[Homeroast] variable transformers

peter zulkowski peterz5743 at gmail.com
Tue Feb 28 19:56:15 CST 2012


Hi Ray,
I trying that now, but when it gets too hot the beans blow out the top of
the roaster, and the fan does not cool it enough if the chamber is taller.
I still need some way to modify the heat from the coil.
Fan speed is not enough. If I use a smaller coil, then my capacity goes
down :(
Only roasting 200 grams at a time now. Smaller coil then the temp rise of
the beans would be too slow, same with more beans. Turning heater power off
and on is difficult to get right :(

Thanks for your input,

PeterZ

On Tue, Feb 28, 2012 at 8:24 PM, <raymanowen at gmail.com> wrote:

> KISS- Do Not, rpt, NOT control temperature of a heat process by varying the
> power applied to the electric heater. Skipping all the details, just run
> the heating device at Full Power- 100%, or whatever you can get with the
> available power.
>
> Instead of trying to control temperature by varying the line potential and
> heater current, just control the low power drawn by the air mover.(fan
> motor)  Low air flow through a heating device or Corvair engine causes the
> air stream to get hotter and the engine to cook a couple dozen O-ring oil
> seals after the fan belt flips.
>
> SCR, Triac/ diac dimmers are extremely non-linear devices and resistive
> heaters respond exponentially to applied potential changes. Kiss
> temperature control goodbye.
> --
> Persist in old ways; expect new results - suborn Insanity...
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