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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I'm surprised no one else has commented on this! Very cool! I use microcontrollers for everything, so the concept of discrete components as logic seems quite difficult to me. :)

Anyways, I like it. It also looked like you spent some time on that 3D model, too.

hi... thanks for your comment... no it isn't as hard as it seems... yeah I like CAD... i love using CAD :D

   Next step, give it a brain.

Maybe... but later.... This should be the cheapest robot I've ever made... didn't want to spend a lot of money on it

ok...replaced the LED and LDR.. with 2 QRD1114 :D working perfect :D

hello , i liked the circuit and will integrate it in my tank as another feature ! :)

here is the circuit i drew , its 1-1 ratio and self explanatory , 2 parts break apart .

your is more simple :D but don't know what goes where... btw... :D I'll show up the drawing later... don't have windows now... realpcb is only for windows :(

Rubbish circuit design ! , i threw away the POTs and the diodes , put in an L293D motor driver to be able to drive the tamiya dual gearbox fitted inside my tank , functioning gr8 now .

dunno... mine working fine... don't need an L293D for this... just the diode is rather enough... i use GM2

anyway do you have a video?