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Registered Member #46251
Joined: Sat May 10 2014, 12:55PM
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Posts: 16
fungus wrote ...
Steve Conner wrote ...
To do that, you want to connect the strike target to a large metal object that has lots of capacitance to its surroundings.
I've read about people using metal tea-trays for this...
Assuming I connect everything to mains ground (ie. base of secondary, base of strike target, tea tray): Does the tea-tray act as a sort of capacitor to smooth out the spikes going into the mains wires?
Would it be better for the neighbors if I connect the strike target to one end of the tea tray and the other end to mains ground? (ie. the tray is between the target and the mains wires).
Registered Member #30
Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706
fungus wrote ...
Assuming I connect everything to mains ground (ie. base of secondary, base of strike target, tea tray): Does the tea-tray act as a sort of capacitor to smooth out the spikes going into the mains wires?
Would it be better for the neighbors if I connect the strike target to one end of the tea tray and the other end to mains ground? (ie. the tray is between the target and the mains wires).
Yes that's exactly it, though something bigger than a tea tray would be preferable. :/
I don't think the exact order of the connections makes much of a difference. Most of the noise from a Tesla coil is in the 10s of MHz, where the tea tray is small compared to a wavelength.
Recently there has been talk of an inductively loaded breakout point. Basically putting a tiny Tesla coil on top of your main coil. The inductance acts as a buffer between the topload capacitance and any arcs to ground, which significantly reduces the amount of HF noise generated. It is still experimental but seems to give good results.
Registered Member #46251
Joined: Sat May 10 2014, 12:55PM
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Posts: 16
Steve Conner wrote ...
Yes that's exactly it, though something bigger than a tea tray would be preferable. :/
I don't think the exact order of the connections makes much of a difference. Most of the noise from a Tesla coil is in the 10s of MHz, where the tea tray is small compared to a wavelength.
One wave of light would be 30m at that frequency. Electricity is a bit slower...but yeah, a 30m tea tray would be difficult to find/install.
So what counts? The total mass of metal? Capacitance is usually about surface area. I don't have a lot of space ... I guess I could stack a couple of tea trays on top of each other if it helps.
Steve Conner wrote ...
Recently there has been talk of an inductively loaded breakout point. Basically putting a tiny Tesla coil on top of your main coil. The inductance acts as a buffer between the topload capacitance and any arcs to ground,
Is there a thread on this subject?
How about a coil of wire between the strike target and the tea tray to take the edge off the pulses? (Or between the tea tray and mains ground?) I've got some magnet wire left, I could wind some around a piece of pipe.
I know it's a lot of questions but I don't really have a feel for this stuff and no way of measuring anything.
Registered Member #46251
Joined: Sat May 10 2014, 12:55PM
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Posts: 16
fungus wrote ...
How about a coil of wire between the strike target and the tea tray to take the edge off the pulses? (Or between the tea tray and mains ground?) I've got some magnet wire left, I could wind some around a piece of pipe.
Registered Member #46251
Joined: Sat May 10 2014, 12:55PM
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Anybody have any ideas? Right now it's freaking out everything in the room when it runs.
My mouse locks up, the monitor flickers, the Arduino has to be unplugged and plugged in again. Not good.
I've tried attacking a large metal tray to the wire. I've put lots of ferrite on the wire from target to GND, they might have helped a bit...but not much.
Without the ground connection target the sparks are leaping off all over the place after they hit the target. I already set my table on fire.
Registered Member #30
Joined: Fri Feb 03 2006, 10:52AM
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The best thing you can do is lose the strike target and just make streamers to air. A 1" gap is actually worse than a larger one, as a shorter gap generates more high frequency EMI.
Registered Member #46251
Joined: Sat May 10 2014, 12:55PM
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Steve Conner wrote ...
The best thing you can do is lose the strike target and just make streamers to air.
I think you may be right.
I just gave it a blast at full power with no strike target and nearly jumped out of my skin. The streamers were scarily long, I didn't even tune the primary yet...
I admit I cowered.
But ... nothing in the room flickered or glitched. That definitely seems to be the way to go.
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Strike target grounding
That definitely seems to be the way to go.