122-28176 Parallax Inc, 122-28176 Datasheet - Page 90

• 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

Challenge 3-2 Solution
Placing the photoresistor on the Vdd side of the potentiometer modifies the circuit for a
darkroom sensor. When more light falls on it, the resistance decreases dropping more
voltage across the bottom half causing voltage to increase. The potentiometer must again
be adjusted for the desired light/dark threshold in the darkroom.
Challenge 3-3 Solution
1. The circuit in the figure is termed Active-Low because when the button is
2. A pull-up resistor used to keep the input high (up = high) when the switch is not
3. Your circuit should look like Figure 3-26. Pressing the button after reconfiguring
pressed (active) a connection is made to Vdd.
active.
should have caused the digital plot to go low.
Figure 3-25
Photographic Darkroom Alarm
Circuit Solution