User Guide

This page is to help you get up and running with the Plasma Speaker demo. If you want to show off the demo, you're in the right place!

Safety

WARNING: This demo uses very high voltage. The voltage generated across the spark gap is high enough to be lethal. Do not operate the demo without the acrylic cover secured in place. Develop and operate at your own risk!

First-Time Setup

This section explains how to set up the Plasma Speaker for the first time. You should only follow these steps if:

• You are running the Plasma Speaker for the first time after a hardware change, or
• The Regular Setup and Operation instructions are not working as expected.

1. With the power disconnected, remove the acrylic cover.
2. Disconnect the primary winding of the flyback transformer from the PCB.
3. Connect an oscilloscope probe to pin 3 of IC2 (NE555). The right side of R9 can also be used.
4. Connect power.
5. Adjust the trim pot VR2 until you can see a square wave on the oscilloscope. Then adjust it back until the square wave just barely disappears. You want the trim pot to be set as close to the threshold as possible, but where the square wave does not appear. The farther you are from the threshold, the more voltage will be required on the audio line to trigger the arc.
6. While pressing the test-fire button (SW1), adjust the trim pot VR1 until the square wave has a frequency of 22.5 kHz.
7. Disconnect power and the oscilloscope. Reattach the primary coil with the correct polarity.
8. Reattach the acrylic cover.

Regular Setup and Operation

The setup of the Plasma Speaker is simple:

1. Plug the power supply into a wall outlet. If you use an extension cord, make sure it is 16 AWG or bigger.
2. Connect the aux cord to the MP3 player or other device. Yes, you can use your phone or laptop for this!

Once you are set up, you are ready to operate the Plasma Speaker:

1. Turn on the main power switch. The green PWR LED on each board should light. The red ACT LED on each board should remain off.
2. Turn on the MP3 player. This is done by pressing the power/play button for 3 seconds.
3. Make sure the volume is turned all the way up. This is done by pressing on the top corner of the screen.
4. Play music! On the MP3 player, this is done by pressing the power/play button briefly. While music is playing, the red ACT LED on each board should light.

WARNING: Do not run the Plasma Speaker for more than 30 minutes at a time. Allow it to cool for 10 minutes between runs.

Preparing Audio Files

There are many ways one could prepare an audio file for use on the Plasma speaker. Here are the 3 simplest:

1. [Easy; Good Sound] Find an "8-bit" audio file on the internet (ex: YouTube), preferably with fewer than 4 tones at once at any given point in the song. These songs generally sound better on the plasma speaker, as they retain the tune while stripping out noisy frequencies and most amplitude modulation.
2. [Easy; OK Sound] Find any (preferably simple) audio file for testing; Some sound great!
3. [Medium; Best Sound] Find a 2-4 voice MIDI file (ideally specifically made for Tesla Coils), bring it into a MIDI Player, and either play it directly to the Plasma speaker or export a .wav or .mp3 file for the mp3 player.
   • If possible, look for ways to split the music into an "upper" and "lower" part in a MIDI editor, and export the parts on different audio channels (balanced left and balanced right), as this will allow the different parts to be played on different plasma arcs.
     • In Anvil Studio (installed on shop computer):
       1. Download MIDI file
       2. Track -> Clone
       3. Change left / right balance to opposite sides for the two tracks
       4. Change instrument to "Lead 2 (sawtooth)" for both channels
       5. Open each track, and delete notes that won't be in that channel
       6. File -> Export Mixed Audio -> Change Audio Format -> "Stereo" -> OK -> Change Volume -> 100% -> OK
       7. NOTE: Anvil Studio limits exports to 1 minute long without a $19 lifetime license. If we use this we'll either stick to 1-minute song clips or buy a license for the shop.
   • Tutorial on Preparing Simplified Tesla Coil MIDI Files from Normal Audio Files
   • Forum Post on High Voltage Forum with MIDI Files
   • Optimized MIDI Files for Classic Tunes

Routine Maintenance

• Sand down electrode points (with power off!)