Rectification straight from mains

little eddy · Post by **little eddy** » Fri Dec 07, 2012 9:09 am

I'm thinking of testing some small valves on the bench and will probably be looking for something between 250 and 325V DC.

Is there any safety or technical reason why with suitable on/off switching and a fuse I can't just rectify straight from the mains? The reason I ask is that I seen an amp design where the main tx had an input of 240V, and one of the used output windings was 0-240V!

andrew Ivimey · Post by **andrew Ivimey** » Fri Dec 07, 2012 9:43 am

Yikes! there are several good reasons why this isn't recommended.

pre65 · Post by **pre65** » Fri Dec 07, 2012 10:18 am

Buy yourself a decent isolation transformer.

Afterwards you could use it in your system to isolate the more sensitive bits like preamp and CD player.

Something like this for £60 +

http://www.airlinktransformers.com/chas ... 00175.html

Paul Barker · Post by **Paul Barker** » Fri Dec 07, 2012 12:24 pm

little eddy wrote:I'm thinking of testing some small valves on the bench and will probably be looking for something between 250 and 325V DC.

Is there any safety or technical reason why with suitable on/off switching and a fuse I can't just rectify straight from the mains? The reason I ask is that I seen an amp design where the main tx had an input of 240V, and one of the used output windings was 0-240V!

The main problem is the earthing arrangement. The only way it is possible is to half wave rectify, but it isn't safe or allowed.

As suggested if you get an external 240v isolating transformer you can play as if it is the mains but it isn't.

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Rectification straight from mains

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