Quote:
Originally Posted by MCahoon
We used an IR Emitter/Detector pair (Radio Shack p/n 276-142). This is powered using a 7805 voltage regulator, connected as a custom circuit to the Power Distribution Board. The Emitter is driven from 5 V, with a 51 ohm series resistor (gives about 90 mA drive, max current on the emitter is 150 mA as I recall), and the sense voltage of the detector photo-transistor is developed across a 10 K (as I recall, possibly 15K) resistor.
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I feel like crying for my mommy. This is almost exactly what I did, but I was not driving the emitter hard enough (270 Ohm versus 51 Ohm, difference is 18 mA vs 98 mA). Is there a reason why you powered your system through a 7805 versus the 5V power provided by the FRC Analog bumper? The Analog Bumper can provide 750mA of current with 5V, and it runs straight off the NI-9201 so there's going to be a constant supply. I guess if you wanted to go from bench-top testing straight to the robot your solution is probably the most convenient, but I was just wondering if there was a technical reason why you went with the 7805...
Thanks so much, you gave me the guts to try again...
-Danny