Joyboy

by Johan_Ha

  • 62 views
  • 0 comments
  • 2 respects

Latae Organi

Project in progress by Johan_Ha

  • 206 views
  • 1 comment
  • 1 respect

Cimini

Project tutorial by Johan_Ha

  • 1,421 views
  • 0 comments
  • 3 respects


Respected projects 1

Bluetooth MIDI-Operated Antique Reed Organ

Project in progress by Willem Hillier

  • 9,107 views
  • 3 comments
  • 28 respects

  • Latae Organi 12 months ago

    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.

  • Self Playing Slide Whistle almost 2 years ago

    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.

  • From KY-039 To Heart Rate over 2 years ago

    Have a look at this curve:
    https://hackster.imgix.net/uploads/attachments/459527/finest_n6KNB7vgPJ.png?auto=compress%2Cformat&w=740&h=555&fit=max

    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:
    https://www.ncbi.nlm.nih.gov/pubmed/8044922

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