OHVM Status

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

Original poster: "David Sharpe by way of Terry Fritz <teslalist-at-qwest-dot-net>" <sccr4us-at-erols-dot-com>

All

Successful operation of main signal path of OHVM
PCB tonight.  Calibration circuits are functional.
Calibrating PCB as I write this, using a 6.3V 3A
filament transformer as input voltage, powered
by a 1kVA TC controller.  Have epoxy to
encapsulate HV divider PCB,  have to build
"rails" around PCB to hold epoxy, and borrow
a vacuum box from work with vacuum pump
to outgas epoxy after poured.

Isolated power I'm using a UCC3808 push-pull
8 pin DIP PWM controller (Digikey <$2.50).
Running open loop (5 passive parts to complete).
PWM driver PCB is only 1.2" x 1.8", and thats
with leaded components.   3808 drives a GDT
of 1:1.5:1.5 turns ratio w/ 4kV BIL.
Isolated rectified and filtered output is +/-21 VDC,
then linear regulated down to +/- 12VDC using
LM320Z, LM340Z TO92 regulators
(current burden is <30mA).

Full up validation tesing will gradually increase
voltage from 2.3kV (PT), to 5kV (NST), to
15kV (NST) and finally 20kV (PT) overdriven
with 140VAC (24kV rms).  Will run with 24kV
for at least 3 hours, prior to final installation in
main controller.  Only problem to date has been
bad solder joints, and a missing analog ground
at main TB input.  Operation to date is more
stable and higher performance then observed on
breadboard (DUH!!).   More pics and updated
report hopefully within a week...

Regards
Dave Sharpe, TCBOR
Chesterfield, VA. USA