122-28176 Parallax Inc, 122-28176 Datasheet - Page 125

• Manufacturer Part Number: 122-28176
• Description: GUIDE STUDENT PROCESS CONTROL
• Manufacturer: Parallax Inc

Specifications of 122-28176

• Accessory Type: Manual
• Product: Microcontroller Accessories
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• For Use With/related Products: Propeller Education (PE) Kit
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Contains lead / RoHS non-compliant

Testing the Encoder Wheels
The encoder wheels work only when the black segments absorb the infrared light emitted
by the QRB1114. A black surface produced by laser toner and inkjet copiers usually
works well, but a home photo printer that accepts glossy paper may use metallic ink that
reflects infrared. Commercial printing processes vary. So, we must test our encoder
wheels before proceeding.
Parts Required
Same circuit as Activity #2
Scissors and double-sided tape or rubber cement (not included)
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Photocopy or tear out the encoder wheels page from Appendix A. You may also
print out this page from the Process Control pdf available from
www.parallax.com.
Repeat Activity 2, but using both the white and the black areas of the 1
Cycle/revolution encoder. Make a note of the distance where both white reflects
and black absorbs the infrared light.
If the printed encoder you are using does not work, try photocopying the page
with a different method, or coloring over the black areas with a felt-tip pen.
When you have confirmed that you have a set of encoders that are visible to the
QRB1114, carefully cut them out.
Using double-sided tape, rubber cement, or some other non-permanent method,
attach the 1 cycle/revolution retro-reflective encoder wheel from Figure 4-17 to
the fan. Do not place tape on the surface as it may reflect, affecting your
readings.