Animatronic Hedwig

by timothy.high

Published on November 4, 2016

Bring Harry's Hedwig to life with the help of littleBits!

Using a few littleBits components and some household tools, you can make the official Hedwig doll (from Harry Potter's World in Universal Studios and elsewhere) move and light up. The circuit is fairly simple, but getting it to move Hedwig's head can be tricky unless done right.

The invention relies on using a servo to move the head of the Hedwig doll via the handle inside the doll (that is normally used to turn the head by hand). In order for this all to work, you need to attach the handle to the servo firmly to the servo, and then make sure that the servo is held in place in a way that leaves the head free to turn back and forth without any additional resistance. For our project, we used a tube from an air conditioner outlet that happened to be the right size, and held it in place with a plastic adapter and some wire. Then we made a perch for Hedwig to give her a good place to stand and watch!

Any of the littleBits triggers can be used for this one: the motion sensor is perfect, but we also tried it with the light sensor (as the lights dim, Hedwig's eyes light up!). But just to surprise people, our favorite was the new BLE chip, with a slider control in the littleBits app!

Make this invention for a Harry Potter party, and have Hedwig greet your guests!


How To Make It


Attach the servo to Hedwig's handle This is the most critical step of the whole project. The servo needs to be affixed to the handle so that when the servo turns, Hedwig's head turns, without slipping any, and without too much resistance that might jam the motor. Our solution was to find a tube just the right size for the handle, and a plastic plug for the tube with holes in the bottom. To make sure the plug fit tight enough to not slip, we actually wrapped the end with some electrical tape to make it thicker. Next, using the wire from inside a twist tie, we tied the plug to one of the servo adapters, nice and tight. Finally, the other end of the tube was twisted on to the handle inside the Hedwig doll. With that, we have the base of a circuit for animating Hedwig.


Build the circuit Start with a power source. We used the USB power source with the wall plug, but the battery source works just as well (and is more portable). Next place whatever you have chosen as the trigger for your circuit. In our case, we went with the Bluetooth LE component together with the slider option in the app for remote control. From there, use the split wire, with one part going to the servo wire coming out of Hedwig, and the other going to the lights for her eyes. The eyes are simply two Long LEDs in series, which will attach to the back of Hedwig's head. Finally, keep the pieces from falling apart by using shoes at each connection point. For the servo chip, we chose the "turn" setting. The "swing" setting works, too, but seemed a little too unnatural. The turn setting together with the slider control has the nice effect that the more power you give, the brighter Hedwig's eyes get as she turns her head. This setting is also good with the light sensor, which makes the LEDs get brighter as the lights go dimmer. Note: we also tried this with the tethered DC motor. It works great, too! But you have to be careful not to get the circuit tangled up after turning the head around several times. The BLE component plus the slider control lets the head go back and forth when set on "variable", which is great.


Attach the lights to Hedwig's head Hedwig's head is a good size for the Long LED lights. You can use elastic, a big rubber band or a string to fix the circuit board of the lights to the back of her head, and then wrap the (luckily white!) wires around the side. Try to angle the LEDs so that they are positioned right under or beside her eyes, but so that they aren't noticeable to the casual observer.


Make Hedwig's perch Choose or make a perch for Hedwig to stand on. We used two cardboard tubes left over from wrapping paper, and taped them together in a cross shape with electrical tape. Then we painted them black to make them look like a wood perch. The important thing is to choose a perch that you can use to fix the servo motor in place, but still have enough room to turn. Also, it should look like a natural place for Hedwig to sit. The perch we made worked perfectly for this, since the top part of the crossed tubes fit up inside the puppet, and gave us a place to attach the servo. We used electrical tape again, but had to use the cap of a 2-liter bottle in between the motor and the tube to provide enough room for the servo to turn. (Ignore the clothespin in the photos - that was left over from a previous experiment!)


Put Hedwig in her place Put the perch, with Hedwig, in her final place. Plug her in/turn on her circuit, and connect via the app (or place the trigger where it needs to go). Then give it a go! Extra challenge: see if you can come up with a way to push the button that triggers her noises (on the tip of her left wing). I thought about using a string and a clothespin, but couldn't get it to work.

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