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Re: I need help with my crappy coil
In a message dated 4/18/00 9:17:00 PM Pacific Daylight Time, tesla-at-pupman-dot-com
writes:
<<
I need some help my coil only makes one inch sparks
Transfomer: an MOT thats current limited to about 0.45 amps by a oven
heating coil.
Tank cap: MOT cap-2100 volts .7 microfarad
Spark gap: single gap 1/16 inch
primary: flat spiral 9.5 turns of 0.125 inch copper wire. outside diameter
is 7.5. and inside diameter is 2.5 inches.
Secondary: 9 by 1.5 inch secondary on a pvc. Total turns 656
This coil really sucks...i had to go with an MOT because i had no access to
a NST or an OBIT. The circuit is the same as a standard tesla coil with
capacitor in series with the primary without any inductors or safety gap
>>
Yuba,
It would be handy to have your name to reply to.
There are a few opportunities for improvement here. First the microwave oven
transformers can handle much more current. I am guessing you are limiting
your secondary current to about 20 or 30 ma. One MOT is kind of low on
voltage. I suggest you use two in series. Tie the cores together and ground
them. Run the primaries in parallel on 120 volts or in series at 240 volts.
Make sure you have them phased properly. You will know if it is wrong, you
will have little or no spark.
Second, this coil is way out of tune. The primary and secondary must be
tuned to the same frequency. The approximate resonant frequency of your
secondary with no toroid is 1.7 MHZ. It would drop to about 940 KHZ with an
8 pf (6" to 8" dia.) toroid on top. To make the primary resonant at this
frequency you need a capacitor of about .0007 uf. In other words, your
present cap is 1,000 times too large.
Good luck, Ed Sonderman