I made a line following robot!

And it works very nicely. Here it is:

The line following robot

The line following robot


The robot in action

The robot in action

It uses a circuit like this (which i thought up and improvised myself):

The schematic of the line following robot

The schematic of the line following robot

The circuit uses a LM324 op-amp. The setup trimmer is a 10k one, with a 100 ohm resistor in series. When supplied from a 3.6V battery, The series resistor for the leds can be, for example, 100 ohms. The resistors in parallel to the photodiodes are 330k. The final transistors can be anything capable of handling the current. This time, BD681 was used. The IR LEDs and the photodiodes were disassembled from an old mouse.

The leds, photodiodes and the operational amplifier (LM324) were just glued to the cardboard, the power transistors soldered to the servo motors and then everything was soldered to them. The robot uses a tiny 50mAh 1S LiPo.