linear power designs...

[Htguy]

Hi

I am pretty new at the power supply building. I have several projects that I would like to build linear power supplies for. (I audio and one for a crt projector) I am looking for +5v, -5v, +15v, -15v and +85v and -85v.

I have seen a design using LM338 (Lv) and tl783(85v). Are these a good idea to use? (Do they work for + and - or only the plus side of the regulator?

Thanks for you help.

God bless....

Mark

 

[richwalters]

Hi there.... have a crack at www.national.com/ application notes data sheets to get you going

richj

 

[Htguy]

datasheets...

Hi

Thanks for the link. I went to data sheet archive and got all the datasheets already, but still am not sure if I need one regulator for each + and - and if they can be the same type, or if there are different ones for the - side.

Thanks

God bless...


Mark

 

[richwalters]

I'm a bit out of touch on linears..........I used to have the old adage that the 9's suffix was neg and 8's pos (i.e79xx negs and u78's pos). You can track this through into the transistors as well.

You will need separate regs for each +/-side. Another pecularity is that the 79 neg series seems to sit roughly -14.8V for a -15V reg and the 78's pretty well at + 15V.

You can use the same type for either but in most conventions sep polarities are mostly used. When designing a universal fixed reggy psu........don't forget the in/out protection diode across the device.

richj

 

[jackinnj]

Hi

I am pretty new at the power supply building. I have several projects that I would like to build linear power supplies for. (I audio and one for a crt projector) I am looking for +5v, -5v, +15v, -15v and +85v and -85v.

I have seen a design using LM338 (Lv) and tl783(85v). Are these a good idea to use? (Do they work for + and - or only the plus side of the regulator?

For a while TI had discontinued the TL783 in TO-220 -- they must have gotten quite a few complaints as it is "apparently" back in production. When they announced that the unit was ceasing production my webstore was "cleaned out" by a bunch of ham radio guys 🙂

If you are going to regulate + 85V, note that the TL873 will only do 700 ma. Texas Instruments will show you how to hook it up for higher power. Here's a link to the PDF:
http://focus.ti.com/lit/ds/symlink/tl783.pdf

I certainly endorse the National Semi application notes if you want ot get into power supply construction -- Horowitz and Hill's book "The Art of Electronics" is also a great reference.