28V dual power supply?

GroupDIY Audio Forum

Help Support GroupDIY Audio Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

fum

Well-known member
Joined
Jun 3, 2004
Messages
861
Location
Seattle
Hey there,

Am starting to look at building a power supply for some quad eight gear ( +/- 28V), and am wondering what people are using for power?

I've checked the usual suspects here in the states ( digikey, mouser), and am not seeing torroids above 22 V dual.

What are you guys using to power these things?

ju
 
The JLM and Seventh Circle supplies will work. I use the Seventh Circle supply for my QE stuff. The rails are +/- 27 vdc. At some point I will replace a couple resistors with trim pots to get the +/- 28 vdc.

Kirk
 
i picked up a pair of power one hc28-2-a 's on ebay for $25 not long ago. kinda clunky having 2 psu's, if i had known about the jlm thing at the time i would have gone w one of those and used one single output psu.
 
Hey Fum -

I got some QE preamps and I am presently using ssltech's dual/+phantom power supply http://www.beatbazar.com/guests/ssltech/kps-1/index.htm.
Mine's a little beefed up though, and the caps are rated at a higher voltage, to allow for the +/-28. I also picked up two 28V Lambda's on Ebay, but have yet to implement them. I pulled a power transformer out of an old Sony integrated home unit, and use that for my current psu, but haven't really checked out toroids. Hope this helps some.

Best Regards,
Jesus
 
I have a couple of 2U +/- supplies from formula sound. They're toroidal, linear supplies that can put out between 5v and 30vdc @ 5A. I use the pair to test but I've recently got a handle on building my supplies so I'd be willing to trade one for something...they're heavy.

I use them at -/+18 & -/+25...


-james
 
[quote author="sverige_cruz"]Hey Fum -


Mine's a little beefed up though, and the caps are rated at a higher voltage, to allow for the +/-28.

Best Regards,
Jesus[/quote]

Jesus,

Thanks for the lead
I just finished doing this same design yesterday for an api style project I'm working on(+/- 18V). Can you share any more details as to "beefed up". What are you using as voltage regulators, cap values, etc.

I've got another board etched and sitting. I'm now spinning through the mouser catalog looking for regulators :grin:

Regards

ju
 
Look at the flat pack transformers. Pretty good hum cancellation, but if its a problem just put them in an outboard box. (cheap too!)
 
Maybe this will work?
There's two diods missing between the adjust pin and the output pin in the main regulators but it will work just fine without them! They should be connected the same way as the diod in the 48v section! but in the opposit direction in the neg circuit!
http://www.vintagedesign.halmstad.net/diy/schem_mods.htm
 
I'll put in a recommendation for the JLM power supply. Easy to build, relatively inexpensive even with shipping to the States, and it provides phantom and two individual bipolar supplies on one small board. Match it with your favorite torroid and you're all set! I just used one to rack up some 15+/-vdc MAP modules. Works like a charm! :)
 
Jesus,

Thanks for the lead
I just finished doing this same design yesterday for an api style project I'm working on(+/- 18V). Can you share any more details as to "beefed up". What are you using as voltage regulators, cap values, etc.

Hey Ju - I'm not really using any special components, just larger value capacitance in the electrolytics, and bypass caps for them. I still have the lm317/337's for regulators, but all in all, it's the same thing. Didn't someone here recently put up another dual/phantom PSU called "uniPSU.pdf"? I have the file, but I don't remember who made it. That might be something to check out as an option, as well. Best of luck!

-- Jesus

**edit** Duh, that unipsu was Tekay's, and he put a link to it up above...gotta get some coffee....
 

Latest posts

Back
Top