| Author | Message | ||
     Mareklew Tinkerer Username: Mareklew Post Number: 157 Registered: 03-2010 Rating: N/A |
Alex, it doesn't matter if the plug is stereo or mono, just remember to connect one leg of a photodiode to the contact going to the tip of the jack, and the other leg to the base (the middle ring of a stereo jack remains unconnected). If you have problems getting any signal back, it may be due to three reasons: 1) wrong diode. Although *all* diodes are 'reversible machines' i.e. powered they make light, illuminated they generate power, the efficiency depends on how they are built. An inherently dim diode with a diffuse plastic housing will not amount to much. Best would be high efficiency photodiode without any filters, but I always used some ultrabright LED I usually had lying around. 2) bad contact. Most of phono jacks sold at outfits of the like of RadioShack are junk, the tip is riveted to a soldering tab and that's supposed to guarantee the electric contact. As soon as you actually solder it, the plastic behind the tab softens and the pressure of this rivet is gone, so is any chance of electric contact. 3) Audio gain in the microphone path is too low. Check for any checkboxes like '20dB boost', or like and check them. Go to audio mixer (volume mixer in 7) and check if microphone is selected as audio recording device. If you start Audacity and click on the bar next to the microphone symbol you should get a bar indicating recording level. It should jump up if you shine some bright light into the diode (it won't react to constant illumination level, even very high, but should react to changes in light like when you point the diode towards a bright window and wave your hand in front of it). Greets, Marek |