On Mon, 03 Sep 2007 08:30:01 GMT, "Arfa Daily"
put finger to keyboard and composed:


"N Cook" wrote in message
...
Those usually 3-legged black blocks containing 2 PTC disc thermistors.
One of a few tens of ohms (cold) feeding to the coil and one of a few
hundred ohms (cold) connected between live and neutral , what is the
function of the one across the mains ?
As that one is separated from the other by 2 sets of spring clips, it
cannot
be there for indirectly heating the one feeding the coil for quick
completion.

--
Diverse Devices, Southampton, England
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Isn't the second one across the back side of the first, rather than directly
across the mains? Sort of a two thermistor series / shunt arrangement. I
seemed to recall from my long-ago theory days, that they were the inverse of
each other, and that the one that's across is initially high resistance, and
gets lower as it heats up, to shunt the degausing coils, mitigating their
effect, and keeping the series thermistor hot - and hence in the high
resistance condition - by continuing to draw just enough current through it
to do that. Could be wrong - it's been a long time ago - but it 'feels'
right, and seems to work, in my head at least ... !!

I think that's correct. Whenever I suspected a 3-pin thermistor as the
cause of a blown fuse, I used to shake it and listen for rattling.

- Franc Zabkar
--
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