Autonomous Theremin

thingiverse

https://youtu.be/yb1v9autypk Firstly, this isn't really a theremin, it only changes pitch, instead of pitch and volume. Also it changes pitch using a reading from a distance sensor instead of using radio waves, but I thought that autonomous theremin was the best description of what this thing is. It was made using mostly spare 3D printer parts, as well as a few other electronic components. It is controlled using an arduino. I've uploaded a rough circuit diagram as well as the code. If you've watched the video I've attached video of this thing in motion, you'll have realised how out of tune it is. It is limited by the accuracy of the distance sensor and the speed of the motor, so if anyone else tries this, in order to play a recognisable song, you'll need a really accurate distance sensor. Materials 3D Printed Parts - Base + Stand (these two parts form a casing for the electronics) - Plate (this is the part that moves up and down that the distance sensor detects) - Upper Bracket (Holds together the rods at the top and the bearing that the timing belt moves around) - Bearing guide for 608zz bearing (I used the one designed by brnrd https://www.thingiverse.com/thing:20032) Other Parts - 2x linear rods - 2x linear bearings - 4x brackets for linear rods (these could easily be printed) https://www.ebay.com/itm/4pc-8mm-500mm-Linear-Rod-Rail-Shafts-Optical-Axis-4-SCS8UU-Bearing-Blocks-Kit/311802254782?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649 - GT2 Timing Belt https://www.ebay.com/itm/LearCNC-GT2-Timing-Belt-2mm-Pitch-6mm-width-Reprap-CNC-RAMPS-Prusa-3D-Printer/201147542781?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649 - 20 tooth GT2 pulley https://www.banggood.com/162030T-GT2-Aluminum-Timing-Drive-Pulley-For-DIY-3D-Printer-p-1001266.html?rmmds=myorder&cur_warehouse=CN - 608zz bearing https://www.banggood.com/Wholesale-10Pcs-8-x-22-x-7mm-Metal-Sealed-Shielded-Deep-Groove-Ball-Bearing-608zz-p-62636.html?rmmds=myorder&cur_warehouse=CN - Arduino Uno - Wire - A4988 Stepper Driver https://www.banggood.com/3D-Printer-A4988-Reprap-Stepping-Stepper-Step-Motor-Driver-Module-p-88765.html?rmmds=myorder&cur_warehouse=CN - 47 microFarad Capacitor (put in parallel with the power input for the stepper driver) - Potentiometer for controlling volume https://www.ebay.com/itm/10pcs-50K-ohm-3362P-Trim-Pot-Trimmer-Potentiometer-3362P-503/201415102052?epid=1331627127&hash=item2ee5468e64:g:5XEAAOSwajVUTaeN - Nema 17 Stepper motor https://www.banggood.com/NEMA-17-42-Hybrid-Stepper-Motor-5mm-Round-Shaft-Two-Phase-Four-Line-Stepper-Motor-p-1148356.html?rmmds=search&cur_warehouse=CN - Mechanical Endstop https://www.banggood.com/5Pcs-Mechanical-End-Stop-Endstop-Limit-Switch-With-Cable-For-CNC-3D-Printer-RAMPS-1_4-p-1117731.html?rmmds=search - IR Sensor (I wanted to use a remote to control this robot, but if you wanted it would be easy to replace this with a button) https://www.banggood.com/Universal-IR-Infrared-Receiver-Head-With-Iron-Shell-TL1838-VS1838B-1838-38Khz-p-1204379.html?rmmds=search&cur_warehouse=CN - Distance Sensor (I used an HCSR04 ultrasonic distance sensor, but if this thing is going to work, you'd need something more accurate) https://www.ebay.com/itm/1pcs-Ultrasonic-Module-HC-SR04-Distance-Measuring-Transducer-Sensor-for-Arduino/400985326881?epid=1638465117&hash=item5d5c968521:g:kLQAAOxyNyFS-xFw - Prototyping PCB (I soldered the stepper driver to this, and used it to help with managing all the power cables that go to the different devices) https://www.banggood.com/1pc-Double-Side-Prototype-Breadboard-PCB-Printed-Circuit-Board-Tinned-Universal-40mmx60mm-FR4-Fiber-p-1135381.html?rmmds=search&cur_warehouse=CN - Speaker - 12v power source I'm not sure of the exact length of the bolts I used, but the list below has the minimum length. If they turn out to be too long, they can always be cut to size. - 1x M8 bolt > 40mm - 1x M8 nut - 8x M5 bolts > 15mm - 8x M5 nuts - 12x M4 bolts > 10mm - 4x M4 nuts - 14x M3 bolts > 7mm - 10x M3 nuts - 4x 1.3mm bolt for distance sensor > 5mm