Assembling Emoto Hardware

Here are the instructions to make the hardware for your own phone charging robotic sidekick! The software counterpart to this tutorial is here: software tutorial.

The following instructions require you to have some general understanding of how 3D printers work as well having some level of proficiency at soldering. Once assembled you’ll have a mobile robotic charging dock for your phone. Feel free to reach out with any questions! Depending on the printer you may have access to printing should take a little under 24 hours. Once printed assembly should take a little less than a few hours :)

If you’re interested you can check out some of the process surrounding the concept based on the physical design here in about a week.

3D Printing:

All of the hardware that went into building Emoto is made from custom 3D printed parts and hardware from the servo motors that allow it to move. Other than that the electronics and cabling are all off the shelf parts. For the wireless charger, we found a magnetic car charger and retrofit the components into our design.

The .stl files can be downloaded from here: thingeverse.

Other parts for purchase:

Bill Of Materials:

Note: Depending on your access to a 3D printer, 3D printing might make up the bulk of the cost if you want to build on these. If you’re lucky enough to have one that is free to use you can probably get away with a single 1kg spool of filament. Of course, you’ll need a phone as well. We did all of our tests using an iPhoneX.


1 — Mounting Servos

1.1) Mount the bottom servo. This servo will enable Emoto to spin around. Use the four mounting screws provided in the little baggie that comes with each servo.

1.2) Thread the middle servo cable through the slot in the back of the housing. While maintaining tension on the servo cable (pulling back the rubber top to fit snuggly inside the enclosure)push the servo to the back of its housing. Use the four mounting screws from your servo parts baggie keep the servo in place

1.3) Thread the top servo as well as the USB power cable that will be used for the Qi Charger through the top enclosure. You might need to press the cables down a bit so that they fit snuggly below the servo. You’ll obviously need to cut the USB-type A side off before threading it through, but do that before installing the servo. This will allow you to fold the cables in neatly underneath the servo. This step might take a bit of messing around with.

2 — Installing Qi Charger

2.1) In this part we’re going to retrofit the components from an existing qi charger on amazon.

The trickiest part is removing the ferrite disk that holds the copper coils. Make sure you’re wearing some sort of eye protection when you remove this part. We were able to peel up the adhesive holding the ferrite disk by fracturing it. We noticed that a ton of the magnetic car qi chargers available online are already fractured (probably not by design) For the most part we realized that if the fracturing was minimal the qi charger still worked.

When you install the 3D printed enclosure make sure that the access port for the cable is set up so that it can rotate from end to end without cutting off access.

3 — Attaching Top Enclosure

3.1) Install the circular servo horn that comes with each HiTech servo.

3.2) Thread the cabling through the base enclosure.

3.3) Fasten the top enclosure.

4 — Installing the Electronics

4.1) Install the raspberry pi, it should fit pretty snug in there. The full software setup instructions can be found here: software instructions

4.2) Install the battery holder and charging circuit.

5) Soldering

Here are some things to keep in mind.

  1. Consider dry fitting everything before you slice up your cables. You should be able to get a sense of how much cabling you’ll need for each connection. Leave some slack for the qi charger which might move around a little bit in the actuated neck joint
  2. we’re hijacking the terminals off of the back of the usb terminals. These are small connections so make sure to clip the leads on your wires close. If you add a little excess solder to the wire you can usually get away with just pressing it down to the contact with the tip of your soldering iron.
  3. Take a look at the gifs below if you’re confused with how to approach this.
how to wire up the power supply
wiring battery terminals & usb

5 — Closing this little bean up:)

To have the phone stick to the magnetic mount you’ll have to install the adhesive metal ring that came with the magnetic car charger centered on the back of your phone.


Building physical experiences @ Google