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Registered Member #2063
Joined: Sat Apr 04 2009, 03:16PM
Location: Toronto
Posts: 352
the arcs i get from the Mazilli's ZVS driver are white with lots of current. but how do i get blue arcs with creates corona and Ozone? I tried lowering the frequency by using lots of capacitors connected is parallel but it didnt make much difference, it only made a high pitch squeal when drawing arcs. so how to make lots of corona and Ozone from a FBT?
Registered Member #2628
Joined: Fri Jan 15 2010, 12:23AM
Location:
Posts: 627
You need more voltage (70kv+ is perfect for this, the more the better)) and less current. the ZVS isn't too good for what your trying to get IMO. maybe a ZVS driven multiplier will get the job done, but requires an AC flyback, and a higher parts count. another method is to use a different driver altogether.
The problem is the driving method. With any form of push-pull driving the output voltage is given by the input voltage multiplied by the number of turns ratio. If you want the absolute maximum voltage, you need to drive the transformer in a true flyback mode, where in the first part of the drive cycle you pass some current trough the transformer, then you turn off any kind of driving. The magnetic field of the transformer will collapse suddenly and give you a nice back emf spike, much higher then the input voltage used. The same back emf spike will also be multiplied by the transformer turn ratio and appear on the secondary output.
Basically, you want the single mosfet/transistor driver for maximum voltage, and some form of push pull (ZVS, half or full bridge) for maximum power.
Registered Member #3610
Joined: Thu Jan 13 2011, 03:29AM
Location: Seattle, WA
Posts: 506
I'm getting good performance from the MK. II design here
If you want to go beyond about 25V input though I highly recommend a good snubber to protect the mosfet. The specified IRFP450 does well at handling large spikes but you get a lot of heating in the mosfet and by 45-50V input you will likely blow the mosfet.
Projection TV flybacks are very high powered and will produce lots of corona. MAT Electronics is a good source of inexpensive flybacks, I used to order from them frequently back when it was cost effective to repair CRT displays.
Registered Member #2063
Joined: Sat Apr 04 2009, 03:16PM
Location: Toronto
Posts: 352
James wrote ...
I'm getting good performance from the MK. II design here
If you want to go beyond about 25V input though I highly recommend a good snubber to protect the mosfet. The specified IRFP450 does well at handling large spikes but you get a lot of heating in the mosfet and by 45-50V input you will likely blow the mosfet.
Projection TV flybacks are very high powered and will produce lots of corona. MAT Electronics is a good source of inexpensive flybacks, I used to order from them frequently back when it was cost effective to repair CRT displays.
awesome, i have an XL FBT from a CRT projection TV lying around. time to smell some ozone
Registered Member #3610
Joined: Thu Jan 13 2011, 03:29AM
Location: Seattle, WA
Posts: 506
I should add that increasing the frequency also tends to increase the corona. Many flybacks can be driven at 75-150 kHz although you may have to immerse them in oil to prevent corona in places you don't want it.
Registered Member #1225
Joined: Sat Jan 12 2008, 01:24AM
Location: Beaumont, Texas, USA
Posts: 2253
Flyback mode is a great way to get high voltage, but so are bridges. You can easily get breakout from an LOPT using an H bridge, because the voltage gets too high and kills the diodes, so it becomes AC. But nevermind that, bridges are good because they are usually run open loop, and you can adjust the freq until you achieve resonance.
If i let the arc extinguish, the flyback would arc over from the output wire to the ground pin... It died fast anyway, they are not made for 1.4kw.
Registered Member #2063
Joined: Sat Apr 04 2009, 03:16PM
Location: Toronto
Posts: 352
is 100 percent silicone sealant a good enough insulator to stop the pins from arcing to each other? NEVER use hot glue! it does not help at all. and it pretty messy to get it off once u got it on.
Registered Member #3610
Joined: Thu Jan 13 2011, 03:29AM
Location: Seattle, WA
Posts: 506
haxor5354 wrote ...
is 100 percent silicone sealant a good enough insulator to stop the pins from arcing to each other? NEVER use hot glue! it does not help at all. and it pretty messy to get it off once u got it on.
I've used it with success You can also clip off pins that you *know* you won't ever need. Less protruding pin makes it easier to insulate. Use the clear stuff, the coloring agents, particularly black are sometimes very slightly conductive.
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how to drive a FBT for corona?
