:: About ::Current Research::Hardware :: Software ::Publications ::Related ::
Pushpin Computing
Responsive Environments Group

Light Sensor and LED Display Expansion Module



• Light Dependent Resistor

• 5 LEDs

This expansion module is equipped with a light dependent resistor (LDR) and five LEDs - green, yellow, orange, and two red. The LDR forms one half of a voltage divider, the value of which is sampled by one of processing module's analog channels. All five LEDs are controlled by lines from the processing module that can be dedicated to pulse-width modulation so as to vary the intensity of each LED independently.

Schematic Diagram

Printed Circuit Board Layout

Parts List for 100 Pieces
Vendor Vendor Part # Qty. $/Unit Description

Digikey 67-1695-1-ND 200 $0.19 Surface mount (1206 package) red LEDs.
Digikey 67-1696-1-ND 100 $0.19 Surface mount (1206 package) orange LEDs.
Digikey 67-1358-1-ND 100 $0.27 Surface mount (1206 package) yellow LEDs.
Digikey 67-1002-1-ND 100 $0.21 Surface mount (1206 package) green LEDs.
Digikey ??? 500 ??? Resistors for use with LEDs.
Digikey ??? 100 ??? Resistor that forms the other half of a voltage divider with the LDR.
Radio Shack 276-1657 ~20 ~$2.40 CDS Photoresistor Multi-Pack, containing an assortment of light dependent resistors.
Newark 33B093 100 $1.85 FCI/Berg 91900-21125 Conan 25-pin 1mm pitch header for connecting with processing module.

Last Updated: 01-DEC-2004
MIT Media Laboratory