Differential Light Sensor for the Fire Fighter

We opted for the sensor from Mr Sensor's homepage http://www.extremenxt.com/lego.htm.

Top view

  • Componentlist:
  • U1: LM 324 
  • R1:  1k 
  • R2:  47R 
  • C1: 16uF (Elco)
  • D1-D6: 1N4148
  • D7: Zener 5,1V
  • CdS1, CdS2   Cadmium Photoresistor


  • That's how we arranged the differential light sensor into Lego-bricks. The connector sorts at the back and may easily be fixed at the RCX-sensor-entry.
  • The sensor uses power-supply from the RCX as being an active sensor. The sensor input should therefore be set to Light-Type. The mode should be set to percent-mode. The returned values signify: 0 - the light is entirely to the left; 100- the light is on the right side.
  • Further information: http://www.extremenxt.com/lego.htm 


Simple temperature sensor: look at Mr Sensor's Homepage.

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