I have a probe head for my mill for doing things like measurements, offsets, and the like. Its an older unit that is self contained and is triggered by a flash unit. It has 6 IR leds around th exterior that transmits a 159khz signal out when it is on and in standby and that jumps up to 174khz when it is activated.
I managed to get it modified to run off something other than $60 lithium primary cells and I found on old amplified photo diode board that I got out of a lot of stuff on ebay probably 10 years ago that can receive the signals from the leds. It uses a couple opamps and a hamamatsu photodiode to detect it and sends the signal out like so:
On, not triggered:
Untitled by macona, on Flickr
On, triggered:
Untitled by macona, on Flickr
The amplitude varies on the distance from the sensor head and the detector runs off +/-15v so technically it could get that high.
What I would like is two logic signals to go to the computer. One goes high when the head is on, and one that goes high on activation. I am guessing something like a PLL is what is called for here but I know nothing about analog.
-Jerry