Motion activated dropping spider, low cost, no programming

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Step 10: Done

Picture of Done
Now it's done, hang it up at a party, or over your porch to scare trick or treaters. It doesn't use much power, so it will last at least all night on one set of batteries.

Variation ideas:
-Install it in a fake hanging plant instead of a pumpkin pail to make the spider even more unexpected
-Replace the motor in this circuit with a relay to power a much bigger motor, wind a couple of bungee cables and drop a prop the size of a basket ball.
-Use the simple motor control circuit for other props, like a rattle snake that shakes it's tail when people walk by.

This is one of my first Instructables, so if anything is unclear let me know and I will update it.

Hope you have fun with this little piece of Halloween tech! If anyone builds this I would love to see pictures, especially if you make a version with a wooden enclosure or another variation.
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scolberg4 years ago
Very clever approach!. What happens if someone stays close enough that the PIR stays triggered? Would the motor wind up the rubber band until it broke?
PaulMakesThings (author)  scolberg4 years ago
No, the spider actually stops when the string unwinds all the way, the rubber band balances it out so that it is strong enough to turn with the help from the weight of the spider but not after it reaches the bottom where the weight works against it. In the opposite direction it is stopped by the spider hitting the hole the string goes through. In short, if you stay under it, the spider just stays down.
Clever and elegant - Well done!
saravananaj4 years ago