Can anyone tell my why this laser diode has three wires?To power up the laser I'm guessing I need to put some VDC across pins 1 and 2? But what's the other diode on pins 2 and 3 for?http://www.mantech.co.za/Datasheets/Products/ADL-65055TL.pdfI guess the datasheet does actually explain this somewhere but it's a tad arcane for me and I'd appreciate it if someone can tell me how to wire this sucker?Also, that operating voltage of 2.2 to 2.5 seems a bit awkward.... wondering if it would be ok to drive it at 3.3 from the Uno which can supply the necessary current.(This one has two wires which makes more sense to me. But apart from being 3 times as long and twice as wide, it's also twice the price: http://www.mantech.co.za/Datasheets/Products/VLM65001-V43.pdf )
Which explains why the second one is bigger and more the point, more costly.Thanks Lefty.Edit.... I see, alas, that it's over the current limit for an Uno I/O pin so I guess I'd need to switch it with a small transistor like a BC548.