Digital IR Theremin

Project Info
Author: Chris
Difficulty: Medium
Time Invested: 4 Hours

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           With our Kickstarter for the next PyroEDU course: An Introduction To Digital Electronics in full swing, we wanted to do an all digital hardware project that was fun but also combined some of the important ideas of electronics together. Thus, the thought of re-imagining the Mini IR theremin was born. The Mini IR theremin was an IR proximity sensor combined with a microcontroller and speaker. When you waved your hand in front of the IR sensor, a tone output from the microcontroller.
           In this article, we will explore how to translate analog voltages from an IR proximity sensor into digital information that we can use to determine distance away from an object. Depending on how far away the object is, a different tone can be heard.

Digital IR Theremin - Demonstration

Digital IR Theremin - Project Setup

Digital IR Theremin - Wiring Bottom

Purpose & Overview Of This Project
          The purpose of this project is to build a system that can translate analog voltages from a sensor into digital signals using window comparators. The comparator output should be used to trigger 1 of 8 tones that should play out of a speaker.
          To build the window comparators that 'translate' the sensor output, we'll use LM339 quad comparators and set constant voltages for the window upper and lower limits. AND Gates, using a 7408, will be used to detect if the sensor's output is inside the 'window' and trigger the tone to play out of the speaker.