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So, here's what happened... I was building the "Start here" robot and as I kept thinking of new little bits and bobs to add I struck a bit of a wall. I wanted to have a propeller on top that would turn on and off whenever the robot was moving forward for a few seconds without obstacles. Turbo mode style! The problem was that the picaxe signal was not enough to turn the little fan motor on so I needed a transistor there. I did not feel confident adding anything that said "amplify" to the circuit until ...
This is a companion discussion topic for the original entry at https://community.robotshop.com/index.php/robots/show/my-first-line-follower