|[AMRadio] Ferroresonant transformer revisited|
rickbras at airmail.net
Sun May 7 12:26:57 EDT 2006
Jim, Geoff, Bob, John and all who responded, thanks for the
excellent information. I scoped the output of the transformer and it is
without doubt NOT a sine wave, Jim. Like you said, it is almost a
Bob, I think I have a couple of those old television transformers I
pulled years ago when I was in the service business. I'd forgotten all
about that, thanks for the memories.
Geoff, I am inclined to agree with you about the heat of the
transformer. I can touch it, but it would be very uncomfortable if not
damaging to my hand to leave it on there more than a very few seconds.
I think maybe one thing I should consider is Bob's thoughts on how
it's mounted. I'm not sure what service it was in before I got it, but
it was likely from a battery charger of maybe even a small arc welder.
It was mounted on a heavy 13" X 19" X 1/4" aluminum plate which I'm sure
helped dissipate the heat. I have it mounted on a 12" X 10" X 3"
aluminum chassis which would not be nearly as effective.
The output is very clean. I'm using 3 - 71,000 mfd @ 25 vdc
capacitors in series, computing to about 23,600 mfd worth of filtering.
There were four of the caps originally, but one went south before I got
Jim, correct me on my math if I am heading the wrong direction.
Since I don't have a true RMS voltmeter can't I take the square root of
the power dissipated in a resistor across the output to find the actual
Thanks again to all for all of the great response and advice.
Jim Candela wrote:
> The ferroresonant transformer is not really
>resonant at all since the winding that feeds the
>capacitor is wrapped around....
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