On Sat, 24 Mar 2001 21:57:27 -0500 "jeff millar" <jeff@wa1hco.mv.com>
writes:
Hello Jeff & Alex,
This a more interesting topic than those old parasitic suppressors!
>How about a switch mode power supply that drops 120-0-120 full wave
>rectified down to 50 volts? This will require a switcher chip, some
hefty
>FET's and a high frequency, high power choke but no transformer.
You could get by with just one FET and a large diode in a minimalist
configuration.
Though running a Buck converter "straight" off the line is going to
induce some nasty transients that may prove harder to filter out than
starting with a more systematic approach.
And don't forget the SCR crowbar on the output to save the expensive
RF FET's if (when!) the pass transistor shorts!
>Using the 240 feed as a 120 each side of center and two big diodes to
rectifiy
>it will produce about 150V. The switcher chip will track the 120 Hz
power ripple
>fairly well, just use enough filter C to hold the voltage to about 60-70
V minimum.
Hmmm, I bet you'd have trouble finding electrolytics that would survive
in that scheme -- Ripple current would be excessive and mylar caps large
enough would be rather pricey.
>If you're interested, I can help with figuring the values and selecting
>parts.
>
>jeff, wa1hco
>
>
73,
Marv WC6W
*
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