[Boatanchors] My model train transfomer variac idea - comments

[D C *Mac* Macdonald]

Hook the output of the toy train transformer
(usually about 2-10 vac or so) to the primary
of a transformer with unknown ratios.  Bring
it up to say 6 vac and measure the output of
the other transformer.  Multiply that output
by 20 and get your unloaded ac output voltage.
I still use the same transformer from a Marx
toy train I probably got during WW II!
 
* * * * * * * * * * *
* 73 - Mac, K2GKK/5 *
* (Since 30 Nov 53) *
* Oklahoma City, OK *
* USAF, Ret (61-81) *
* * * * * * * * * * *
 


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> Date: Mon, 20 Dec 2010 10:07:07 -0800
> From: jfor at quik.com
> To: meils at get2net.dk
> CC: boatanchors at mailman.qth.net
> Subject: Re: [Boatanchors] My model train transfomer variac idea - comments
>
> Henry,
>
> It's a clever idea. I need a 0-150 VDC supply at a few mA and might use it.
>
> -John
>
> ================
>
>
> > There seemed to be a misunderstanding -- the variable low voltage (0-
> > about 30 Vac) is fed to
> > directly to a separate filament (or old fashioned door-bell)
> > transformer's low voltage/filament secondary winding and will thus produce
> > from 0 to >120 Vac (0 to >240 ) at the primary winding, depending on the
> > setting of the control arm on the train transformer and the rated voltage
> > of the reverse connected transformer's low voltage winding(s).
> >
> > This not is a conventional series- connected few-volt
> > bucking/subtractive or additive configuration.
> >
> > My point is that variacs can be expensive (at least on this side of the
> > pond) and this is
> > a cost-free way of controlling low wattage gear if you happen to have one
> > of these model train
> > units and a filament transformer at hand.
> >
> > (Some (most?) model train control units supply dc so the ac voltage output
> > would have to be tapped
> > ahead of the rectifier(s).)
> >
> > 73,
> > Henry OZ1UF / N2NR