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Fairchild GRB1134 Support
The Fairchild QRB1134 is generally used as a line
following sensor. White reflects light, black does not reflect. The sensor
will needs about a 0.25” to 0.5” black line on a white surface in order to
work. The sensor needs a “pull-up” resistor on each line follower output. The
pull-up resistor does exactly what it sounds like, it pulls up the value to 5
volts. The reason you pull up is to eliminate the effects of a drifting
circuit. If the output is floating so could the value the OOPic reads hence
giving erroneous readings. So when no signal is present the output the OOPic
sees is pulled up to 5V. When the sensor does send a signal it has enough
current to overcome the pull-up resistor and ground (~0 Volts) the output. A
capacitor to each of the outputs is recommended to ground to eliminate spikes
and any other spurious readings and smooth out the outputs (polarity capacitors
will have one leg longer than the other, the longer leg is the "+" leg).
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