dsbryant@telocity.com
Date: 12/10/01-01:14:17 PM Z
Jeff,
> What you can also do is place a thin piece of sheet metal under the
> bulbs and tie this in to the common ground. That is what one would
> typically do in building a unit from individual bipin holders. To get
> maximum reflectivity paint the metal white. The metal can be very
> thin for this purpose.
>
As Linas pointed out in an earlier e-mail the ballasts need to be grounded. When I built my UV printer, I simply extended a bare ground wire that touched the top of each tube (12 20w BLs). This provides for an unobtrusive and safe way to let the bulbs "see" ground to allow for easy startup and no flickering. In addition I painted the inside of the enclosure a flat white to allow maximum reflectivity without creating a specular diffuse light source like you may get with say crumbled aluminum foil or unpainted metal surfaces.
Please note that you will need to be certain that the AC wiring from your wall outlet is correctly polarized.
Polarity checkers may be purchased at any hardware store or outlet for a few dollars if you do not know how to check this with a volt meter, and are good for a life time.
> >hmm, interesting. The 2 tubes I have put in to
> >test the unit did flicker on startup and then were steady - less
> >than 1 minute to get there.
I have noticed that the BL tubes don't start well when they are cold, such as might be expected in an unheated room in the winter time, which is where I my exposure unit is located. This can be over come by allowing the tubes to heat up for 5 or 10 minutes prior to your printing session. When they are cold they are also less likely to come on instantly.
Hope this helps,
Don Bryant
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