Re: Simple DIY tachometer made from old serial ball mouse

Thanks for the advice, there is one problem, the phototransistor/diode
has three leads to it.  Im not sure what it is exactly.  Do you have
any idea? I mean, i have played around with the IR
phototransistor/diodes sold at radio shack that have two leads (look
very similar to a LED), but this is different. Anyway, if anyone knows
what exactly im dealing with, I guess thats what I need to know. thanks
a lot, Lucas.