LAIRD KELLY wrote in a message to ROY J. TELLASON:

 RJT> I have one here,  a *big* one,  rated at something like 10A output.
 RJT> Dunno what I'm gonna do with it yet.  It was apparently a part of a
 RJT> telephone system at one point,  as that's what else was out there at
 RJT> curbside with it.  Local kids picked up the phones to play with,  and
 RJT> the other thing was the box that this PS plugged into,  I didn't snag
 RJT> that,  maybe I should have.    It would have at least given me the
 RJT> mating connector for the other end of this cable that's attached to
 RJT> this thing.

 RJT> It's got a big ferroresonant transformer in there,  an extra winding or
 RJT> two, apparently some provision for battery backup which isn't
 RJT> implemented,  and I can't recall what else.

 LK> Sounds like a supply for a 1A2 Key System (or the earlier 1A/1A1) -
 LK> large, old-fashoned phones with 6, 10, 20, or 30 buttons, including
 LK> a big red hold button

That roughly describes those phones the kids were playing with,  lots of
buttons,  and rather old-fashioned these days.

 LK> (http://www.customphones.com/productCat38382.ctlg), a heavy cord
 LK> with a 'Centronics' style plug...

Yeah,  50-pin.  It's been a while since I've seen any of that stuff, 
though I may have a bit of wire of that sort around as well.

 LK> The outputs on the supply (mfg by Lorain Electronics or a 
 LK> licensee) should be 24vdc 1/2A signal and talk (unfiltered *and* 
 LK> filtered), 10vac 10A lamp, 20vac 1/2A low-voltage buzzer, and 
 LK> 105vac 20Hz ringing (Yes, 20Hz from 60Hz using just a 
 LK> ferroresonant transformer (called a 'Subcycle' ring generator - it 
 LK> uses a 40Hz parasitic to heterodyne the 60Hz to 20Hz or something 
 LK> of the sort requiring ten pages of calculus to say "it works" 
 LK> *g*))

Not this one,  it's just 24vdc out.  I have the cover off it and there's a
barrier-type terminal strip where the output cable goes,  three wires there
only,  black white and green for ground.

 LK> I still have a rack-mounted 10(IIRC) line Key Service Unit, that I
 LK> used to use as a test system to repair the phones when I was still
 LK> in the phone business, out in my garage. 8-)

That sort of equipment has always fascinated me,  but I've never been able
to find out much of anything about it,  they keep that info pretty well
locked up tight.  Although I haven't looked out there on the web or
anything...

About the only time I've encountered anything higher than 12v in recent
years has been on the inside of equipment,  most commonly in the power
supplies of audio amps and things like monitors and tvs.  Aside from that
I'm thinking that this might be useful in some signaling applications, 
things where I need to run lots of wire and don't want to worry too much
about voltage drops and such.  And that's not going to happen anytime soon,
 unfortunately.  I also have a fair amount of 24v and 48v relays,  salvaged
out of something I think was also phone-related,  I'll figure something fun
or useful to do with this stuff at some point...

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