Instructables

Childhood Laser: Building a HeNe Laser Kit

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This is about building a Class II <1mW Helium-Neon (HeNe) laser. It's also about a dream that's been a long time coming. A little back story would help.

As a kid, back in the 80s and 90s, I used to get Elenco electronic kits from my Dad and Mom as presents. I had them all, the Digital Roulette (K-25), the Space War Gun (K-10), the Pocket Game Dice (K-28) and many more. Even a few robot kits. Then I discovered lasers and all I could talk about for months was getting the brand new Class II Laser Kit (LK-1).

Of course lasers are dangerous and so both my parents said no, responsibly. I continued to pester them and a deal was struck: I write a report on lasers, about their history and safety, and they would buy it for me. So I went to the library, studied up on lasers, wrote the report, and in 1992 I got it. I was so happy I couldn't believe it.

Well, as chance would have it, I lost the instructions and we put off building the kit for a while. Then the whole thing got forgotten and packed away, lost to me for about 15 years. I found it about 5 years ago while I was moving and surprisingly everything was in mint condition. The instructions were still lost and so I checked the internet every year seeing if the schematics would pop up but they never did.

You see the board has no markings and I didn't have a full parts list, only the parts in the box. So the best I could do would be to reverse engineer the circuit, something I'm not great at. A picture would have helped tremendously but I couldn't even find one of those. Finally I tried looking at the Way Back Machine for even the smallest clue but only found this:

http://web.archive.org/web/19970125020504/http://www.elenco.com/dlxkits.htm#lk1

With all hope lost I finally decided to write Elenco for help, hoping that they had the 20 year old plans in their archive. I probably should have tried that first but it never occurred to me. Well wouldn't you know they sent me a PDF of the schematics and instructions the very next day! Suddenly I became a 12 year old again, giddy with excitement. So here I am ready to make a 20 year old dream come true and build that laser kit I begged for as a kid.

So if you're ready then come watch me build this old kit and bring my laser to life!
 
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A really nice story and a well documented project in case anyone happens to have one of those things knocking around. Even if it's been assembled, this instructable might give clues to how to repair and replace parts.
natantus (author)  Dream Dragon2 years ago
That's what I was thinking. This is probably the only documentation of the LK-1 kit on the internet right now. Plus, people probably have variations on this design and this could give them some help too.
mazda49522 years ago
what type of transformers are used?
i cant seem to find the right ones and none of the shematics show any markings.
mazda49522 years ago
do i need a certain size of laser tube, or can i use any size?
LaserRage2 years ago
Awesome story man!
Xonk612 years ago
OK, I read the instructable, and was really pleased to see the details included, Thanks! I've got a box of HeNe tubes and several Hi voltage blocks, all the electronics are encased in epoxy, so as each one quit working, I had no way to repair them. And from this article, I see there's not really that much to one! I can build one, but for a single piece of information I didn't find. What is the voltage input/output of the transformers? (the ratio, I guess is what I'd need to know?)

Thanks so much for posting this!
natantus (author)  Xonk612 years ago
I'm going to have to look into that for you. I'm not quite sure myself. I only have the labels T1 and T2. I'll see if I can't measure it and get back to you. Good luck with your project!
Xonk61 natantus2 years ago
I would very much appreciate it! Thanks for the reply
OrenLeavitt2 years ago
Nice!
I tinkered with my first HeNe laser tube as a teen in the late 1970's. I still have that tube (it's one like yours but housed in a nice aluminum tube) and another larger one that is 2 feet long.
Thanks for sharing!
Every month I looked forward to receiving Popular Electronics, Radio Electronics, the Edmund Scientific, and other electronics catalogs every month!
natantus (author)  OrenLeavitt2 years ago
Have you ever thought of putting them together again? It would be great to see them work. We definitely need more instructables with lasers.
I would love to put this back together sometime and share it - time permitting...
I have been thinking about a revised compact power supply design using a TV fly-back transformer. Thanks to flat-screen technology, there is a glut of surplus CRT fly-back transformers out there for cheap.
My old power supply was simply a small transformer (120 VAC primary/900VAC secondary) coupled to a half-wave voltage multiplier (like the network of diodes and 0.01µF capacitors on yours) to get the open-circuit output voltage up to the several kV needed to start the tube, and a current limit resistor.
rkimball42 years ago
Great story. I will say though that this is probably out of reach for most. I have used these same tubes for over 30 years in my career field. They are now cost prohibitive as the HeNe tubes are priced over $800. Maybe you can find cheaper but not by much.
Hang on to way you have and enjoy.
natantus (author)  rkimball42 years ago
I noticed that the price has gone up if you buy them new. However I did see some deals on ebay and other sites. Some people have old tubes in good condition and have no idea what they're worth. Might be a good deal for an intrepid engineer.
astrong02 years ago
I wish you could shoot the laser around the house like that newer James Bond movie.
natantus (author)  astrong02 years ago
My fiancee will wish you'd never given me that idea;)
Ace Frahm2 years ago
What is that red triangular tool? Is that for bending leads?
natantus (author)  Ace Frahm2 years ago
Yep. I use it when I want my parts to look nice on the boards I put together. But for most of my life I've just used my fingers to bend leads. You can pick one up for a couple dollars I think.
venom15392 years ago
LOL, don't look into laser with REMAINING eye.
natantus (author)  venom15392 years ago
Glad you liked it. I've seen that poster put up in a lot of Hackerspaces.
Could NOT download the 'LK1_Study.pdf' Instructable site didn't seem to want to download. Is there a way to get a download???

