[GreenKeys] Loop supply options

[Jeffrey Angus]

On 9/7/19 9:56 AM, John, W9DDD wrote:
>
> An old trick was to use a couple of filament transformers back to 
> back. The hard way to get an isolation transformer.?? You get the 140 
> to 160 VDC this way also.
>
> Another trick is using a dual primary transformer.?? You have 2 120 VAC 
> primary windings which are either wired in parallel for 120 VAC supply 
> or in series for 240 VAC supply.?? If you ignore the secondary 
> windings, you again have a 1:1 transformer to get you the 140-160 VDC 
> by using one of the 120 VAC windings as the primary and the other as 
> the secondary. (The original secondary windings might be of use at a 
> lower current rating).
An important thing to keep in mind is the VA rating of the transformer.
80 VA would be a safe minimum.
For example a pair of back to back 12v transformers should be rated at
1 amp @ 12 volts minimum. (making the primaries rated at 0.1 amp.)
Same thing with dual primaries.

Sometimes it's just easier to do it right instead of trying to think of
some clever way to do it wrong.


-- 
"I am a river to my people."
Jeff-1.0
WA6FWI
www.foxsmercantile.com