New Design: remote controlled DAC

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Merry Christmas to all!

Introducing "WolfDAC"...
(so called because it's based on Wolfson chipsets)

* 1x SPDIF input
* Stereo Line level outputs
* Digital attenuator with mute function
* All controlled via an old Apple Remote - just a single LED on the front panel to display power & remote command.

The design is split into two boards: WolfDAC and WolfBrains. The former contains the SPDIF receiver, DAC and pre-amp. It's about the size of a pack of fags. The latter is dinky, containing an MSP430 micro with IR receiver and LED. 10way IDC cable connects the two together. Both circuits fit onto single-sided PCBs using a combination of SMD (1206 size) and through-hole. Using solder paste, it's quite simple and straight forward to construct.

This design has been a while in the making. I got the first revision together in feburary, but been plagued with a couple of problems (especially software glitches which I've only just ironed out). Been running at home connected to a Tripath class-D board for a while.

The last glitch is the pre-amp circuit. This is a 3rd order Butterworth to drop out any remaining hysterics from the DAC. However, the gain is a little mucked up - would appreciate any analogue experts to cast their eyes over it (I am definitely not an analogue expert!)

Software-wise, I've included the TI CCS project. MSP430's are dead easy to program and you can pick up the programming kit for a couple of quid (MSP430 launchpad).

I've not included the gerbers because theres still a couple of tweaks to iron out from original prototype.

Enjoy and have a Merry Christmas...

Mat
 

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  • WolfDACv21.pdf
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  • brains_sch.pdf
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  • Wolfbrains.zip
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