30 Oct
2002
30 Oct
'02
8:04 a.m.
From: "Patrick Finnegan"
<pat(a)purdueriots.com>
I know this is a bit OT, becuase it's not really computer related, but the
hardware is at least 23 years old, so that's my excuse for posting to the
list...
I've got a 35mW HeNe Laser + Power supply that I picked up today for next
to nothing. It seems to be having some problems - the laser (somtimes)
blinks a few times when I first turn it on, and then stops. From the
sound of the power supply it's either a loose connection (which I doubt
after opening it up and taking a good look around) or there's a problem
with the power supply.
Now, I've never really worked on a HV power supply before, and I'm trying
to be careful when I play with things. First off, does anyone have a
general idea of what sized dummy load ("resisitor") I should try haning
off of the HV output to properly load it? I noticed that the laser tube
has 3x27kohm resistors in series, would a couple watt approx 81kohm
resistor be a good idea?
Also, does anyone have an idea for a failure mode to look for? I've got
an O'scope, dmm, and various other tools at my disposal, but no
'authentic' HV test/mesurement gear.
Hi
I know this doesn't make sense at first but it is most likely
that the failure is in the HeNe tube and not the power supply.
The general failure starts with the lasing pulsing at slower
and slower rates until it stops working.
The problem is caused by the He leaking out of the tube.
I know you'd say, how can that happen when inside the tube
is a partial vacuum. Well, it has to do with partial pressures.
The partial pressure of He is lower out side of the tube than
inside, so it leaks out. It is also related to the slipperiness
of He. It leaks through everything, including glass.
Try another tube that is known to be good.
Dwight
I'm just looking for general guidelines.
Thanks!
Pat
--
"The Microsoft/IBM FORTRAN was adequate for teaching FORTRAN 77. But the
performance was AMAZING! It could actually take longer to run a benchmark
like sieve of Erastothanes with compiled FORTRAN than with interpreted
BASIC."
-- Fred Cisin (XenoSoft)
http://dilbert.com/comics/dilbert/archive/images/dilbert2040637020924.gif
31 Oct
31 Oct
11:39 a.m.
I know this doesn't make sense at first but it is
most likely
that the failure is in the HeNe tube and not the power supply.
The general failure starts with the lasing pulsing at slower
and slower rates until it stops working.
The problem is caused by the He leaking out of the tube.
I know you'd say, how can that happen when inside the tube
is a partial vacuum. Well, it has to do with partial pressures.
The partial pressure of He is lower out side of the tube than
inside, so it leaks out. It is also related to the slipperiness
of He. It leaks through everything, including glass.
Try another tube that is known to be good.
Dwight
He is atom weight (that's old style bec I was taught this 14 years
ago), of 2 (I think) so it is MUCH lighter than everything except H
and will float out on top of everything too. Hence used in balloons.
Also He is noble means it doens't react to anything because their
electron layer is filled, only two electrons orbiting core made up
of two photons, two neutons. Utter stable except to split it with
energy knocking them apart (fission).
H reacts to oxiziders becuase oxidizers has electron holes availble
shell that can share more electrons with another different type of
atoms: for example. Burn H and O2 you get water and heat.
Knowing the basic rules of electron shells of given atoms and you
can mentally "build" elements. H20 is element, water.
Cheers,
Wizard
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dwightk.elvey＠amd.com -
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