Purchasing Parts and Kits for Robot Day
Let's be honest here. Finding low-cost electronic parts and robotics kits that focus on teaching computational thinking is hard. Many online retailers focus on customers with high disposable incomes who are not price-sensitive. Retailers like Amazon frequently take 30% margins and robot parts suppliers are forced to pay Amazon's reseller fees and use Amazon's warehouses. Amazon uses every opportunity to use AI to keep its profit margins high. That puts the burden on teachers and event organizers to be clever and find the best value for your organization. We hope these suggestions help you find value for your Robot Day funding.
As one example, let's take the "2WD Smart Robot Car Chassis" problem.
Here are some identical items:
The price for the chassis alone varies from $3.80 to $95! You can find similar items by searching for "2WD Smart Robot Car Chassis".
The first item is probably priced by an AI agent that is a little out of touch with reality. The second from the retailer BOTs and four DOTs is a lot more reasonable. But the Cytron listing clearly not only has a lower price, but the price goes down if you order multiple items.
If you don't have worries about budgets, the vendor SparkFun sells high-quality parts and you can filter by which robots support MicroPython like Kitronik Autonomous Robotics Platform for Pico. This kit is nice but does not support room for a breadboard on top like the standard Smart Car Chassis.
Avoid Older Arduino Microcontrollers
With the incredible growth of the new Raspberry Pi Pico and RP2040 parts, there is still a flood of older Arduino robot kits on the market.
These kits are severely limited by a lack of RAM (2K compared to the Pico's 264K) and are not breadboard-friendly. I would strongly suggest avoiding these kits. To use OLED displays we need lots of RAM.
Arduino software also requires our users to compile their code and re-download the binaries each time the program code is changed. This works well for small projects but starts to get slower as our programs get more complex.
MicroPython is interpreted so that after any small change the program runs immediately. Our coding labs depend on fast feedback, so MicroPython is a great fit.
Suggested Parts
We are going to go into a sample Robot Day parts list in detail. Here is a summary of some of the parts we suggest.
- Raspberry Pi Pico - Just $4 at MicroCenter
- Breadboard - the "400-tie" 1/2 size versions are fine for our projects
- 2WD Smart Robot Car Chassis - includes motors and battery pack
- Motor Controller - or Cytron Maker Pi RP2040 - used to drive the motors
- Distance sensor - time of flight sensor preferred
- Wires - 20 gauge is the best hookup wire
- Batteries - Costco has great prices
Breadboards, Wire, LEDs and Sensors
You can also purchase bulk breadboards, LEDs, wire, and sensor packages for your Robot Day events.
Breadboards
We like to use the 400-tie breadboards. We use hot glue to keep the pins from slipping out when kids are using them. You can find them on eBay for $1.50 each.
Hookup Wire
We love multi-colored solid-core hookup wire:
LEDs
Here is an example of a kit of 200 LEDs for $6:
We use these with 330-ohm resistors for our 3.3V power from the Pico.
Push Buttons
Many of our breadboard projects use these low-cost push buttons. You can find them on eBay for about 10 cents each.
You can use the following keywords to find them on eBay:
B3F 12x12x7.3mm tactile switch key buttons QTY 10PCS
You can also purchase the 6mm versions but they are a little harder for kids to press. You can also purchase the buttons and caps separably.
10PCS New B3F Tactile Switch Key Button Switch 12x12x7.3mm Blue
Sensor Kit
Rather than purchase individual sensors, you can get a kit that contains 37 sensors. These can be connected using Female-to-Female Dupont connectors with no soldering required.
Raspberry Pi Pico 37 in 1 Sensor Kit
Cytron Maker Pi RP2040
This is our favorite robotics board by far. It is well-designed with many features that make it easy for the students to test their motors and connections.
MAKER-PI-RP2040 at Digikey - great value for $11
The Cytron Maker Pi RP2040 Robotics Board
Elecrow Raspberry Pi Pico Advanced Kit
At $31, the Elecrow Raspberry Pi Pico Advanced Kit is an excellent value.
Sparkfun
Kitronik Autonomous Robotics Platform for Pico
SunFounder Raspberry Pi Pico Robot Kit
Although this kit uses 4 motors (not the usual 2), and it uses the older ultrasonic distance sensor, at $71 it still has some good value. Note that the LiPo batteries are included.