The Plasma Speaker

Step 7: Build the circuit

After you have tested to make sure everything is working, start building the prototype onto the veroboard.

If you notice in the pictures, I use an 16 pin socket for the TL494, it is really good idea to use sockets for the IC' s because you won't risk heat damage from soldering, and if the IC fails, you can easily replace it instead of desoldering it and solder another one in..
I also added an LED indicator, that is a good idea to add that on too, so you know whether the circuit is on or off. The LED indicator is connected to the TL494's power supply line.

After you had done soldering, make sure you made nice shiny solder joints and they are no solder bridges. If you think it is all good enough, add some dab of hot glue onto the loose components and wires for strain relief.

Comments

[Never_Quit]

If you add two separate Schottky diodes from the two audio output leads from ground, you can prevent voltage spikes to your audio device.

[Never_Quit]

(removed by author or community request)

[jaapiyo]

how much gonna cost it ?

[iacon50]

Hey, I have it mostly assembled but im having somed issues. mostly because its been a while since i've done circuit theory. do you have any more clear pictures of the actual circuit and how you built it? i must not be reading the diagram correctly. either in pc board or breadboard mode. mine is turning out a lot more complex than the pictures im seeing.

[Plasmana]

The plasma speaker is harder than it looks... Unfortunately, I do not have my plasma speaker available to take more picture of, I have taken it apart because it has an unknown problem that I cannot find or fix.

[Cybot Rules]

Would you ba able to do it in EAGLE or something similar?

[izidor7]

and what where the sympthoms???, what happened? did your mosfet burned out? or something else? you say you don't know what is the problem, so maybe sombodey could help.

[Plasmana]

When the unknown problem begin, the MOSFET's, slowly dies until it pops from high heat build up. When I replace the MOSFET's, it does it again, the plasma speaker works when I first powered up, then it goes out. I replaced the MOSFET's 4 or 5 times, and they just slowly die and never work again. I look at the oscillator very closely and all components are in perfectly condition.

There must be some be some sort of electronic plague on the oscillator because I built another oscillator, it works for a few days then the "electronic plague" came back to kill the MOSFET's.

For right know, I call that problem "electronic plague".

[knoxarama]

well, instead of just using a heat sink, you could probably make a compact liquid cooling system and have the tubes wrap around the heat sink and MOS FET... or put a fan by it...

[girrrrrrr2]

well the cure for the black plague involved burning bodies... so maybe the same fix here too?

[izidor7]

try to put a zener diode between gate-surse
lets say something over 15V but less them 20V....

I have the same problem, and one of my friends also,

i tried to put 4 in parallel mosfets... and what happened ofcors, they got boiling hot... but, one after another died, and they died when i turned on the psu, and i think that this could be the problem, "gate overvoltage" , so, one died, and i have had put him to my R.I.P: jar and soon another died, and the third, and the fourth i broke a leg .:-) (four 400V 14A mosfets )

could it be possible that the gate stayed opened after shutting off the psu, and while the powering it up, to add the voltages... and cross the limit,
The fact is , the gate behaves like a cup.,

i, got now 4 IRF620 'S , so i have now somthing to kill, so i'll truy it out...

I think its normal that the mos eklsplodes after a longer time when the heat build's up. but ,
It is a bit strange that they die right the second when i turn on the power???? i think the zener would help there.

Just to say... i even tried to use the low voltage mosfets form a motherboard... (30V 20-60A), and the funny thing is, thay are smd.. and i dolderd them down on a heatsing, and, thay work nice, but they got so hot, realy hot, the wires desoldered_{, and after that it worked(after it cooled down)... that was strange....}

[Xellers]

Maybe you need to replace the diode between the gate and source. Otherwise, you could just get a gate driver like the UCC37321 and hook it up to the output of the TL494 and then use a HEXFET in the irfp series to be able to handle more power.

