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Chris Jones[_3_] Chris Jones[_3_] is offline
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Default Weller PU-1D / TCP-1 / PT-H6 parts info

On 18/09/2017 01:53, T i m wrote:
On Sun, 17 Sep 2017 15:23:46 +0100, N_Cook wrote:

snip

[1] Just looking up Curie Point science again it explains what was
happening the other day. When the iron was cold and the permanent
magnetic field was high in the tip it held itself into the element
(the end of the barrel was worn oversize and didn't retain the tip)
until it warmed up and then would fall out, just as it was up to
temperature. ;-)


While at it , if your one is like mine and lacks an indication , other
than slight clicks, that the magnastat is functioning.


That's how it was designed but I was reminded when talking to Chris
that I modified mine 40 years ago with a red LED in the front that
comes on when the element is drawing current.

With a selected collection of zeners and diodes it is possible to put a
droppered LED, across the AC supply line.
Unfortunately LED off when iron is on (supply loaded), but at least , it
shows the switch is not stuck on.


Ah, my LED definitely comes on when the heated element comes on but I
can't remember how I got there?


Oh well, I was hoping to find out how you did it. I can think of a few
ways but none of them are very elegant.