Elenco Snap Circuits SnapMicro I Deluxe ® - Manual (Page 62)

61
Project 17, The Photo Resistor (RP) or Light Dependent Resistor
RP is an example of an analogue sensor that drops from a very high resistance to a low resistance
as light is increased. It is connected between the micro-controller input pin 2 and ground. A 100k
resistor from B+ to pin 2 allows the voltage on pin 2 to rise when it is dark and fall when there is light on
RP. Build the snap circuit shown here.
Next page shows program and flowchart.
B
C
D
E
F
2 3 4 5 6
A
G
1 7 8 9 10
To Computer
1
1
2
2
2
1
2
2
2
1
1
1
2
1
1
2
2