Lm 317 as negative by switching ground and positive

[bruce0]

I have never understood it.  It seems to me that the LM337 and the LM317 seem to differ only in the number stamped on the outside.  The input pin on one is the output pin on the other and visa versa.  One is Adj, In, Out.. the other is Adj, out, in.  But every time I try to think about it my brain hurts.

Someday I have to just try putting the wrong regulator in a power supply and see if it works.

Is anyone sure they are actually different?

 

[home_listening]

LM333!

I had the same thoughts when I needed a + / - 15 V power supply with LM350's.
Obviously it is a strange 'twist' in your (=my) mind, that you can't use a positive regulator for a negative* voltage.
(AFAIK there is no negative equivalent of a LM350.)
But there are no theoretical objections, and the power supply that I built works perfectly!

*: Of course you will need separate tranformer windings for the + and - voltage!

 

[henk]

Have a look in the old Fairchild Handbook called "Voltage Regulator Handbook" and you will find many design for your powersupply.