No Toroid Discharges
Nyx, Sun Mar 18 2007, 09:05PMHello Ive setup a SGTC and got it to start. The spark gap fires but I dont get any discharges from the toroid. I noticed that a fan 1m away started rotating when I switch on the power to the TC.
Im using a 9kV 30mA TC, 15x2strings 0.67uF 1kV polypropene caps, about 11 turns of 9mm diameter primary coil in a conical shape ('inverse-saucer') with an angle of about 45 degrees. My secondary is 900turns, 4in by 20in of 24AWG enamel wires. My dischare terminal is spherical with 10cm diameter and looks kinda small sitting on top of the secondary. I connected the secondary ground to a water pipe 10m away from the coils.
Will a poorly tuned/untuned TC give any streamers?
Re: No Toroid Discharges
..., Sun Mar 18 2007, 10:13PM
Can you draw sparks off the output sphere with a grounded wire?
It is possible that it is too smooth, and you are not producing enough voltage for breakout. Try adding a piece of solid copper wire (or whatever) sticking out 8" from the sphere.
Also, a mistuned coil can definitely do what yours is.
Did you use any software to calculate the values of the tank cap/primary turns?
..., Sun Mar 18 2007, 10:13PM
Can you draw sparks off the output sphere with a grounded wire?
It is possible that it is too smooth, and you are not producing enough voltage for breakout. Try adding a piece of solid copper wire (or whatever) sticking out 8" from the sphere.
Also, a mistuned coil can definitely do what yours is.
Did you use any software to calculate the values of the tank cap/primary turns?
Re: No Toroid Discharges
Nyx, Sun Mar 18 2007, 10:58PM
... Thanks for your reply.
When you mentioned grounded wire, do you mean a wire connected to the AC mains ground, or to the same ground as the secondary coil?
I'll try sticking the wire to the topload.
I used DeepFriendNeon.com's javascript calculations but my primary coil is conical instead of flat spiral which is what the javascript calculated for me.
I probably fried my transformer. Resistance across the output terminals is infinite and the spark gap doesnt fire when the primary coil is connected but does fire without the primary coil connected. Are these signs of a dead transformer?
Nyx, Sun Mar 18 2007, 10:58PM
... Thanks for your reply.
When you mentioned grounded wire, do you mean a wire connected to the AC mains ground, or to the same ground as the secondary coil?
I'll try sticking the wire to the topload.
I used DeepFriendNeon.com's javascript calculations but my primary coil is conical instead of flat spiral which is what the javascript calculated for me.
I probably fried my transformer. Resistance across the output terminals is infinite and the spark gap doesnt fire when the primary coil is connected but does fire without the primary coil connected. Are these signs of a dead transformer?
Re: No Toroid Discharges
Myke, Mon Mar 19 2007, 12:03AM
Remove the Xfmr and see if you can draw an arc from it. If you can't then your Xfmr night be dead (check your breaker or your GFI if you have one).
Don't conect the ground to the mains ground otherwise you will get a lot of RF put into the ground and it may kill some sensitive equipment. The ground should be conecteed to the other end of the secondary. If it is a big coil outside then conect it to the ground (earth) too.
Myke, Mon Mar 19 2007, 12:03AM
Remove the Xfmr and see if you can draw an arc from it. If you can't then your Xfmr night be dead (check your breaker or your GFI if you have one).
Don't conect the ground to the mains ground otherwise you will get a lot of RF put into the ground and it may kill some sensitive equipment. The ground should be conecteed to the other end of the secondary. If it is a big coil outside then conect it to the ground (earth) too.
Re: No Toroid Discharges
Nyx, Tue Mar 20 2007, 01:34AM
My xfmr seems to be working again lol. Used a crocodile clip connected to the secondary ground and got a 5in spark between the clip and the wire you asked me to place on the output sphere.
Is my sphere too smooth being the reason i dont get sparks coming out from all over the output sphere like those i see in photos?
Nyx, Tue Mar 20 2007, 01:34AM
My xfmr seems to be working again lol. Used a crocodile clip connected to the secondary ground and got a 5in spark between the clip and the wire you asked me to place on the output sphere.
Is my sphere too smooth being the reason i dont get sparks coming out from all over the output sphere like those i see in photos?
Re: No Toroid Discharges
Nyx, Tue Mar 20 2007, 03:31AM
Here's how mine looks like
Nyx, Tue Mar 20 2007, 03:31AM
Here's how mine looks like
Re: No Toroid Discharges
Coronafix, Tue Mar 20 2007, 08:46AM
I'd say that you have about seven times the amount of capacitance that you need.
You have 89.3nf when you need about 12nf to be LTR.
Your transformer is not able to charge that large a capacitance.
It would have been resonantly charging if your caps were 0.067uf instead of 0.67uf.
Your top load should be bigger too, you'll get arcing to your secondary.
Coronafix, Tue Mar 20 2007, 08:46AM
I'd say that you have about seven times the amount of capacitance that you need.
You have 89.3nf when you need about 12nf to be LTR.
Your transformer is not able to charge that large a capacitance.
It would have been resonantly charging if your caps were 0.067uf instead of 0.67uf.
Your top load should be bigger too, you'll get arcing to your secondary.
Re: No Toroid Discharges
Nyx, Tue Mar 20 2007, 11:03AM
Sorry i meant to say my caps are 0.067uF. I'll try a larger topload. How do you get the top load to have sparks coming out in all directions?
