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Hans
Newbie Alert
Joined: 13 Aug 2007
Posts: 1
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 Posted: Tue Aug 14, 2007 1:20 am Post subject: Genaral transformer question |
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| Why is the secondary on many (if not most) power transformers about twice the rated secondary voltage typically needed in the amp? - For example, let's say that I have a typical transformer with 350V - CenterTap - 350V on the secondary and wish to use a diode rectifier. Here, I can choose to use one of the two tappings offered by the secondary (i.e. 350V - CT OR CT - 350V) and bridge recify and filter it. Using the entire potential on the secondary side will give about 700V rms (and around 1000V after the recitifier bridge) and is of course much to high to be used in any tube amp. My other option it to "half" rectify each of the 350V's, connect them together and filter them. This way I will have a "balanced" pull on my power transformer, but with more ripple noise on the output voltage, and perhaps the need for larger and more expensive filter caps. So - why is this, really? Wouldn't it be better to have half the 350V on each sec. tappings and use a bridge rectifier? |
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nigelwright7557
Tadpole
Joined: 19 May 2008
Posts: 18
Location: Carlisle, Cumbria, England
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| Posted: Mon May 19, 2008 9:10 am Post subject: Re: Genaral transformer question |
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| Hans wrote: | | Why is the secondary on many (if not most) power transformers about twice the rated secondary voltage typically needed in the amp? - For example, let's say that I have a typical transformer with 350V - CenterTap - 350V on the secondary and wish to use a diode rectifier. Here, I can choose to use one of the two tappings offered by the secondary (i.e. 350V - CT OR CT - 350V) and bridge recify and filter it. Using the entire potential on the secondary side will give about 700V rms (and around 1000V after the recitifier bridge) and is of course much to high to be used in any tube amp. My other option it to "half" rectify each of the 350V's, connect them together and filter them. This way I will have a "balanced" pull on my power transformer, but with more ripple noise on the output voltage, and perhaps the need for larger and more expensive filter caps. So - why is this, really? Wouldn't it be better to have half the 350V on each sec. tappings and use a bridge rectifier? |
This is so you can full wave rectify the output from the tarnsformer. |
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