Hot wire cutter question, power supply
Joseph Gwinn wrote:
In ,
wrote:
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That all looks inductively reactive to me.
Then there is problem with the spice model. More below.
Joe, I did the experiment in the real world just now.
You are right. With a resistive load on the secondary
I saw undetectable phase shift between voltage and
current on the primary. With an inductively reactive
load on the secondary, I saw the expected significant
lag in the current peak in relation to the voltage peak
on the primary.
That will be what I learned today and I thank you.
(...)
War story: Many years ago, I was interested in the physics of xenon
flash lamps. The physical model is pretty simple, a charged capacitor
discharging into an arc, which arc heated the xenon to incandescence,
the resulting light and heat radiation carrying the energy away. This
yields a set of coupled ordinary differential equations that one solves
numerically, time step by time step. I got it all working, and all was
well. Then I changed the duration of the time steps, and more energy
came out as light and heat than was stored in the capacitor. Oops.
Violated the conservation of energy.
Turns out I had made two mathematical mistakes, which mistakes cancelled
one another only for the original step duration.
Wow!
That one must have had you scratching your head for a while!
Thanks again
--Winston
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