Elenco Snap Circuits SnapMicro ® I Standard - Manual (Page 54)

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PROJECT 14
– Analogue Sensors & Analogue to Digital Conversion (adc)
Analogue Sensors:
An analogue sensor measures continuous signals such as light, sound level, position, or voltage.
Common examples of analogue sensors are:
• Variable Resistor (RV)
• The “Photo Resistor” (RP) or “Light Dependant Resistor” (LDR)
• Microphone (X1)
The variable resistor provides a varying voltage dependent
on the center arm position. A voltage signal from 0 to 4.5
volts can be placed on pin 1 by adjusting the slider. The
micro-controller converts this analog input into a digital
number that can be represented by a decimal number in the
range 0 to 255 (8 bits) or 0 to 1023 (10 bits).
The photo resistor or light dependent resistor provides a
varying voltage dependent on the amount of light. A voltage
signal that changes with the intensity of light can be placed
on a microchip input by using the photo resistor. The micro-
controller converts this analog input into a number that
represents the amount of light on the resistor.
The microphone provides a varying voltage dependent on the amount
of sound present. A voltage signal that changes with the intensity of
sound can be placed on a microchip input by using the microphone.
The micro-controller converts this analog input into a number that
represents the amount of sound present.