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Re: [TCML] Quick Question



HI Everyone
I am going to give you so information on EMI with Tesla coil. I have a 1500 sq. ft. shop with metal and solar barrier around it, which blocks everything. I work on radio's and repair my wife's ATM machines so I have to make sure the EMI and EMF is very low in the shop. I went to the local college were I teach night class's at and use there HP Spectrum analyzer 8569 if I remember right and there Carnel labs EMI/field meter and a hand held, I don't remember what it was. the first thing I did was put my O scope on the AC line at my work bench turn on my 4 in Tesla coil and the scope show a big spike in EMI and noise. MY shop is 150 feet from the power pole were the ground rod is so I put another ground rod right at my breaker box in the shop. The scope noise signal drop about 65%. I still did not like that so I took the 3 outlets in my shop tied them to a single ground wire 6 feet from the outlet put a 10 ft. ground rod in the ground hook everything up, try it again this time the signal was total clean, I tried my 6in coil still was clean, I fix the AC side but
not the air  EMI. With a one spark gap the HP show a wide range of EMI,
the EMI/field was real high up to 15 ft away. I made a wire cage and put over the spark gap ran it straight to a ground rod. this got rid of 65-70% of the EMI. I do a lot of experiments with Crooks and Geissler tube, a lot of crooks give soft Xray's so play with different think to stop the Xray's, one thing my research came up with was 1/4 in acrylic would help with the Xray's. I made a cover 3 sides made of 1/4 acrylic put wire on the two ends and did the test again, this time it was 75% gone. I than put aluminum tape on the inside of the acrylic but was no help, than I used the copper foil tape which work great I got 90% the of the EMI out of the room from the spark gap. ON my big Tesla coil it has 5 copper tubes in a PVC pipe and it seems like the EMI came more out of the top and bottom than through the PVC pipe itself. I try a rotary spark gap they had at the school, the EMI was off the scale on the analyzer and the EMI/Field meter up to 25 ft away. The most I ever got the EMI down was 60% with a cage, and the more gaps on the rotary the worst it got. The actual arc's itself did not emit a lot of EMI unless they hit the strike rail or my metal door than the EMI spike. I also tested this with my solid state coil's and there was little air EMI readings. Both my drsstc are small not large the best only does 2.5 ft. but I run it in the same room with my work bench and my wife's ATM machine on and running with no effect on them but it is being run on the grounded outlet too. In the end there is no way to total stop air EMI but you can stop 90% of it coming across the ac line for sure. I am no expert at Tesla coiling this is just the testing I
did with the test gear I could use.
Alton




On 7/7/2013 3:24 PM, Mike Gray wrote:
Hi all, just a quick one. I was running my rotary spark gap the other day
to do some testing, and so I had a multimeter out on my bench top, fairly
close to the spark gap assembly. When I ran the spark gap the display on
the multimeter went a bit haywire - it all flashed up and started rapidly
cycling through random numbers and symbols etc. It only did this when the
spark gap was firing. Would this be due to RFI coming off the spark gap and
interfering with the multimeters internal circuitry?

Cheers

Mike
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