[izidor7]

and, why would I want to put the UCC37321??? nothing would change..... the zener would eventualy protect the gate from to high voltages, and i could even use IGBT's , and one and the other, are very fragual when they get too high gate voltages....... the power isn't here the problem...., what would you say??? and, i must say, the AC flyback is much better for a plasma speaker.... althou, i have 10 of the DC vith a cup in ti , and 5 only DC, and 3 AC flyback's , i like the AC's the most :-)

[Xellers]

AC flybacks... I wish. If you are really having problems, then why not go with something a little more complicated. Use the TL494 and a couple gate drivers through a GDT to switch a half bridge of MOSFETs, then you could either stay with a flyback transformer, or you could just make a Solid State Tesla Coil. If I had the money, it would be my next project.

[izidor7]

ofcors.... but, tesla coils are a litle too big to me... but it's a great project to make..... For the GDT you don't need tu use a high current diriver.... i think a 751 would be enuf..., (two of them....) oh, and ofcors, not a HALF bridge, but a H-brudte.... so you could have the the supply voltage on your primary... and with the halfbrige only the half of the suply voltage... a fiew minutes ago i killed my 4th irf630 :-) and now i have 4 more to go.... :-) and 4 more........ :-) anyhow, i'll be playing with hv... in one way or another

[Xellers]

Right now, I'm trying to figure out how I can make something like I described using what I already have... My junkbox doesn't have any parts that I bought other than a few resistors and capacitors. The plasma speaker's only component that I paid for was the TL494, everything else came from old electronics.

[izidor7]

if you, could find some pream's in your junk box... that coulld do the thing...or, some amplifiers.... thay have some good componentes....like a Operational Amplifier (741 or any other....).. that's what you'll need for a gdt...

[Xellers]

Can you help me a little more? How would I use a 741 op amp with a GDT, I know that I have one somewhere... And how do you properly make a GDT anyways? Is it just three wires wrapped around each other and then wrapped around a ferrite toroid? By the way, I just found an old vacuum tube television that had a beautiful AC flyback transformer in it. I made a plasma globe from a light bulb with it! Unfortunately, I haven't been able to try it out with the Plasma Speaker because when I soldiered everything to a circuit board, the thing stopped working.

[iacon50]

hey, what is that one piece that you added to the board to connect the tl494 chip to the breadboard? the tl494 chip is very tiny and i was just wondering where you get that adapter or how you are supposed to work with it in the breadboard or soldering the circuit because its so tiny.

[izidor7]

Hy, did you mean : SOCKET DIL 16 ? if that is so, the socket alowes you to solder it down on the board, or breadboard and change, the chip in case of a burning of the chip....., if you would solder the chip directly, you would have some dificulties by removing it.... and, it cam easily burn out... if you dont take care of it, and whatch what you're doing.

[iacon50]

yes, i guess that's the part im looking for. I'm ordering a bunch of parts on electronic goldmine, but Im having trouble finding that one. my tl494 chip definitely can't be soldered in directly so does anyone know any good online electronics stores that would have the socket dil 16 adapter you mentioned in the US? or might radio shack or something have them?

[izidor7]

you have this at the same store where you bought the tl494.... This is useful because as you said you won't need to solder the chip directly. and you are going to be able to replace the chip....... You have somewhere a search bar, type there DIL 16 and you'll find it... (on the website of your closest store) or just wisit a store and ask the clark... he'll give it to you...

[iacon50]

i dont have the DIL chip though, i have the SOP. do they make sockets for sop so that i can use it in a breadboard or should i try to buy a DIL chip? and if so, where? I've been looking online and the only places that seem to have the tl494 only offer the sop kind

[izidor7]

listen_{, if your chip si SOP, you'l need to solder it down on a board, and it makes it a litle bit dificult to put it on a bread boar....}

You don't nedd to use the tl494 . if you can't but one .... just go to a neerest shop and ask for a PWM controler, any other chip will do the job.... If you'r not shure abaout some chip, checkout the datasheet, and you won't have any problems... ofcors you would need to convert the pin setup... but that isn't a problem

ka7500 lock for that, it is the same as the tl494, the same pin order, she shame block diagram.... and more likely you'l find that...