[ Craig Smith wrote in 200331 MMDigest

> Anyway, the power supply schematic included a double-pole
> double-throw (DPDT) switch to reverse the voltage polarity now
> and then, to keep from magnetizing the solenoids.  Sounded like
> a good idea to me.

I use the same arrangement with the addendum: definitely do not throw
the switch whilst it is playing!  We do switch it from time to time,
but, as Craig says, I'm not sure that, in practice, it is actually
essential to do so.

I only find problems with original rolls where the paper has dried out.
I never have had a problem with conflagration, but have had rolls split
into two during rewind!  Dick Hack's excellent rolls solve the problem
and aren't nearly 90 years old.

David Evans - Nickelodeon Museum
Cowichan Bay, British Columbia, Canada