Bottlehead Forum

General Category => Technical topics => Topic started by: dmannnnn on November 11, 2009, 02:43:19 PM

Title: Power Transformer Help (non BH)
Post by: dmannnnn on November 11, 2009, 02:43:19 PM

I have a piece of equipment for sale and an interested buyer in asia.  He wants me to convert it to 230vac.  It currently uses an Avel Lindberg 250va torroidal with dual 25vac secondaries.  I cannot seem to find anything equivalent in 230 volts.  It seems that both Avel Lindberg and Plitron only make 120vac transformers. 

Any ideas where to look?  A custom transformer would probably cost too much or take too long.  Is a step down his only option?

Title: Re: Power Transformer Help (non BH)
Post by: Paul Joppa on November 11, 2009, 03:37:45 PM

Many companies - Hammond is one - make toroids with dual primaries for 117/234 volts. Mouser lists them.

Title: Re: Power Transformer Help (non BH)
Post by: dmannnnn on November 11, 2009, 03:51:10 PM

One set of each? so it could be switchable?

Thanks!

Title: Re: Power Transformer Help (non BH)
Post by: Tre on November 18, 2009, 05:55:39 AM

I believe there are two 117 volt primaries. Use them in parallel for 117 and series for 234. So yes, you could make the amp switchable.

Title: Re: Power Transformer Help (non BH)
Post by: dmannnnn on November 20, 2009, 07:20:41 PM

Yes, the transformer I'm using now has two 117v primaries and two 25v secondaries.  So if I wire the primaries in series and plug into a 234v line I will still get 25v at the secondaries?

Title: Re: Power Transformer Help (non BH)
Post by: Tre on November 22, 2009, 06:55:05 AM

Yes.

Title: Re: Power Transformer Help (non BH)
Post by: Grainger49 on November 22, 2009, 08:07:52 AM

Be sure to wire the two windings so they add.  If you get the second winding out of phase I think the output will be zero, theoretically zero.

Title: Re: Power Transformer Help (non BH)
Post by: dmannnnn on November 22, 2009, 10:29:39 AM

Excellent.  Thanks guys.