Let's Make Robots!

custom line follower problems[one IR led, is bright, the other two are dim]

Hi, i learned eagle basics, so as a first eagle project i made this line follower with sparkfun's QRD1114 IR detector thing.


the project is attached.


what could be wrong here?


from left to right the first QRD is dim, the middle one is bright, the last one is dimmer then the bright one, but brighter than the dim one :S



LinefollowerV1.brd16.27 KB

Comment viewing options

Select your preferred way to display the comments and click "Save settings" to activate your changes.

Led n1 is getting 1.19V, led n2 is getting 1.32v led n3 is getting 1.19v... soldering is fine, i think it maybe bad copper traces, gonna tin 'em all...




OMGGG i failed so hard, for the middle led i was using 220ohm resistors (red, red, brown) and for the other two i was using 1200ohm resistors (brown, red, red)

:( they are working fine now, lol, guess tomorrow i'll have a few extra sensors...

1st - 5v

2nd - GND

3rd - signal 1

4th - signal 2 

5th signal 3


it makes no sense, i'll order some more sensors, i'll check if the problem is with them or not



Well unless there's some problem with the soldering, which I doubt, or your power supply can't produce enough current, then it must surely be a problem with the LEDs themselves. I guess I'll wait and see how the replacements go =)

Ordered 10, lol 2 are for encoders...

should be here tomorrow, in the mean time i'll switch positions of the sensors, if their brightness/dimness remains, they are bad, if their brightness/dimness depends on the position, i divided something by zero :S

Where exactly do the 1st and 2nd pins on JP1 connect to? I can't see anything in this part of the circuit that would cause this problem, the IR LEDs have their own current limiting resistor so they should all run evenly, unless the problem is with the IR LEDs themselves.