I once made a negative ion generator that was based on one of these
devices.  The one I used was .5 micro-curie of radium sulfate.  This was
placed in a plastic housing that was designed to sit next to the
spinning record..  I attached the device to a wire mesh screen to which
I applied a negative 600 volts.  A fan blew the negative ions off the
screen.  Don't know if this device is still available.  That was back in
1964...

-------------------------------------------------
Work all day & night,
deliver on time & on budget,       Regards,
and justice for all...             Bill Bryson


>-----Original Message-----
>From:  Ram Krishnan [SMTP:krish@MEGSINET.NET]
>Sent:  Sunday, December 07, 1997 6:25 PM
>To:    PICLIST@MITVMA.MIT.EDU
>Subject:       Re: PIC-based angle sensor...
>
>There are anti-static brushes still being used in the photography biz.
>These come in a variety of sizes, and contain a polonium cartridge that's a
>mild (so I am told!) radioactive emitter. I also remember reading in an R/C
>Modelling magazine (in 1974?) about someone who built a diffrential
>electrostatic field sensor with electrodes mounted on each wingtip. The
>sensors picked up the gradient of the earth's electrostatic field. If
>memory serves, the device was switched in when the plane went into an
>uncontrolled spin, and would correct it to level flight. Interestingly
>enough, I never heard of this again!
>
>In theses days of femtoamp bias input opamps, rigging one of these should
>be a lot easier.