On Fri, 30 Sep 2011 09:10:01 +0100,
lid (Adrian Tuddenham) wrote:

Any Dictabelt model

I just tore apart many boxes of junk that I haven't seen for 20 years,
but didn't find my Dictaphone or belts. Sorry. I think asking in the
rec.antiques.radio+phono
newsgroup might be more productive in finding someone with a working
Dictaphone machine.

I am constructing a playback machine for archival work, which needs to
be able to cope with any Dictabelt. There was a standard speed which
applied to all the normal models and all belts, so as to allow
interchangeability of the belts world-wide.

The basic machine was designed for 60 c/s mains, but there were
adaptations to allow the machines to run at the correct belt speeds on
50 c/s. Some special machines were also designed to run at half speed
for logging purposes . I have already encountered some belts which were
recorded on unadapted half-speed 60 c/s machines working from 50 c/s
supplies - and, no doubt, there will be others which were recorded at
different non-standard speeds for various reasons.

That explains the strange errors in apparent belt speed. I would have
expected South Africa to use the same standards as UK (230V 50Hz).

What I need to know is the manufacturer's specification for the standard
belt speed which was supposed to allow interchangeability between all
the machines. I can then calibrate the speed control on my machine to
show the %age speed variation from the norm, so as to deduce information
about the circumstances under which each belt was recorded.

If that's the situation, you may need to handle a fairly wide range of
belt speeds. I suspect that it might be easier to setup a servo
controlled motor, external belt tensioner, and stylus attached to a
linear actuator. In effect, a belt recorder implimented mostly in
software. That should give you control over speed and head position,
which should also solve the track skipping problem. It would also
allow you to run at some high speed (i.e. 15 ips) and slow down the
playback in software.

Good luck. Sounds like an interesting project.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558