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On 10/3/15 9:20 PM, msweeney23@xxxxxxxxx wrote:
I purchased a few cheapo 12VDC/15KV negative ion generators and set one up with my VDG.
I was using an expensive 30 amp lab grade power supply set to 4VDC. I grounded the case of the power supply and used the +/- of the ion generator to produce corona from the lower brush.
It worked amazing ive never seen that power output before, very thick loud sparks 10 inches for a few seconds then smoke from the power supply :(
Can ayone explain why this might have occured? I just wasted a $200 variable supply and not entirely sure how to go about fixing it (it still outputs 12VDC but no longer variable).
That nice snappy spark is a very fast rise time high current pulse, and
will induce remarkably high voltages in a victim loop. It's all about
di/dt, and the area of the loop.
More than one person on this list has killed their power supply driving
a voltage multiplier or Marx system. The typical scenario has a 20kV or
so multiplier running off a switcher feeding a Marx with half a dozen or
more stages. The 12V power is a couple of clip leads or similar laying
on the bench feeding the switcher, and separated by a few inches.
The Marx goes "bang", the power supply fails.
Another scenario is that there's a "ground bounce" when the system
fires, and that pushes the power supply output way out of the common
mode range for some component.
Your power supply may not tolerate several hundred volt spikes coming
back from the load very well. If it has current and voltage limiting,
there's some sort of error amplifiers across a measuring resistor. Those
amplifiers often have a "not very many volts" common mode limit
(particularly in the negative direction). An unexpected 100V transient
fries the current error amplifier which is usually measuring the voltage
drop across a small resistor in series with the output.
I wish i had a video to share, but it all happened to fast. I think its something to do with grounding the case.
Thanks!
Matt
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