simple power supply question.....

[Luke]

Im building an XBOSOZ and have a 60 0 60 transformer. It has 3 secondary windings one is a centre tap, not two pairs of windings.
Can I use two bridge rectifiers to get plus minus rails or can I only do this with one? I get a buzzing and warm transformer when I try using 2 bridges

cheers ab

[Panelhead]

Originally posted by Luke
Im building an XBOSOZ and have a 60 0 60 transformer. It has 3 secondary windings one is a centre tap, not two pairs of windings.
Can I use two bridge rectifiers to get plus minus rails or can I only do this with one? I get a buzzing and warm transformer when I try using 2 bridges

cheers ab

Luke,
You may have the polarity of one bridge reversed. Are you getting close to 90 volts dc out of each side?
I normally would wire one of these for dual rail, -90 +90 volt operation.

George

[Ouroboros]

This is the normal way to use a CT winding with a bridge.

[Luke]

thanks for your replies.

Panelhead, I dont think I have polarity reversed, Im quite tired and will check again tomorrow

Ouroboros, I know this method, but want dual bridges if possible, Im not sure it is?

[Ouroboros]

With totally split secondaries, then you can use two separate bridges. If you try to do that with a CT winding, you'll find that you're shorting different diodes out on +ve and -ve half-cycles of the mains.

(Just draw out the route the currents take and you'll see it. Your transformer would be getting a bit warm!)

[Luke]

hi Ouroboros,

thanks, yes i get it now Was tired last night but Ive had another look tonight and drawn it out. Makes sense. Not sure wether to get another tx or go with one bridge?

thanks for your help arthur