Path: utzoo!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!zaphod.mps.ohio-state.edu!ub!kitty!larry
From: larry@kitty.UUCP (Larry Lippman)
Newsgroups: sci.electronics
Subject: Re: How to light a UV tube
Summary: Sounds like a medium pressure mercury lamp...
Keywords: UV
Message-ID: <4795@kitty.UUCP>
Date: 13 Mar 91 14:14:19 GMT
References: <1991Mar12.214815.11808@amd.com>
Followup-To: sci.electronics
Organization: Recognition Research Corp., Clarence, NY
Lines: 35

In article <1991Mar12.214815.11808@amd.com> lpdjb@brahms.amd.com (Jerry Bemis) writes:
>I get a bargin price on a UV tube.  In measures .3" x 2.5" with a 2.5" base.
>It has a 6" zip cord coming out the end of the base.
>
>    glass tube
>    |       ______________
>/-----------  base        |====== cord 
>\-----------______________|
>
>Now I need to know how to light it.    120 volt AC doesn't light it up.

	This is pure speculation on my part, but it sounds like you have
a pencil-type UV lamp manufactured by Ultraviolet Products, Inc. that is
in their model series called "Pen-Ray".

	A Pen-Ray lamp is a medium pressure mercury lamp which requires a
high voltage for starting, with a low voltage through a ballast for
continuous operation.  While I have seen and used Pen-Ray lamps, I don't
know the exact design of the Pen-Ray ballast circuit.  They may use what
is called an "iso-stabilized constant wattage ballast", which resembles
a transformer.  The primary goes to the 120 volt AC line, and the secondary
connects to the lamp in series with a capacitor.  Open-circuit voltage
(i.e., lamp not fired) may be 300 to 700 volts, depending upon lamp size.
Voltage across the lamp may drop as much as by a factor of 10 while the
lamp is in operation.

	Assuming that I am correct for your particular lamp, the problem
is that the above ballast is not a simple two-winding transformer.  It
is specially designed with particular saturation losses at given secondary
currents.  Offhand, I can't think of a simple and cost-effective way to
duplicate the required ballast circuit.

Larry Lippman @ Recognition Research Corp.  "Have you hugged your cat today?"
VOICE: 716/688-1231       {boulder, rutgers, watmath}!ub!kitty!larry
FAX:   716/741-9635   [note: ub=acsu.buffalo.edu] uunet!/      \aerion!larry