Homemade plasma globe problem.

[Sceadwian]

Impedance is a ***** at this point isn't it?

 

[Hero999]

Learning complex numbers helps a lot. Luckilly my scientific calculator can use complex numbers so I don't need to bother.

 

[Blueteeth]

Sooo, overclocked: You have a flyback transformer and some form of DC chopper circuit. Those 'articles on the web' almost always use flybacks with a custom primary coil, I tihnk I've said this before, but its usually about 16 turns, split, with a small feedback winding. Two power transistors, in a typical flyback configuration, this 'boosts' (technically is doesn't but hey) the p-p voltage across the primary, which is then stepped up. THAT is how they get the big sparks. Also, I often see '12v @ 3A' as the power source. I don't think you'll need 3A for a plasma globe, cheap lightbulb version or otherwise, but less than an amp at 12v and its output will be weak. PSU first, then plasma globe.

So, my guess is you're expecting a healthy 10-15kV on the output, but its much less than that. You need to remove all the primary windings and wind yourself one if you're going to copy that 'internet' design. Also they recommend older flybacks that don't have a built in rectifier diode (on the output) which will obviously reduce efficiency.

Failing that...I've successfully got very scary sparks from a land rover ignition coil, 12V, driven with a MOSFET/555 timer. Its bigger than a flyback, but no need to rewind anything, its got more than enough kick, and it looks nice as a stand for the shiney orb

Sorry if I've said this before, wanted to say something useful.

Blueteeth.

 

[Hero999]

That's another point, you need AC not DC for a plasma globe.

Modern flyback transformers produce DC, not only is there a diode built into the module but there is a small voltage multiplier and as it's potted into the module it's impossible to remove.

I don't know what to suggest, maybe a very small solid state tesla coil is what you need.

 

[Overclocked]

Sooo, overclocked: You have a flyback transformer and some form of DC chopper circuit. Those 'articles on the web' almost always use flybacks with a custom primary coil, I tihnk I've said this before, but its usually about 16 turns, split, with a small feedback winding. Two power transistors, in a typical flyback configuration, this 'boosts' (technically is doesn't but hey) the p-p voltage across the primary, which is then stepped up. THAT is how they get the big sparks. Also, I often see '12v @ 3A' as the power source. I don't think you'll need 3A for a plasma globe, cheap lightbulb version or otherwise, but less than an amp at 12v and its output will be weak. PSU first, then plasma globe.

So, my guess is you're expecting a healthy 10-15kV on the output, but its much less than that. You need to remove all the primary windings and wind yourself one if you're going to copy that 'internet' design. Also they recommend older flybacks that don't have a built in rectifier diode (on the output) which will obviously reduce efficiency.

Failing that...I've successfully got very scary sparks from a land rover ignition coil, 12V, driven with a MOSFET/555 timer. Its bigger than a flyback, but no need to rewind anything, its got more than enough kick, and it looks nice as a stand for the shiney orb

Sorry if I've said this before, wanted to say something useful.

Blueteeth.

Ive been looking for a Ignition coil, but I cant seem to find any cheap. Ive also heard of people hacking inside the Flyback and cutting out the diodes and caps...

 

[Sceadwian]

CRT's and car ignition coils from older cars are always prime sources for decent ignition coils.

 

[Hayato]

Hello,

Those new flybacks (I mean flybacks made since the 90's), do likes LOW duty cycle.

Try to build a 555 timer with fixed frequency and variable duty cycle. The flyback should work with 10% or less of duty.