Has anyone seen ThereminVision in action?

Martin_H

This looks interesting as it is an object detection system that uses Theremin to sense the capacitance of objects: http://thereminvision.com/

What is interesting to me is the claim that it does edge detection as well as collision avoidance.

graffix

Did you find a price for the system?
heres some detail of the system http://thereminvision.com/version-2/ThereminVision-II-manual.pdf

Martin_H

It looks like their vendor link is dead, but I saw a comment in an online forum that the kits were around fifty dollars.

I just wanted to see a video, but no luck so far.

graffix

youtube turned up few results heres one http://www.youtube.com/watch?v=9iSi8sDvppQ

Martin_H

I saw that video, but he was only playing around with it on his bench. I may write the creator to see if he has any. It is an interesting idea for short range collision avoidance.

GordonMcComb

You don't really need heterodyne oscillators to detect objects via capacitance. The capacitor plates of a theremin (yes, I own one -- and yes, I'm a terrible player) merely change the frequency of the local oscillator to beat against the reference oscillator, thus producing a tone within the range of human hearing. You need one oscillator to charge the antenna, but you can interface to the antenna in simpler ways that aren't so touchy -- a real theremin always requires touch-up before it's stable.

There are specialty ICs that do all the oscillator stuff (like http://www.sparkfun.com/products/7902) and playing with the antenna and loading coils can extend the range. Aluminum foil works well. This guy did some interesting stuff: http://www.nerdkits.com/videos/halloween_capacitive_touch_sensor/

If you have a Propeller QuickStart you can see how the metal stripe on the back makes for a good close-proximity detector. The QuickStart even knows when it's resting on your table!

-- Gordon

PS: My theremin -- http://www.paia.com/theremax.asp

Publison

Ahh,,,PAIA

Built many PAIA projects, and still have my 2700 Synthesizer.

Martin_H

Gordon, thanks for the pointer to those pages. I will take a look.

Update: It turns out that capacitance proximity sensors is a better search term as it turned up this page:

http://www.solarbotics.net/library/pieces/assy_sensors_field.html#capaciflector