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+-5v dual rail power 1amp per rail ! 20uV noise, phantom power & digi power 20uV noise

A project log for DSP Field Mixer Recorder

USBmidi, bluetooth app controll 8 chan portable DSP mixer.balanced audio IO,phantom power,flexible routing,ISO recording. networked Timecode

ben biles 02/12/2017 at 16:310 Comments

+/-5v dual rail power 1amp per rail ! 20uV noise per rail.

phantom power 48v 50ma ( no filter yet working on it )

<edit> I tried all kinds of filters with inductors large capacitors etc , basically the ripple is a bit to agressive to be smoothed with a simple filter I think. its nearly 1vpp !! I think I will just add a 48v capable ultra low noise LDO on the next revision. looking like it will be LT3012 with 100 microVolts noise. :)

It looks like the large decoupling caps in the middle of the board can be replaced with ceramic 47uf 25v or so.

<edit>

& +5v 500ma digi power 20uV noise

phantom power has 120mV ripple and filter needs work but room for a large thru hole capacitor if needed.

tested 800ma per +- rail and it does'nt get hot at all.

it will run on 5.5 - 25v input

it can be configured for +-18v +-15v +-12v etc but need +/-5v for PGA2500's

rev 2 will have smaller inductor pads and I think I can swap electro caps for ceramic in middle of board. I need about 35uf in total there.

Not sure about large input caps yet , might need them to protect LDO's from inrush voltage / current so ceramic would'nt work there.

I'm thinking of adding a variable oscilator and syncing the chips, not sure if its worth the trouble.

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