On Fri, 11 Dec 1998, Sean Breheny wrote:

> > Weeks ago  I left  my UV erasable chips under the sun for hours and I did
> >not notice any change (even using the magnifier glass someone
> >suggested)until they flew away from  my home balcony in 7th floor,just
> >because of the wind.
>
> I have always heard that many types of glass do not pass UV well. You may
> need to use a UV lens for this instead. Also, the UV focus would be
> somewhat closer in toward the lens than the visible light foci.

Actually the battery powered unit uses no lens (i.e. it is removed
completely, or painted over, a piece of static foam glued inside, and
provided with a hinge to serve as chip carrier and loading door at the
same time).

I use the exact same device for home use, without lens and battery, but
with coil + starter + cap on mains power. I also bolted a mild steel tape
to the lamp case all round so you can't see the light when it is put on a
table, lamp facing down. The lamp is about 12 mm above a DIL chip window
standing on the table. Some day soon I'll add a micro switch to cut power
when the device is not laying flat on the table.

Along the same lines: How do you mark down the original calibration on JW
508s and 509s ? I use a steel needle to scratch it into the brazed window
bezel but sometimes more scratches are added during handling and then it's
gone. Is there a marker pen that uses non-transparent non-removable ink
and has a fine tip ?

tia,

Peter