Autonomous Theremin by RestoredOlive

Last crawled date: 3 years ago

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