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Flyback Converter
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To: "'Tesla List'" <tesla@pupman.com>
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Subject: Flyback Converter
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From: Tesla List <tesla@stic.net>
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Date: Tue, 23 Dec 1997 22:44:04 -0600
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Approved: tesla@stic.net
From: RODERICK MAXWELL[SMTP:tank@mail.magnolia.net]
Reply To: tank@mail.magnolia.net
Sent: Tuesday, December 23, 1997 8:00 PM
To: tesla@pupman.com
Subject: Flyback Converter
I have tested The flyback converter that I,ve been working on for the
last couple of weeks. With the new spilt supply I am able to attach the
o,scope probe directly to the drains of the transistors. True to it's
name the flyback voltage is much greater than the applied voltage. At
40vdc I am seeing abot 150 volts on the o,scope. The waveform looks
somewhat trapazoidal in shape. This is due in part to the capacitor
snubber I have across the two parrallel transistors. Current draw at
40volts is about two amps. The transformer is the same one used for the
push-pull supply except that the center tap has been removed, and I,m
using the entire primary. No sign of saturaration so far. I cannot test
it at a higher supply voltage yet because the heat sink I have the
transistors mounted on is not large enough. I have ordered a whole bar
of heat sink material to solve this problem. It come in four foot long
sections! I plan to use about a foot of the material to mount 5 or 6
transistors in parrallel. I'm back to using fets because the bipolar
blew as soon as I applied power!? I also have this large fan to keep the
whole thing cool.
Also I finally finished winding the secondary. I think I'll call it
stumpy because it's wide and squat. The resonant freq. should be around
200khz. All I have to do to it is coat it with epoxy.
Frankensteins Helper
Max