If you know the person who came up with the term ‘cardboardTronics’, please feel free to thank them. Its such a cool and catchy term for an activity!

Cardboardtronics is the combination of using cardboard in making electronic circuits. Although salvaging electronics components and repurposing in the classroom is something I have been doing for a very long time, I had never come across this website until someone shared it with me.

A LED dimmer circuit
Click on the picture to take you to the website.

First, you salvage material carefully. Ensure you follow the tips provided in the website. A quick reminder that if you see any large capacitors, avoid them as they might still be holding charge. There are plenty of places you could go salvage electronics. For me, its the local tip shop (recycling shop) or salvation army. Most times they have rc toys with a missing remote or the batteries have leaked, but most of the other components are fine.

Follow the resource link on the image to learn more about cardboardtronics. My blog post will be focused on how to program them once you have salvaged the components.

Let’s have a look at LED lights. Most times the led lights that come out of rc toys are the standard 20mA led lights. However with a multimeter you could check the current rating of the led. Do not exceed more than 3v to led lights to test them.

This example is to control 1 led light but you can do multiple. Plug a crocodile clip to pin 0 and the other end to the positive terminal (long end) of the led light. Negative terminal need to go back to ground on the microbit to complete the circuit.

Go to makecode.microbit.org and code up the button presses to turn on the pins as a digitalWrite. I’ve added button b pressed to clear the lights (you could do any event such as shake).

Test your code. The led lights should turn on when buttons are pressed and turned off when you shake the microbit. This is due to the 3v supply to the pins from the microbit supplied as a digital write (either on or off).

Next- to control a motor or servo. For either of those you need attachments called shields. There are separate ones for motors and servos, however there are certain robotics shields made for the microbit which have both motor and servo connections which can be very handy. Check manufacturers for available extension prior to purchasing. Some of the manufacturers will leave you high and dry when it comes to software.

Motor(left) and servo shields

Depending on which shield you get, each manufacturer will have their extension in the store (under advanced in the blocks menu or on github). Try get your cardboard circuit going with the relevant code. Remember, motors are not precise and will keep spinning until the stop function. Servos are more precise. Choose your shield based on your project requirements.

Finally- some analog. Controlling analog components such as a potentiometer is similar to digital in its connections. Programming the controller is via Analog write and the values are from 0 to 1023 ( so it is essentially converting the voltage discreetly due to the 10 bit analog to digital converter on the chip – so 2 ^10 = 1024 values). Connection is via 3 pins (ground, positive and signal). Have a look at this little tutorial to get you going with a pot and microbit.

Embedded below is the cardboardtronics workshop I hosted for teachers. The edit is average, as I had to try make a 6 hour long workshop into something useful to watch. I have also embedded a similar student workshop further below. Resource links to valuable providers and tips/tricks are in the attached slideshow.

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