[hackspacebristol] A visit from Cheltenham Hackspace

David Smith David.Smith at imgtec.com
Mon Sep 15 15:44:22 UTC 2014

> From: Richard Sewell [mailto:richard at jarkman.co.uk]
> On 15/09/2014 14:19, David Smith wrote:
> >> From: Hackspacebristol
> >> [mailto:hackspacebristol-bounces at lists.aktivix.org]
> >> David - isn't that a scrap transformer with one end of the core sawn off ?
> > Probably.  I guess I need to find something old with a nice big transformer
> > in, as I'll need a few cm gap between the two ends of the "C" - I don't think
> > they make many things with big transformers nowadays as everything's gone
> > to SMPS.
> I'm sure there's somthing in the bin at the Hackspace that'll serve.

Possibly; I've got an old B&W TV in the loft that was left behind by the previous
owner; that might have one in. If I'm lucky I might even be able to find one with
a winding that I can reuse... :)

> > I've already worked out that the best source for the magnets for the
> electromagnet to attract/repel is probably an old HDD...
> Yes, or just us a big lump of iron if you only want attraction. Might make for
> easier timing.

True, but adding a big lump of iron to the end of the pendulum will change the
effective length of the pendulum, meaning that it'll have to work harder to keep 
it properly in sync.  Also I was planning to use both attraction and repulsion so 
that (hopefully) the electronics won't have to do much most of the time, but it
will be able to speed it up or slow it down occasionally as required.

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