Electrical Assembly

Gather Materials 

Gather the materials below and get ready to build the Thimble WiFi Robot! As you follow through our tutorial, please know that we see this as a living document. If you discover anything unclear in the instructions, let us know and we will do our best to fix it as fast as we can. Each page of every module on our learning platform has a section for discussion at the bottom of it, so please use that to let us know about anything that is unclear. We believe strongly in the philosophy of empathy-driven development, and if something is unclear to you, it is likely unclear to others.

Our tutorials are meant to be a fun way to explore the world of electronics. We have included not only instructions, but also some theory, history, and challenges for you to explore on your own. If you only want to build the robot, you can skip over these discussions and links, but we encourage you to spend some time exploring and discussing all the resources we included here.

Introduction video
This 1 minute video introduces the Thimble WiFi robot.


All Parts
All Parts
WiFi-Bot v2.0 PCB
Laser Cut Platform
Laser Cut Motor Mounts
Laser Cut Rotary Encoders
Wire (For Motors)
Terminal Blocks
Female Headers 1x4
Photointerruptor (Optical Switch)
Ultrasonic Module (HCSR04)
WiFi Module (ESP8266)
Stackable Headers
Battery Holder (4XAA)
Batteries (4xAA not included)
WiFi-Bot v2.0 PCB 1
Laser Cut Platform 1
Laser Cut Motor Mounts 2
Laser Cut Rotary Encoders 2
Motors 2
Wire (For Motors) 1
Wheels 2
Caster 1
Terminal Blocks 3
Female Headers 1x4 3
Photointerruptor (Optical Switch) 2
Ultrasonic Module (HCSR04) 1
WiFi Module (ESP8266) 1
Stackable Headers 4
Breadboard 1
Battery Holder (4XAA) 1
Batteries (4xAA not included) 1

Tools you'll need

Soldering Iron
Solder Wire
Wire Strippers/Cutters
Flush Diagonal Cutters
Hot Glue Gun
Solder Sucker (optional)
Solder Wick (optional)

Getting Started Assembling the PCB 

We've found most people prefer following along in the tutorial step by step, clicking on the videos and images that accompany each video to look at more detail. However, some people may prefer to watch the entire assembly process first.

Complete Assembly Instructions Video
This ~25 minute video shows the entire process of assembling the WiFi robot.

Assembling the PCB

The first thing to do is un-box your kit and lay the components out on the table. We'll start by assembling the printed circuit board (PCB). In the Arduino world, PCBs are commonly referred to as "shields."

How to Use a Soldering Iron
A short instructional video to learn how to use a soldering iron safely and properly.

The PCB comes with all of the surface mount parts (highlighted in the photo below) pre-soldered to the board.

We'll start by inserting the stackable headers into the PCB and using solder to tack them into place. These headers allow us to insert the PCB into the Arduino (or Arduino-compatible board) while still allowing us access to the sockets on top of the Arduino in order to add additional circuitry.

Once you’re done putting in all the headers on both sides of the PCB, carefully flip the PCB over. Use your fingers to keep the headers intact as you flip it over so they don’t fall out. This can be a little tricky at first but you’ll get the hang of it.

Start soldering video clip
Start soldering video clip
Bare, unpopulated Thimble WiFi Bot PCB
Through hole parts to be populated
Surface mount parts
Insert the stackable headers into the PCB
Insert the 10-pin stackable header into the PCB
Insert the 10-pin stackable header into the PCB
Insert the 8-pin stackable header into the PCB
Insert the 8-pin stackable header into the PCB
Insert the rest of the stackable headers and flip the board over
Tack headers in place

Now we're ready to start soldering! As mentioned before, start by using solder to tack the headers in place (only solder one pin for each header). Grab your soldering iron and solder wire. Place the soldering iron on the top right pin; slowly push solder wire into the pad and soldering iron tip. Solder should start to flow as you push it (solder should resemble a little dot or joint).

Using a Solder Sucker
Make a mess while soldering your pins? The solder sucker has you covered. Learn how to clean up your solder joints with this video.

At this point, all headers should be soldered firmly onto the PCB. If you have made it this far, give yourself a firm pat on the back. You have soldered more than most people do in their lifetime. :-D


You may want to wait to solder the green terminal blocks until after you have soldered all of the other headers (black pieces) to the board. The terminal blocks are slightly taller and may make it more difficult for you to hold the pieces in place when soldering on a table top.

Now it’s time to solder the other through-hole components onto the PCB. Using your hands, take the little green connectors (aka terminal blocks) and attach them together. There is a little notch that will allow each green connector to slide into one another.

The three green terminal blocks
The three green terminal blocks
Slide each terminal block together to form one unit
Insert the terminal blocks into the PCB
Flip the PCB over
Use solder to tack the terminal blocks in place
Place two 4-pin stackable headers onto the PCB
Place two 4-pin stackable headers onto the PCB
Carefully flip over PCB board and tack the two 4-pin headers in place. You can use tape to hold these headers in place
Flip the board back over and tack the 2x4 header in place. This will connect to the WiFi module ESP8266
The last part - the final 4-pin header. This holds the ultrasonic module in place

Once you have all the parts tacked in place, flip the board over and you're ready to solder all of the pins. Again, remember to be careful to make sure there are no solder bridges. A solder bridge is where two or more pins have solder touching. This is bad as it results in an electrical short (both pins will have the same voltage). Depending on the circuit, this can cause damage if we apply electricity. However, again, if you find yourself in this situation, don't dismay - it can be fixed! Just scroll up and watch the video about using a solder sucker and solder wick.

Inspect your solder joints
Once you have soldered all of the electrical pieces in place, do a careful visual inspection to double check for and fix any shorts. Then give yourself a serious high five! This is great progress! Next, we're ready to solder the motors and move on to the mechanical assembly of the robot!

Connecting the Motors 

For the electrical connection of the motors, you'll need two sets of two wires and the wire cutters. We use the black and white wires included in the kit, but you can use the color of your choice.

Grab the piece of wire you need and gently strip the ends of the wire with your wire cutters.

Solder wires onto the motors
Solder wires onto the motors
Grab the piece of wire you'd like to use
Strip the ends of the wire with your wire cutters

Place the wire through the copper contacts of the motor on both sides. Then solder the wire onto the joint. Repeat for the other motor. Make sure the wire has some flexibility to it and wrap it around the motor so it will not rip the copper contact off the motor. You may want to use some hot glue here (after it is soldered) to provide some strain relief and ensure the wire will not rip.

Now you're ready for the last part of assembling the robot - the mechanical assembly.