Top Mall-Fi poster. The T in META42. Formerly with Tangentsoft Parts Store
Sep 27, 2001
I bought zhtham's converter box, and it arrived today. Opened it up, and inside is a receiver module, a few resistors, caps and diodes, and a 74HC04. Sound familiar? Yep, it's the bog standard circuit you find everywhere online! So if someone was thinking about DIYing one of these, you might be better off buying one of these boxes instead -- it's every bit as good as you could DIY yourself.
Oh, I suppose a DIYer could do things like use really nice parts and a high-quality power supply. Personally I plan on using a 9V power supply with a linear regultor to take it down to the 6V it wants instead of the generic wall wart that came with it. I doubt I'll mod it any further.
I still have one of those Sharp receivers coming, so I'll still build one of my own for the heck of it. I may clone this box's circuit and compare the two implementations. If I do, I'll have to trace out the schematic, so I'll probably take the time to 'capture' it and make some PDFs for y'all to scope.
Yes, I forgot to mention that the $16 box is excellent value for money. You are not going to be able to make it cheaper unless you value your time at $0/hr. There is no point in building one yourself unless it is a part of a bigger project.
However, any of these circuits can introduce additional jitter. In order to achieve better results than the $16 box, it would require a fair bit of engineering (layout, voltage regulation, bypassing etc.) to eliminate spikes on the power lines (which optical receiver will make in abundance and at fairly high frequencies) making it into the output signal.
Re the M-Audio CO-3 -- one major feature is that it can strip the copy protection bit from digital files (the damned SCMS). (It's optional/user-set-able). Got mine from Minidisco, find it useful in many instances, like ripping DAT tapes to the computer for editing and duping MDs to share with friends.
Minidisco now advertises the Edirol UA-1D Digital Audio interface. Sells for $99, so it's close to your budget. It has coax and optical ins and outs, and connects to USB port. I wonder if it would work for your purposes by using the Toslink in and coax out, and just not using the USB connection?