Linear PS with no ground pin
 

Hi all,

I just finished building a Pass DIY Phono preamp (actually two, one for each channel), and I'm looking at ways to power it. It requires +28-34v, ground, and -28-34v connections. I tested the boards with 6 9v batteries in series, with ground connected at the midpoint, and they work well.

So I purchased this PS: Power Supplies, Power Supply, Bench Supplies, Transformers

Unfortunately there's no ground connection on the supply, and I can't locate a schematic for it. Any ideas for using this particular supply with my project? Or is it a writeoff?

Thanks :)

That appears to be a 28V supply, which will give you 0 and +28V. Not what you need.

OK, that's what I thought. Live and learn :(

The instructions for the preamp say wall warts can be used. I assume I could connect two 30v wall warts together in the same way I connected the batteries?

If their outputs are isolated from the mains, then yes. This will probably be the case.

Why not buy or build a proper power supply?

I was hoping to buy rather than get into another project at this time. Anything you can recommend? The Pearl 2 already has voltage regulation and filtering (doc here) http://www.passdiy.com/pdf/PEARL%202.pdf

Thanks for your advice.

Here's another thought. Since I already invested in the PS, I could just buy another of the same model, and connect them in series with the midpoint going to the ground.

If the output is isolated.

I can't tell if it is or not. Can you tell from the photo and data sheet linked below? Thanks again.

http://dl.dropbox.com/u/370002/Pearl...024x576%29.jpg

http://dl.dropbox.com/u/370002/PS%20data%20sheet.pdf

The power supply has an isolated output.
You can safely use two of them to create a bipolar supply.
Connect the - of one supply to the + of the other supply.

:D Thanks.