Advanced Plasma Arc Speaker

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About: Electromechanical Engineer, Product Designer, Maker. I love to make prototypes and teach others in the process. I graduated from UCF and spent two years working at NASA.

Intro: Advanced Plasma Arc Speaker

Yes, what you hear in that video is only coming from the scorching hot, high voltage plasma arc. It is vibrating the surrounding air similar to a regular speaker but it does so but sending electrons across the spark gap at the same frequency of the music. It's a great conversation starter to keep in your office!

Plasma speakers make amazing tweeters because they can reproduce high frequency sounds better than regular speakers due to the lack of a heavy diaphragm to move. From an audiophiles perspective, plasma tweeters are as good as it gets for high frequency sounds. For low frequency sounds, larger speakers perform much better.

Warning! This is not a beginner project and has the potential to kill you if you are not careful. Please do not attempt this instructable unless you are aware of all the risks involved and have experience with high power, high voltage applications. The speaker can also generate dangerous levels of ozone if left on for too long in confined spaces. Use in a large room and don't use it for long periods of time(More than a few songs at a time).

Step 1: What You Will Need

1. 12V 50A Power Supply: http://amzn.to/1SqM8qd

2. Flyback Transformer: http://amzn.to/1NiRWkc

3. Stainless steel electrodes(or tungsten). You can make them from rods found in printers. The larger, the better because small electrodes will melt.

4. Copper Grounding lugs: http://amzn.to/1Sawjdq

5. Block of wood to mount the grounding lugs. http://amzn.to/1Sawjdq

6. At least 2 Logic Level MOSFETs- http://amzn.to/1Sawjdq The STP40NF10L I used are great because they have a super low Rdson at 5V and even lower at higher voltages.

7. Heatsinks - http://amzn.to/1Sawjdq Preferrably with a fan to further cool them down.

8. Heatsink compound: http://amzn.to/1Sawjdq

9. NE555 Timer - http://amzn.to/1Sawjdq Be wary of using other 555 variants as some are not capable of driving the MOSFETS directly.

10. 3.5mm audio cable: http://amzn.to/1Sawjdq

11. Other components shown in the schematic.

Step 2: Schematic and Optimizing Setup

As noted in the schematic, the power supply is very important here. I suggest using the same 12V 50A power supply that I used in order to have a very reliable supply and the ability to upgrade your speaker if needed. Yes, a 12V 12A power supply will work but it will not be nearly as loud.

The capacitor labeled 10nF in my schematic will need to be changed to suit your flyback transformer's resonant frequency along with the two potentiometers. If you wire yours up exactly as I have do, be sure not to turn the potentiometers to either of their extremes. This is because most potentiometers are poor made and turning all the way clockwise or all the way counterclockwise can result in opening up the circuit at that point. To avoid this limitation, just add a small resistor in series with each potentiometer. Using the two MOSFETs in parallel is a great way to keep the temperature of the MOSFETs from getting too hot. You can even add a third MOSFET in parallel to handle even more power without overheating. The max temperature my MOSFETs get are about 70C which is just fine seeing the max that can handle is 175C.

Instead of the paralleled MOSFETs, you can opt for much more expensive alternatives that can handle high voltages across the drain and source with a low Rds ON and a low voltage threshold.

The RC snubber found across the primary is a great way to dissipate the flyback transformer's inductive spike when the MOSFETs turn off as well as the ringing associated with the leakage inductance of the flyback transformer. The capacitor you use needs to be able to handle the current you are operating at. The resistor should also be free of an inductive components. Be sure to measure the inductance of the resistor you use to make sure is isn't inductive. Carbon film resistors are ideal and you can always use small resistors in series to evenly distribute the power dissipation.

Start with 8 windings on your flyback transformer primary and monitor your MOSFETs temperatures. Remove one winding at a time to increase the power. You can add an audio jack or hard wire in an audio cable for your audio input.

Step 3: Enjoy!

I hope you found this instructable helpful. Feel free to ask any questions you might have and please vote for me for the Circuits contest and the Amps & Speakers contest.

