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Need idea for SGTC

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quicksilver

Wed May 19 2010, 08:19PM

Registered Member #1408 Joined: Fri Mar 21 2008, 03:49PM
Location: Oracle, AZ
Posts: 679

You could always try a flat secondary!

Renesis

Wed May 19 2010, 09:22PM

Registered Member #2028 Joined: Mon Mar 16 2009, 08:13PM
Location: Norway
Posts: 319

I have heard stories of people observing sparks from unused secondaries stored in their workshop while running their tesla coils. Perhaps you could use this effect to build a wireless power demonstrator?

tulkas

Thu May 20 2010, 09:35AM

Registered Member #2865 Joined: Tue May 18 2010, 10:59AM
Location: persia
Posts: 37

thanks everyone.
i'm sure about primary now .
please answer to this too :
can someone give me simple schematics for magnifier and safety gap?( where should i place safety ?)
my primary

is it going to work wrong( i've connected 2 wires by wounding a thin copper wire on them) 1274347894 2865 FT89391 Dsc00858

my biggest secondary

smaller secondary

parallel plate caps

Sulaiman

Thu May 20 2010, 09:50AM

Registered Member #162 Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140

I have used 3xparallel (19/0.15 = 1mm2 multistrand pvc insulated) wire for the primary of sgtc(s) and it works fine with very little heating. So your 3mm wire primary will be ok.
Your primary probably needs more work, when the large primary currens flow the wires will jump around, possibly short-circuiting each other. Cotton/string and plastic/wood sticks will do.
Your first diagram is unworkable, the second has possibilities for many many experiments,
FIRST you need to build one working sgtc so that you can learn some of the many ways such a simple circuit can give problems!
My advice;

1 Get an NST, more watts = better and it MUST be one of the old heavy iron types, not the new electronic type. You will probably destroy this NST ;) so don't spend too much, maybe an OBIT (oil burner ignition transformer) would be easier/cheaper for your first experiments.

2 Fit a safety spark gap to the NST/OBIT output, this should be the FIRST thing that you attach !

3 Make a simple main spark gap with forced air, hairdrier/fan/vacuum cleaner..whatever.

4 Make your sgtc as quickly as possible, don't over-calculate it or worry about how it looks, or over-engineer, just get something working. e.g. you don't need a beautiful sphere/toroid topload,
a large tin can or cooking pot will do fine..

5 Part-by-part you can optimise your sgtc.
Primary capacitor and spark gap seem the most important to me.
I have never managed to build a homemade plate or rolled primary capacitor that was reliable, so good luck with yours. Before you build your plate cap I would get the NST/OBIT and do a few experiments, it's amazing how many ways there are to do it wrong!
Carefully, in the dark, inspect your primary capacitor with the NST only (safety spark gap ALWAYS present) looking for purple-blue glows that indicate imminent failure!

6 Now that you are on version 6.3 of your sgtc you can try the other secondary with the same primary etc.
Adjust the topload of the second secondary to resonate at the same frequency as the first.

7 With two secondary/topload pairs of the same resonant frequency you can now place one of the secondaries in your sgtc and the other several feet away with the bottom of the winding 'grounded'
... a few fine-tuning tweaks and stand back!

8 A second primary for the second secondary (!) would allow a lower voltage output from the remote coil,
e.g. a lamp.

There are many excellent online documents,calculators,circuits etc. but initially I advise against (?) too much research, just enough to achieve your goals.
I have wasted too much time researching and theorising
.. just do it!

If you start a thread in the Projects area and give circuit diagrams and photographs you'll surely get more than enough help from members.

So, start looking for a cheap (?) NST or OBIT, aim for an operating frequency lower than the quarter-wavelength frequency of the secondary wire length, consider a good MMC primary capacitor and do a little research on spark gaps.

Take care and Good coiling

quicksilver

Thu May 20 2010, 04:28PM

Registered Member #1408 Joined: Fri Mar 21 2008, 03:49PM
Location: Oracle, AZ
Posts: 679

Sulaiman wrote ...

There are many excellent online documents,calculators,circuits etc. but initially I advise against (?) too much research, just enough to achieve your goals.
I have wasted too much time researching and theorising
.. just do it!

I have fallen prey to this as well! Suliman's advise is very good. Just do it! I have found that I can always get in my own way by learning contradictory aspects of what I wish to do.
But the fun comes from leaning and SEEING what RESULTS you get! As long as you are safe; experiment with joy; try unique things & you will be pleased with the results, even if the object is not the prettiness thing around. There will be time for making it pretty later - and it will cost you less because you will not spend money on what you don't need.

tulkas

Thu May 20 2010, 06:46PM

Registered Member #2865 Joined: Tue May 18 2010, 10:59AM
Location: persia
Posts: 37

thanks all.
1- i already have an NST rated 30 mA & i want to know how to remove current limiting ?
2- i don't know anything about safety gap where should i place it ?(As pic?)
3- i have a 2400 RPM AC motor with a 11 cm rotary disk with 10 electrodes on it .

Renesis

Thu May 20 2010, 07:00PM

Registered Member #2028 Joined: Mon Mar 16 2009, 08:13PM
Location: Norway
Posts: 319

tulkas:

1- Search for a MOT instead, dont destroy your NST like that. Shouldt be too hard to find.

2- Place the safety gap in paralell with whatever you wish to protect. Your placement here will protect the transformer from overvoltage. But, you cant use a safety gap in paralell with your transformer without some kind of current limiting, because it shorts out the transformer when triggered.

ScotchTapeLord

Thu May 20 2010, 08:59PM

Registered Member #1875 Joined: Sun Dec 21 2008, 06:36PM
Location:
Posts: 635

If you include a picture of your NST we can probably tell you if it's good or not. If it's "good" then it will have magnetic shunts for current limiting, which will just make sure you never exceed 30mA on the output. If it's "bad" then it will have active current limiting that may just shut it down when 30mA is exceeded. The good news is that the values you describe SUGGEST that you have a "good" NST.

The safety gap in your image is place correctly. Make sure it is as close to the NST as possible.

tulkas

Fri May 21 2010, 07:48AM

Registered Member #2865 Joined: Tue May 18 2010, 10:59AM
Location: persia
Posts: 37

hi first one is my NST and second is safety gap.
is my safety gap right?
how does it works?

Sulaiman

Fri May 21 2010, 03:14PM

Registered Member #162 Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140

Your static gap needs re-doing;
- Exposed eht wires isn't a good idea
- The gap will not remain fixed/set properly
- Larger smooth/rounded surfaces for the spark gap are prefered.

Make your safety spark gap rigid
Adjust the gap so that it just about fires with nothing else atached.
Don't be tempted to open it any farther!

The basic circuit diagram is as here

Notice anything missing?

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