How to get +15v and -15v from 12vdc

[mbcouple]

I have a 12vdc source that fluctuates, and i need a clean +/-15v dc power supply from it. Does anyone have any ideas?
Thanks
Hans

 

[imix500]

How much current? Maybe a dc-dc convertor?

 

[mbcouple]

Sorry, good point. I dont need very much current. Less than an amp, maybe between 250 and 500mA, more is ok though. I am looking for something i can build, instead of an off the shelf product. I am hoping to keep the cost of the circuit beloew $30 if i can.
Thanks
Hans

 

[richie00boy]

You're looking at a DC-DC converter and you'll need a transformer. I'll be putting a simple design on my website soon, but you need to be able to wind your own little transformer. I'm thinking of getting some made up if there is enough demand.

 

[imix500]

Like this?
http://www.jameco.com/webapp/wcs/st...toreId=10001&catalogId=10001&productId=217111

 

[richie00boy]

That looks like a good solution.

 

[pinkmouse]

For $30, surely it would be easier just to build a proper one from scratch?

 

[Mike Gergen]

Go to the national Semi web site. You put in the requirements and the site designs the supply you need.

 

[DigitalJunkie]

Maybe something like:
http://www.users.qwest.net/~ptaylor/Electronics/DC-PCsupply/DC-PC-Neg-supply.jpg

It's a small dc-dc from older Fluke DMM's.
The input is +5V and the output is +/- 15V (theres a 78/7915,thats not in the schematic,along with the + output diodes,and filtering caps.I modified one a bit for another project-only needed a Neg output.)
I'm not sure of the current available,but it's pretty decent.. Maybe 500ma?

 

[richie00boy]

For $30, surely it would be easier just to build a proper one from scratch?

US$30 is around £16.50, consider that you have to source a transformer or parts then wind your own, I think that's cheap not to mention a compact solution. A custom transformer will be easily £15 on it's own.

 

[pinkmouse]

Not in the states, dollar and pound prices are just about equivalent, so 30$ will buy about the same as £30 over here.

So how much are those dc-dc converters to do 500mA anyway.
?

 

[paulb]

Well, maybe...

Somebody suggested National. Here's a schematic from their LM2585 datasheet. Looks like the transformer may be available from Coilcraft.
A word of warning: switching power supplies are notorious for being difficult to build. Chances are you'll probably face a few problems while building.

 

[jacco vermeulen]

is a voltage doubler followed by a voltage regulator not easier ?

 

[richie00boy]

Not in the states, dollar and pound prices are just about equivalent, so 30$ will buy about the same as £30 over here.

So how much are those dc-dc converters to do 500mA anyway.
?

Check your facts I did with today's exchange rate before I made that post. US$30 = £16.44 if you want to be picky

 

[pinkmouse]

Richie, you misunderstand. An item that costs £30 in the UK will usually cost around 30$ in the US.

 

[paulb]

is a voltage doubler followed by a voltage regulator not easier ?

Not for that much current (0.25+ amp).

Richie, you misunderstand. An item that costs £30 in the UK will usually cost around 30$ in the US.

Yup, dollars for pounds. Also works in Canada.