I am looking for a board with that is able to take a ~12v signal and and send 3.3v to the Raspberry Pi. I have drawn up a quick schematic of what the ideal board would be like (with screw terminals on each end).
The board also needs to be able to process input extremely quickly, so a relay wont work.
I can't seem to find any boards like this... is there anything out there?
Not able to comment on the previous answer, I'll complete d3noob's answer here. The Fiber Optics Kit from Jaycar is out-of-stock at the moment.
The following Kit seems to be a very similar (exact?) copy of it, and even cheaper :
http://i-fiberoptics.com/educational-detail.php?id=14200&cat=kits-projects&sum=1666
The datasheet is available on the linked page as a PDF.
You may also be interested in the Fiber Optics A/D Kit (Part Number: IF 545) available from the same shop, which includes "an on-board microphone for an audio analog signal source and a built-in 15 Hz oscillator for digital signals. It also has input connections for external analog and CMOS-compatible signals." This 2nd kit seems to be more "stand-alone" than the first one.
There is quite a neat Fibre Optic Communication Kit available from Jaycar (In New Zealand and I presume Australia). Probably a bit over the top of your requirements, but you never know.
Text from the description is as follows;
This kit gives you a hands on introduction to fibre optics. It contains all the components needed to build a fibre optic data link, both transmitter and receiver, including one metre of fibre optic cable and fantastic quality double sided plated-thry PCB's. A fantastic 26 page booklet is included which gives you assembly instructions, theory ( which is quit simple), a quick quiz and other helpful information. When you have built this kit you will be able to transmit and receive high speed data in serial format across one metre of fibre optic cable. The transmitter is powerful enough to actually transmit up to 16 metres!
