Welcome to Laser Pointer Forums - discuss green laser pointers, blue laser pointers, and all types of lasers

LPF Donation via Stripe | LPF Donation - Other Methods

Links below open in new window

ArcticMyst Security by Avery

Tesla Coil Build Thread






Joined
Jun 22, 2011
Messages
2,431
Points
83
Pretty cool. Can't see clearly from the pictures but the strike ring should have a considerable gap (1-2 cm) to avoid losses.
 
Joined
Jun 22, 2011
Messages
2,431
Points
83
The strike ring shouldn't be a whole circle, else induction will cause eddy currents in it and waste part of your coil's power as heat. Just cut out 1 or 2 cm of copper and leave the circle incomplete.
 
Joined
Dec 11, 2011
Messages
4,364
Points
83
Yep, otherwise the ring appears as a shorted turn. Just make sure to leave no sharp edges where you cut it.
 

Fiddy

0
Joined
May 22, 2011
Messages
2,726
Points
63
Did you measure your resonance frequency's Speedy?

I had to order a small uF tank cap to raise my primary to meet the secondary resonance.

I tuned my EVR microbrute by ear, but now i have a scope and function generator, i measured i was 70kHz off the mark! Ordered new tank caps for that also.

Also bought some alumina oxide isolation pads for the IGBT's on the onetesla too.
 
Joined
Dec 17, 2012
Messages
2,081
Points
63
Its whatever I want it to be now :). Per build instructions it came out to 245/333. 5 Turn primary was 307/333. With the bare copper horizontal primary I'm sitting around 311/333 but still messing around with it.
 

Fiddy

0
Joined
May 22, 2011
Messages
2,726
Points
63
good stuff! yeah mine was similar at 267/334.

im planning a small spark gap coil for the holidays.

Reckon this will work?

Diagram.png
 

Fiddy

0
Joined
May 22, 2011
Messages
2,726
Points
63
hahaa yeah, im not sure if the igntion coil puts out ac or dc, i seen a few diagrams with a HV diode in their so im thinking ac.

my coil puts out ~30-40kV too so not sure if its too high for the spark gap.

someone will chime in with more advice i hope :D
 
Joined
Aug 14, 2013
Messages
2,655
Points
63
good stuff! yeah mine was similar at 267/334.

im planning a small spark gap coil for the holidays.

Reckon this will work?

Diagram.png

You need something between the diode and capacitor or else the RF energies will kill the
diode. Either a HV resistor or possibly an air coil. I don't know for sure weather the coil
would work as I've never tried it. If you don't have a HV resistor, you can make one by putting
lots of regular ones in series. They can be hard to find. A ballast resistor from a HeNe might
work. Regular resistors are only rated like 1kV, so you would have to put a lot in series.

Ignition coils are always AC.
 
Last edited:
Joined
Aug 14, 2013
Messages
2,655
Points
63
I don't know why exactly, but any time you have a diode charging a low ESR HV capacitor that goes
into a spark gap unprotected like that it will die.
 
Last edited:

Fiddy

0
Joined
May 22, 2011
Messages
2,726
Points
63
so would i go for a high ohms or relatively low ohms resistor bank? im going to get a RC charging circuit there of the capacitor with this too.
 
Joined
Dec 11, 2011
Messages
4,364
Points
83
*cough* Ahem. Hello gentlemen! I believe I am needed here...

Hey Fiddy, remove the diode and swap the position of the spark gap and the tank capacitor. The gap will essentially short the LF side while the HF side is ringing, which prevents RF feedback into the LF stuff. SGTCs will operate fine on AC or DC, no need to introduce a lossy (and capacitive at TC frequencies) rectifier in there. DC resonant coils do exist but gain no improvement over AC coils until you reach the 10kW or so level.

TLS the reason the diode will die is because it appears as a capacitor at TC frequencies because the NP junction can't populate/depopulate fast enough, thus it no longer conducts in one direction above a certain frequency. Also, resonant rise in the tank circuit quickly exceeds the Vbr causing the diode to be overvolted.

Oh, btw, 30kV is a lot easier to set up a SG for than 3kV, tell you that much!

Edit: NO lossy resister bank. NO. haha.
 
Last edited:




Top