[TCML] pig Jacobs (don't totally blow off resistive ballasting)
J. Aaron Holmes
jaholmes at silicon-arcana.com
Tue Nov 27 21:29:43 MST 2007
... Isn't that exactly what I said? :-)
Even pushing 40A @ 240V through the thing, it took
some time for the water to get "hot".
--- Tim Meehan <btmeehan at gmail.com> wrote:
> This is pretty similar to the garbage
> can with water and
> baking soda idea, but these things can carry a lot
> of current as long as you
> make sure that you aren't heating up your mass of
> water too much.
> > If the element is immersed in water, even if it
> > "open", it may not actually be completely "open"
> > because of the water.
> > ...which brings me to another suggestion for a
> > ballast: My first pig ballast was just two copper
> > pipes held in parallel by nylon bolts and immersed
> > a plastic garbage can full of water. I put a PVC
> > sleeve over one of the pipes which could be raised
> > lowered to vary the resistance, then doped the
> > with baking soda until I'd achieve the desired
> > resistance range. It worked great and allowed for
> > very smooth control, albiet farily lossy. Since
> > PVC had to be raised to reduce the resistance,
> > would naturally turn the power down if I let go of
> > control handle (A PVC "T" joint with another small
> > section of PVC sticking off the side). Also, this
> > meant that the heat production was always near the
> > bottom of the garbage can, allowing for plenty of
> > convection cooling. It took quite a while for the
> > water to get hot, even with many kVA's involved.
> > So, despite the lossiness of resistive ballasting,
> > it's still hard to beat for simplicity and
> > of control. And also (probably) cost. Check the
> > prices on 500ft rolls of #10 wire these days ...
> > Then compare to the prices of a few short
> sections of
> > PVC, water pipe, and a plastic Rubbermaid (or
> > garbage can. I think I spent about $20 total
> > (although I already had the PVC).
> > My ballast these days is a big variac which I
> > into at a great price. If you want to build a big
> > variable inductor for cheap, however, Goodle for
> > "slide choke" and "tesla" and you'll get lots of
> > hits, I'm sure.
> > Cheers,
> > Aaron, N7OE
> > --- david baehr <dfb25 at hotmail.com> wrote:
> > >
> > > Yea, 50+ amps is high for a JL , but, if ya
> > > see the big , thick plasma ( ? ) , ya gots too
> > >
> > > Oh, if the element fails , this would
> > > an 'open' circuit , woulnt it ?? it would just
> > > off ?
> > >
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