Skip to content

Sourcing Parts

One of the key values of CoderDojo clubs around the world is to not charge any fees for attending these clubs. Parts need to be purchase by limited funds raised through donations. Club organizers need to be frugal about getting low-cost parts for the participants.

Our experience is that is difficult to get the right parts at low cost using firms that promise quick delivery times of a few days. The lowest price parts often must be purchased weeks in advance from places like China and Taiwan. As a result, clubs that use funds carefully must plan weeks if not months in advance of classes and events. So we strongly suggest bringing an robot part procurement team together two months before you begin to offer robot courses where students can each have their own robots.

Purchasing The Raspberry Pi Kits

As of June 2021, the Raspberry Pi Pico did not come integrated into low-cost development kits that include robot kit parts. You frequently must to purchase the independent parts yourself.

Here are some of the parts we recommend.

The Raspberry Pi Pico

In the US, our best source of these has been Microcenter stores. They sell them for $3.99 and they often have them on sale for $1.99.

Microcenter Pico Part Listing

Microcenter has around 25 Locations in the US.

USB Cable

For a Mac with USB-C connectors, you will need to get a USB micro to C cable: USB Micro to USB C for Mac

Headers

We need male breakaway headers with standard 1/10th inch spacing. The Raspberry Pi Pico will need 20 pins on each side. If you get 40-pin versions they can easily be broken in half.

Solderless Breadboards

We like the 1/2 size boards that have 400 connection points. We like to mount them with the USB connector at the top with the numbers running down the left side to align with the pin numbers.

Hookup Wire

Use 22 gauge wire. Get a large spool of black and red and smaller spools of other colors.

Male-to-Male Breadboard Jumper Wires

You can use 22 gauge wire to build your projects, however kids that don't have fine motor skills sometimes get frustrated with raw wires. You can purchase a Jumper Wire Kit with 65 jumpers on EBay for under $2 that has nice plastic ends that are easier to use.

Momentary Press Buttons

A B3F Momentary Press Button with a blue cap.

Note the schematic in the lower right corner that shows the internal connections of the button.

We like the B3F-4055 12 x12x7.3mm Tactile Switch Momentary Press Buttons that have small dimples on the bottom that fit into the breadboard center trough. They can be purchased for under 10 cents per unit on eBay. You can by them with our without colored caps. The links below have example listings on eBay.

Sensor Kit

Although not all of these items are really "sensors" (some are displays), these kits provide high value at a low price-per item cost. Note that some of these kits contain tilt switches that contain Mercery. I remove these from the kits.

Linear 10K Potentiometers

We use linear 10K potentiometers in many labs and kits. The pre-wired options are very handy but you will need some male-to-male jumpers.

Momentary Press Buttons

We like these small momentary press buttons because they are easy to mount directly on the breadboard. They provide ideal "Mode Programming" buttons to put the microcontroller into a programming mode.

Switches

These are ideal for turning your project boxes on and off.

Small 0.96" OLED displays

We love these low-cost 128X64 OLED displays. They are bright and draw very little power. There are two different connectors: 4-wire I2C and 7-wire SPI. I would suggest the simpler I2C for most starter projects.

Larger 2.42" OLEDs

For our robot projects our students like to view the values from a distance. For them we use these $17 OLED displays that are about twice the size.

2.42" OLED Display wired with SPI

Non-rechargeable AA and AAA Battery Packs

Rechargeable Battery Packs

If you are work on project that need long-lasting portable power such as LED strip costumes, there are a wide variety of long-lasting rechargeable battery packs available from prices around $9 to $15. My favorites are ones that have percentage of power remaining displayed.

Ultrasonic Distance Sensors

These inexpensive "ping" sensors are used in many robot projects.

Motor Controllers

We like two motor three wheel robots in our classrooms. They need a H-Bridge circuit for controlling the motor direction. The popular L293D chip takes four PWM signals and will use these to drive two 3-12v DC motors. The L293D chip can be mounted directly on your breadboard. However, we like the low-cost Mini motor controller boards that are only $2 that also have handy screw headers for easily attaching and removing the motor and power wires.

Here are the specs: Here

Note that the L293D Mini Motor Drive shield also has a voltage regulator that delivers a constant 5 volt signal to the robot microcontroller.