Outstanding project and one I remember from my own youth. Great piece of work and thanks for the memories!!!
natantus (author)  trike road poet2 years ago
I think I've got it replaced and working now. Take a look. If not I can try to email it to you. Nothing important inside, just notes from when I was a kid. Pretty fun to look back on.

Thanks for the reply!
Dr.Bill2 years ago
I remember waaaay back in '69' when I got my HeNe Laser Plans from Lindsey Publications. I had to go to a neon sign maker to get the transformer and a 12 inch HeNe tube made. My mom worked for Montclair Electronics so that's where I purchased the dilectric mirrors for $60 buckolas. There were Brewster Windows back then too.

I used little standards to mount the mirrors in casting sand from metal shop.
When the thing was turned on I was blown away when it worked and so were the teachers. Their Laser came from Edmond Scientific.

We spent the next week playing with the focus and measuring beam divergence at different distances.

I know how cool it is to put something, like what you did, together.

Great I'ble keep going with it and put together a holographic table. You should have a lot of fun with your device.
natantus (author)  Dr.Bill2 years ago
What a great story! And thanks for the support. I definitely need to do some cool projects with this. The holographic table sounds like a great start. I'm sure there are a ton of great projects for HeNe lasers.
I have a laser like in 1980 which operated until 1990 the pictures of the old laser here: http://micbric.free.fr/laser/
Bye
natantus (author)  bricmic2 years ago
Thanks for sharing these. What a great resource for people to have. Before I found my schematic I was definitely trying to find pictures of similar circuits for help reverse engineering my components.
Back in the fifties I was intrigued in lasers, $100,000 from Mr Howard Hughes to Mr Goodman to research lasers,Got a pink ruby light enhanced laser going,Mr Hughes did not patent it for good reason Mr Testler had done it in the thirties and all books relating to it was removed from my local library soon as I mentioned it,
Instead a volumetric book by testler was lodged at my library in scientific language.From the American library of Congress!
natantus (author)  stephenfitton2 years ago
That sounds so cool!
XTL2 years ago
some of those capcitors must be rated at a very high voltage - please mention which ones.
natantus (author)  XTL2 years ago
I'll try to figure this out in the next week. I've only got the schematics to guide me but I'm pretty sure all the high voltage caps are on the right side of the board. I definitely tried not to hold that side after I'd turned it on for a while. I bet the discharge would hurt a bit.
Amazing, well written and enjoyable instructible. I'd rate this 10/10.
I can see how excited you were to put this together in your instructable.
natantus (author)  lurkingdevil2 years ago
I'm glad you enjoyed it! I had a great time with this project.
Kiteman2 years ago
Oh, that's nice!

How powerful is the finished laser?

(And I'm the only one who thought "Oh, light sabre!" when they saw the close-up of the lasing chamber?)
natantus (author)  Kiteman2 years ago
Not sure I answered how powerful it is. It's rated as a 0.62mW laser. I don't have the means to measure the output but if I do I'll be sure to post it.
natantus (author)  Kiteman2 years ago
I definitely thought this looked like a light sabre when I saw it turn on. That 12 year old inside me was super pleased:)
tim1272 years ago
Is there any way i could get one of those kits or something similar? really cool laser by the way
lspicer tim1272 years ago
Follow this link for all you want to know about Lasers. http://community.wickedlasers.com/
natantus (author)  tim1272 years ago
Elenco stopped selling this kit in the late 90's. I'd love it if they still sold something like this but I imagine there's something to do with regulations getting in the way. However, you can probably make your own using this instructable as a reference.
caitlinsdad2 years ago
I'll tell ya, these were things of inspiration back in the day. You would go through the edmund scientific catalog to see if you could ever afford one, those machined aluminum mounting rails were cool. If you had one, then you would point it at the moon and see if you could put a spot on there. Of course, you had to dream about getting or building a high enough power telescope to see if it worked. I thought HeNe lasers were in the green range? It is way more fun than taking apart an ordinary laser pointer.
natantus (author)  caitlinsdad2 years ago
That's exactly how I felt about those catalogues when I was a kid. It's actually a great idea to use my laser and point it at the moon. They have those mirrors up there that will reflect the light back. Now all I need is a good collector:)
fsargent2 years ago
Excellent job! It's so great to see a childhood dream come to "light!" Hahahahaha
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