[sdiy] Telharmonium motors, perhaps?

[Gene Stopp]

Random thoughts which keep popping into my head despite my attempts to
suppress them...

Smaller motor = less portamento?

Tone wheel idea - metal disk with "waveform" around the edge, again the
smaller the better for inertial reasons?

Disk can be made with Dremel tool - any accidental (or intentional)
asymmetry would be a subharmonic?

Can the teeth of a metal tonewheel with a tapehead pickup ever be made such
that the electrical waveform has sharp edges? Any tooth, no matter the
shape, must approach the head and then move away, meaning that a vertical
edge is not possible?

Optical disk may have less weight, less momentum, sharper possible waveform
edges?

Drive voltage can be via MOSFET in opamp feedback loop - easy solution with
modern parts?

<Graham Chapman voice chimes in - "stop! too silly, too silly!">

- Gene



-----Original Message-----
From: owner-synth-diy at dropmix.xs4all.nl
[mailto:owner-synth-diy at dropmix.xs4all.nl]On Behalf Of
sasami at hotkey.net.au
Sent: Tuesday, November 23, 2004 2:11 PM
To: synth-diy at dropmix.xs4all.nl
Subject: Re: [sdiy] Telharmonium motors, perhaps?


Would you believe, shortly after my last message on the subject, I found
such a motor in a VCR I was pulling apart so ...

1) they produce an audio frequency at a quile low rpm - obviously several
cycles per revolution of the motor.

2) adding a load across the sensor may act as a brake to speed up
portamento.

3) an alternative to braking that produces a weird portamento and is QUICK
is to reverse the voltage to the motor at each pitch change. The portamento
is down to 0 then back up to the new frequency. 

4) with a number of rheostats, a relay based sequencer and one of these
motors ... all installed in a '30s style cabinet... hmmm sounds
interseting...

Ken
_______________________________________________________________________
Ken Stone   sasami at hotkey.net.au or sasami at cgs.synth.net
Modular Synth PCBs for sale <http://www.blaze.net.au/~sasami/synth/>
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