My (failed) singing arc plasma speaker project.
My (failed) singing arc plasma speaker project.
My (failed) singing arc plasma speaker project.
This instructable will show you how to make a simple plasma speaker (UPDATE: this circuit was a FAIL, so I moved on to a ZVS topology. Please see my new instructable if you are interested in building a working singing arc.)

A plasma speaker (singing arc) is a device that generates a high voltage discharge that emits audible music. all the sound comes from the arc or plasma.

How It Works.
in this version, we will use the magic of PWM to create audible sparks.

Astable 555 circuitry is the heart of the circuit. It makes a initial high frequency signal of about 18,000 Hz and the pulse-width is controlled by an audio source. This signal controls a high power transistor that turns on and off the power to the flyback transformer. this "oscillation" drives the flyback, and the flyback's output spark will essentially get thicker and thinner as a result.

Its sort of like flipping a light switch ON and OFF. (Just 18,000 times a second, easy!) If you leave the switch ON longer than you leave it OFF, the light will be brighter than half. and if its OFF for longer than it is ON, the light would be dimmer. That's PWM's core.

Now just flip the light switch on and off 18 thousand times a second, and control how long each pulse is in proportion with the amplitude of an mp3 output, and now your light will dance to the music, (with the slight chance you'll break the light switch)

Step 1: Parts

My (failed) singing arc plasma speaker project.
My (failed) singing arc plasma speaker project.
My (failed) singing arc plasma speaker project.
My (failed) singing arc plasma speaker project.
My (failed) singing arc plasma speaker project.
My (failed) singing arc plasma speaker project.
you will need:

? power supply (SLA battery's work, or a plug in power supply capable (PSU) of 4A)

? heatsink (your mosfet will go POOF without it, and get a big one too, I use the heatsink that was an
my power supply, and a fan)

? flyback transformer (you can get it out of old TV's or online. the larger, the better,)

? high power MOSFET ( find it online or one in the TV you found the flyback or online)

? 555 timer (you can get one at radioshack or 10 of them for the same price online)

? a 8-pin IC holder (to make it possible to replace the 555 if it goes POOF)

? (2) 5K POT (i ordered both online,available online and local electronics shop )

? 0.01uF ceramic capacitor (buy it online,local electronics shop, or in my case, junkbox)

? 0.1uF film capacitor (buy it online, local electronics shop, or in my case, junkbox)

? 0.47uF electrolytic capacitor (buy it online, local electronics shop, or in my case, junkbox)

? high value (470uF) electrolytic capacitor (buy it online, local electronics shop, or in my case, junkbox)

? PCB (available online and local electronics shop)

? computer fan (a small computer fan i found in a computer power supply unit)

? wire (buy it online, local electronics shop, or in my case, junkbox)

? duct tape and electrical tape (for use to cover the bottom of the PSU and better insulate internal components)

----------------------------------------------------------------------------------OPTIONAL--------------------------------------------------------------------------------

? a housing for everything (i am making a custom wooden box as shown later in the instructable)
* quartercut white oak half inch thick, 5 inches wide, and at least 3 feet (with some extra)
* small brass wood screws
* small screws with matching nut
* wood finish
* wood-working equipment
* wood glue
* belt sander, random orbit sander, and good old handheld sandpaper
* jointer
* plainer
* router with 3/8ths inch rabbiting bit
* table saw
* box joint jig
* drill w/ small drill but for the 8 wood screws and metal

? sheet of metal (10 X 5 inch)

? metalworking equipment
* Something to cut it to size. I used a dremel but i didn't get a good straight cut, so I cut a bit bigger and ground it down with a
large stationary belt sander
* Drill press with various bits ranging from 1/16 inch to over 1/2 inch
* Sand-blaster
* Clear-coat

? indicator light
(I got myself one from online for a buck, but i replaced the inside ne2 bulb with a 5V light)

Step 2: Tools required

My (failed) singing arc plasma speaker project.
My (failed) singing arc plasma speaker project.
My (failed) singing arc plasma speaker project.
? Soldering iron

? Solder

? Sponge (for cleaning the tip of the iron)

? Flux solder paste

? Breadboard with wire

? Wire strippers

? Needle nose pliers and diagonal cutting pliers(highly recommended)

? Helping hands

? Screw-driver

? Tape

? Tape measure

Step 3: Circuit diagram and prototyping

My (failed) singing arc plasma speaker project.
My (failed) singing arc plasma speaker project.
My (failed) singing arc plasma speaker project.
My (failed) singing arc plasma speaker project.
My (failed) singing arc plasma speaker project.
The circuitry is very simple. its just your standard 555 with an audio input connected to pin 5 as you see below.
the 555 drives a high power MOSFET which drives the flyback.

Gather all your parts and build your circuit according to the schematic on a breadboard.

Step 4: Installing the parts

My (failed) singing arc plasma speaker project.
My (failed) singing arc plasma speaker project.
My (failed) singing arc plasma speaker project.
My (failed) singing arc plasma speaker project.
1) Get your PCB ready and place all the parts on, solder them in place.

2) Flip the board over and connect all the parts together.(tip: i go about this by bending over the leads i want connected towards each other so they touch and soldering then in place) remember, when you flip the board around, you are looking at a flipped view of the board so be double sure you are looking at the right lead on the underside

3) Check all your work again and make sure all your connection are good. I included a little mspaint drawn out board of how I made mine.


