inside the theremini

Posted: 2/11/2015 11:14:53 AM

From: Croxley Green, Hertfordshire, UK

Joined: 10/5/2005

Not the most accurate history of the theremin (the polyphonic theremin was an April Fool with some historical basis - Lev's original patents did include designs for a multiple antenna polyphonic theremin, but Moog did not build one) and the electronics might be a bit shaky, but if you want to have a good look inside the plastic case without invalidating your warranty this is the video for you.

Posted: 2/11/2015 4:08:38 PM

From: Northern NJ, USA

Joined: 2/17/2012

Nice find Gordon!  I've seen some of his other teardowns in the past and it's nice to see him do one on a piece of equipment that I have experience with.  Some nits:

@8:40 - That circuit is most likely heterodyning and low pass filtering.  Not sure how he got the idea that it's fixed pitch oscillator.  The fixed pitch is most likely generated by the DSP.

@11:50 - mystery connector!

@16:30 - The human body isn't a capacitor.

@17:20 - The fixed oscillator doesn't radiate. 

@18:10 - We really don't know how the Theremini handles the volume side.

The heterodyning is probably offset and almost certainly not used directly.  Kind of surprised he didn't pull either PWB to see what's underneath.

Posted: 2/11/2015 10:27:59 PM

From: Georgia, USA

Joined: 2/4/2015

Cool! Thanks for posting. 

Posted: 2/13/2015 9:12:42 PM

From: züriCH

Joined: 3/15/2014

along with dewster's hi-res observations, and that video  it's like a call: get the screwdriver and loose the warranty. it lost it's rubber-hooves already, just by pushing it over a bit on the table, want to replace the volume antenna sooner or later any way to fit the gig bag. because that shortens the unit a bit to play, i'll do afterwards more sideways. (no/less interference with pitchfield).

i see also a possibility, to get that blinding display dimmed with that power cabel for the led. dimming led's is not that difficult with some resistance. fix or variable..not sure.a dim-pot?

@17:20 - The fixed oscillator doesn't radiate.  

it's already 22:10 and I have a oscillating radiator. :-(  

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