Bottlehead Forum

General Category => Tech Tools => Topic started by: syncro on January 14, 2011, 03:38:51 PM

Title: Powerstat autotransformer - variac?
Post by: syncro on January 14, 2011, 03:38:51 PM

I was given a vintage Branson brand Power Control.  Thinking it might be of use in powering up vintage tube electronics, I accepted.  I have attached some photos, and have some questions.  It is a 240v input unit with 0-240v output. 

Is this the same as a "variac"?
Can it be used with 120v input to get 0-120v?
The % output meter does not work.  Any hints on a repair of this?
Any other potential uses for tube audio newbie/amateur?

Thanks in advance, David.

Title: Re: Powerstat autotransformer - variac?
Post by: 2wo on January 15, 2011, 10:42:33 AM

I would think that as it is an autoformer, it should work with 120V. Hook a lamp to it and see. As far as the meter, give it tap or two to see if it is stuck. Check for voltage  at the back of the meter, to rule out the wiring...John   

Title: Re: Powerstat autotransformer - variac?
Post by: Grainger49 on January 16, 2011, 10:14:09 AM

In general an autoformer rated at 220V in but with 120V in it will be able to put out 0-120V out.  The power meter wouldn't have been useful anyway, but you want to measure the output voltage.  I would suggest putting out 117V as Doc specifies for his equipment.

Title: Re: Powerstat autotransformer - variac?
Post by: Paul Joppa on January 16, 2011, 11:43:39 AM

Our current gear is all designed for a nominal 120vAC, 50/60Hz. The PGP8 power transformer from Magnequest, which was used in many older products, was designed for 117vAC.

Title: Re: Powerstat autotransformer - variac?
Post by: syncro on January 18, 2011, 04:31:22 PM

Quote from: Grainger49 on January 16, 2011, 10:14:09 AM

In general an autoformer rated at 220V in but with 120V in it will be able to put out 0-120V out.....

Thanks, Granger.  That's what I needed to _know_.  I could intuit that, but I don't trust my lay-person knowledge of electron behavior.  I will change the plug and receptacle for conventional 120v configuration and use, and keep an eye out for dusty old tube amps.  I can meter the output manually during use.