Holiday Project: DRSSTC :D

[Meatball]

ok thanks, whats the good reason?

The DRSSTC
= "Dual Resonant" Solid State Telsa Coil

The tank circuits run at the same resonant frequency, and are magnetically coupled to together.

Normally, a SSTC doesn't have an MMC cap in the primary circuit like an SGTC does. This removes the imaginary component to resonator reactance, and also help limit the current through the primary by adding to the ESR. So its like taking a SSTC and making it think its a SGTC of sorts.

Changing the resonant freq in the secondary tank means you now need to match the resonant freq of the primary to the new freq of the secondary. You just adjust L or C to match the freq, and in this case, the kit has a constant C on the board which cannot be increased like your topload did, so you must increase the L of the primary to compensate.

 

[Fiddy]

oh ok, i knew that i think just inerprited your post wrong.

because the length included does not allow much extra length for good reason.

I read it as, they limit the primary turns for a good reason, meaning adding more turns has adverse effects.

 

[Meatball]

No, more like the length of wire they give you for the primary might not allow for extra turns.

 

[Fiddy]

Ahh no worries then

 

[DashApple]

Haha IGBT murderer!

You get Used to it eventually , Good luck with the Build .

 

[Fiddy]

got 3 full turns on the primary and got plenty of extra length

wrapped the plastic top load with some aluminum top load (pretty crap, don't plan on using it)

I did some calculations with some online calculators to find out how many turns to put on the primary:


-----------------------------------------
Secondary
-----------------------------------------

===============
Standard Top Load
===============

3.22" x 10"

Capacitance = 5.792pF

Turns = 1000
Wire = 30 Gauge
Diameter = 3.22"
Length = 10"

Inducatance = 22.64mH


Resonant Frequency: 439.5khz

===========
New Top Load
===========

3.22" x 10"

Capacitance = 8.897pF

Turns = 1000
Wire = 30 Gauge
Diameter = 3.22"
Length = 10"

Inductance = 22.64mH

Resonant Frequency: 354.6kHz



------------------------------------------
Primary
------------------------------------------

==================
Standard Primary Turns
==================

4" x 0.2424"

Capacitance = 0.075uF

Turns = 3
Wire = 12 Gauge
Diameter = 4"
Length = 0.2424" (0.0808" per turn)

Inductance = 1.917mH

Resonant Frequency: 419.7khz

===============
New Primary Turns
===============

4" x 0.29088"

Capacitance = 0.075uF

Turns = 3.6
Wire = 12 Gauge
Diameter = 4"
Length = 0.29088" (0.0808" per turn)

Inductance = 2.65uH

Resonant Frequency: 357khz

 

[Fiddy]

Finished the circuit board

 

[Things]

Enough maths, more sparks!!

Tank caps seem really small on that though, is it directly mains powered, or are the caps charged through a stepup transformer?

The tesla coil I had charged the caps up (3300uF each at 300V) through a stepup transformer, but you could only get limited burst rates or it'd overload the transformer. Direct mains powered is more awesome, but less safe

 

[Fiddy]

Haha

there's 2 in series, rated at 2kV 0.15uF each.

Its 110V powered, DC buss runs at 340VDC.

Safety isn't a problem, i work with 3MW induction heating units at work with massive semiconductors

 

[Things]

How's it run the DC bus at 340V from 110VAC? Voltage multiplier, stepup transformer?

 

[Fiddy]

ding ding ding! voltage multiplier

 

[Things]

Cool beans!

Probably could have saved yourself a few bucks by just removing the multiplier and feeding 240VAC (Through a rectifier of course) into the bus caps, wouldn't need a 110V stepdown transformer then. But transformers provide isolation, which is always good to have

 

[Fiddy]

Probably, there's a whole bunch of other gear inside that would probably affect tho.

 

[Things]

Are those inductor looking things on the right bottom of the board current sense coils to monitor the input mains power? Being mains powered I'd imagine it would have to have some kind of current monitoring.

Either way the burst rate of the kit looks impressive, can't wait to see the results. Then I can go cry in the corner not having enough money to buy one, always working on a project when you post something else awesome

 

[Fiddy]

Your right, those are 2 current transformers that monitor the primary current.

Yeah me too i want my spun top load so i can polish the crap out of it then sit it up on its perch.

Ive told all my friends who ask about it that it a doomsday device for 21/12/12

 

[Things]

Haha, spun toroids add the best finishing touch you can get for a tesla coil. I tried polishing mine when I had it and ended up just scratching it more. Probably because it was a bit rough, so I tried taking to it with sandpaper too. Probably should have just ignored that and made it shiny anyway