On 2013-06-06 12:08 PM, Dwayne Reid wrote:
> 2) Consider using the copper tube as a shorted 1-turn secondary on a=20
> transformer.  In other words, wrap however many turns of insulated=20
> wire you need around the pipe and feed with enough high-frequency=20
> current as you need to bring the pipe up to the desired temperature.
>=20
> Note that the primary wire does NOT get hot, so space it away from=20
> the copper tube if desired.  Better yet, wrap the copper tube with=20
> insulation, then wrap the primary coil over top of that insulation.
>=20
> Details left as an exercise for the student <grin>.

I was considering this, and if done right, would be ideal. But it would
complicate the electronics. With the NiCr wire, I could get away with a
MOSFET and switch it to control temperature. With the induction heating
method, I'd need at least an H bridge and potentially complicated PWM
control to shape the output signal into a sine wave.

Also, how would I go about calculating the inductance, coupling, number
of turns, frequency, etc...? I'm assuming this is far from an ideal
transformer and losses will be great.

--=20
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