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Pigs and other barnyard experiments.
Coilers,
Here are some results of some pig tests I performed tonight.
First I attempted to measure the inductance of the pig primary, from the
0 to the 120 lug on the LV side. My battery-powered LCR meter indicated
1.5 mH, which is clearly much too low. I suppose the little meter just
doesn't put out enough juice to overcome core hysteresis in the iron.
Comments??
Next I measured the pig's no-load current by applying 120v to the 0-120
lugs (with a 65 mH limiting reactor in series to keep accidents down if
the HV side should flash over). The no-load current was 0.69 amps,
which (assuming 90degrees phase angle) yields a calculated approx. 0.45
H of core inductance, a much more reasonable value. Comments??
Oh, the primary's resistance is on the order of 0.04 ohms, real real
tiny!
Then I tried a bit of Jacob's ladder action. First I used my 0.065 H
limiting inductor in series with the pig's 120v input. Note - this
0.065 H inductor is an un-shorted-out MOT primary. The Jacob's action
was sort of erratic, but more strangely, each time I'd get an arc out
the HV side of the pig, I'd hear a "bump" coming from the variac and the
MOT. Is this normal??? I was powering the whole thing off a 10A variac,
if this makes a difference...
Finally I tried using a resistive ballast, in the form of an old toaster
oven in series with the pig. Setting the oven on "Toast" provided the
most power to the pig :) . The Jacob's Ladder action was much much
smoother this way.
I though most people had the best results when using inductive limiting.
This was not the case with me. What is going on here? Average current
using the toaster oven ballast was about 12 amps, and average current
using the MOT was something like 6-8 amps, although it swung around
wildly. In a previous experiment I'd determined that the V vs I curve of
this MOT core was rather nonlinear, ie, I increases rapidly with
increasing V.
I can only assume that once the HV arc ceased to conduct, there was
still a current flowing in the MOT (?). This current would then
collapse, causing the "thump" noise from various components... Any
clues??
-Bill
(chicken of my pig lest it gets my goat and I become BACON!)
Starting arcs in Cinci, OH
http://www.geocities-dot-com/CapeCanaveral/Hangar/6160
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