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Registered Member #599
Joined: Thu Mar 22 2007, 07:40PM
Location: Northern Finland, Rovaniemi
Posts: 624
Yeah. Frozen ground is really poor conductor and even at TC voltages i wont get much ground strikes at all without that ground wire. And it does produce some nasty EMI indeed. I had to faraday cage my microphone to stop all those crack and pops during heavier ground strikes
Registered Member #6038
Joined: Mon Aug 06 2012, 11:31AM
Location: Salado, TX
Posts: 248
Aaahhh - that makes sense. Forests don't care about EMI All of this helps me understand why I get hanging notes on the midi controller when it hits the strike ring. USB cable is picking up all sorts of noise. Good stuff - thanks guys.
Did anybody try putting a ferrite bead on the breakout rod? Might flash over during a ground strike, but perhaps the high frequency components don't carry that much voltage.
Registered Member #30
Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706
Arc Attack reported good results using a breakout point with an air-cored inductor built in, like a small Tesla secondary. It was enclosed in an oil-filled plexi tube with insulating ribs on the outside to discourage flashover.
It apparently made a substantial improvement in EMI and they now use it in all of their shows.
Registered Member #30656
Joined: Tue Jul 30 2013, 02:40AM
Location: UK
Posts: 208
Bushman wrote ...
Aaahhh - that makes sense. Forests don't care about EMI All of this helps me understand why I get hanging notes on the midi controller when it hits the strike ring. USB cable is picking up all sorts of noise. Good stuff - thanks guys.
USB is awfully susceptible to EMI - it uses single ended signalling for some functions (e.g. bus reset) and tends to form ground loops as well. This causes all sorts of problems when running in a tesla coil type EMI environment, especially with poorly made devices such as the $5 chinese MIDI cables (note that you don't get ground loops with MIDI - it uses optical isolation when done right).
I had issues with the connection dropping out when using a USB oscilloscope to make measurements of my DRSSTC - I improved it a bit with ferrite beads etc, but the real solution was to change the scope connection to ethernet, which is fully differential, AC coupled (via pulse transformers) and does not form ground loops when using UTP. An added benefit is that I can now plug it into a wifi router and use it remotely, enabling me to wirelessly scope the coil waveforms while it's running, or (with battery power) float the scope with only a few pF to ground.
Registered Member #6038
Joined: Mon Aug 06 2012, 11:31AM
Location: Salado, TX
Posts: 248
These last two posts are really cool - great info that is not widely broadcast. I would love to know more about the configuration of the arc attack breakout. Any details on the web that you know of.
Glad to hear its not just me having trouble with USB. I do admit i have a cheap USB/MIDI cable, but didn't want to drop more $$ until I understood the problem. This helps - thanks.
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Grounded strike target
All of this helps me understand why I get hanging notes on the midi controller when it hits the strike ring. USB cable is picking up all sorts of noise. Good stuff - thanks guys.
