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ragnar

Thu Mar 02 2006, 12:24PM

Registered Member #63 Joined: Thu Feb 09 2006, 06:18AM
Location:
Posts: 1425

well, thanks to my new 20MHz scope, I just got "first light" which was nice... and also the first chunk of MOSFET to ever get this |-----| close to my eye.

I suspect the gate was overvolted - the cross-sectional area of my feedback winding is seemingly not small enough =P

Hit 6.5MHz, was able to draw plenty of arcs... upped the primary/input voltage to 48V, managed to coax it to breakout of its own accord, but then the left half of one of my FETs urgently desired to be very far away from that hot metal die. Oops. =)

Nik

Thu Mar 02 2006, 01:32PM

Registered Member #53 Joined: Thu Feb 09 2006, 04:31AM
Location: Ontario, Canada
Posts: 638

Now when you say |-----| close, do you mean |-----| close at 1024x768 on a 16in monitor?

Glad to hear you are ok but it sounds like your coil is/was comeing along well. Keep it up! (and wear goggles)

Self Defenestrate

Thu Mar 02 2006, 02:38PM

Registered Member #87 Joined: Thu Feb 09 2006, 01:36PM
Location: San Jose
Posts: 191

Cover up all your components with a few standoff's and a towel during testing, keeps those bits of mosfet shrapnel contained. Got any pics?

Marko

Thu Mar 02 2006, 02:58PM

Registered Member #89 Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145

High-frequency royer coils obivously dont like high voltages.
Feedback overvolts gate and there is obivously not too much help.
You can hack bigger arc using just single diode halfwave rectifier and no filter caps, and here I hit the limit - 36V halfwave rectified input, tried to filter it with cap and blew mosfet too.
Feedback overvolts gates and zener causes trouble (probably by its capacitance) if connected across agte.
This is for 2 mhz mini coil now I intend something bigger and try to beat 10 mhz...

Topic is somewhere down, 'mini monster SSTC)

where pics can be seen.
Arc is incredibly hot for size of coil and just few tens of watts.

It actually loses lots of power at secondary (skin-effect) heating it up, mosfets do not dissipate lot of power and can be tortured unlimited time on small heatsinks.

Coil jamms internet connection, all forms of radio, TV, telephone... so I cant run it for much

robert

Thu Mar 02 2006, 04:16PM

Registered Member #188 Joined: Thu Feb 16 2006, 05:18PM
Location:
Posts: 67

Other things can explode too (just happened to me before):
I had a 300w halogen lamp (cheap thing, 10 euro or so) and had it on for maybe 15min for taking some photos with good light, and when i just was in another room i heraed a very loud explosion and when i looked in, the lamp was exploded ant there were hot glass fragments everywhere and even burned a hole in some plastic thing 5meters away.

HV Enthusiast

Thu Mar 02 2006, 06:02PM

Registered Member #15 Joined: Thu Feb 02 2006, 01:11PM
Location:
Posts: 3068

wrote ...

well, thanks to my new 20MHz scope, I just got "first light" which was nice... and also the first chunk of MOSFET to ever get this |-----| close to my eye.

Hopefully you were wearing safety goggles.

ragnar

Fri Mar 03 2006, 05:40AM

Registered Member #63 Joined: Thu Feb 09 2006, 06:18AM
Location:
Posts: 1425

EVR, believe it or not, in my ignorance, I'd chosen not to wake the household up by going outside to the garage where I'd left them. It would have been even worse if I'd needed an ambulance at 11pm to pull warm semiconductor shrapnel out of my eye.

The goggles start today.

Learn from my mistakes, guys. :)

IamSmooth

Fri Mar 03 2006, 06:13AM

Registered Member #190 Joined: Fri Feb 17 2006, 12:00AM
Location:
Posts: 1567

Any time I am around high voltage or high rpm machinery I wear goggles. It just isn't worth it....

I am curious, how many people wear goggles when working with high voltage and capacitors or just high voltage?

Nik

Fri Mar 03 2006, 06:16AM

Registered Member #53 Joined: Thu Feb 09 2006, 04:31AM
Location: Ontario, Canada
Posts: 638

After discharging my first MWO cap I started wearing goggles aroudn all my HV stuff. (other then the van de graff) The cap discharge didnt hit me with anythign but the bang gave me enough of an idea about what could happen.

...

Fri Mar 03 2006, 07:01AM

Registered Member #56 Joined: Thu Feb 09 2006, 05:02AM
Location: Southern Califorina, USA
Posts: 2445

I definantly wear them when using power tools (mainly dremel), and when I am first pwering up something I am not sure about... Other than that I do not have enough things explode that I really worry about it... (no sstc's yet)

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