Step 5: Testing the finished circuit with a small power supply

My (failed) singing arc plasma speaker project.
My (failed) singing arc plasma speaker project.
My (failed) singing arc plasma speaker project.
My (failed) singing arc plasma speaker project.
My (failed) singing arc plasma speaker project.
My (failed) singing arc plasma speaker project.
My (failed) singing arc plasma speaker project.
Show All 7 Items
After you put together the final circuit, it should look like below. With a 0.8A 12V wall wart a get about 1 cm ark and can gets arks as long as 1 1/2 inch.

I found this is not very loud, and you may need a preamp between the audio source and the input on the circuit.

Step 6: Building the wood case

My (failed) singing arc plasma speaker project.
My (failed) singing arc plasma speaker project.
My (failed) singing arc plasma speaker project.
My (failed) singing arc plasma speaker project.
My (failed) singing arc plasma speaker project.
My (failed) singing arc plasma speaker project.
My (failed) singing arc plasma speaker project.
My (failed) singing arc plasma speaker project.
My (failed) singing arc plasma speaker project.
Show All 9 Items
lay out the scheme for the 1/2 inch wood. the box when finished should be 10 x 5.5 x 4.5 inches. There are slits 1/4 deep and 1/4 inch wide to fit the control panel and backside.

The first thing that needs to be done is polishing up the quartercut board. To do this, first run the board though a jointer on all 4 sides. then, run it through the planer. Also, get the board down to 4 1/2 inch thickness. Then cut it to size with a saw. (Two 10 inch long pieces and two 5 1/2 inch long pieces.)

Now make box joints as shown in the first graphic below. (note: I screwed up on the 10 by 4 1/2 piece, there should be box joints on both ends, not just one.)

After I finished all the pieces, glue them together. The pieces may need to be hammered together. After it has finished gluing, fill in all the holes and spots left over with wood putty. Then start the sanding, First with a belt sander, then a random orbit sander, then with handheld sandpaper. You should end up with something that looks like picture 6.

then use a router to cut the slit or notch (whatever you want to call it) into the open sides as shown in picture 7, 8 and 9.


Step 7: The front plate and back cover

My (failed) singing arc plasma speaker project.
My (failed) singing arc plasma speaker project.
My (failed) singing arc plasma speaker project.
For the front control plate we will need a sheet of steel to make a front control plate and a back cover plate. So by the appropriate sized sheet. It may be good to buy one that is larger than what you need for a backup in case you messed up on the first one, but I went cheap and bought just enough for 2. Try to pick up one with minimal scratches and dings on it. Spots are OK if they can be wiped off.

I used a dremel to cut out the plates, then used a stationary belt sander to finish off the edges. Then figure out how you want your layout. I show my layout in the first picture. After you made the measurements and you are sure of where everything is going, mark the spots and drill them out.Then finish off with filing the leftover trash.


Step 8: FAIL

My (failed) singing arc plasma speaker project.
Well the train hit the wall. After getting the circuit to work, I crammed everything into the relatively small box and just after a few seconds, the circuit failed. MOSFET blown, 555 damaged, and $1 wasted. fit it up, replace the parts, and FAIL again. At one point I even popped the flyback transformer!!! OK, another $20, them power supply fails, and was forced to call it quits. ERRR! Anyway, After thinking about it a long time, and I think I have some reasons this failed so hard.

First, I was trying to cram everything inside a small wooden box. The circuit seemingly worked fine while on the breadboard, but the second I shoved it all in, It would fail, even though all the wires were insulated.

Second, the circuit board I made for this is SLOPPY. I realized after getting it working, the audio input did not work as intended. When I went to see what went wrong this time, I realized my wiring was very wrong and was surprised the chip didn't explode!, let alone give me a good output!

Third, problem is simply the operation of this driver. I kept tring to stop the HV spikes from killing MOSFETS, but when I used a reverse-biased diode to hopefully short the spikes, I lost almost all the output power! Then my diode overheated. After reading up on more info about this driver, I learned one of the fundamental principles of inductors. the current flowing though them can not be changed instantaneously.

This means voltage on both the primary and secondary will rise until it discharges somewhere, either though the output, or the sensitive MOSFET These voltage spikes are necessary for this circuit to function. FACEPALM! So I figured there is not much more that can be done with this type of driver without a 100V supply and IGBT's



Step 9: New ideas, better, more reliable driver (hopefully)

So after realizing that driving an inductor or transformer in the flyback mode of operation will basicly lead to failure at higher powers, I decided it was time to change tactics. Instead of driving the flyback in it's flyback mode, I will drive it with resonance!

One of the most popular circuits for drivers is the ZVS flyback driver. This circuit is essentially a Royer oscillator, that uses two MOSFETS to drive a tank circuit with the transformer for the inductor. This circuit relies on resonance rather than flyback operation.

Think of resonance like pushing someone on a swing. Push them at just the right time, and they will gain momentum (like the voltage) This means those huge voltage spikes will not exist. However, like the person on the swing, the circuit does "gain momentum" and cause the voltage to rise almost 4 times the input voltage, when the output is open.

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To solve the "cramming everything in" problem, I think I will just have to have an external supply for power. (unless 12V 4A proves to be enough for this circuit) This is not optimal, but that is better than nothing. Besides, that gives me more options for supplies!

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I'm also going to attempt to etch my own PCB, with nice, thick traces to carry the amps. it is also fairly compact and should easily fit into my box I made.

If you would like to see my new instructable for the singing arc, click here.
 
 

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