Back when I was designing broadcast transmitters, I used the tables
in the old Motorola Silicon Rectifier manual for all of my DC power
supply designs. Its the green book, mine is dated 1980.
It lists transformer secondary rating in VA/Pdc as 1.23 for a single
phase FWB and 1.75 for a center tapped full wave rectifier. PIV for
the diodes is of course halved for the FWB also. In another chapter
it states: "The utilization factor of the power transformer is much
poorer with the capacitor-input system because of the higher ratio of
peak-to-average current flowing through the rectifier diode, and
likewise the diode is less efficiently utilized."
I think this is what you mean, wiht the 1.6-1.8 X factor for
secondary current to DC current ratio. Is this for RMS or peak
secondary current (charging the cap?). I didn't see half voltage taps
on the transformer I found yesterday, it was mounted in the bottom of
a massive Westinghouse RF generator, using some big mercury vapor
looking rectifiers and two RF tubes which i cannot remember. Thing
was as large as a standalone freezer chest. I have no idea what Ed
would charge for the unit, usually too much. I only would want the
iron and maybe some insulators.
I also found another nice looking brand new transformer in a wooden
crate, all it had marked was a single primary for 208 VAC and two
separate secondaries marked 0 - 1600 with some taps in between. It
was about 10 x 8 x 8 inch sized, and might have some use somewhere.
If the secondaries were adequately insulated, they could be series
wired for 3200 Vrms, but that might be risky.
So going on what you (Will) said, the LS184 UTC transformer would not
be adequate for a 0.6 Amp DC load, with cap input. Thats about an Amp
of secondary current.
73
John
K5PRO
>John,
>
>It's according to what type of rectifier circuit you'd use with the
>capacitor. For a full wave bridge and capacitor input, the secondary
>current is from 1.6 to 1.8 times the DC current. That variance I
>don't know for sure where both came from as some formulas I've seen
>use either. It has a lot to do with the size of capacitor of course.
>Hammond has a downloadable pdf with these formulas in it, and I'm
>pretty sure they use 1.6. Ohter transformer manufacturers though
>I've seen use 1.8.
>
>The one you found, didn't the primary have it where you could change
>the voltage? Most always had this because there are some places
>using 220/240 VAC.
>
>Best,
>
>Will
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