A shot of the complete circuit. (via me)
Digital musical instruments are in every facet of music today. Arguably, you can trace digital music’s origin to the original Theremin. Today, the Theremin is more of an art installation than a practical instrument. Synthesizers can imitate just about any sound, including Theremins.
This project is the first step towards making a simple light-based Theremin.
The software works as follows:
- When the Micro:bit powers up, you set the ambient light level limit by pressing the button “A.”
- Then cover the phototransistor with your hand, press the “B” button. This sets the other limit.
- Now when you place you can over the phototransistor, the sound the Micro:bit is producing will change.
First, let’s gather all the necessary components you’ll need to build this project.
1x Breadboard from the Kitronik Inventor's Kit
Project Wires Female - Male
1x Speaker (Powered speaker recommended.)
Video demonstration of the project:
STEP 1
Load the code onto the Micro:bit.
I am providing the hex file you need to drag and drop onto the Micro:bit, and the python code as two separate files. For the below process, just use the hex file.
Plug the MicroUSB cable into the Micro:bit, and plug the other end of the cable to a PC or MAC.
At this point, you are going to copy over the code to the Micro:bit. I am providing the program (code) in this posts that needs to be copied over. When the Micro:bit plugs into a computer, it shows up as a USB flash drive. All you have to do is copy the file over to the Micro:bit, like it’s a USB Flash Drive, and the Micro:bit will reset, and the program is active.
You can remove the Micro:bit from the computer at this point. The program will start running, and without the rest of the circuit, it will not function.
A little bit about the code:
The system itself can be fairly quiet. I suggested a powered speaker. However, you can change the volume in the top declarations.
Also, you can turn the screen LEDs on and off here too by changing the “LED_ON” variable from “True” to “False”
The rest of the code is commented fairly well if you want to see what is going on in it.
STEP 2
I used the breakout board for this project. It’s great for testing and setting up where space and reliability isn’t an issue. It also help to quickly get at the pins on the Micro:bit.
A small breadboard is definitely recommended for the phototransistor circuit.
Lay the Micro:bit and Kitronik Inventor’s Kit on a table. Insert the edge-card end of the Micro:bit into the Inventor’s Kit socket and stick a breadboard to the bottom part of the Inventor’s Kit.
STEP 3
Wire up the schematic to the breakout board.
STEP 4
Plug USB 5V power to the Micro:bit.
At this point, you will hear a little sound.
- Now, press the “A” button to set the ambient light level limit.
- Cover the phototransistor and press the “B” button to set the other limit.
STEP 5
Now you can wave your hand over the phototransistor to change the sound outputted by the Micro:bit.
A simple Theremin!
Conclusion:
This is a great first step towards making a digital musical instrument.
Now, I plan on taking this Theremin to the next level with more features and tones. Expect it in January 2019!
Have a story tip? Message me at: cabe(at)element14(dot)com
