Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: TIMBO on January 28, 2023, 05:19:10 pm

Title: Power transformer to choke Doable
Post by: TIMBO on January 28, 2023, 05:19:10 pm

Hey guys, My Fuzzniverb requires a 1H choke.
Hard to find and not much on line, Evatco are out of stock of the lower Henry chokes and to top it off they start at $50 delivered
So has anyone converted a PT to a Choke.
From what I have found on the net and what my tiny brain can work out it may be possible.
A small PT primary (240v) has a DC resistance of approx. 500ohms which could put it into a high Henry value ( I'll guess maybe 30-40H)
The difference between A PT and at Choke is the E L laminates arrangements.
As we know a PT laminates don't have a "air gap" I know this but never understood what an air gap really is.
Internet was good and now I know.
Using the same E L laminates the PT was restacked the create an air gap
(https://i.imgur.com/a7Jdzwj.jpg?1)
(https://i.imgur.com/Ih2hm2N.jpg?1)
A piece of Insulated cardboard to create the air gap
(https://i.imgur.com/WRexRaZ.jpg)
The I laminates are then be stacked to finish
(https://i.imgur.com/u7GHOfR.jpg?1)
(https://i.imgur.com/48SziXm.jpg?1)
So what's ya think

Title: Re: Power transformer to choke Doable
Post by: shooter on January 28, 2023, 05:45:33 pm

works for me.
Sluckey did mention an SE OT and leave the secondary open, already air gaped i believe, so as long as you're opening 'em up anyway  :dontknow:
or you could drive to the Ocean and do some surf fishing  :icon_biggrin:

Title: Re: Power transformer to choke Doable
Post by: TIMBO on January 28, 2023, 06:00:13 pm

Hey shooter, Got plenty of these little transformers, no SE OT's
Too about half an hour