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A tiny thing for optical audio

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Veland

Member
Joined
Aug 13, 2001
Location
Bergen, Norway
After visiting this site, I decided to try out making a CD ROM digital out to optical.

Some specs first:
CD ROM digital out is a 5V TTL output (SPDIF, or COAX digital use 1V p-p signaling)
Optical digital devices are "tuned" to see red light, with 630nm as minimum wavelenght.

So, I found the drawing of the "Super-cheap TOSLINK Module" on the page, and after going through my drawers, and 15 minutes of preparation and soldering, I was done!

So I turned

1 reset switch (cut of the switch, used the connector and the cable)
1 bright red 3mm LED (1.7V)
1 140 ohm resistor
some solder and shrink tubing

into

CD ROM digital to TOSLINK optical!!

It's fascinating, because the optical interface works at several MHz, so all you see is a constant red light. Put it into the optical input, and suddenly this red light comes back as music!

And by removing some of the "lip" at the base of the LED, it even fits the optical input directly. Neat.

Here's the pic:
 
OP
Veland

Veland

Member
Joined
Aug 13, 2001
Location
Bergen, Norway
Right!

Of course, I've got a soundcard, but having both DVD and CDR, and my Live! only got one CD digital input, I could use the other one to copy my CD's digitally to my MD player.

Perfect!
 

Diggrr

Underwater Senior Member
Joined
Nov 29, 2001
That is very cool. Now what could I do with that, hmmm.......

By the way, I have a "Y" cable for my cd and cdrw to both use the same input on my sblive. Hard to find little buggar, but the computer show had one. You could probably make one too, but I'm sure the light output mod is much cleaner audio.

Thanks for showing us the "light"! (pun intended)
 

Big Nuttz

Always one step ahead of jdmcnudgent
Joined
Jan 10, 2002
Location
Toledo, Ohio
Nice job modding and thats a good find on the site. I'm gonna bookmark and check it out later and maybe attempt it myself.
 
OP
Veland

Veland

Member
Joined
Aug 13, 2001
Location
Bergen, Norway
I always believed optical audio was complicated, and here a normal LED works perfectly! So if you need an optical out, this site makes it easy. So go for it!
 
OP
Veland

Veland

Member
Joined
Aug 13, 2001
Location
Bergen, Norway
The thinhy I made and posted a picture of, is just a TOSLINK compatible optical out from a CD ROM. This is therfore nomal stereo. If you build the coax digital -> optical converter and your digital out is outputting 5.1 signal, then it would probably work.

As for the receving end, I built this to transfer CD's to my minidisc which got an optical input. If you have no equipment with optical inputs, this thing is not for you. Building a receiver involves a lot more then a led. (Just thinking since I have no knowledge: Receiving foto detector, syncronizing, decoding, line amp. All fairly complicated..)