paul in your microgram balance circuit i see there is an opto interuptor do you remember the specific type you used as im using this one
its not making the meter work and is reducing the input voltage to the sensor to 1.6v
uk.farnell.com/.../ProductDisplay
again any help is welcome
The sensor is a Honeywell HOA1873-13 - which is what I had in the junk bin...
http://uk.farnell.com/honeywell-s-c/hoa1873-013/opto-switch-transmissive/dp/1611538
It is a simple IR LED and Photodiode.
The sensor you selected has the schmidt trigger amp built-in, which will not work. You want a "photodiode" output.
Here is a closeup of the sensor. Note the vane covers the entire beam path. It needs to establish an "edge" brightness where it will "grab" the vane. You may need to move the movement until you find a "sweet spot".