Nyx, Tue Mar 20 2007, 11:03AM
Sorry i meant to say my caps are 0.067uF. I'll try a larger topload. How do you get the top load to have sparks coming out in all directions?
Re: No Toroid Discharges
uzzors2k, Tue Mar 20 2007, 05:38PM
Is that an ikea topload? I have two of those 12 cm bowls which are going in my TC too. You should be able to achieve 10-15 inch sparks if you tune your TC properly, and if you can achieve that sparks shooting out in all directions will occur too. Your topload should be pretty smooth to send sparks out everywhere though.
What is your secondary's resonant frequency? I would try making the flat spiral coil that you calculated first, the inductance of your current primary could be off by quite a bit, which will throw your TC out of resonance.
uzzors2k, Tue Mar 20 2007, 05:38PM
Is that an ikea topload? I have two of those 12 cm bowls which are going in my TC too. You should be able to achieve 10-15 inch sparks if you tune your TC properly, and if you can achieve that sparks shooting out in all directions will occur too. Your topload should be pretty smooth to send sparks out everywhere though.
What is your secondary's resonant frequency? I would try making the flat spiral coil that you calculated first, the inductance of your current primary could be off by quite a bit, which will throw your TC out of resonance.
Re: No Toroid Discharges
gentoo_daemon, Tue Mar 20 2007, 06:36PM
Isn't 67nF still very large?
gentoo_daemon, Tue Mar 20 2007, 06:36PM
Isn't 67nF still very large?
Re: No Toroid Discharges
Marko, Tue Mar 20 2007, 07:00PM
As far as I figured him out, each cap is 67nF. 15 in string give 4,46nF and two strings give some 8,9nF wich is almost exactly resonant to his transformer. I guess he would want to use a nf or two bigger cap for safety of his NST.
What are you using as a sparkgap now?
In most cases poor performance is caused by gap failing to quench properly. Use a fan to blow air across your gap, and make sure it is set *just* far enough for transfoprmer (without primary tank circuit) to arc across it.
Marko, Tue Mar 20 2007, 07:00PM
As far as I figured him out, each cap is 67nF. 15 in string give 4,46nF and two strings give some 8,9nF wich is almost exactly resonant to his transformer. I guess he would want to use a nf or two bigger cap for safety of his NST.
What are you using as a sparkgap now?
In most cases poor performance is caused by gap failing to quench properly. Use a fan to blow air across your gap, and make sure it is set *just* far enough for transfoprmer (without primary tank circuit) to arc across it.
Re: No Toroid Discharges
Nyx, Tue Mar 20 2007, 09:52PM
Yes, those are ikea toploads :)
My secondary resonant frequency is 299.68KHz according to DeepFriedNeon's javascript calculator. Does the performance of the TC vary alot as you are about to tune to resonance?
My sparkgap is made up of 10 copper tube electrodes bolted to acrylic in a flat planar manner. A ac fan is blowing through all the gaps. Fan and planar array of spark gaps are parallel to each other. However my fan rated for 220v is running at 100v as my xfmr uses 120v. Both are connected to a variac. Will using 2 fans quench about twice as good?
Nyx, Tue Mar 20 2007, 09:52PM
Yes, those are ikea toploads :)
My secondary resonant frequency is 299.68KHz according to DeepFriedNeon's javascript calculator. Does the performance of the TC vary alot as you are about to tune to resonance?
My sparkgap is made up of 10 copper tube electrodes bolted to acrylic in a flat planar manner. A ac fan is blowing through all the gaps. Fan and planar array of spark gaps are parallel to each other. However my fan rated for 220v is running at 100v as my xfmr uses 120v. Both are connected to a variac. Will using 2 fans quench about twice as good?
Re: No Toroid Discharges
uzzors2k, Wed Mar 21 2007, 08:20PM
Tuning your tesla coil to resonance is necessary to get the best output, and depending by how much your're off tune the ouptut can just a fraction of what it would be at resonance. Untuned coils may or may not give streamers, as it depends on how far off tune you are.
Given the air flow is twice as fast, two fans will blow twice as good. Otherwise there is little point.
Since your gap quenching sounds alright, I bet it is just an issue of tuning. Since your primary coil is all that deviates from your calculations, I would start there. Getting the right amount of turns is important, and even one extra turn on a spiral coil can increase inductance greatly. If you used bare copper pipe adjusting turns is an easy task. Wind a flat spiral coil like you calculated, and if possible measure the iductance. It should be 31.7µH. Good Luck!
uzzors2k, Wed Mar 21 2007, 08:20PM
Tuning your tesla coil to resonance is necessary to get the best output, and depending by how much your're off tune the ouptut can just a fraction of what it would be at resonance. Untuned coils may or may not give streamers, as it depends on how far off tune you are.
Given the air flow is twice as fast, two fans will blow twice as good. Otherwise there is little point.
Since your gap quenching sounds alright, I bet it is just an issue of tuning. Since your primary coil is all that deviates from your calculations, I would start there. Getting the right amount of turns is important, and even one extra turn on a spiral coil can increase inductance greatly. If you used bare copper pipe adjusting turns is an easy task. Wind a flat spiral coil like you calculated, and if possible measure the iductance. It should be 31.7µH. Good Luck!
Print this page