Don Klipstein wrote:
In article , Sylvia Else wrote:
Steve Barker wrote:

Well when you get right down to it, why does it need circuitry at all?
It's a motor and a heat element.
Marketing. I saw a washing machine that was advertised as having
"crystal control". Presumably, it timed its wash cycles to one part in
10^9.

Crystals aren't that good unless especially good and in
temperatrure-controlled ovens. I would hope for one part in 10^6 to one
part in 10^7 or so.

A washing machine could be out by 20% or more without causing a problem.

The traditional synchronous motor is more than accurate enough for the
application.

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