An Arduboy with a Leonardo and an analog joystick
A reed organ capable of playing midi files
Project in progress by Johan_Ha
Chimes that everyone can operate using their own smartphone.
Project tutorial by Johan_Ha
Antique reed organ + solenoids + custom driver boards + 3 Arduino Megas + Bluetooth = MIDI-driven reed organ
Project in progress by Willem Hillier
So this is an unfinished project. It was meant to participate in a competition, the deadline of which was a few minutes ago. Anyway, I'm continuing on the project and will be uploading videos in a few days.
Only a professional can tell the difference between the original soundtrack and this!
What a fun project. I think you can actually improve it a lot. Minimize the movement of the servo poking the sound hole. The friction of the slide of the toy whistle is not big, is it? So the movement could be much faster with the help of some gear and perhaps a better stepper motor and driver.
Have a look at this curve:
It's the filtered curve. After the first two peaks there's a notch in the curve when it goes down after the peak. The notch is somewhere at 1/3 of the way down. If the curve goes up at the notch, it might be recognised as a heart beat. A better filter would even out that notch.
It's all about filtering the original signal, plotting the filtered signal, refining the filtering algorithm, doing a kind of a pattern recognition on the plotted signal and measuring the time between repeated patterns. How the signal looks like depends on your sensor, your finger tip, your nail lacquer, your electronics, ambient light and whatnot.
The best of algorithms would be self adjusting. I guess professional heart rate monitors work like that. Usually one is interested in the mean value of the heart rate at a given time, say within 30 seconds. Finding out how much each beat deviates from the mean might also be interesting, as this paper proposes:
Or connect with your social account:
New here? Create an account