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Registered Member #989
Joined: Sat Sept 08 2007, 02:15AM
Location: São Paulo, Brazil
Posts: 476
Hi all, I was made some tesla coils with a 5kV 30mA NST (150W) and I get some 15cm sparks.
Now I want to make a medium one.
Ok what I get here:
I discrambled a Microwave and I get all pieces that is on it:
1 0,82uF 2400VAC Capacitor 1 High Voltage Diode 1 MOT 2kV 750mA (1,5kW one, the big ones)
Also I have too: 100 - 1n4007 Diodes (1A 1kV) 10nF 6400V Cap Bank (Polyester) Some 1600V 8nF capacitors
I plan to make a medium on with only one MOT, can I use it? I see the voltage is too low (2kV I get only a few mm with arc start), I think to use a Voltage doubler and a Charge Choke. I already built the Charge Choke.
Its a good think to use a Voltage doubler to MOT Tesla Coil?
Registered Member #989
Joined: Sat Sept 08 2007, 02:15AM
Location: São Paulo, Brazil
Posts: 476
Ok, I was have a serious problem, when I turn on my coil worked for a few secs and the Charge Choke has burn out. I have made 800 Turns arround a Good Ferrite core. Any Ideias what can I use for better Charge Choke?
Registered Member #1025
Joined: Sun Sept 23 2007, 07:53PM
Location: Czech Rep.
Posts: 566
Mestre Racerxdl wrote ...
Ok, I was have a serious problem, when I turn on my coil worked for a few secs and the Charge Choke has burn out. I have made 800 Turns arround a Good Ferrite core. Any Ideias what can I use for better Charge Choke?
You should separate the windings with some kind of isolation (like the HV voltage transformers are done) or put more chokes in series. I also built a MOT based TC, with quadrupler. As a choke I used 15 ferrite core chokes in series grabbed from old repro-boxes (they are used as dividers for bass and trebles).
Registered Member #72
Joined: Thu Feb 09 2006, 08:29AM
Location: UK St. Albans
Posts: 1659
Your charge choke needs to support at least your supply voltage. For a doubled doubler from a MOT (like "the guy here" uses), that's approaching 12kV end to end on a good day.
Divide and conquer is a good plan, put several seperate chokes in series. Any piece of mains equipment is likely to withstand at least 1500v, as it's designed to withstand mains transients, and a 1500v "flash test" is a common one for mains-connected stuff. I am using several flourescent tube ballasts in series (I reckon 2kV each), and Steve used "proper" 2.5H chokes from Maplin.
People use MOT primaries with the secondaries shorted for mains ballasts. Why would a secondary with the primary shorted be a bad choice for this aplication? (* answer at the bottom)
Given the insultation levels, a MOT secondary, dismantled and re-assambeld with an air-gap, would be a very good choice, only 2 or 3 in series would be needed for confidence at 12kV. But, you need spare MOTs for that. I think I said in another thread somewhere that "you can never have too many MOTs". Both sets of windings, and the core, are variously useful for other stuff.
Registered Member #989
Joined: Sat Sept 08 2007, 02:15AM
Location: São Paulo, Brazil
Posts: 476
The Choke coil didnt burnout beacuse internal arcs, its burnout because current, the wires get red and hot :P I think I made it too small. The Choke was made with a Half Yoke Ferrite core with 8 layers of insulate tape (that black tape) and after I go to another layer I put 2 more of these over the wires. I wound it like tesla coil secondary, turn by turn side by side. I will make a bigger one, I think 800 Turns its not 30H.
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MOT Tesla Coil
