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Gday Sheeny
Whilst i agree that resistors are a good ( and inherently safe ) solution
for small dia objects, ( and amateur construction )
you can use nichrome wire ( and hence get a thinner more flexible strap ),
as long as you provide some form of current limiting.
If you are using a PWM controller, this can be a simple limit on the max available duty cycle.
If a variable voltage regulator ( like say an LM317 ) in constant current mode , then you limit the max current.
Of course, you do need to ensure you NEVER plug the strap directly into a raw 12V supply ( which isnt a problem for resistors ),
but you can end up with a smaller heater strap if space is a problem
( ie straps for EPs in a Binoviewer,
when the user has close set beady eyes :-) )
Andrew
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