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Registered Member #4081
Joined: Wed Aug 31 2011, 06:40PM
Location: UK
Posts: 139
1. Yes. 2. Also yes, I think Steve Ward did some destructive testing and found that they broke at around 10KVDC, the peak of 2.5kVAC is around 3.5KVDC so you should be fine. Also how old is that transformer? It may have something to do with the voltage
The microwave I ripped open had a stamp of '02, but it was a solid state mot. I don't think the age of it matters much really, unless you ripped open a 20 year old microwave. Then again, I only have ripped open one microwave, so I can't be sure. One thing is for sure: I want to see you post threads of you arcing that MOT!
Registered Member #4081
Joined: Wed Aug 31 2011, 06:40PM
Location: UK
Posts: 139
Just be careful with arcing it without a ballast because it may trip your breaker/blow a fuse and it WILL overheat very quickly (I had one that I arced for less than a minute and it burst into flames). What many people do is ballast it; this is to put a load in series with it. Good ballasts are heaters or another MOT with the secondary shorted. Though I'm guessing you're not going to arc it if you're rectifying and smoothing it :) Also many people are just giving away microwaves, I'm not sure if you have Freecycle/Gumtree in France though.
Registered Member #152
Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384
Sorry for OT, PhilGood, if you're going to use the MOT in a VTTC I strongly suggest to use a half wave doubler and a tube which is capable of the voltage, this way you get rid of the core saturation and huge current draw on the primary. I actually get 60cm (24") sparks from a single big MOT with 8.8A @ 230V input, half wave doubled, no staccato.
Registered Member #3806
Joined: Sat Apr 02 2011, 09:20PM
Location: France
Posts: 259
Hey Dr. Dark Current,
Your post is not OT at all, especially considering I'm talking about my VTTC in the previous post, and any suggestion is always welcomed, especially for a beginner like me :)
You are right, this MOT is for sure able to output a lot more than with my little 811A coil ^^
I am planning to build an HFVTTC using full wave rectified and smoothed MOT output as next coil.
What tube are you using in the coil you are talking about ? Did you post it on 4HV ?
Registered Member #152
Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384
Phil, I posted the coil in the "Add your Tesla coil here" thread. Seems not much people acutally check it out. See here:
I'm using the GU-81M russian pentode.
PS, you can't full wave rectify a MOT and ground the negative output, because one end of the secondary is connected to the core and you'll most likely get an arc over to the primary of the transformer. Or leave the negative floating, but then you'll need to use a filament transformer with at least 3kV isolation between the windings.
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Question about MOT output voltage
