Path: utzoo!attcan!uunet!cs.utexas.edu!sdd.hp.com!uakari.primate.wisc.edu!aplcen!jhunix!ins_atge
From: ins_atge@jhunix.HCF.JHU.EDU (Thomas G Edwards)
Newsgroups: sci.electronics
Subject: Kludged Laser Power Supply
Summary: finally got laser working
Message-ID: <5395@jhunix.HCF.JHU.EDU>
Date: 29 May 90 22:10:33 GMT
Reply-To: ins_atge@jhunix.UUCP (Thomas G Edwards)
Organization: The Johns Hopkins University - HCF
Lines: 51

About a year ago, I purchased a .5 mW helium-neon
laser tube at a hamfest.  Unfortunately, the
guy didn't have a power supply, but for $30 for
the tube, I figured I could make my own.

I went around the hamfest and found a 120V to 630V
transformer.  I also got enough pieces for a 
voltage quadrupler with 1000V capacitors and
6500 PIV diode packages.

It turned out that the laser did not fire when
I hooked up the circuit.  I tried different
balast resistors, but still nothing.

Much later, I decided to work on the project again.
I finally bought a VOM with a 1000V scale.
I also came into a 120V-30V transformer, a
120V-6V transformer, and a variable transformer
for 400 cycles.

So, I kludged together the following circuit:
120V to 30V transformer feeds the variable
transformer (not getting it too warm at 60 cycles).
The variable transformer feeds the 6V-120V
transformer.  That feeds the 120V-600V transformer,
which finally feeds the quadrupler.  I slowly
turned up the variable transformer, and the laser
lased at around 700V input to the quadrupler
(thus only slightly overpowering the 6V-120V and
120V-600V transformers).  

I woudln't reccomend anyone to copy this circuit,
seeing how there are multiple overvoltages and
the variable transformer must be kept at a
fairly low voltage, but it is an example of
how one can work with a bunch of free and
inexpensive parts to put together a laser system.
total cost was around $60 (not including VOM).

I spent last night bouncing the laser around with
mirrors around my room, down the hall, out the
door to the late-night barbecue on our porch.
Lighting up neigborhood stop signs
from the second floor window is also fun.
And finally, we passed the laser beam through 
various multi-faceted glass dishes we had for
interesting refraction results.

Now all I need are two galvometers...

-Tom