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Low Voltage MOT coil - first, brief lights
I finaly put the stuff I've been scrounging together and got my first coil
(worth mentioning) lit!
Specs:
1 MOT
.001uF & toroid choke (F-high pass 30KHz)
spark gap - in development
Pri- 2 turns 20" dia. 3/8" 10' long, copper pipe, around 7uH,
Pri cap- .5uF 1.5" dia x 4" long ceramic cap (looks like fit for RF use by
large metal terminal rings)
Secondary - 5" dia 4' long, too many turns of closewound around #26 wire
Terminal - 30" dia x 4" dia torroid
Fr- 100KHz
Puts out 20" hot blue arcs to ground wire, 40" thin violet streamers in air.
I'm having big problems with the spark gap. The voltage is so low, probably
around 1.5 - 2 KV, that when a couple 1/4" dia copper pipes spaced around
3mm will arc a couple times, then foul (oxidize) and stop. Moving them
closer results in a very hot, non-quenching arc after a few good pops.
Tried using multiple gaps, with no improvement. Just tried using a car coil
on a trigger wire in between. Worked real good, until the 1mm dia wire
started melting! Switched to flattened copper pipe, and the other
pipe-electrodes got hot and melted the solder off!
So tomarrow I'll try a triggered, 5-section 3/4" dia, flattened pipe. Of
course I'm blowing air from a 40 watt squirrel cage blower. Tried corona
from the car coil in a glass tube, to no avail. Triggering with 20KV from a
car coil is a real pain as it wants to flow around the mica insulators,
which the arc then procedes to burn up!
>From what I read about the Newark .1, 3KV $2.60 cap, for $10 (for 5 caps)
and a MOT a pleasant small coil can be built. But the spark gap is turning
out to be a real problem. Perhaps submerging the spark gap in oil might
help? Then of course there's IGBT's. Anyone price them lately?
Scott