Rich,
The main thing for any transformer is power in = power out, this in watts or
VA. That is minus the losses which is the efficiency. Each rectifier/filter
circuit has its own formula to determine the secondary current needed. The only
difference between a choke and a capacitor input is the output voltage you'll
have and the secondary current. The choke input is DC out = 0.9 x the rms
voltage. Of course for a capacitor input the DC voltage is rms voltage x 1.414.
The seconday current for a full wave bridge choke input is, Iac = Sec. Idc X
1.064. Below is a link to a webpage I done on this topic that can help you.
Hope this helps.
http://amateur-transformer.125mb.com/pf.htm
Best,
Will
*********** REPLY SEPARATOR ***********
On 3/24/06 at 11:44 AM Rich wrote:
>Ian wrote: Have you told us everything that is printed on the capacitors
>
>themselves?
> Well I went back to CD web pages and did a little more digging. The 381
>type caps are high ripple and have a rating of 1.8 amps at 120 Hz. This
>should work for my P/S as I do not intend to load it very heavy.
>
>>This also brings up another question, I am going to use an old
>transformer. It has 230v input, three input terminals, out put is with
>terminals 1-2, 3000vac, with terminals 1-3 ,2090vac. Resistance is
>.45ohms
>input(1-2) or 1.02ohms input (1-3), output R is 41.4 ohms at terminal
>4-5.
>In another thread it was brought up about transformers for a choke input
>might be a problem?? How do I tell and why do I care? This is an old
>surplus transformer even to the point of having spark gap balls in
>parallel with the output terminals.
>I intend to build this with a soft start relay set up.
>
>Rich, kd0zz
>>
>
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