A 3-Pin Regulator Question

[saurus]

Hello,

I have read every thread about 3-pin regulators so far, but I have a question.

I want to build a +/- 15 vdc power supply. Since the LT1086 has no negative compliment, I would have to built it with the separate-secondaries trick like this.
My question is about how to hook up the sense points for the "negative" regulator. For the positive side, it is straightforward (hook the end of the adjust resistor to the ground of the circuit being powered), but what about the "negative" sense point?

The adjust pin on the "negative" LT1086 is related to the -15 v rail, not to the common ground like the positive one. Do I hook it up to the -15 v rail of the circuit being powered? Or to the ground? Or am I stuck with the LT317/337's?

Thanks for any help!

 

[peranders]

If you have two separate raw voltages you can do as in page 13 at the bottom in the datasheet.

 

[djk]

The complete schematic is at the link you posted. It is correct.

What part don't you get?

I could call the + output 'ground' and then the - output would be -48V.

I could call the - output 'ground' and the terminal marked ground would be +24V and the terminal marked +24 would be +48.

Is the glass half empty or half full?

 

[saurus]

Thanks! I just wanted to be sure.