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1st timer with Tesla Coils (coil kicks ass)

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Hazmatt_(The Underdog)

Tue Aug 14 2007, 01:13AM

Registered Member #135 Joined: Sat Feb 11 2006, 12:06AM
Location: Anywhere is fine
Posts: 1735

The only heating problems I've ever had were the connecting leads to the primary coil, and this is with 300A pulse current cycling through my tank circuit.

Don't forget that the solid state coils push hundreds of amps continuously through their primaries with no problems.

For connecting leads I'm using 10 AWG silver teflon which has an exceptionally tight twist but still manages to get slightly warm because its still more resistive then the copper tube.

sparky

Tue Aug 14 2007, 01:30AM

Registered Member #530 Joined: Sat Feb 17 2007, 07:56AM
Location: Victoria BC, Canada
Posts: 178

Thats what I was speaking about... primary wires and ANY wire that passes high pulse current through it. To be clear I wasn't speaking about input wires from the transformer.

Thats why I use thick low AWG wiring...

Coronafix

Tue Aug 14 2007, 03:13AM

Registered Member #160 Joined: Mon Feb 13 2006, 02:07AM
Location: Melbourne, Australia
Posts: 938

I use 3 AWG for the connections between cap-spark gap, spark gap-primary, primary-cap.
As said, because of the high currents running in the tank circuit it is imperative that suitable sized
wire be used.
Between transformer and spark gap, normal sized wire is used because (in my case) only 60mA is
travelling down these wires.

Kizmo

Tue Aug 14 2007, 09:05PM

Registered Member #599 Joined: Thu Mar 22 2007, 07:40PM
Location: Northern Finland, Rovaniemi
Posts: 624

Secondary done:

8" PVC pipe wound with AWG24 wire 1300 turns (1327 to be exact). Winding is 24" tall and coated (actually soaked) by several layers of urethane based lacquer. I just bough 72pcs of cornell dubilier 942 series capacitors (150nF/2kV). MMC will be 6 strings of 12 in parallel. Gives 75nF 24kV.

And again few questions:

1. how i should close pipe? I thought to make two 200mm discs out of plastic and glue them carefully to both ends of the pipe.
2. because secondary is not as tall as i hoped, could i just raise top load to prevent coil striking itself @ higher kW runs. Like this:

Is there any good reson why not to do that?

Hazmatt_(The Underdog)

Tue Aug 14 2007, 09:58PM

Registered Member #135 Joined: Sat Feb 11 2006, 12:06AM
Location: Anywhere is fine
Posts: 1735

If you use pipe glue it will trap volitiles inside the tube which you really don't want, so be careful about selecting the glue.

GimpyJoe

Wed Aug 15 2007, 02:23AM

Registered Member #316 Joined: Mon Mar 13 2006, 01:30PM
Location: Marietta, GA
Posts: 212

Raising the topload will keep it from shielding the top turns of the secondary and will cause breakout from the secondary windings.

Kizmo

Tue Aug 21 2007, 08:17PM

Registered Member #599 Joined: Thu Mar 22 2007, 07:40PM
Location: Northern Finland, Rovaniemi
Posts: 624

YEAH!

I was looking for motor for my ASRSG from local scrap yard and i found pile of old medical stuff, blood heaters and oxygen pumps etc and centrifuge. It was very dirty (sand, leaves, mud, spider nets etc). I think it has been there for a while. I cleaned it up with petrol based engine cleaning solvent and blew all spider nets and leaves away with airgun. I checked that motor was ok, gerased bearings and put some crc to potentiometers. I put plug to wall and turned it on. Red light appeared which told me that power was on. Then i slowly turned speed control up to 50% and that thing worked like new one :) It is steplessly adjustable 0-6000rpm and holds revs quite well (measured with laser tachometer only 1-2rpm fluctuating @ 4000rpm)

Now i need to figure out how i convert this to ASRSG without loosing possibility to use it as centrifuge if i sometime need one..

Pics:

Vid: Motor is pretty strong, large rotating mass (the thing which holds testing tubes) causes long spin-up time

sparky

Tue Aug 21 2007, 08:33PM

Registered Member #530 Joined: Sat Feb 17 2007, 07:56AM
Location: Victoria BC, Canada
Posts: 178

Funky wrote ...

Raising the topload will keep it from shielding the top turns of the secondary and will cause breakout from the secondary windings.

You can have a few inches of bare connection to the topload- that will do fine. The larger the topload the less likely you are to have premature breakout and most definately you won't have secondary turn breakout too.

Steve Conner

Tue Aug 21 2007, 10:36PM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

Hey Kizmo,

That's cool that you found a centrifuge. The motors in them seem to be excellent for ARSGs.

I dumpster-dived a centrifuge a while ago, and got a friend who is a very good machinist to make a spark-gap rotor for it. The test tube holder rotor was detachable: it just fitted onto the tapered shaft of the motor. So he machined the arms off the rotor, and converted the centre of it into a hub, which he attached to a tufnol disc.

He then did a great job of balancing the rotor and its 6mm tungsten electrodes and aluminium electrode holder, so it runs at 6000rpm with practically no vibration. You can stand a coin on its edge on top of the motor while revving it up, and it just stays there.

There is no way I could have done this myself, it needed a well equipped machine shop and a great deal of skill :|

Kizmo

Sat Aug 25 2007, 09:38PM

Registered Member #599 Joined: Thu Mar 22 2007, 07:40PM
Location: Northern Finland, Rovaniemi
Posts: 624

Slowly it comes together.

These are ready:
- powersupply (+ filters and safety gap)
- Secondary, toroid, primary
- base for entire build

Things to do:
- MMC (haven't got my 942C's yet)
- RSG

I have yet another question about MMC and its bleed resistors. My MMC will be 72pcs of cornell dubilier 942C 2kV/150nF caps, 12 caps per string and 6 strings in parallel. Makes 75nF / 24kV. Do i need to add bleeder resistor to every 72 caps or is it ok just to put one between MMC terminals?

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