Help needed

Hi digitalearth, welcome to theremin world. :-)

I haven't heard from Tony Bassett in several years, and his website ceased a while ago too. Considering his advancing years, I suspect that he has gone to heterodyne heaven. :-(

You might like to look at the pitch only theremins made by Dan Burns (http://soundslikeburns.com/) and Theremaniacs (http://www.theremaniacs.com/) and Art Harrison (http://www.theremin.us/)'s minimum theremin kit.

digital said:

[i]"Or does anyone else make a Theremin with a 1/4 inch antenna output? Or is it easy to bypass the antenna and use another conductive material to do this"[/i]

These are easily changeable variables as long as you have understanding for making adjustments to the oscillator coil tuning.

I agree with Gordon about using the Theremaniac pitch only version for $80.

I have used it many times when I needed a quick proximity effect or just experimenting. Your output is going to be a variable freq line level low freq tone. You will need some electronic experience to make a circuit to use this in your own application.

If your surroundings are an open area I could see a useful range of at least 4' to 5'. You must have a connection with a good earth ground to the negative side of the circuit board! You may get this ground from connection to a grounded amplifier but you may be doing something different. Stay away from digital theremin oscillators if you need distance away from the antenna.

Edit: The Theremaniac is a natural heterodyning theremin radiating a radio wave around 800 kHz so tuning can be done with a battery operated AM Radio within 2'. No fancy equipment required! Not knowing your application normal theremin pitch drift may be an issue.

Cool. :-)

I am curious about what your project is. Maybe you'll keep us updated?

My email to this address just bounced ("retry timeout exceeded"), four days after I sent it.

gordonc at theremin dot org dot uk

2 questions before:
A) what is a bollard? (sorry for my weak English)
B) is a schematic of this theremin available?

I think I will be able to give a qualified answer when I'll have these informations.

It's all about the relationships between the capacitance of the tank circuit, the static capacitance of the device which acts as the antenna and the dynamic capacitance which adds when approaching...

Think of theremin behavior as a dancing butterfly in an open field, being pursued by a Thereminist waving their arms in space.

The theremin oscillators are alive, providing energy to its wings which in turn give it an aerial response.

Not having a good earth ground is like ripping off one wing and expecting it to fly.

Not having a proper pitch antenna would be like taking a pair of scissors to the other wing and trimming a little off.

Using a large metal mass, a bollard as a theremin pitch antenna would be like putting duck tape on one of the butterfly wings. The theremin is based upon very low energy levels which would not be able to drive enough energy (normally) into the bollard to get the results you need.

A simple solution uses a plastic bollard, then use a normal internal antenna.

You must have balance between both wings or the butterfly will fly in circles or worse if one wing has been trimmed spin around on the floor screaming.

I hear this scream from some theremins, all of my early theremin designs screamed, this is what might be called the cry of the butterfly if you can hear what I am saying.

This raises another off topic question though actually related. How do some theremins develop that rich or throatier almost vocal sound? If anyone dare post your logic then post your sound byte to back it up. ( ‘ I double dare you! I would like to think that not all scratch theremin designers have faded away.

David: Where are you getting your “good earth ground” from? If you did get response from a larger metallic object for an antenna you need to raise it up away from the ground a couple of feet. The Theremaniac operates around 800 kHz; it's Hartley oscillators and circuits draw about 5 ma. at 9 volts. To reveal a schematic would not be fair to Chuck Collins the designer though its availability is online and no secret.

David I hope you stick with your theremin research, a journey to which few are called.

Good Luck,

Christopher

Couple of thoughts...

That's a [i]big[/i] antenna. An off-the-shelf theremin will likely need some adaptation to accommodate it.

Pitch correction. OK. Have you considered using a resonant comb filter as an alternative? It could give an interesting field for people to explore, with zones of constructive and destructive interference, and a goodly measure of consonance to boot.

David, when doing research you must let the project lead you to places that you may never have thought of. It is often a journey of serendipity. For success it is not uncommon to have to back up on the road you went down and then take another direction.

Scratch theremin designers spend thousands of dollars and hours if not more going down roads that lead to a dead end around the corner.

Not knowing the finale situation and behavior you expect from your design makes it even more difficult to propose possibilities.

Does the final response flip a momentary switch on or give a theremin pitch rise in sound?

The earth spike is excellent?

I visualize your construction as standing alone and it must self adjust the pitch frequency over the course of the day where temperatures may change greater than 10 degrees F.

David said: [i]Also i will be using modern technology to stabilize the pitch output (Pitch correction)[/i]

This is a fascinating concept, how are you doing this?

The only method I can imagine so far working is to use an ultrasonic approach. It will not be as mysterious as an energized theremin bollard and gives an on/off response. It does have “stability” using a crystal, and a more usable range/distance detection than you could get from a theremin.

Ultra-Sonic Sensor (http://www.eio.com/p-17421-velleman-vm125-ultrasonic-radar-module.aspx)

I have one of these still in the package, only tested it out to see if it could work for a theremin volume control. It did work, but not as fluid as I would have liked.

I will give it to you at no cost if you can use it, email me a mailing address, I am not hard to find.

Christopher

Looks great, sounds great. Good one.

 

Thierry asked: "What is a bollard?"

The word comes from "bohle" (obsolete) meaning the trunk of a tree. A "bollard" was a post of wood or iron, usually on board a ship or whaling vessel, for fixing ropes. 

I don't know why these proximity devices are so often called "theremins". They're wonderful fun, but they have more in common with an automatic sliding door than they do with a theremin.