OCB100-KIT Datasheet, PDF (17/24 Pages) OPTEK Technologies – Auto-Calibration Design Kit

to a higher load resistor value in those cases. Place the shorting bar
between pins 2 & 3 and try calibrating again. In this case the OP-
B885CZ only needs to reach an Ic_(ON) value of 2.5V / 10K = 0.25mA
to calibrate. We could have suggested the 10K load resistor to begin
with, but this exercise can show the importance of matching the
phototransistor load resistance to data sheet specifications of the par-
ticular sensor being interfaced to the OCB100CZ.
An example of an application where the OPB885Z could be used
in combination with the OCB100CZ would be where a semi-opaque
or semi-transmissive material needs to be sensed. Since the material
does not block all of the light, the sensor might see through the mate-
rial and not be able to detect its presence. The OCB100CZ solves this
problem by calibrating the sensor output at a level slightly higher than ¹⁷
the detection trip point. If the material to sense is 50% transmissive
or less, it will be sensed.
Another example would be when the difference in two semi-
transmissive materials needs to be detected, such as in a label
printer where a sensor is required to see through the liner of a roll of
labels, but detect the label. A sample label / liner is included in this
OCB100-KIT. Try the following experiment:
Insure that the shorting bar is placed between pins 2 & 3 to set
the load resistor at approximately 10K ohms. Place the gap between
the two labels in the center of the optical path. Calibrate the sensor.
Now move the labels back and forth in the gap to see that the green
LED lights when the labels are present, but does not light when the
label is present. Remove the label / liner from the gap completely.
The blue light of the OCB100CZ should now be lit.
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