What is the purpose in putting radioactive substances in these brushes? Is
it to help ionize the air so there will be less static buildup?

Sean


At 11:55 AM 12/8/97 -0600, you wrote:
>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.
>
+--------------------------------+
| Sean Breheny                   |
| Amateur Radio Callsign: KA3YXM |
| Electrical Engineering Student |
+--------------------------------+
http://www.people.cornell.edu/pages/shb7
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