Bucking Transformer

I was asked about bucking transformers just recently. Something that could be seen as a permanent fix against chronically high line voltages.

There is nothing special about them, nor are the parts costly by any reasonable standard.

http://www.angelfire.com/electronic/funwithtubes/images/XFMR_Buck_Boost.gif

How to do it. Note that with a center-tapped secondary and a switch, one could buck either the full, or half the rating of the transformer. Just switch between the two taps. If one gets fancy, one might even add a pilot light (or two) to indicate which buck is in play.

https://www.digikey.com/products/en?keywords=266N12B%09%20

4 A at a 12 V buck. 8 A at a 6 V buck. And may be switched out if desired for no buck. There are 10 V and 5 V transformers as well, but being not as common, costs are usually higher. DO NOT cheap out on the transformer used here - it carries all the current connected to it.

For less than $50 in parts, and a little care.

Enjoy!

I put one together with a hammond 6.3 and used the center tap as you noted with a switch. Worked fine until last Sat into Tues when the utility power was 128-130. It's now back to 'normal' and with the bucker I'm at 114. Wonder what happened. why did it climb up so high and stay there for a few days.

cci1492 wrote:I put one together with a hammond 6.3 and used the center tap as you noted with a switch. Worked fine until last Sat into Tues when the utility power was 128-130. It's now back to 'normal' and with the bucker I'm at 114. Wonder what happened. why did it climb up so high and stay there for a few days.

Here is how it works with Utilities. It is called Infrastructure Creep.

Condition: Older neighborhood, fully built out, but in the days before central AC, multiple appliances and so fort. Overhead wiring:

a) Individuals start to add AC & even small space heaters.
b) Hot Tubs
c) Electric Dryers

At which point, the Utility has two choices:

a) Increase the overhead line gauge AND change out the distribution transformers to stay a the same at-the-service-head voltage.
b) Increase the primary voltage so that the existing lines may carry the increased load. Much cheaper.

In areas where there are extremes of heat and cold, during such an extreme, the Utilities will often push right to the tariff limits to prevent sags and brownouts. And where they do not have that capacity, sags and brownouts are very real and dangerous phenomena.

More info from several years ago....

https://dynacotubeaudio.forumotion.com/t3223-6-v-bucking-transformer

Here's the one I threw together (that meter is a POS):