the Dis* Player

Posted: 4/19/2007 10:16:51 PM

Joined: 3/4/2007

Hi all,

I just thought I would share this super cool little discovery I recently made.

I told the folks at my local electronics shop (in small town Nelson, BC, Canada) about my newly acquired obsession with the theremin.

they immediately told me about this guy Fred Nachbauer who worked there until he passed away unexpectedly a few years ago.

Besides coming up with what appears to be a number of really cool mods for the Theremax he also invented this device.

What it does is show you what note you are hitting (or about to hit) while or before you play it. That is to say that it will display the note represented with an LED before you take your hand up off the volume.

very cool.. I want to build one. But since he passed away I'm having a heck of a time trying to track down a circuit board. Luckily he did document the project very well on that page so if anyone is interested.. maybe we can revive this project somehow? He even included images of the board for burning..

check it out
Posted: 4/19/2007 10:55:34 PM
Brian R

From: Somerville, MA

Joined: 10/7/2005

So, um... is that pronounced "Disaster-Risk Player"?

[sorry, couldn't resist]
Posted: 4/20/2007 8:13:52 AM

From: new haven ct.

Joined: 7/8/2005

sounds like the tuner output on the Pro, which can be modified to produce the actual pitch for previewing

Posted: 4/20/2007 9:39:09 AM

From: Kansas City, Mo.

Joined: 8/23/2005

** edit **

THe Dis*player accepts an audio frequency input, extracts the fundamental, and produces its own CV internally -- I originally thought that it was driven directly from the Theremax's CV out.

Thus, the dis*player would work with any monophonic instrument.
Posted: 4/20/2007 1:19:25 PM

Joined: 3/4/2007

If it just sits on the audio output though how does it know what frequency you are on before you take you hand off the volume?
Posted: 4/20/2007 5:24:38 PM

From: Kansas City, Mo.

Joined: 8/23/2005

The Dis*Player would have to be connected to a pitch-preview in order to display the note prior to increasing the volume.
Posted: 4/20/2007 5:41:29 PM

Joined: 3/4/2007

does the theremax have such a pitch preview?
Posted: 4/20/2007 9:39:57 PM

From: Kansas City, Mo.

Joined: 8/23/2005

This link:

... is Paia's FAQ page about the Theremax. Scroll about halfway down and you will find the pitch preview mod.
Posted: 4/22/2007 3:05:54 PM

Joined: 3/4/2007

Anybody here who has a theremax or another model theremin with a pitch preview that would be interested in this project?
Posted: 4/24/2007 4:46:41 PM

From: Florida

Joined: 11/24/2006

I'm actually about 90% done with building my own Dis*Player! You'll have to make your own circuit board but it isn't that hard. Use the photocopy iron on method. It works pretty well.

I had someone help me choose substitute parts because I couldn't find some of the listed parts. I also had to have an engineer buddy help me locate some of the input points on the circuit board because they didn't seem obvious to me.

If you look through Fred's construction article he tells you exactly where to connect the Dis*Player to the theremax.

"The Volume CV input plugs right into the corresponding jack on Theremax, but you'll have to add a jack to Theremax to bring out the constant-amplitude frequency signal. You can take this from pin 2 of Theremax's IC2, with a 470K resistor in series. (Without the resistor, adjusting your DRIVE control gets very touchy). The advantage to this is that the signal is already a square-wave. The disadvantage is that there is little or no suppression of the odd signals you can get when the pitch oscillators are close to locking.

I prefer to take the signal from the output of the pitch buffer amp, i.e. the collector of Q8. This point has the added advantage of being usable as a "monitor" output, for feeding into a small local amplifier (via a coupling capacitor) so you can make fine adjustments to your pitch before bringing up the volume and sending the note out to the main amplifier."

Also be careful if you decide to try this project. There are some resistors and capacitors that need to be installed on the LED portion of the circuit board. They aren't shown in the component layout but they are labeled in the the circuit board art... There were a couple of other things I had to puzzle out as well...

I don't have it working yet so I can't go boasting that I'm an authority or anything but if you want to confer notes I'd be happy to...

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