the volume. Trouble comes when you try to tune it so that:
1. the fixed BFO oscilator is in a position where it gives the desired range wiht the varaible pitch oscillator
AND, 2. the variable RF oscillator for the volume is working outside the range covered by the variable pitch oscillator.

I notice that the new Silicon Chip theremin no longer is a beat frequency one, it is just the volume section twice over. This might have a bad effect on the tonal richness of the audio output, whihc in the classical heterodyning theremin has a very interesting waveform (changing with pitch).

[mathflan]

Ok I find some IF in old radio.
I don't find BLACK slug IF .
But it's begin to sound but I have a trouble with the volume.
In fact the sound is very low and When I touch with my hand the left pin of the 1 k resitor above the MC1496, the sound is loud and I'd like to keep this volume, It's strange.
I think its becaus I place a IF (color brown) instead of the black IF.

[vfr800fiman]

A few projects here:http://www.oldtemecula.com/theremin/
I'm in the middle of building the "RS Ultimate 2." There's also some add-on boards you can build to expand it's capabilities. There are sound samples posted and all electronic parts can be found at Radio Shack.

I also built the RS theremin, and am very happy with it.
Simple to build also.
Christopher did an excellent and creative job with the coil designs.
Glenn

[mathflan]

is there someone, who had a sample sound of the theremin I'am building.
I want to compare the sound.

thanks

[Killer Queen]

If you want anything playable, I'd stay well away from a telescopic antenna (like on the silliconchip.com diagram)- you'll never get that to stay in tune properly. You'll need something more solid. As long as you can take it off when you need to transport it, it shouldnt be too much of a problem to have  aproper solid antenna. (Or you could use a sheet of metal rather than a rod for the antenna, which would probably be more space-efficant.)
Anyway, whatever antenna you use, just dont use a telescopic one

[casey]

i have a theremin circuit on my site:

look below:




best of luck to you:

casey

[KORGULL]

Paul Perry wrote:

KORGULL wrote:
I built the Silicon Chip theremin. It is tricky to tune and very temperamental. I was having one problem while initially tuning it where the sound would almost completely cut out then come on again. I might have a bad IF can, I'm still not 100% sure of the cause though.  


It isn't a bad IF can  What is probably happening, is interaction between one of the two hetrodyning oscilators (that generate the pitch) and the other RF oscillator that does the volume. Trouble comes when you try to tune it so that:
1. the fixed BFO oscilator is in a position where it gives the desired range wiht the varaible pitch oscillator
AND, 2. the variable RF oscillator for the volume is working outside the range covered by the variable pitch oscillator.

I thought maybe a damaged component or PCB trace could've been at fault because pushing (with finger or screwdriver) on T2 or the area around it would sometimes trigger (or fix) the problem. I'll go with your theory though as there have been no problems with it since the final tuning - I have not tried pushing anything (including my luck) after it finally started operating acceptably - just put the lid on with a sigh of relief.
vfr800fiman wrote:

I also built the RS theremin, and am very happy with it.
Simple to build also.
Christopher did an excellent and creative job with the coil designs.
Glenn

Good to hear you like it. Christopher really seems like a very dedicated/knowledgable theremin enthusiast. I have very high hopes for this project. I finally have all the parts gathered and the coil forms assembled, just need to etch the board.
I'm hoping it will be in the same league as the Theremax - as far as sound & playability.

[niftydog]

Introducing the one transistor theremin!

Hmmm... deja vu.

[vfr800fiman]

Paul Perry wrote:

KORGULL wrote:
I built the Silicon Chip theremin. It is tricky to tune and very temperamental. I was having one problem while initially tuning it where the sound would almost completely cut out then come on again. I might have a bad IF can, I'm still not 100% sure of the cause though.  


It isn't a bad IF can  What is probably happening, is interaction between one of the two hetrodyning oscilators (that generate the pitch) and the other RF oscillator that does the volume. Trouble comes when you try to tune it so that:
1. the fixed BFO oscilator is in a position where it gives the desired range wiht the varaible pitch oscillator
AND, 2. the variable RF oscillator for the volume is working outside the range covered by the variable pitch oscillator.

I thought maybe a damaged component or PCB trace could've been at fault because pushing (with finger or screwdriver) on T2 or the area around it would sometimes trigger (or fix) the problem. I'll go with your theory though as there have been no problems with it since the final tuning - I have not tried pushing anything (including my luck) after it finally started operating acceptably - just put the lid on with a sigh of relief.
vfr800fiman wrote:

I also built the RS theremin, and am very happy with it.
Simple to build also.
Christopher did an excellent and creative job with the coil designs.
Glenn

Good to hear you like it. Christopher really seems like a very dedicated/knowledgable theremin enthusiast. I have very high hopes for this project. I finally have all the parts gathered and the coil forms assembled, just need to etch the board.
I'm hoping it will be in the same league as the Theremax - as far as sound & playability.

The most challenging part was hand winding the coils. They actually
came-out rather well first try. I actually finished them by coating them
in a light film of wax using a heatshrink gun. This really helped the wires
from sliding around on the form.
I've done this on a few old radios that I've restored, rewinding
tuning coils.

The theremin is the ultimate way to drive my cats nuts :twisted:

Seriously though, you really have to run the theremin with a delay
effect to get that cool 50's sci-fi sound. I actually bought (I know) a
Danelectro delay pedal just to use on it.
Glenn

[mathflan]

HI,

I have seen one a french website that there are differents impedances (Resistor) for IF COILS,

LMCS4100A   7x7    1  YEllow   Z= 50K:500      05175 1.80 â,¬
LMCS4101A   7x7    2  White   Z=30K:500       05176 1.80 â,¬
LMCS4102A   7x7    3   Black   Z=15k:5k        05177 1.80 â,¬
LMCS4200A   7x7    1  Yellow  Z=15K:150      15190 1.80 â,¬
LMCS4201A   7x7    2  White   Z=35K:150      15191 1.80 â,¬
LMCS4202A   7x7    3   Black  Z=37k:12k        15192 1.80  


What I have to choose for the silicon theremin, 30K:500 or 35K:150 for white and 15k:5k  or 37k:12k for BLack

THanks

[mathflan]

SO , I finish the silicon theremin of jaycar.
I' happy with it but there a big problem of BUZZ!.

In fact when the volume is low the sound is good but when  I approach more and more my hand to the volume antenna, a buzz arrive ans is more and more loud.

I did the mods from Maxie mods to reduce gain distortion but it was non effect.
Do you know what i have to do to remove this buzz??
That will be very cool!