>From: "Patrick Finnegan" <pat_at_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
>
>
>
Received on Wed Oct 30 2002 - 16:04:01 GMT
