Update on Digitally controlled spark gap

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Jeremy Scott by way of Terry Fritz <teslalist-at-qwest-dot-net>" <supertux1-at-yahoo-dot-com>


I tried some experimenting with the vacuum gap
under digital control. The problem is the vacuum
gap doesn't respond fast enough, nor does it
quench very well -- operation was erratic even
under manual control.

So we're back to the digital RSG idea.

I had US Digital make me a custom shaft encoder
that'll send 2048 TTL pulses per revolution.

At 1800 RPM, that's 61,440 pulses per second
to be counted by the COUNT command.
(1800/60 * 2048) for 3600 RPM, I'll count
for only 1/2 second. I'm going to build
the disc with 5 electrodes so I'll be running
at speeds 80% of what would normally be done
with 4 electrodes.

I've got a 120V 4800RPM 2HP DC motor, I purchased
a neat controller for it: The KB-212D

http://www.kbelectronics-dot-com/components/catalog/gc115/kbmg212d.pdf

I'm hoping this controller will work, it accepts a
0-+10V isolated external signal which represents
0-%100 motor speed (positive voltage for forward,
negative for reverse) OR control it via a
potentiometer based voltage divider. It's a feedback
based controller so you set it's speed and the
controller keeps it that way no matter what happens
with the load.

Phase control will be dropping the RPM down a notch
for a fixed period of time to allow the electrodes
to roll backwards along the sinewave.

Next step:

I need a high resolution TTL DAC -- at least 12 bits
(4096 steps) from 0 - 10V (or 0-5V) I2C or serial
control would be nice, but not necessary. I have 40
pins to work with on the microcontroller.

My first choice is the AD565A:

http://www.analog-dot-com/UploadedFiles/Data_Sheets/62189282AD565A_6A_e.pdf






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