I tried the simple phototransistor->soundcard cable.
Before you try the more complicated circuit tell me the colour of each wire and which part of the jack-plug it connects to.
Is there a voltage between ring and shield when it is plugged into the sound card ?
I finally find out, why the phototransistor method is not working for me.
It is (like i expected) the used photodiode/transistor from the old computer mouse, which makes trouble here. The mouse uses infrared light (>780nm) led, an so the photodiode in my mouse is only sensitive to infrared light. If i use a led-lamp or the af-light of the G11, i got no peak on the mic-input of my soundcard. But if i use are "real" lamp, or use one of my infra-red tv-remotes, i got huge impules on the mic-input, which can be perfectly recorded.
So, bottom line is: Use only photodiodes which are sensitive to "visible" light, like the SFH 300 (420...1130nm) , because the G11 LEDs does not emit light in the infrared spectrum. So i am grounded now and have to wait until my photodiode order arrives... damned!
