W2FCA says:
>What about the use of the thermistor gizmos?
No problem. You just have to make sure that when it has heated up, you still
get the right filament voltage. As it appears that filaments tend to get
over, rather under volted, that shouldn't be a problem.
You need a thermistor rated for the necessary amps; Siemens do them up to
3A. Price 1 off is abt $1.
Worth getting one not too overated, as you want it to get hot enough to drop
in resistance.
The resistance varies with temperature according to some factor Beta. I
can't remember the equations, though.
73
Peter G3RZP
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