122-28176 Parallax Inc, 122-28176 Datasheet - Page 99

• 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

Label your plot:
Did the voltage drop far enough to register as a LOW, that is, does it drop below the
BASIC Stamp TTL threshold of 1.4 V? With some resistor values, it may drop below
1.4 V, but with others it may never drop below 4 V, indicating that there is not sufficient
current to reach saturation. Some choices may be to use a more reflective material, to
increase the power output of the LED (not an option – near 40 mA already), or to
increase the size of R
Using the 1 MΩ resistor, the cutoff voltage may not read 5 V. The value of RC is
approaching the input impedance value for the ADC and the BASIC Stamp causing
loading effects. As long as the voltage is above 2.0 V (V
not be an issue.
√
√
√
√
√
√
√
√
√
√
√
√
√
Repeat for at least 10 readings, moving a little closer to the switch each time.
Each time you click Plot, a new point will appear on the graph.
Be sure to include the lowest voltage achieved and at least one closer where
voltage begins to rise again. The change in voltage may not be very significant
(lowest voltage around 4.5 V).
In the bottom-right corner of the StampPlot screen, it says “Double-Click Plot to
add Text,” with a drop-down text box underneath. (You may have to expand
your window size to see this area.)
Click in the text box at the bottom right of the StampPlot screen.
Highlight and delete anything that is in there, and type in a new phrase: "10 k
Ohm response".
Now double-click on the plot where you want to place the label, and then your
text will show up on the plot.
Save or print your plot.
Replace R
Select 100 from the RC(K) drop-down menu.
Repeat the activity, and label the resulting line "100 K Ohm response"
Replace R
Select 1000 from the RC(K) drop-down menu.
Repeat the activity, and label the resulting line "1 M Ohm response"
C
C
with a 100 kΩ resistor.
with a 1 MΩ resistor.
C
. Let’s try some other resistors
IH
for the BASIC Stamp) it will