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Old 11th February 2009, 10:05 PM   #1
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Default need a PS for a pre, DAC, and headphone amp

i want to build a Pass B1 pre, this DAC (http://www.amb.org/audio/gamma1/ DAC), and this headphone amp (http://www.amb.org/audio/mini3/) - all in a single chassis.

PS requirements are:
B1 = 18-24V
DAC = 5V
HP amp = 9V

hanging 3 wall-warts off the rear chassis is not kosher.

i've only built HP amp kits and not "designed" anything like this before.

can i use a single 24V transformer (assuming appropriate current capability) with separate bridge rectifiers for each of the circuits? would the LM338 cicuit be an appropriate from Nuuk's D.D.: http://myweb.tiscali.co.uk/nuukspot/...inclone6.html.

any other options?
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Old 11th February 2009, 11:23 PM   #2
Khron is offline Khron  Romania
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I doubt separate rectifiers will be necesary. Just strap on the adequate voltage regulators after the rectifier bridge and smoothing caps. One for each of the components (pre, HP amp and DAC).

There's some ideas on a few sites, like this or this .

I just hope i could help
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Old 12th February 2009, 03:15 AM   #3
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not sure why the D.D. link didn't work. let's try this one:
http://myweb.tiscali.co.uk/nuukspot/...clone_psu.html

i'm looking at building a regulated rectifier bridges.
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Old 12th February 2009, 03:38 AM   #4
star882 is offline star882  United States
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From the schematic, the amplifier can operate on 12v. The DAC uses 5v. The preamp (is it even necessary? modern DACs have internal buffers) only uses a small amount of current.

A power supply originally intended for powering a CD-ROM or external hard drive or something should work fine for the amplifier and DAC. Add an auxiliary winding to boost the 12v for the preamp.
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Old 12th February 2009, 04:18 AM   #5
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thanks!

so basically, i need to rectify the AC from the transformer, then add a LM317 voltage regulator for each powered circuit based on this schematic from the datasheets: http://www.national.com/mpf/LM/LM317...%20Description

i have the NEETS modules and need to study PS design. i'll see what i can get through tonight.
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Old 12th February 2009, 05:08 PM   #6
star882 is offline star882  United States
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Quote:
Originally posted by fishski13
thanks!

so basically, i need to rectify the AC from the transformer, then add a LM317 voltage regulator for each powered circuit based on this schematic from the datasheets: http://www.national.com/mpf/LM/LM317...%20Description

i have the NEETS modules and need to study PS design. i'll see what i can get through tonight.
It would be very inefficient to just linear regulate 24+v to 5v. Use a separate winding or use the center tap. Or use a switching regulator if you don't know how to design a high voltage switcher and do not want an off-the-shelf solution. (Check the off-the-shelf switching power supply solution, however, as it can often be cheaper than building your own power supply.)
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Old 12th February 2009, 06:59 PM   #7
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alright, i didn't think about using a CT - makes sense.

i would rather attempt building my own PS than buying an off the shelf PS.

now i just need to figure out how to implement the LM317 regulators and with a single rectifier bridge.
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