[GreenKeys] Another idea for a loop supply transformer

[Don Robert House]

> Nice explanation! Even I can understand with 40 year old electronic  
> training
Don K9TTY

> Many transformers have two PRIMARY windings - both for 115V input.  
> If you put
> both windings in series (phased adding) you can then apply 230VAC  
> across
> the pair - and the transformer will provide the correct voltage(s)  
> out.
> If you put the two primaries in parallel - you can apply 115V and  
> still
> get the same output(s) from the secondary(s).  In Gil's example - he's
> talking about a transformer with dual 115V primaries and a single 115V
> secondary. By wiring the two primaries in series - but instead of
> applying 230V as usual - apply only 115V - the 115V (rated) secondary
> will only provide half the voltage - or 57.5V - since only half the
> "expected" primary voltage is applied.  As he noted "further on" in  
> his
> post - since the secondary is now only supplying "half" - after
> rectifying and filtering - you can expect around 80VDC for your loop
> supply. This is a good solution if you don't have a "well stocked"  
> junk
> box.
>
> For those of us with the spare (free) parts - the "back to back"
> filament supply is quite attractive.
>
> The circuit for a battery eliminator for a "farm sets" is on this  
> page:
>
> http://www.comcents.com/mhrs/theprsup.html
>
> While this supply is way more "complicated" than needed for a TTY loop
> supply - it shows "back to back" transformers in circuit - and can be
> quite useful for other similar projects.
>
> best regards...
> -- 
> randy guttery
>
> A Tender Tale - a page dedicated to those Ships and Crews
> so vital to the United States Silent Service:
> http://tendertale.com
>
> _______________________________________________
> GreenKeys mailing list
> GreenKeys at mailman.qth.net
> http://mailman.qth.net/mailman/listinfo/greenkeys