Homebrew PCBs

On Friday 06 May 2005 03:13 pm, Stefan Trethan wrote:
> On Fri, 6 May 2005 14:57:54 -0400, Roy J. Tellason
>
> <rtellason@...> wrote:
> >> Light bulbs contain inert gas at atmospheric pressure.
> >
> > I was of the impression that it was at somewhat lower than atmospheric
> > pressure,  otherwise you wouldn't get that "pop" when they break.
>
> It is lower than athm., put a propane torch against it and the softening
> glass will be pulled in.
> (yes i am aware that experiment could have resulted in shattering hot
> shards and be beeing blind...)

It takes a certain technique to work with glass and have it not shatter.  I 
found that out the hard way back when I was into messing around with 
chemistry sets and such stuff.

> There's Argon in there.

What I thought.

> > The other reason it's that thick is because of lead in the glass to absorb
> > x-rays,  at least for color tubes,  which is what makes TV sets and
> > monitors a bit "hazmat" rather than just being able to put 'em in the
> > trash.  Monochrome monitors and old B&W tv sets don't have that issue.
>
> Why is x-rays created, and why is it not beeing created in BW TVs?
> Always wondered..

Higher voltage.  Typical monocrhome tube uses no more than 12-15KV for an 
acceleratign potential,  color tubes use 25-30KV.  Apparently that's enough 
to make a difference.

I can still remember the old tube-type color sets where the HV rectifier and 
regulator tube were enclosed in metal,  and if they'd been in service for a 
while the glass would be a dark brown color from xray bombardment.