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Weird Shunts & Homemade Vaseline
From: Thomas McGahee[SMTP:tom_mcgahee-at-sigmais-dot-com]
Sent: Friday, December 12, 1997 10:19 AM
To: Tesla List
Cc: lau-at-hdecad.ENET.dec-dot-com
Subject: Weird Shunts & Homemade Vaseline
>
> From: Gary Lau 01-Dec-1997 1352[SMTP:lau-at-hdecad.ENET.dec-dot-com]
> Sent: Monday, December 01, 1997 12:05 PM
> To: tesla-at-pupman-dot-com
> Cc: lau-at-hdecad.ENET.dec-dot-com
> Subject: Death & rebuilding of a Neon
>
> After obsessing over optimal transformer protection network, saturating
> chokes, and the like for many posts, I fired up my coil last week. I
> cranked the variac up to maybe 25%, had good spark breakout, but the
> safety gaps were firing almost continuously. This was strange, it had
> previously been working at 100% variac just fine, I know it was tuned. I
> observed this for maybe 5 seconds, then a dreadful silence. Post mortem:
> a dead 15KV/60mA neon transformer. One side measured 7.5K to case, the
> other 1.1K. This in spite of having .25" safety gaps, 14 mH chokes, 750
> Ohm/50W series R's, and 600 pF bypass caps. I still don't know what was
> different this time, just that I lost one very-hard-to-come-by
> transformer. My main RQ static gap was 10 gaps -at- .03".
>
> I read the archives on depotting. Since I was determined to re-use the
> case and insulators, I fired up my charcoal Weber grill, put the xfmr in
> an aluminum pan, and cooked it for about 4 hours. After the whole
> stinkin' mess was good and liquid, I dumped the contents of the case into
> another pan and seperated the core from the goo. After several dips in
> paint thinner, I have now seperated the individual windings from the E
> and I laminations. My plan was to remove some of the magnetic shunts, but
> I'm not sure what exactly these are. I have E's and I's, and on the
> two faces where the center segments of the E's meet the I's (represented
> by # in the diagram below) there were a pair of small (~ .5" x 1") curved
> metal springs.
>
> Where are the shunts?
>
>
> SSSS PPPPPPP SSSS
> SSSS PPPPPPP SSSS
> SSSS PPPPPPP SSSS
> SSSS PPPPPPP SSSS
> ----SSSS-----PPPPPPP-----SSSS----
> / / SSSS PPPPPPP SSSS \ \
> / / SSSS PPPPPPP SSSS \ \
> | \ SSSS PPPPPPP SSSS / |
> | \-SSSS#####PPPPPPP#####SSSS-/ |
> | |SSSS| |PPPPPPP| |SSSS| |
> | |SSSS| |PPPPPPP| |SSSS| |
> | |SSSS| |PPPPPPP| |SSSS| |
> | |SSSS| |PPPPPPP| |SSSS| |
> | ------ --------- ------ |
> | |
> | |
> |_____________________________________|
>
> --------------------------
> / \
> / I's \
> \ /
> \--------------------------/
>
> ---- ----
> / / \ \
> / / \ \
> | \ / |
> | \ ----- ----- / |
> | | | | | | | |
> | | | | | | | |
> | | | | | | | |
> | | | | | | | |
> | ------ -------- ------ |
> | |
> | E's |
> |______________________________________|
>
> After reassembly, I plan to reuse the case and insulators, fulling the
> case with melted Vasoline jelly, this so it won't leak after it gels.
> Anyone know a way to buy Vasoline in bulk so I don't have to carry a
> shopping cart of small jars to the register?
>
> Gary Lau
> Waltham, MA USA
>
Gary,
The shunts are the little protrusions on the E core. They form a GAP
with the I section. Obviously this form of shunt is harder to
modify than the more usual block style shunt structure.
I modified your ASCII art to show the gaps and shunts more clearly.
Note that the shunt/gap structure is now integral to the design
instead of a separate add-on. I would imagine that if you increased the
size of the GAP by cutting a bit off of each E section, then that
would modify the Maximum short circuit current you would get.
>
>
> SSSS PPPPPPP SSSS
> SSSS PPPPPPP SSSS
> SSSS PPPPPPP SSSS
> SSSS PPPPPPP SSSS
> ----SSSS-----PPPPPPP-----SSSS----
> / / SSSS PPPPPPP SSSS \ \
> / / SSSS PPPPPPP SSSS \ \
> | \ SSSS PPPPPPP SSSS / |
> | \-SSSS=====PPPPPPP=====SSSS-/ |
> | |SSSS| S |PPPPPPP| S |SSSS| |
> | |SSSS| H |PPPPPPP| H |SSSS| |
> | |SSSS| U |PPPPPPP| U |SSSS| |
> | |SSSS| N |PPPPPPP| N |SSSS| |
> | ------ T --------- T ------ |
> | |
> | |
> |_____________________________________|
>
> --------------------------
> / \
> / I's \
> \ /
> \--------------------------/
>
> ---- ----
> / / \ \
> / / \ \
> | \ / |
> | \ ----- ----- / |
> | | | S | | S | | |
> | | | H | | H | | |
> | | | U | | U | | |
> | | | N | | N | | |
> | ------ T -------- T ------ |
> | |
> | E's |
> |______________________________________|
>
As to the vasoline, why not try adding paraffin or beeswax to
transformer oil (at elevated temperatures the wax will dissolve).
Be very careful as an open flame can enkindle the hot oil. Do
this where you have adequate ventilation also. A double boiler
setup might be in order for the sake of safety.
Keep adding wax until you get the consistency you desire. This
should be cheaper than vasoline and you can control the
consistency. I recommend first mixing up a VERY SMALL batch
to find the proportions of wax/oil desired. Then make up several
medium sized batches using the formula determined. This is
safer than trying to make up one HUGE batch all at once.
Let us know how you fare.
Hope this helps.
Fr. Tom McGahee