Thank you!

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23 Discussions

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WilliamG238

Question 6 months ago on Step 3

What voltage ratins are used for the caps?

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David the R

1 year ago

If you'd like to hear and see a band use similar speakers, check out ArcAttack on youtube.

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bob8898David the R

Reply 9 months ago

This is nothing like arc attack. This uses analog signals to produce a high voltage output. They are using dual resonant solid state tesla coils. These are using digital signals, and can only play midi. The duty cycle of the frequency being played has to be somewhere in the 1-5% range to keep the transistor from (literally) blowing up. The telsa coils can only safely play 4 notes at once where this flyback driver is streaming analog signals modulated at the resonant frequency of the flyback's secondary tank. This is possible because these small transistors can handle switching upwards of five amps. They are not trying to switch <1000 amps at the zero voltage point of the primary coil. This allows them to have extremely high duty cycles, because they can manage the lower currents

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Dario DavidD

10 months ago

what does the 555 do?

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LastOfTheGamers.

1 year ago

What size wire should you use for the primary of the Flyback Transformer.

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IlanE1

1 year ago

Color me impressed! THX!

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CalebTanner

1 year ago

Do you know the maximum decibel it can reach?

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bmiller91

1 year ago

It might be the ultimate audiophile tweeter, and ignoring complete
impracticality, wouldn't you basically need the rest of the system in a
faraday cage to filter out massive EMI? :-0

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pmk222bmiller91

Reply 1 year ago

I dont have enough knowledge to answer in a very intelligable way, but wouldnt it be easier to put just these in a faraday cage instead of the rest of the system?

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TimothyJ999

1 year ago

Very cool project!

Just a couple quick things questions: I have a 24v 30A PSU: will I run into problems with that or do I need to step it down to 12V?

Also, I have a 600W stx PSU from a computer. Will the 12V supply from that be sufficient, or does it need to be a switching supply as shown?

Thanks!

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louis.m

1 year ago

The only thing I found on this page is a component diagram, do you have a real schema of this project ?

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dregalia

1 year ago

This project doesn't actually pull all 50 amps on the power supply, does it? Do you know what the actual amp usage is on the circuit?

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Proto Gdregalia

Reply 1 year ago

I have done all the way to 30 but I've found that around 15-20 amps is best for reliability. It's nice to have the range and you don't want to run most power supplies at their max rating so I would advise against a 12V 20A supply.

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silverx

1 year ago

cool, I've made one with tip31c-32c pair few years back, but not powerful as yours. increase the gap to get a cool violet arc.

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Proto Gsilverx

Reply 1 year ago

Thanks! Mine won't produce a violet arc unless I turn the power down. It's a pretty hot arc all the way until it breaks. It makes a pretty good jacob's ladder too!

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juliadee

1 year ago

Nice job. I made a plasma speaker as a science fair experiment in 1968, but it didn't sound as good as yours :) Back then it was deemed necessary to add ions to the plasma to increase its conductivity - there was an asbestos wick and some kind of metal chloride solution I think.

A couple of points:

- Paralleling MOSFETs increases their current handling capability, not their voltage handling. For higher voltage you must put them in series.

- The 175ºC max temp for the devices is their _junction_ temperature, not the temperature of the outside of the case. The junction temperature is probably significantly higher than your 70ºC case, depending on heat sinking.

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Proto Gjuliadee

Reply 1 year ago

Thanks!

Correct, on both points. I was just stating that if you were to select a single MOSFET, it would have to withstand the inductive spike from the flyback transformers as well as have a very low RdsON coupled with a low gate threshold voltage to reliable handle the current without overheating.

That's why I like to stay far from the max temperature on the data sheets.

The MOSFETs I listed are a cheap option but Infineon's IPW65R070C6 work much cooler with less chance they will fail due to transient voltage spikes, but they are roughly 10x more expensive. http://www.mouser.com/ds/2/196/IPW65R070C6_2_0-446...