DC powersupply +-15V 2-3A

[JensRasmussen]

Hello,

I hope this is the right place to ask.

I would like to make a mulitpurpuse PSU for my different small projects.

I need it to be able to deliver something like 2-3 A @ +- 15V

Is this best done by making a positive supply and then "mirror" (NPN->PNP and PNP->NPN) all active devices to make the negative part?

Any help would be great

thanks

\Jens

[Jan Dupont]

I'm interested to

[tcpip]

Me too. I've already started a thread on sort-of this issue; see here.

[maylar]

3-terminal solutions are readily available up to 1.5 amps (LM7815/LM7915 fixed or LM117/LM337 adjustable). If you really need 2-3 amps, you can use the LM338 and configure 2 positive supplies in series for +/- operation. The extra cost of doing it this way is you need separate secondary windings and bridges.

If you want better noise/regulation/precision or adjustable current limiting the regulator of choice is still the venerable LM723. You can use series pass transistors to get any current you want. Again, 2 in series for +/- operation.

It seems that linear regulators are a thing of the past. The major vendors don't list squat any more.

[Elso Kwak]

Originally posted by maylar
t seems that linear regulators are a thing of the past. The major vendors don't list squat any more.

Huh,
You must be kidding........

[peranders]

Originally posted by maylar
It seems that linear regulators are a thing of the past. The major vendors don't list squat any more.

Elso, his has a point here if we talk about the general trend but for audio it's a little but hard to make real good SMPS but they are becoming better and better.

BTW: My new revision of my QSXPS has options for more current. I have added the possibility to have external heatsinks and bigger current shunts.

Picture here

[maylar]

Originally posted by Elso Kwak



Huh,
You must be kidding........

There are no negative regulators other than 3-terminal devices any more. National, Motorola and Fairchild all used to have them. Motorola had a +/- 15V regulator chip with a common reference. Not any more. They don't even do linear any more (it's now ON Semiconductor). They also had a floating regulator that I used for HV power supplies (150V). National also had the LM105, which is now discontinued.

Linear power supply parts vendors now cater to low voltage battery monitor crap for cell phones. You can get 3V low-dropout regulators but not +/- 15V chips. That's reality.

[tcpip]

Originally posted by maylar
If you want better noise/regulation/precision or adjustable current limiting the regulator of choice is still the venerable LM723. You can use series pass transistors to get any current you want. Again, 2 in series for +/- operation.

What about the LM317/337? These are easily available where I live, and I don't need adjustable current limiting... just a simple PSU to be used as a building block for preamps and other opamp circuits.

[Elso Kwak]

Originally posted by maylar


There are no negative regulators other than 3-terminal devices any more. National, Motorola and Fairchild all used to have them. Motorola had a +/- 15V regulator chip with a common reference. Not any more. They don't even do linear any more (it's now ON Semiconductor). They also had a floating regulator that I used for HV power supplies (150V). National also had the LM105, which is now discontinued.

Linear power supply parts vendors now cater to low voltage battery monitor crap for cell phones. You can get 3V low-dropout regulators but not +/- 15V chips. That's reality.

Hi maylar,
There are plenty of positive linear regulators. but you are right about the negative regulators situation as I found out.
Of course the Semiconductor industry is market orientated so there are plenty of options for cell phone circuits with low permissible input voltage.
For higher current and voltage input regulators see f.a.
http://www.linear.com/pdf/ldo_regulators.pdf
http://www.onsemi.com/site/products/...46,250,00.html
http://www.onsemi.com/site/products/...46,366,00.html
http://www.fairchildsemi.com/collate..._pp.pdf#page=1

[Matttcattt]

i though about building this, but never did. http://sound.westhost.com/project77.htm

i drew (spelling?) a dual version, (attached, i had to squash it ), but i am not sure of its accuracy.

it is 12v, but i think by changing the zener, the volatge could be changed to 15v.