The emitter is a TSUS5400, which was suggested by the vendor as spectrally matched to the detector. Distance that that measurement was taken at was very small, only about 2 inches at most!!! Ambient light was 3 low energy lightbulb, each equivalent to 60w
For a full picture, the sensor rig (wired as per the diagram on prev page) is two 3ft lengths of a medium quality speaker cable, one end is a 3.5mm stereo jack. The 470o resistor is at the emitter end of the cable, the two +ve's are joined at the stereo jack.
The funny thing is, I have had problems with pretty much every circuit I've tried off the internet, I've made lots of sensors up in the past with different lengths and qualities of wire, different emitters and detectors... I ended up finding a simple detector circuit on the net and made up a simple dedicated unit to test the leads involving a thyristor a 220 ohm resistor and an LED. All the leads I have, tested, work well on the unit. All the sensors I've made light the LED (albeit dimly) at a distance of about 2ft, but as soon as I plug it into a trigger circuit it seems to drop to a matter of an inch or so!