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From: firstname.lastname@example.org (Tim Shoppa)
Subject: Re: 2.5kW-3kW-SMPS-(cheap)-suggestions?
Date: 19 Dec 2002 05:32:00 -0800
NNTP-Posting-Date: 19 Dec 2002 13:32:00 GMT
"John Jardine" wrote in message news:...
> Heating energy is best being supplied at a constant rate for an optimum
> time. This implies a constant voltage (stable to maybe 1V) or a constant
> current. Too low a power flow for too long a time and the end of cycle
> internal temperature profile from the hot wire feeding heat into the
> surrounding material is too 'flat' to give the amount of localised focussed
> heating needed. Too much energy=localised high temps with resulting material
> degradation and little heat flow or spread into the surrounding material.
> Hence an optimum heater voltage may end up in the 20V to 60V area.
> AC,DC,Hf,lf, chopped, or any mix doesn't matter, it's just the controlled,
> RMS energy equivalent that's required.
Then it sounds like (given your energy source is an AC generator) a Triac
will do the job just fine. Combine with a little circuit to measure true
RMS delivered and put in a feedback loop (which may very well be a guy
watching the RMS meter and turning a knob...)
A SMPS to deliver filtered DC is way overkill.
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