[Lowfer] A power supply head scratcher

[Paul Daulton]

Andy old pin ball machines had 24v stepping relays and had large 
transformers with a secondary of 0-24-32volts.  Do you know any industrial 
electricians? Pre solid state machine controls transfromers
were 440 pri 220 sec at 3/4 kva. One of these with 120 on primary will give 
50 volts at lots of amps. I have turned these around and serised the 440 
volt for HV doubler supplies. 220 winding is actually
two ;110 windings you can series or parallel for 110/220. These were 
connected across one phase of the 440 three phase to give 110 or 220 for the 
control circuits.

JB's suggestion is right on the money, most power transformers are wound 
with the primary next to the core. Remove the outer windings( counting 
turns) and rewind with the number of turns to give the voltage you want. 
Wire size should be selected to give 900 to 1200 circular mils per amp for 
class A temp rise(70 degrees c over ambient). Ive made a lot of fil 
transformers for odd voltages like 10 volts this way.Glass reinforced tape 
is a good insulator for rewinding, or mylar or even strips of paper bags if 
you can still find them.A coat or dip in varnish will keep the turns in 
place and prevent audible hum for the windings vibrating.

Or you could borrow the battery from your wifes car and series it with 
another.


Paul k5wms
----- Original Message ----- 
From: "John Bruce McCreath" <weazle at hurontel.on.ca>
To: "Discussion of the Lowfer (US, European, &amp;UK) and MedFer bands" 
<lowfer at mailman.qth.net>
Sent: Sunday, April 18, 2010 7:49 AM
Subject: Re: [Lowfer] A power supply head scratcher


> Hi Andy, Lowfers,
>
> I made a typo in my previous post....wind a new SECONDARY of #10 THHN 
> wire.
> It's early Sunday morning and I'm not fully awake yet!
>
> 73, J.B., VE3EAR
>
> LowFER Beacon "EAR"
> 188.830 kHz. QRSS30
>
>
>
>
>
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