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SSTC earth and antenna

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loveHV

Sat Jan 03 2009, 06:52PM

Registered Member #1854 Joined: Wed Dec 10 2008, 06:09PM
Location: West-Flanders Belgium
Posts: 88

i finished my SSTC and my spark lenght has increased

the more i improve my ground the longer the sparks but i still don't have an good ground any suggestions what could be a good ground ? (hammering a copper tube in the floor is not an option

)

also i noticed when my or something else gets closer to the coil the sparks start dissapearing
i think there might be something wrong with the feedback system but what ???

any advice is welcome

jovica

Sat Jan 03 2009, 10:24PM

Registered Member #1790 Joined: Fri Oct 31 2008, 10:10AM
Location: Sydney, Australia
Posts: 40

I think you would need to add some more details to your post for members to actualy help you.

What chip are you using for the controler?

What topology are you runing it with, class e ? half/full bridge ?

Value are your timing caps/resistor ?

What are your coil dimentions?

How many turns sec ? pri ?

Thanks

loveHV

Sat Jan 03 2009, 11:07PM

Registered Member #1854 Joined: Wed Dec 10 2008, 06:09PM
Location: West-Flanders Belgium
Posts: 88

im using PLL driving a half bridge of IRFP450 FET's

i use the UCC's to drive the GDT

the UCC's are interrupted by an 555-timer

i use as resistors and timing caps on the pll 2 trimmers 100K as resistors and as capacitor a variable capacitor trimmer 0-500pF

my secondary coil dimensions are:

50 cm tall

10cm wide

about 1000 turns of 0.5mm diameter wire

my primary consists of 23windings

i do not use a topload just yet as my driver ain't powerfull enough and the last time i tried i blew the UCC's

i use 12V to feed the driver 60V to feed the halfbridge but if ready im gonna switch over to half wave rectified mains

enough details ??

LithiumLord

Sun Jan 04 2009, 12:46AM

Registered Member #1739 Joined: Fri Oct 03 2008, 10:05AM
Location: Moscow, Russia
Posts: 261

Bet there's something wrong with the PLL range - whenever you get closer to the coil, the PLL runs out of sync due to the frequency drop.

Arcstarter

Sun Jan 04 2009, 01:06AM

Registered Member #1225 Joined: Sat Jan 12 2008, 01:24AM
Location: Beaumont, Texas, USA
Posts: 2253

A kinda good ground would be a large plate of metal or aluminum foil on cement. Might not work great, but it will do better that grounding to some small object.

About the spark shrinking, it must be the PLL getting far away from resonance. Are you sure the PLL is locking? If not, you are losing length because when something gets closer, the capacitance changes therefor resonant frequency lowers. Make it lock if possible, or if it is locking you need a larger tuning range so that it will lock at lower frequencies.

Dr. Dark Current

Sun Jan 04 2009, 10:28AM

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

Are the outlets grounded? If so you can use that.

Btw. "50 cm tall 10cm wide about 1000 turns" is not the perfect SSTC secondary. I've found that about 1:3 d/h ratio works better and something like 1500-2000 turns. This might get you bigger sparks with the transistors suffering less.

loveHV

Sun Jan 04 2009, 12:15PM

Registered Member #1854 Joined: Wed Dec 10 2008, 06:09PM
Location: West-Flanders Belgium
Posts: 88

i know that the dimensions for the secondary aren't ideal but first i wanted to make an SGTC but then i found the idea of an SSTC and i started making that.

i don't know why the PLL can't lock im using uzzors PLL driver

i use 100K trimmers for R1 and R2 and a veriable capacitor for 6-7 of 0-500pF
is that a large enough tuning range or do i need to extend it more ???

the best i get from the TC is 1cm spark with 60V over the half bridge so 30V trough the primary

as for the grounding i know use the metal frame of my workbench as grounding, but i found out it was a SHOCKING mistake

I tried the aluminum foil on cement but it didn't work that great

when ive browsed some forums on TC's i saw that grounding the secundary to mains can give a lot of problems

but now do to bad grounding you can hear my coil's interuptor on the radio and the interference range of my coil is big its like 50M or so (never thought that a TC was capable of doing that)

Dr. Dark Current

Sun Jan 04 2009, 12:28PM

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

loveHV wrote ...

when ive browsed some forums on TC's i saw that grounding the secundary to mains can give a lot of problems

This is bad expecially for spark gap coils because they make a lot of EM noise. Smaller solid state coils are OK to ground to mains ground.
For bigger coils I can use the central heating radiator

loveHV

Sun Jan 04 2009, 01:08PM

Registered Member #1854 Joined: Wed Dec 10 2008, 06:09PM
Location: West-Flanders Belgium
Posts: 88

so it will be ok to ground my coil to mains and nothing weird will occur thats nice

? also not at higher power levels ?? like half wave rectified mains ?

now the only thing that needs to be done is preventing the pll to go out of sync
but how do you make it lock ??

Dieu

Sun Jan 04 2009, 01:30PM

Registered Member #1730 Joined: Thu Oct 02 2008, 08:12AM
Location: Poland
Posts: 35

Can you make some photos and show them to us?
Espesialy elkctroncs?

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