[Milsurplus] [ARC5] 28 volt transformer question ?

[Richard]

39 volts is plenty of head room for a simple voltage regulating 
circuit.  I've done this many times.

Richard, AA1P

On 9/7/20 10:47 AM, Mark K3MSB wrote:
> I disagree.    If for a receiver,  the current draw is constant and a 
> suitable dropping resistor can be used.    I've done this frequently 
> with ARC-5 receivers.
>
> Or, just put a variac in front of it and drop the input voltage.
>
> Mark K3MSB
>
> On Mon, Sep 7, 2020 at 10:42 AM J Mcvey via ARC5 <arc5 at mailman.qth.net 
> <mailto:arc5 at mailman.qth.net>> wrote:
>
>     Using that xfmr with full wave rectification and filter cap would
>     yield about 39 volts out.
>     So, it's a good candidate for the scrap yard.
>
>
>
>     On Sunday, September 6, 2020, 11:10:08 PM EDT, Hubert Miller
>     <kargo_cult at msn.com <mailto:kargo_cult at msn.com>> wrote:
>
>
>     I had this AM-FM broadcast receiver, with step tuning, and the
>     logic developed a problem.
>
>     As you know, these are impractical to repair, with this kind of
>     problem, uneconomical.
>
>     Well, in my city, there is very limited collection of ewaste, and
>     an irrational I think, regulation
>
>     of categories. So instead of tossing the whole thing in the
>     garbage, I disassembled it, tossed
>
>     the cabinet and chassis in the recycle, and the circuit boards in
>     the regular garbage.
>     I found that the power transformer is 28-0-28 volts and looks good
>     for a steady 5+ amp. What
>
>     I'm wondering, should I keep this for a dynamotor spinnner, for
>     dynos like the command sets
>
>     or RU-GF class? With a filter cap, the output should stay "near"
>     28 volts under load. You just
>
>     don't want to have such PS charged up to peak and then connect it
>     to the load, which might
>
>     be hard on tubes. Or what if I just used it without filter cap, to
>     spin a dynamotor? Or instead,
>
>     go ahead with a multiple thousands mFd filter cap and maybe a
>     small series resistance to
>
>     adjust voltage under load?
>     Many years ago I used such a brute force supply I bought from Fair
>     Radio to power an ARR-15
>
>     receiver. At that time, I didn't even think to worry about the
>     exact output voltage.
>
>     So what about this transformer? 24 volts would be preferable but
>     the price on this one was
>
>     right.
>
>     -Hue Miller
>
>
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