Trolley Modeling in N Scale

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EXTERMINATE!!! ~ Sunday, June 06, 2010

Wini told me that the moment she learned about her 4th grade circuit project assignment, she knew she had to make a working Dalek (see the official fan site or Wikipedia).

Her design for a self-propelled, steerable Dalek was inspired by looking at the underside of our Roomba robot vacuum cleaner. There are separate motors for the left wheel and the right wheel. Turn on the left one to turn right, the right one to turn left, and both to move forward--also satisfying a requirement of demonstrating a parallel circuit. Here's her schematic, which also includes two white lightbulbs on the top (to demonstrate a series circuit) and a blue LED "eye" on an antenna (because real Daleks have them, and LED's are cool)!

The body of the Dalek is a hacked up plastic pitcher. Here it is on display at school.

The mechanical side of the design was my department. The Mark I design had motors driving wheels by gears, but did not work well because it was difficult to keep things in alignment. The Mark II design used rubber bands and was more successful. I built up motor mounts from scraps of wood (crown molding with a quarter circle cut out of the profile, arranged in fours to make a cylindrical space for each motor).

Here's a test run in front of our house, where the Dalek moves ok at first, and then EXTERMINATES itself.

Here's a less self-destructive run out back, demonstrating the Dalek's ability to steer by using the left and right wheel motors separately.

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