Greetings,
I am working on a new line follower for an event Sept 6.
I have some Fairchild QRB1114 sensors that I got from sparkfun.
http://www.sparkfun.com/datasheets/Sensors/QRB1114.pdfI was hoping to wire them in voltage dividers and feed the outputs to an A2D.
The concern is that the max current is VERY LOW 0.60mA. So I need a
BIG resistor (1M to 10M) to get a significant voltage swing.
My questions:
With so little current flowing will the signal get swamped by noise?
Should I use a smaller resistor (perhaps 10k or 100k) to get
a bit more current to overcome the noise.
Do I need op amps?
How about a transistor arranged as a darlington with the
photo transistor? Or do I need feedback?
Will some small value caps help if I have a noise problem?
Any other ideas?
Am I just overly concerned?
I now plan to move the controller (ATmega8) very close to the line
sensors with short wires.
Thanks
Kirk
PS this is helpful
http://www.societyofrobots.com/schematics_photoresistor.shtml