Line following Circuit

[Xyver]

I'm am finally getting around to making the line following add-on for my 50$ robot, and I just had a few questions to start.  I am using 5 pairs of IR LEDs and IR LED detectors I got from futurlec.

For the LEDs, I can pretty much just wire them together, and then just keep them on?  No fancy coding for that? Im thinking they should be wired in series, please correct me if it should be parallel.

For the detectors, is it pretty much like making a Photo-sensor for the 50$ robot, but with a IR detector instead of a photoresistor?

Those are the only 2 for now.  Thanks alot!

[knossos]

All of the LEDs can be powered on all the time.  As for parallel vs series, reading this might help you make a decision.

TLDR: LEDs in series are good for powering off a higher voltage source.
         LEDs in parallel are good for powering multiple LEDs off a lower voltage.

[Soeren]

Hi,

IR LEDs usually have a voltage drop of around 1.5V, so 5 in series will mean ~7.5V (+ swome to drop over a current limiter) - if you don't have that, there are plenty of switcher chips made for driving series connected LED's
Depending on how you go about it, you should be able to make do with eg. 4 IR LEDs with 5 detectors.

You'll get more reliable results with modulated light (amd receivers for same), as other sources of IR can be more or less suppressed.

[Xyver]

I'm using a 9 volt battery to power the Arduino, then using the Arduino power supply to power my sensors (so far 2 IR range finders and an ultrasonic) so that will give 5 volts to the LED's.  That is too little to run the in series...  There is also a 3.3 volt power supply that can come from the Arduino, so should I use that, and add resistors to the LEDs so they equal 3.3 volts each instead of 1.5?  Or would that be too much waste... 

For the whole board, I'm imagining it with 2 power wires, then 5 output wires, one for each of the detectors.  Correct?  Is there anyway to slim it down to less then 5?  I only have 6 analogue inputs, and 2 are being used by the range finders.  I might have to make it either a obstacle avoider or a line follower, not both.  The only ways I can imagine using less wires are pretty complicated, and require a new controller to process the line following module, then outputting only 3 wires, telling the Arduino to go forwards, left or right.  Kinda like a master/slave setup.  But thats too complicated for now, just going to use 5 control wires.  Is that correct, and will work out ok?

[knossos]

I would avoid using the 3.3v for powering the LEDs.  Also, I would guess that a 9v battery would be a little underpowered for that many LEDs and sensors.  Lastly, would your design work with only 4 detectors?

[Xyver]

The design i made only used 3 detectors, but that seems limited in my mind, and my friend just built a line follower in university, and he says 5 is the best and he can teach me all the programming.  So i was kinda just going to go along with what he said, then when I know what im doing i was going to custom build my own.