This was a fun Halloween project to build. When I set out to build a project for Halloween, I drew inspiration from creepy things that scared me when I was a kid, specifically creepy dolls and clowns. Overall this project was fairly simple to build, and this build guide will help you make one of your own. I used a scary doll decoration that can be found at Halloween stores like Spirit, but any similar sized doll should do the trick. Just make sure you can move the doll's head, since part of the project includes head movement.
You don’t necessarily have to use this specific bit, screw and nut size; however, the idea is to attach these two pieces together so you'll need to make sure the holes you choose to make are compatible with your mounting hardware and each other.
Make sure the screw and nut are not to tight, you want the joint it creates to move freely.
The body movement mechanism should end up looking like this:
Now that you have your two servo motion mechanisms built, it is time to mount them to the doll. Again, servo positioning is very important to get your desired motion. The combination of what position you mounted the servo horn into its spline and the actual position of the servo when you glue into the doll’s body makes a huge difference in the range of motion you’re going to get.
Now you are ready to mount the servo on your platform of choice. You can mount the servo to a wall, bookshelf, waste basket etc. I chose to mount it onto a box. Remember the doll's front needs to face the object you mount the servo to so it can "peek" out from behind it. If it's an object you don't want to potentially ruin with hot glue, you might need to find alternative ways to mount the servo or use a different item.
In this project I wanted the doll’s head to use the entire 180 degrees of motion, so I positioned the servos mechanical start position accordingly.
With any good Halloween prop, it’s ideal to have it be somehow motion activated. I added a PIR motion sensor (included in the Animation Kit) to add motion-sensing capability. This way when someone walks anywhere near the front of your prop, the sensor will detect movement and prompt your servo to move the doll out from behind the wall.
I mounted my PIR motion sensor about 2ft ahead of the doll along a walking path so when someone passes by it triggers the doll to move. This ensures it has time to fully peep out when that person arrives at the doll’s location.
To add a lighting effect, I used a NeoPixel Ring included with the Animation Kit. I used a soldering iron to solder posts into all the Neopixel ring’s available solder pads (Power, Ground, OUT, IN) and inserted it into the breadboard. Based on where you want your lighting effect to be, you may need to solder the ring to jumper wires instead of posts and mount the ring somewhere on the box or doll. This is completely up to you. Where I chose to place the ring gave the doll a spooky back-glow effect once the Activity Board was mounted to the box.
I don't expect you to recreate this project yourself, so the image below is just for visual reference. Download the blocks file and upload it into your own project.
Links
[1] https://www.parallax.com/product/910-28088
[2] https://www.parallax.com/product/32912
[3] https://www.parallax.com/product/753-00007
[4] https://learn.parallax.com/sites/default/files/content/AB-Blockly/Projects/PeekingDoll/Peeking-Doll-BlocklyProp-Blocks.svg