Since last year I have taken iointerrupt's design and have re-done the circuit with a new board. I have used surface mount components, adding in some nice features and have made this into a plug-N-play unit. I contacted him last year for some help and even though I didn't need to I asked for his consent in making these to sell, because it was his idea to start with. He said that was fine and to go for it. I had the project on hold for months but I just got it finished and tested. These units are all done and ready to run. All you need to do is make a mount for the sensor.
They can have an input voltage of 6 to 60V, so you can use your existing power supply that runs your Driver board. I also adding in a off and on switch incase you need to use a different power supply to run it. I implimented a terminal block for easy wire connections.