[sdiy] DIY slide-bars

[William Inman]

Grant, et. al.,

For a 2-page pdf spec sheet on the Scotch No. 13 tape, go to www.3m.com and
type "Scotch #13" in the search field (with the number sign and without the
quotes).  The first result will take you to a very interesting 2-page
summary of the tape.  Grant, is the tape sticky enough to be stuck to
something like a thick piece of plastic or even wood?

Elliot


> [Original Message]
> From: Grant Richter <grichter at asapnet.net>
> To: Gene Stopp <gene at ixiacom.com>; <synth-diy at dropmix.xs4all.nl>
> Date: 7/28/2004 5:56:57 AM
> Subject: Re: [sdiy] DIY slide-bars
>
> Scotch No. 13 Semi Conducting Electrical Tape. Mouser has it. I just
> measured it at 5K per inch.
>
> The make the tape for over wrapping high voltage splices to drain away
> electrostatic charges.
>
> It is soft material though.
>
> > From: Gene Stopp <gene at ixiacom.com>
> > Date: Tue, 27 Jul 2004 17:24:27 -0700
> > To: synth-diy at dropmix.xs4all.nl
> > Subject: RE: [sdiy] DIY slide-bars
> > 
> > I've done two experiments with two different types of material.
> > 
> > First experiment: black antistatic bag material (opaque and rubbery),
cut
> > into a strip. Second experiment: conductive rubber cord (maybe 1/8"
dia.)
> > used for EMI gaskets. Both of these materials had a fairly high
resistance
> > per distance (several K per inch). What this caused is non-linear
behavior
> > and moving voltage points (i.e. yesterday 2 volts may be right *here*,
and
> > today it's over *here*, a couple inches away). Something like the Moog
> > controller is more stable and repeatable, meaning you could mark the
> > fingerboard with the voltages and they'll always be at the same places.
I
> > think it's because the resistive element was a pretty low resistance,
driven
> > by higher current. This would imply some kind of heating element wire,
like
> > in an electric heater. It may be only a couple of ohms so something
like a
> > power regulator might be needed, perhaps configured in constant current
> > mode.
> > 
> > I've not run across such an element yet but I do have a note to self to
be
> > on the lookout for the next trashed bathroom heater or hairdryer.
> > 
> > - Gene
> > 
> > 
> > -----Original Message-----
> > From: owner-synth-diy at dropmix.xs4all.nl
> > [mailto:owner-synth-diy at dropmix.xs4all.nl]On Behalf Of Rainer Buchty
> > Sent: Tuesday, July 27, 2004 6:57 AM
> > To: Magnus Danielson
> > Cc: synth-diy at dropmix.xs4all.nl
> > Subject: Re: [sdiy] DIY slide-bars
> > 
> > 
> >> 1) How did these classic slide bars work? What materials etc. was
there?
> > 
> > In the Elektor magazine they just used graphite, i.e. you literally drew
> > the slide bar, but then had a metal probe for sliding so your finger
> > stayed clean :)
> > 
> >> 2) How could one make one today? I am looking for a fairly stable
design,
> > so
> >> antistatic foam is out, OK?
> > 
> > I wonder if recording tape could be used in a setup like this:
> > 
> > ========    cover foil
> > --------    recording tape
> > ________    copper or some other conductor
> > 
> > The copper is attached to some sensible voltage. The recording tape
> > basically acts as a trimmer, so that touching -- thus closing the
> > contact -- is equivalent to the wiper. Now you take the difference (or
> > better: the ratio) between the voltages measured at the ends of the tape
> > and get the tap position. Could probably be further refined if the tape
> > is crescendo-shaped.
> > 
> > (I'm quite sure people on this list have done something like this before
> > and can tell me why that's a bad idea.)
> > 
> > Rainer