LED dining table circuit, how it works

The main problem that I'm having with this circuit is that I don't understand completely how a photo-diode works. I would like to build a working example of this and put it into an electric guitar.

The other main problem is that I tried to put the 14 LEDs in series and none of them lit up, so I think that the problem might be that they used high efficiency LEDs in the schematic.

Any help on this topic would be appreciated.

**broken link removed**

Link to construction documentation

It's also not that sensitive, I would like to make it more sensitive like this:

A red LED uses about 1.8V. A blue or white LED uses about 3.5V. So 14 of them in series use about 25V to 49V. If the opamps have a plus and minus 15V supply then red ones should light. Blue or white LEDs will not light unless there are only 7 in series on each side.

Photodiodes work two different ways:
1) They can have a reverse voltage then "leak" current when exposed to light.
2) They can generate a current (like a tiny photo-cell) when exposed to light like in your circuit.
Their polarity must be as shown!

Thanks for the help AG.

thats a cool setup would love to build one myself, where did you get the diagram ? the website seems to only sell the stuff, do we have a part number for that photodiode (never used one myself)