Let's Make Robots!

Transistor based line follower

follows a black line on a white surface

Hi guys....



Finally today arrived the last order for this robot... the wheels and the caster....


I took me 2 night of CAD-ing...


This is  my first entry and I hope that you'll like this... I made this robot based on ermicro schematic and tutorial...  http://www.ermicro.com/blog/?p=1097


I used near the same things excepting the transistor... I'm using two 2N2222 transistor which allows 800mA on its collector... So the basic ideea is to follow a black line on a white surface... The principle of working is simple... I used a white LED to illuminate the surface... and one LDR as reciever/sensor.... when the white light contacts a white surface it will be reflected so the LDR lower his voltage opening the transistor... as the transistor is opening, the gearmotor gets more curent and will spin faster making it to turn...





unfortunatly I get tired with setting the trimpots every time when the illuminance changed... this way I was going to use QRD1114 fairchild sensor... and finally it's working... no more white light... :D just IR...


the only problem is that when my trimpots are at 0 Ohm, my LED isn't glowing :( the blue flashing LED :(

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Are the blue rectangle like things terminal blocks?


yes they are

If I am using 4 or more sensors could I use the faster GM8 motor instead of the GM2?

give it a try :D if you don't try you never know btw thoreticaly it should work, but in practice?

Hi!  Thanks a lot for your cheap project which is great and simple. I also have a tank and will use this circuit.

Keep posting new ideas for us my friend and I like your design too. :D

thanky you for your comment :D

Cool design)


tell me what program did 3d model?

that is Autodesk Inventor...

Since you helped I shall help you. Here are the directions to the simple line following switch to make the robot follow dark and light lines. Hope this helps :D

Link: http://letsmakerobots.com/node/20968

request not found... but... aplying a resistance to base will make it work :D no problem :D