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Re: Death & rebuilding of a Neon
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