Tiny Time-of-Flight Plasma Theremin: the Plasmino

Details

Theremin are awesome, but designing Analog electronics is hard...

Plasma is awesome, but winding a Tesla coil is hard...

So, lets do it digitally, and use mass produced components to create a tiny, MIDI compatible, digital Time-of-Flight, plasma-speaker Theremin!

Inspired by Pode Coet (http://ultrakeet.com.au/write-ups/modulated-arc-lighter), this project will use a plasma lighter as the starting point, and with the infrared lasers in the VL53LOX distance-sensor, will measure the players hands with millimeter accuracy and generate musical notes.

With two sensors, you can vary both the tone and volume smoothly, or stepwise in any musical key. It will also generate MIDI data, which can be sent back to the PC via USB.

Files

plan.jpg

block diagram of the Plasmino

JPEG Image - 75.20 kB - 09/01/2018 at 12:00

Preview

Components

1 × Arduino Nano Clone wars is OK with me

1 × Dual Arc lighter order from China, wait 4 weeks

2 × VL53L0X on Breakout board Who wants to hand-solder these things!?

Project Logs

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Acoustic Horn
David • 10/12/2018 at 07:23 • 0 comments

Time to think about Impedance matching!
The shockwave produced by the plasma has a lot of force, but over a small small volume. So it probably is not very well acoustically matched to the surrounding air. An Acoustic horn is a geometrical structure that helps match the impedance to get as much power into the surrounding air:
The plan is to use a bilaterally symmetrical horn to acoustically match the approximately 1-dimensional plasma speaker to the surrounding air:
This will be printed in PLA, and contain the Arduino Nano, the VL53L0X sensors, and in the middle, the plsma spark-gap.
Demo time!
David • 10/07/2018 at 16:14 • 0 comments

As promised, here are some demo's:

Sorry the sound it's a bit quiet, its recorded on a phone (and in vertical)!
How this thing works
David • 10/05/2018 at 19:38 • 0 comments

OK, Go the VL53LOX sensors working. Will post a video tomorrow.

Basically it works like this

We generate 2 sets of square wave pulses, at ultrasonic frequencies

1) ⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍
2) _⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍⎍

They are out of phase, and the generated plasma expands the air.

If we turn this on and off at audio frequencies, we cause vibrations in the air, as the plasma expands and contracts.

1) ⎍⎍⎍⎍⎍⎍____⎍⎍⎍⎍⎍⎍⎍____⎍⎍⎍⎍⎍⎍⎍____⎍⎍⎍⎍⎍⎍____⎍⎍⎍⎍⎍⎍
2) _⎍⎍⎍⎍⎍⎍____⎍⎍⎍⎍⎍⎍⎍____⎍⎍⎍⎍⎍⎍⎍____⎍⎍⎍⎍⎍⎍____⎍⎍⎍⎍⎍⎍

We can also modulate the volume by changing the duty-cycle, but keeping the frequency the same:

Louder
1) ⎍⎍⎍⎍⎍_____⎍⎍⎍⎍⎍_____⎍⎍⎍⎍⎍_____⎍⎍⎍⎍⎍_____⎍⎍⎍⎍⎍_____
2) _⎍⎍⎍⎍⎍_____⎍⎍⎍⎍⎍_____⎍⎍⎍⎍⎍_____⎍⎍⎍⎍⎍_____⎍⎍⎍⎍⎍_____

Quiter

1) ⎍⎍⎍_______⎍⎍⎍_______⎍⎍⎍_______⎍⎍⎍_______⎍⎍⎍_______
2) _⎍⎍⎍_______⎍⎍⎍_______⎍⎍⎍_______⎍⎍⎍_______⎍⎍⎍______

Pretty simple!
PPPPLLLLLLAAAASSSSSMMMMMAAAAAAA
David • 09/01/2018 at 10:55 • 0 comments

OK, plasma speakers are GO!
More details
David • 08/31/2018 at 18:27 • 0 comments

Here's the rough schematic for the plasma lighter:

Two opposite PWM signals are fed into s1 and s2 to pulse current though the coils in the high voltage transformer, at ultrasonic frequencies.

I plan to pulse the PWM signals to generate audible tones. More to come soon.
Project started!
David • 08/31/2018 at 10:12 • 0 comments

OK, I've stripped down a dual-arc lighter, and reverse engineered the circuit.

Seems to be just 2 mosfets, a few resistors and the pulse generator/LiPo charger that I won't be needing at this stage.

I've started coding a Arduino Nano clone to generate the note, as done previously here:

http://ultrakeet.com.au/write-ups/modulated-arc-lighter

After that, I'll add in VL53LOX TOF sensor support.