power supply project, voltage reduction

[tomcat1976]

power supply project

hi, all. i'm new on the forum, so i hope i have this subject in the right board. anyways i have a 48 volt, 8 amp output transformer that i want to build as a 13.8 volt, 8 amp power supply for my work bench. what i need though is to reduce the voltage down before i hook it up to my dc voltage regulator circuit. i was wondering if anyone has knowledge of how to reduce the voltage for this project? i have built a smaller power supply before out of a 13.8 transformer, but that was easy and i never run into a position like this before. the transformer is a 48 volt ac 8 amp type. i have already run it through a 100 volt rectifier and through the 63 volt 4700uf caps, i just need to reduce voltage more. i hope this all makes sense. thanks for any help.

 

[eem2am]

power supply project

that must be quite a big transormer you have, ~300W.

Really you would best do a power factor corrected SMPS.

but if you need to use that transformer, then why not just go for a buck convereter. which is the easiest.

fairchilsemi.com national.com have chips for you.

does it have to be exact 13.8 volt?

if not you will find an open frame smps that you can throw in there.

a synchronous buck would get rid of output diode conduction loss.

you will need heatsinking on semiconductors.

the rectifier diodes will get hot and this is why you would better do offline SMPS rather than your 50hz transformer.