I haven't had a chance to actually try this yet, but since I am sitting at my
'work'
computer, I simulated it with the PSU Designer program (which I think came with
a recent
ARRL handbook). I entered the primary and secondary resistance values of the
transformer, etc.
The DC voltage was about 0.9 times the AC voltage when the load was adjusted to
80 mA.
Very encouraging! When I do the 'live' test, I'll let it sit for a few hours
and see how
warm the transformer gets.
As several folks noted, it will be helpful that I'm not going to use the
filament windings.
On 8/26/2012 1:35 PM, Carl wrote:
> Wire up a couple of diodes, a 500 Ohm resistor simulating a choke and a
> 10-20uF cap. With
> a variable bleeder adjust until the DC is .9 of the AC. I prefer the choke
> input as youre
> not at the mercy of the input cap effect.
>
> Meanwhile I'll stumble thru my Philco literature.
>
> Carl
> KM1H
>
>
> ----- Original Message ----- From: "Vic K2VCO" <k2vco.vic@gmail.com>
> To: "Amps reflector" <amps@contesting.com>
> Sent: Sunday, August 26, 2012 4:20 PM
> Subject: [Amps] Transformer guess?
>
>
>> I have a small power transformer here, Philco 45-7011-7, which I would like
>> to use for a
>> screen supply. It has the usual center tapped HV winding, which measures
>> 380-0-380v, just
>> right, as well as 5v and 6v filament windings.
>>
>> What I want to know is how much DC I can draw from the HV winding with a
>> full-wave CT
>> circuit. Googling the number reveals a similar, but smaller transformer
>> rated at
>> 350-0-350v at 40 mA, the 45-7011-1. This one is bigger so I am hoping it
>> will be capable
>> of more current.
>>
>> The transformer weighs 3 pounds 10 ounces (1.63 kg). The lamination stack
>> measures 3-3/8"
>> x 2-7/8" x 1-1/2" (8.57cm x 7.3cm x 3.8cm).
>>
>> Can one of the transformer gurus hazard a guess as to the current
>> capability? I'm hoping
>> for 75 mA.
--
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco/
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