Of all the creatures that inhabit the world of Sesame Street, the strangest (and arguably the funniest) are the Yip Yip aliens.

In this guide I’ll show you how I took an off-the-shelf Yip Yip costume (or one you made) and made a remote controlled version that you can drive around, trigger sounds, and make the mouth move.

Supplies

I've listed all the materials on this Google Sheet, also attached here as a downloadable PDF.

RC Yip Yip Materials - Sheet1.pdf
Download

Step 1: Why I Made It

I really enjoy making projects that I can perform in some way. Until recently, I didn’t realize this was a connecting thread to all my favorite projects. It was a big insight for me, and I mention it because maybe it’s something that clicks for you too.

For example, I was always a little envious of people who made their own remote controlled R2-D2 droids. I’d see them at my local Maker Faire as they’d drive R2 up someone, trigger some lights and sounds, and watch people smile and take pictures with R2 – sometimes wholly unaware of the human being making it all happen from a distance.

The problem is that I don’t have R2-making time, or an R2-making budget. I also imagine that these R2 builders get a little bent out of shape when some kid steps on or accidentally knocks over their expensive, methodically constructed droid.

So I’ve been exploring some ideas on how to relatively make inexpensive RC characters that are fun to take out in the world (especially on Halloween) and make people happy.

If you like this project, you should also check out the remote controlled tricycle-riding puppet I made last year.

Step 2: What to Know Before You Start

This project is a proof of concept. I didn’t design this project for reproducibility. Most of it is cobbled from things I had laying around – an Ikea shade puller, scrap plywood, a spare caster, a costume I found on the curb. The list of materials is certainly incomplete when I consider the spare washers and glue, specialty zip ties, and odd bits I grabbed in a flurry of trial and error.

The project itself is way different than I originally imagined it and undertook a lot of twists and turns, some of which I don’t remember clearly.

This is all to say that I make guarantees that even if you buy all of the items listed above and follow my instructions to the letter, that you’ll end up with an identical result.

I also have to admit that I’ve been doing this stuff long enough to take a lot for granted. I’m going to assume you know how to cut wood and aluminum to the shapes you need, or drill holes in stuff. I’m going to assume you know how to fumble around with microcontrollers and copy-pasted code. I assume you know how to solder, how to create your own custom lengths of wiring, and how to use heat shrink to keep things from shorting. I’m going to assume you know what things will need 12 volts and what things will need 5 volts, how to tell them apart, and how to route power between them.

If you don’t know this stuff, that’s fine. With determination and looking things up on YouTube, projects like this are a great way to learn. Just know that there are a lot of places in this guide where I’m going to breeze over stuff, blindly assuming you know what I know.

You’re on your own. I’m unlikely to reply if you message me for help (nothing personal). Whatever you end up with in the end, you’ll be a more interesting, capable weirdo for having given it a try.

Step 3: Making the RC Platform

The platform design here is the core of the project, and really the thing I’m proudest of pulling together.

It’s not any great feat of engineering. It’s just a great example of “minimum viable product”. I wanted to see if there was a way I could slap just two motors onto a piece of scrap wood and drive it around with a remote control. The answer is yes, yes you can.

So these are the motors I used. I already had them on hand from another project. I think they work great for this application in terms of speed, torque, size, how relatively quiet they are. That said, you could probably substitute in something less expensive (like the plastic gearbox motor I use for the mouth) and get an equally great result. Just make sure it’s a 12v motor and that you have a way to mount it to your board.

I mounted these motors using these brackets. In hindsight, a stronger bracket would have been better, since these bend with just a little pressure. Fortunately, they also bend back into shape. I reinforced the motor by drilling a few holes into the plywood near the rear of the motor and adding zip ties to hug the motor into the board. It’s not pretty, but it works.

And this is a good time to mention the beauty of using plywood. There’s no problem that you can’t drill, glue, screw, or undo your way out of. I changed the location of components multiple times as the project evolved. You probably will too.

With the motors mounted and the scooter wheels mounted to the shafts, I dug around for a caster for the front with the right height to keep the platform more or less even. The one I used had a 2.5 inch wheel and the whole things stands around 3.25 inches tall. I only used one, but two casters would also work and probably make the thing a little more stable.

