[sdiy] The Story of the Theremin

[harrybissell]

The PWM output is not much of a feature for fast motion like maracas...
The analog output is really not that great... but if you think the ADXL210
is good... I'll have to try that.  I think that you will break your wrists
trying
to get out of the mud with that part...even with LOTS of amplification.

The biggest problem I found is the recoil.  In the real maracas... you
accelerate
the beans (peas, BB's ... no not BBDs...) and then when you make the sudden
stop...
they give up all the energy in one shot, and don't have enough left to make
another sound.

The accelerometer output will FAITHFULLY follow the overshoot of your real hand
motion...
may be hard to control. Mine was...

hey maybe "Quantized MIDI maracas" ???  what'dya think :^P

H^) harry

"Paddock, Toby" wrote:

> Michael Bacich wrote:
> >
> > In a message dated 10/17/04 6:05:09 PM, tpaddock at seanet.com writes:
> >
> > << Nope, I can't nail it on an accelerometer either.  :)
> > I haven't heard the song lately, but I don't think it would help.
> >
> > http://www.seanet.com/~tpaddock/public/g_vib.mp3 (230KB mono) >>
> >
> > OK, that was funny.  However, I'm now feeling a little seasick.  Now you
> > need
> > to learn to play the theme from "Lassie".  Originally it was performed by
> > somebody whistling, but a Theremin would be even cooler -- Kind of like
> > "Lassie,
> > come home... To MARS!"
> >
> > BTW, I think you need a name for your gizmo.  I respectfully submit The
> > Accelerometin  (or maybe The Acceleromotron).  Or, if you're an egomaniac
> > (like
> > me), you could call it The Tobytron...
> >
> > Are you going to publish your design for all of us DIY geeks?
> >
> > Michael Bacich
>
> Oh yeah, an "accelerometin", I like it. I can't quite remember the Lassie
> theme. Almost, but my brain keeps sliding off to the Andy Griffith show and
> a part of Tubular Bells that I can't quite pin down. Need to find Lassie on
> a tv theme website.
>
> There's not much to publish, It's just some Analog Devices accelerometers
> and buffers. 9v battery, 5v regulator, a ADXL203 +/-2g 2 axis accel for the
> 2 horizontal axes, a ADXL105 (I think) +/-5g 1 axis accel for vertical, cmos
> rail-rail quad opamp (TI TLV2474 I think) for buffers.
>
> Now it needs changeable gain and offset. The VCA is pretty happy with 0-5V,
> but the VCF wants MORE RANGE!, and the VCO wants +/- instead of 0/+. And the
> VCO really wants more range too sometimes for crazy noises.
>
> Next time I'd use ADXL202 (like Harry did) for the horizontal axes because
> it also has PWM output. I used the ADXL203 because I was helping someone
> test a tilt sensor with them.
>
> For vertical, gravity is pulling a 1g offset and with a 2g part, that only
> leaves 1g for shaking. Maybe that's OK for easy shaking.
>
> Or for the vertical axis, maybe one half of a ADXL210 +/-10g and boost the
> gain.
>
> Using 2 different parts means getting twice as many free samples  :)
> And then get header boards for them at
> http://www.sparkfun.com/shop/index.php?shop=1&cart=107674&cat=71&
> http://tinyurl.com/53eq2
> who also have some interesting looking rf link modules.
>
> There's some other choices
> http://www.analog.com/en/subCat/0,2879,764%255F800%255F0%255F%255F0%255F,00.
> html
> http://tinyurl.com/3ogtk
> What is a CP-16 package? Sounds too small for me.
>
> I'm going to try mounting to a larger heavier thing to try to damp out the
> coffee jitters.
>
> Here's another quick sample with the 3 axes controlling VCO, VCF, and VCA of
> a minimoog. Tilting and shaking only, no knob twisting.
>
> http://www.seanet.com/~tpaddock/public/accel1_128.mp3 (1.4MB 128kbps)
> http://www.seanet.com/~tpaddock/public/accel1_48.mp3 (0.5MB 48kbps)
>
> Toby