Using half of a bridge?

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Using half of a bridge?

Postby gavinhaley » Mon Apr 04, 2016 1:21 am

Hi all. I have a nice IXYS hexfred bridge module that I would like to use as a full wave rectifier. What I would like to do is connect a transformer with a 330-0-330 secondary and just use half of the module. I would like to use the centertap as the negative rail instead of taking the negative off of the module thereby making it a simple full wave rectifier rather than a fullwave bridge rectifier. Am I making sense? I don't want to use half of the module. Just two of the diodes. Will this work?
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Re: Using half of a bridge?

Postby TomMcNally » Mon Apr 04, 2016 10:04 am

Hi Gavin -

That will work. A bridge is just 4 diodes in an epoxy molded case.

... tom
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Re: Using half of a bridge?

Postby Geek » Mon Apr 04, 2016 2:09 pm

Speaking of this, you'll even see some commercial manufacturers using a hybrid bridge - a tube for the positive rail and 1/2 a bridge like you describe for the negative. It's a trick to get a tube rectifier in a design without a CT'd transformer ;)

Cheers!
-= Gregg =-
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Re: Using half of a bridge?

Postby gavinhaley » Tue Apr 05, 2016 12:36 am

I would use the full bridge if I could find the right Edcor transformer for what I have in mind but they don't seem to make it. I want to use a 330V transformer and basically build a point to point Clementine using a 5670 as the input tube rather than a 6SL7. The only suitable transformers use a centertapped secondary. I have a couple of nice Hashimoto output transformers that are huge compared to the normal Edcors. The top plate is going to be quite large. This is definitely going to be a long term project. Thanks for your replies.

Gavin
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Re: Using half of a bridge?

Postby Geek » Tue Apr 05, 2016 2:05 am

Edcor will make a custom transformer for only $40 more than the closest listed one ;)
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Re: Using half of a bridge?

Postby gavinhaley » Tue Apr 05, 2016 3:26 am

Geek wrote:Edcor will make a custom transformer for only $40 more than the closest listed one ;)


I looked around the site for a way to order a "custom transformer" but I could not find one. I guess I could do the "old fashioned" thing and just call them on the phone huh? Imagine that. ;)
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Re: Using half of a bridge?

Postby Geek » Tue Apr 05, 2016 2:01 pm

Phone or email and the person you want to talk to is Phyllis Weston.

They don't advertise it because they're like a shop of only a dozen people.... 4 of them family (Phyllis, Brian, Larry and Lucy).

The other girls are very profficient at running the machines, but custom jobs are hand wound by Larry or Brian.

I haven't ordered a custom one one in a while, so the $40 might be $50 by now :$

Cheers!
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Re: Using half of a bridge?

Postby Gingertube » Mon Apr 11, 2016 12:36 am

Remember that when using HT - 0 - HT winding each half secondary is used on alternate half cycles of the AC waveform.
If changing to a bridge with just HT - HT secondary then you need to specify the new transformer for HALF the total voltage (same as HT to 0) and TWICE the AC current rating - why? Because with a bridge the the secondary is conducting (in opposite directions) on both of the 2 half cycles of the AC waveform.
This TWICE the AC current rating is often missed - resulting in transformer melt down.
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