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Old 17th May 2021, 3:14 pm   #21
Hartley118
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Join Date: Aug 2015
Location: Cambridge, Cambs. UK.
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Default Re: Metamec A909 clock- broken coil

Quote:
Originally Posted by Jamey80 View Post
If I unwind it gently on to a suitable bobbin as far as the break, would I damage the insulation on the wire or would it be ok? Not sure how much you can flex enamelled wire, but reusing it would avoid problems sourcing a replacement.
Looks like I'm going to need to find some meccano.
I will protect it with a 20mA fuse if I rewind it like this- don't want it catching fire if I screw something up!
If you were to find the break early on in your unwinding process, I guess it would be worth checking the resistance of the remaining coil and comparing it with the resistance of the removed wire. That would give you an idea of the appropriate transformer ratio required to run the clock, or even a series lamp or capacitor.

I guess though that Murphy's Law would ensure that the break turns out to be near the centre of the coil. In that case, as already suggested, a rewind with a manageable thicker wire gauge and running from a lower voltage transformer would work, Maybe 110V?

I guess that none of this is economically sensible, but we all know what it's like to get one's teeth into a technical challenge!

Best of luck.

Martin
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