Electronics query

This may not be the appropriate place to post this but I have an electronics question. I was looking at the below listed site and see that diodes are used before the output. What is the reason for this, and what other/ better methods could be used here?
thanks

http://www.getlofi.com/2006/02/4093-based-oscillator.html

This is a very clever circuit to utilize a quad-comparator chip (schmidt triggers) to create oscillations.

In this case the output of each trigger feeds the output buss and the trigger's own feedback loop. The diodes, then, would keep a trigger's feedback loop from being back-fed from the output of the other triggers.

Even if you fed the four outputs to an active mixing circuit (i.e., an opamp configured as a summer) you might discover that you need the diodes anyway to isolate the feedback loops.

Would it be possible to create new sounds by feeding the output of one schmitt trigger in the ic into the open side of one of the others (putting a pot before to allow for mixing in/out of the signal)? Also, what kind of diodes should I use? can i use LEDs? Would infrared LEDs put there control the sound in any way ala photocell optotheremin?

Thanks for your help- I really appreciate it!

One other question- IS anyonE familiar i\wth the STEIM CrackleBox (Kraakdoos)? I understand that you can only use a 709 opamp in the circuit. Why can't you replace it with something else?

Well, my suggestion would be to first breadboard the circuit as-is and make sure it runs.

Once everything is working, then you would be in a good position to start experimenting.

Bear in mind that the comparator's output is either "on" of "off" depending on the input voltage: when the input voltage rises above a threshold value, then output of is "on", when the voltage drops below the threshold, the output is "off". So, use of a pot may or may not do a lot for you.

You might want to experiment with capacitors of different values in addition to diodes and resistors.

Someone with an engineering background would be able to provide more specific information however for what you are wanting to do just go to radio shack, get one of those $5 bag of parts, and just start experimenting.

Very scientific, huh? :)

Have fun!

-- Kevin