The third model in the EM1 kit was particularly cool to build as it is the first model where the electric circuit is controlled by a mechanical component. It starts with a wheel hub whose rotation is driven by a motor. The wings on the hub are used as a cam to cyclically push a lever down and then release it; it reminds me a bit of a trip-hammer .

At the other end of the lever, a metal contact piece is affixed which, at its lowest position will close the lighting circuit by touching its complementary piece on the lighting riser. It was impressive seeing how neatly this piece fits with the end of a standard block and how the wire connector anchors it in place.

This model also introduces a new cable management technique, using a single gear chain link to hold an individual cable in place in the groove of a standard block. This feels quite clever and neat; however, I’m torn on whether or not I prefer it to the previously introduced flat block approach.

Overall, this was fun to build and satisfying to watch run. While I am a huge fan of LEDs, there’s something very pleasant about the more gradual on-off transition of an incandescent bulb. I did find that adding a few extra blocks at the base of the light riser stiffened it and helped with making sure the two metal contacts continued to make a solid connection even after several cycles.