Can't find negative regulator for bipolar supply

[riggler]

Hi everyone,

I am building a +-25V supply for a project. Current draw will be about 2.2A. I was looking for a 3A reg in case I need a little more for more channel strips later. I am having a tough time finding a negative regulator. LM333 appears to be obsolete. Any ideas? Nothing on the Fairchild or TI sites. Maybe I am not looking in the right places.

Thanks!

 

[sahib]

Check LT.

LT1185 is a negative 2.5A.

 

[riggler]

Ah Sahib, thank you!

 

[glorymorris]

For future reference, you can also use LM317/337 standard 1amp or 1.5amp adjustable regulator (or a zener if you're so inclined) with an emitter follower. Just use a high power transistor.

 

[riggler]

Looks like I have some reading to do! Must read about how the emitter follower concept works to increase current capacity!

 

[RuudNL]

You could do it like this:

You can of course do the same with a negative power supply, in that case you will need a NPN power transistor.

 

[JohnRoberts]

It seems there was a thread recently where a member here repaired a broken PS using a pass element to boost the current output of 3 terminal regulators. Good to look at a production design as a starting point. That repair thread posted a copy of the schematic.

JR

 

[riggler]

John, do you remember what it was for? I am not seeing anything in the Lab, but maybe I am using bad search terms. Thanks!
Damian

 

[JohnRoberts]

John, do you remember what it was for? I am not seeing anything in the Lab, but maybe I am using bad search terms. Thanks!
Damian

no I don't remember but here it is http://www.groupdiy.com/index.php?topic=48716.0

I tried searching for it using power supply, repair, transistor, etc and didn't find it, then searched posts made by the poster.

I don't know that this design is optimal, but it is a production design so should work...



JR

PS: You owe me several minutes...  8)

 

[riggler]

I owe you more than a couple minutes! Have learned so much here! Thank you!!!