Piezo HV Power Supply

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

Original poster: "Ed Phillips by way of Terry Fritz <twftesla-at-qwest-dot-net>" <evp-at-pacbell-dot-net>

Just realized I left a few things out of that note I wrote about trying
an HV power supply made from an igniter stack.  First, since the thing
has a capacitive output impedance, it's necessary to connect a reverse
diode across it to allow it to recharge after each click.  Second, the
rectifier diodes came from a swap meet and, although they were labled
"600 microamps, 28 kV", weren't much longer than a 1N4007.  They start
to conduct at about 6.5 volts, implying there are of the order of ten
junctions in series.  I suspected that I was getting significant leakage
across them so tried substituting two in series, with no noticeable
difference in performance.

	Second, there is a commercial outfit (FAXITRON) which makes an
interesting portable emergency X-ray machine using a piezo stack for
generating the HV.  It has a field-emission cold-cathode tube which I
seem to remember (read this several years ago) operates at around 70 kV.
The energy for operating the HV supply comes from a 32 blank cartridge
or something similar.  To operate the thing you insert the cartridge and
pull the trigger.  Still not enough total energy to run a TC......

	Finally, there is enough dope about piezoelectricity on the web to
permit one (I'm too lazy) to calculate the output from any given stack
of any given material.  Maybe someone else has enough interest to give
it a go.

Ed