Monthly Archives: April 2019

€5 PPG – photoplethysmogram amplifier / Arduino circuit

The photoplethysmogram (PPG) is a signal that measures changes in blood volume in some part of the body (e.g. the fingertip) by shining light into the skin and detecting small changes in the level of light absorption that occur due … Continue reading

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Clap detector circuit / AirSpell typing system

This circuit combines a simple audio amplifier (based on an LM358 opamp) with an Arduino Nano to facilitate the detection of clapping sounds or blowing on the microphone. This is my breadboard circuit: I actually used a loudspeaker for my … Continue reading

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AirMouse – control mouse pointer in Linux using one switch or by blowing on microphone

Article under construction! To install xdotool: Bash script (save as “airmouse” and “chmod 755 airmouse” to make it executable): Arduino code:

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