gainclone power supply regulation

[cryo]

I am breadboarding up the power supply for my new amp. I happen to have a couple of nice small toroids (100va) which would be great to use. They put out 36-0-36, which when rectified might be a bit much.

Any objections to using a voltage regulator like the lm317 to bring the voltage into a tamer range?

Would it be best to place the regulator(s) before or after the bridge?

Any specific schematics that anyone can suggest?

Thanks for any help, and for all of the great info on this site.

 

[Daveze]

My biggest concern would be how you get the required current out of your regulator...a single 317 might give you a few 1-2A if you treat it with care but you'll need a few in parallel to get what you really want. And when you're all finished, you'll probably only achieve ~60VA out of your 100VA transformers (the rest being burned off by the 317's).

Put your sets of primaries in series? That should cut your secondary voltages in half...

 

[cryo]

Thanks Daveze, I didn't realize I would lose so much using a regulator like the lm317. The thought of putting the primaries in series is a novel idea. I will try that out in the shop this weekend and see what I can come up with.

 

[Minion]

You can use a pass transistor with a LM317/337 regulator to increase it"s output current to 4 Amps+ ...The LM317 datasheet should show you how it is done...

I did this with a 10w Class A amp I built a while ago and it worked very well and only needed a couple power resistors and a power transistor....

Cheers

 

[AndrewT]

Hi,
putting the primaries in series will reduce the input voltage by 50%. That will reduce the VA by 50%.
You still end up with 100VA for the pair.

Instead build a discrete amp that operates from +-50Vdc.

 

[Daveze]

Oops. I got a little caught up in my nifty idea and forgot about what the consequences of halving the voltage would be...

I was also thinking the discrete amp option too, though I'd be thinking you have the gainclone as the amp...some sort of preamp might in order?

 

[cryo]

Thanks everyone for your ideas. Sounds like I need to pop for a new transformer for my gainclone. Then I will keep the 100va toroids for a new project, I think a pre-amp sounds like a logical next project.