Step 4: Wiring Diagram

I mean, well... someday.

For now, here’s a photo of a total mess, and a general description of what's going on.

Power is all coming from the 12v battery, which splits off to both the speed controllers and the power distribution block.

I subdivided the power distribution block into a 12v half and a 5v half. The 5v power feeding the 5v half of the distribution block is coming from the power output on the Mecanum mixer module, but you could also take it from the receiver module.

The 12v side of the block feeds the mouth motor (switched on and off by the Remote Aux switch) and the audio board.

The 5v side of the block feeds the NodeMCU board and the LED light strip connected to it.

As far as the wiring for all the GoBilda components go, I've attached their documentation here (incorporating the Mecanum mixer).

For wiring the audio module, I've included their wiring diagram here, as well. A more in-depth PDF is included in the audio section below.

Step 5: Adding the Center Column and Mouth Mechanism

The platform bit is great, but to mount a Yip Yip (or whatever you’re adding) you’ll need some kind of central pole or column to hang it on. I used a combination of GoBilda brand aluminum channel (with pre-drilled hole patterns for motors, plus an end piece I ordered that bolts in and allows it to be mounted easily to the plywood) and some generic hardware store aluminum channel.

The GoBilda channel just extends around 10 inches of the platform, with the mouth motor mounted at the top. The generic channel is zip tied to the GoBilda channel and is just needed to prop up the head of the costume.

The metal arm I attached to the mouth motor extends around X inches and is made from generic aluminum stock. I drilled holes in a few different locations so that I could make adjustments easily.

To give the YipYip some internal structure, I bent some cheap metal shelving brackets across each other and screwed them down to the plywood. This structure also have me a place to mount the PVC pipe ring that I used to constrain the movement of the dowel that runs out to the mouth.

There’s probably an exact science to how and where to place the motor, the PVC ring, the length of the motor arm and the length of the dowel. But instead of consulting the science I just tried combinations until I got something I liked. The ring is just held in place with zip ties and some leftover armature wire. It’s janky, but also easy to adjust and fix.

This is all to say, don’t let science and math get in the way of just excitedly trying things until it’s good enough. You get happy accidents this way. Like, the way the mouth kinda scoops open instead of going straight up and down – I didn’t plan that. I just fiddled around until it worked out that way.

Step 6: Modifying the Costume

There are two necessary modifications to the costume. The first is to cut off all the tentacles. You’ll mount them to the platform separately so that they stick up instead of drag behind.

The second necessary modification is to cut out some of the internal wire at the corners of the Yip Yip’s mouth. This allows the mouth to move freely and also removes some weight.

While you’re in there, cut out a little spot to access the wire in the lower lip. Run a zip tie around the wire to create a loop that you can later attach to the rod that moves the mouth up and down.

For this, and all other modifications to the stitching on the costume, be sure to liberally smear some E6000 adhesive on the cut threads to prevent them from unraveling.

Step 7: Making Poseable Tentacles

Cut lengths of armature wire just slightly longer than tentacle fabric. Place all the tentacle fabric pieces fur side down on a surface (outside ideally). Then use a strong spray adhesive to coat the exposed fabric, lay in the armature wire, and fold the fabric around the wire. Press the sides firmly together and let dry.

When you’re done, you’ll have what looks like a muppet Yakitori feast. Using a pair of pliers, create small loops in the exposed ends of the wire. Screw those ends down to the platform.

To create some extra strong tentacles capable of supporting small bike lights/spotlights, remove the steel wire from the skirt of the Yip Yip costume and use it to make a few tentacles. This wire is harder to work with, but it doesn’t bend as easily under weight.

Step 8: Adding Sound

I mean, what’s a Yip Yip with no “Yip”?

I think this still would have been a fun project without sound, but adding amplified Yip Yip clips really makes a big difference. It also gave me an opportunity to try a new audio board I’ve been interested in.

The DY-HV20T Audio Board with amplifier is a great, cheap, all-in-one project audio solution I learned about from Playful Technology in his video on adding audio to projects.

There’s a bunch of sophisticated ways you can use it to trigger specific audio clips by pairing it up with an Arduino. For me, I just use it like a generic shuffle MP3 player.

