Re: DC coil help

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Jan Florian Wagner by way of Terry Fritz <twftesla-at-qwest-dot-net>" <jwagner-at-cc.hut.fi>


> secondary, 450W input). My next coil project is going to be a small
> table top (2") coil. I want to make it battery powered (24vdc) but i
> don't understand how to step up the voltage with DC. last time i checked
> transformers are useless with DC input.

Yeah, transformers work only with AC. Anyways, a modern TV flyback from
a dead TV set is a good DC output power supply, but you need a little bit
knowledge about electronics to use it... And don't change anything on the
TV flyback (like remove diode or something).

My own, over-complicated version, should do about 100 watts:
http://www.hut.fi/~jwagner/tesla/tv-driver/schematics.htm

Simple versions:
http://www.geocities-dot-com/CapeCanaveral/Lab/5322/hv2.html
(look at links "TV flyback driver") Should be very cheap to build.

TV flybacks can run from up to 100 volts DC peak input (that's at least
what my old TV set used), so 24V or 48V driver input should be no problem
although you might need different transistors i.e. BUH315 or S2000AF 
or similar instead of 2n3055 (well just ask for high-voltage replacement
NPN transistors for TV - they're CHEAP!).

The output of the flyback can go to 30kVDC or so. Of course, you should
not set the TC spark gap THAT wide... the tank capacitor would not like
the overvoltage. Spark gap must be small enough.

greetz,
Jan

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 high voltage at http://www.hut.fi/~jwagner/tesla