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ZakWolf

Thu May 23 2013, 07:56PM

Registered Member #3114 Joined: Sat Aug 14 2010, 08:33AM
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Posts: 608

Heres a video

The driver died i think it was a diode that failed, i like the results so i think i will mess with this a little more.

I had a couple questions:

why can i only get break out if i draw the arc first?

and why does the output increase over time until it failed?

input voltage was around 43v

thanks

Ash Small

Thu May 23 2013, 08:44PM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

I think the voltage rang up until failure. I think DRSSTC's have interruptors to prevent this. I suspect it may not quite be in tune either, as starting the breakout as you did would increase the capacitance, I think. Also, as the streamers get longer, capacitance increases as well.

I may be wrong, but that's my opinion.

ZakWolf

Thu May 23 2013, 09:04PM

Registered Member #3114 Joined: Sat Aug 14 2010, 08:33AM
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Posts: 608

Ash Small wrote ...

I think the voltage rang up until failure. I think DRSSTC's have interruptors to prevent this. I suspect it may not quite be in tune either, as starting the breakout as you did would increase the capacitance, I think. Also, as the streamers get longer, capacitance increases as well.

I may be wrong, but that's my opinion.

so I should try a small toroid with a breakout on it, how could i add an interrupter in and were ?

I would prefer if it was a quite are no loud popping sounds, im not 100% about sstc design and application, technically this is my first sstc thingy

HV Enthusiast

Fri May 24 2013, 12:09AM

Registered Member #15 Joined: Thu Feb 02 2006, 01:11PM
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This is a CW coil, so i don't believe modulating the output (i.e. interrupter) is going to make a difference.

Are you driving this open loop or does it have an auto-tuning circuit built into the driver?

From looking at your output, it appears the coil isn't properly in tune. Hence, you are able to excite the break-out by drawing an arc which means you are loading it somewhat with your knife to cause it to break-out.

Also, please be aware that when you draw an arc like that, you are conducting RF currents through your hand and arm. Nerves aren't sensitive to high frequency current, so even though you may not feel it, it could be doing harm to tissue / nerves.

ZakWolf

Fri May 24 2013, 05:01AM

Registered Member #3114 Joined: Sat Aug 14 2010, 08:33AM
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Posts: 608

EasternVoltageResearch wrote ...

This is a CW coil, so i don't believe modulating the output (i.e. interrupter) is going to make a difference.

Are you driving this open loop or does it have an auto-tuning circuit built into the driver?

From looking at your output, it appears the coil isn't properly in tune. Hence, you are able to excite the break-out by drawing an arc which means you are loading it somewhat with your knife to cause it to break-out.

Also, please be aware that when you draw an arc like that, you are conducting RF currents through your hand and arm. Nerves aren't sensitive to high frequency current, so even though you may not feel it, it could be doing harm to tissue / nerves.

I figured it was running in CW mode.

I made a small torroid and im going to make a primary with tap points to tune it. (I dont have a oscilloscope :( )

Its running open loop, I am just using the ZVS driver with two inductors.

I will use a grounded rod haha I forgot about that

Thanks

HV Enthusiast

Fri May 24 2013, 12:09PM

Registered Member #15 Joined: Thu Feb 02 2006, 01:11PM
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For a CW coil, the only reason you would really add a toroid is if you wanted to lower the resonant frequency. Other than that, you really do not need a toroid.

Ash Small

Fri May 24 2013, 01:13PM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

EasternVoltageResearch wrote ...

For a CW coil, the only reason you would really add a toroid is if you wanted to lower the resonant frequency. Other than that, you really do not need a toroid.

I'm guessing that's the objective here. I'm guessing that loading with the knife lowers the resonant frequency by adding capacitance. Adding a toroid should achieve the same thing, as long as it doesn't add too much capacitance.

Maybe just a bit of tuning (primary taps) is all that's required, though.

HV Enthusiast

Fri May 24 2013, 01:32PM

Registered Member #15 Joined: Thu Feb 02 2006, 01:11PM
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You can raise capacitance by simply raising the wire above the secondary.

Each inch of height of the wire is approximately equivalent to 1pF of capacitance.

So if the wire is 3 inches above the secondary, the equivalent capacitance is about 3pF.

Dr. Dark Current

Fri May 24 2013, 01:38PM

Registered Member #152 Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384

I'm pretty sure it died because of the capacitor overheating, and the intermittent output might have something to do with the DR system switching poles.

HV Enthusiast

Fri May 24 2013, 03:18PM

Registered Member #15 Joined: Thu Feb 02 2006, 01:11PM
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Posts: 3068

Oh. You're doing this double resonant?

What is your end goal for this coil?
If its just a CW coil you are looking for, then you really don't need to go double resonant.
We use double resonant for DRSSTC because want to to get the maximum surge impedance possible so we can ring up the secondary as quickly as possible to generate those long pulsed arcs.

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