I loaded up a bunch of clips I recorded off my computer by looking through old Yip Yip episodes online. I converted those clips to MP3 using Audacity. Then I loaded those clips onto a microSD card and loaded the card into the board.

I have the jumper switches on the board set to 1 (up) 2 (down) 3 (up). In this mode, any time you connect the first pin to ground (the top pin to the bottom pin) it will advance to the next clip.

The trick to preventing all the clips from continuously playing and driving you crazy is to add 2-5 minutes of silence at the end of each clip. This way, your Yip Yip will make sounds automatically without you doing anything, but you also get the ability to call up a random sound at a moment's notice.

A1qP5OvjqpL.pdf
Download

Step 9: RC Switch Trigger Mechanism

So how do you remotely trigger the sound? There’s probably some cool ways to do it, but I kept it simple by essentially attaching a servo to a switch.

You can copy, modify, or download my 3D printed bracket. It holds a standard SG90 servo and a mini microswitch (limit switch). Positioned in just the right way, the servo horn sweeps over the microswitch lever and momentarily activates the switch. Again, it’s not pretty, but easy to adjust and fix.

Limit Switch.stl
Download View in 3D

Step 10: Adding the Speaker

I have a ton of old speakers in my spare parts bin that I could’ve, should’ve used. Instead, I had this Tactile Transducer from Dayton Audio that I was itching to try. It’s interesting because it essentially turns whatever you screw it onto (in this case the plywood platform) into a speaker.

Running on the audio boards amplifier at full volume, it’s enough to be heard through the clatter of Halloween trick or treaters. I also like that it’s got enough low end to not sound as irritating as some project speakers I’ve used in the past.

It’s worth noting that the audio board has a hardware potentiometer for adjusting the volume. I kept it low during testing, so as not to go crazy.

Also worth noting that this board can get much louder if you supply a higher voltage to it. I’m only giving it 12 volts, but it can take up to 35 volts.

Step 11: Adding Platform Lights

Now we’re just dealing with the extra touches. Since Yip Yip was primarily going to be seen at night, I thought it would be great to add some lighting effects.

To make it seem like he’s floating around on a kind of futuristic hover platform, I ran a strip of addressable LED lights (Neopixels) around the front. To drive the LED animation, I could have used any of the Arduino or Adafruit boards in my collection. Instead I went with an inexpensive NodeMCU Microcontroller Board and set it up without any code by using the WLED online installer.

By using WLED, you can connect the board to your phone and browse different preset animations and create a looping playlist of different animations that the lights cycle through. It’s neat.

If it hadn’t worked out, I would have gone back to the trust FastLED library demo that I’ve used in prior projects.

Step 12: Adding Metal Mesh

To protect the delicate platform electronics from meddling, curious kids, I cut sections of metal mesh and attached them to the framework with short sheet metal screws.

It doesn’t protect everything, but it can take a kick or stomp better than not having anything.

Do make sure to leave some spots open so that you can make repairs and swap out the battery when needed.

Also, be sure to fold over or file down any sharp edges on the mesh. Not only will you save yourself some cuts, but you’ll also prevent the costume from catching or tearing on the mesh.

Step 13: Adding Eyeball Lights

Again, since it’s night, I wanted people to be able to notice features on the Yip Yip, like its eyes.

I lit these up by drilling a hole at the base of each eye (on the back side) and pushing in a standard 3mm white LED.

Because I wanted to keep it so that the Yip Yip costume could be pulled off easily for repairs and battery swaps, I steered clear of wiring the LEDs to the platform power block.

Instead, I just took a coin cell battery holder I had leftover from a set of fairy lights, zip tied that inside the head and routed the power leads up through one of the existing antenna holes.

You can see the witing on top of the head if you look close, but it’s still pretty discreet.

Step 14: Adding Tentacle Spotlights

Even with the glowing platform and the illuminated eyes, it’s still pretty hard to see the Yip Yip’s body at night.

To fix this, I bought a few small, rechargeable LED bike lights and attached them to tentacles on the front and back.

The aluminum wire is a little weak to support their weight, though, so you may need to fold over or double up the tentacles. I ended up creating a few tentacles using the leftover steel wire from the bottom of the Yip Yip to create a few extra strong tentacles just for the spotlights.