Max the Spider – powered by LEGO and PIC microcontroller

So Max the spider visited us in the lab today, and wanted to get into the halloween spirit. “I’d like to drop down on people in the elevator,” he smirked, in a way only a spider could.

Max the Spider - powered by LEGO and PIC microcontroller

“I’ve got just the thing,” I winked, and put a little something together. You’re looking at a clear Lego motor (comes with its own gearbox), mounted on a Lego platform. The platform is not going to win any design awards, but it is stable and holds the motor, circuit board and 3 AAA batteries pretty well.

I tied a thread to max, and hoisted him on the plastic winch. When I press a button on any regular remote control, he descends on hapless victims with relish. Tee hee.


Step 1: Circuit board

The circuit board contains:

– PIC 12f675 microcontroller
– PNA4602M infrared detector
– 2 IRL9530N power MOSFETs (P-channel)
– 2 IRL520N power MOSFETs (N-channel)
– 100uF capacitor
– five 1n914 diodes
– 3 AAA batteries

The whole thing is probably over-designed, and the transistors are overkill, but this is what I could grab and put together in 30 minutes. If the inputs to the H-bridge (four transistors) are different, your motor will turn (eg. 0,1 to turn CW, and 1,0 to turn CCW). If the inputs are the same ( 0,0 or 1,1) the motor is shorted and it stops very quickly. Don’t leave out the diodes, as they prevent the motor from spiking energy back into the transistors.


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