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Registered Member #3781
Joined: Sat Mar 26 2011, 02:25AM
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Posts: 701
I built this plasma speaker following the schematic: ( I used a computer power supply for the 12 volts and im pretty sure I found the correct pins on the flyack driver. But when i hooked it all up and tried to arc it, all i got was a tiny spark? I'm wondering if there is an obvious problem someone can point out to me or if there is a better way to build it. I really want to run it off of a 555 timer (I have ~100 of them) and IRF 644 transistor. I was frustrated and I took it apart but I can easily rebuild it and post pictures if need be. Thanks for any help!
Registered Member #3766
Joined: Sun Mar 20 2011, 05:39AM
Location:
Posts: 624
you need to wind your own primary of 20ga or larger magnet wire, 5-8 turns the other primaries on a flyback have too many windings. also, try powering the 555 off a lead acid battery or separate power supply and the flyback on the computer power supply, the flyback makes an enormous amount of noise (common ground of course)
Registered Member #3766
Joined: Sun Mar 20 2011, 05:39AM
Location:
Posts: 624
if the FET can handle it, just go 14 volts with the 5 turns, it will deliver more power for each pulse, which will prevent your speaker from sounding like nails on chalkboard. (if it doesn't get enough power it will take multiple pulses to arc, lowering the frequency)
I spent all of last weekend and all day yesterday getting one of these things to work good, you probably need to ice cool your fet, you may also want to consider increasing the frequency of the timer to 40kHz ish with a 60-70% duty cycle, if youre unsure of the math its in the astable section here
Yes to your wiring question and if you have problems getting an arc try switching the leads of the primary, the flyback rectifies internally so it only works one way
Registered Member #3781
Joined: Sat Mar 26 2011, 02:25AM
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Posts: 701
ok so im waiting on another flyback because the one i have has a ferrite core that is to close to the plastic housing to wrap magnetic wire around, and I think the sound quality on your setup sounds really good! On a side note: what if you wired up two transistors instead of one? You would probably not need to ice cool it like you do in the video... I only have one in my plan because it's not supposed to heat up very much. Oh and I cannot find that 14.4 volt powersupply at the moment but would a 12volt car battery charger work? and if so should i run it at 2 amps or 10?
Registered Member #3766
Joined: Sun Mar 20 2011, 05:39AM
Location:
Posts: 624
I wouldn't the the battery charger, but the battery would work fine. I would guess there would be a lot of electrical noise. If you decide to give it a shot (can't really hurt) try it at the lower current setting first.
Ive never tried paralleling MOSFETs, but I know it can be done and it will reduce the current on each one.
Are you ordering your flybacks? Just rip apart anything with a CRT, discharge the caps and carefully stick a screwdriver with a grounded alligator lead attached to it under the suctionie cup thingie. As long as you follow the HV saftey rules you should be fine.
Registered Member #3766
Joined: Sun Mar 20 2011, 05:39AM
Location:
Posts: 624
You said you used a computer PSU in the first post, it should still work. If you have nothing with a CRT that you want to sacrifice, goodwill should be able to provide.
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555 Timer Plasma Speaker
