Re. Weird Shunts & Homemade Vaseline

From: 	Gary Lau  12-Dec-1997 1436[SMTP:lau-at-hdecad.ENET.dec-dot-com]
Sent: 	Friday, December 12, 1997 12:45 PM
To: 	tesla-at-pupman-dot-com
Subject: 	Re. Weird Shunts & Homemade Vaseline

>> 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?
>> 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

>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 ------     |
>      |                                     |
>      |                                     |
>      |_____________________________________|
>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

Since this is a transformer geometry (Jefferson Electric 15k/60mA) that
doesn't seem to be widely used with no documented experience on exactly
how much of the shunt sections to remove, I decided to leave well enough
alone and do nothing to modify the shunts, rather than risk removing too
much and permanently ruining my transformer.

I found the best deal on Vasoline at a Costco, my local wholesale-club
type of store, selling two 13 oz tubs for $5.  I bought 8 tubs for $20 and
used a double boiler to melt it on a stove.  I ruined one tub by
splashing a few drops of water into it.  Turns out I needed a total of 6
13 oz tubs to fill the transformer case to the brim.  All in all, I'm
very pleased with the way it turned out and was very glad to be able to
re-use the case and insulators, I never could have found anything else as
compact and nice looking.  Using vasoline, I know I'll never face an oil
leak and should I ever have to open things up, it will be a simple matter
to heat it up in a moderate oven and drain it.

Performance: 43" sparks.  Brief specs: 15K/60ma xfmr, 4.25"x23" #22AWG
secondary, 4.5" x 15.5" toroid, 15 degree .25" Cu tubing primary, .01uF
100KV FCI cap, 10x.03" RQ static gap.

Gary Lau
Waltham, MA USA