WTB:  Helium-Neon laser power supply 6.5 mA - Page 1
Forum section: electronics / general

author: Alex
author_rank: Regular Contributor
timestamp: February 09, 2017, 11:41:33 am
content: I am after a power supply that can supply 6.5 mA at 3kV or so. This is for a helium-neon laser.I don't mind what type it is or anything else.ThanksAlex

author: Gyro
author_rank: Super Contributor
timestamp: February 09, 2017, 12:20:13 pm
content: Just a note that you need a PSU that will output 8-10kV (low current) when open circuit - HeNe laser tubes need a higher striking voltage than running. It is normally done by a supply with a voltage multipler output that has artificially small capacitor on the upper stages so that the otput collapses to running voltage after striking.You just need to avoid ones with a regulated output voltage of 3kV.P.S. You might find this site helpful:http://www.repairfaq.org/sam/laserhps.htm

author: Alex
author_rank: Regular Contributor
timestamp: February 09, 2017, 12:35:23 pm
content: Thanks for the additional information Gyro.If it can readily supply the 6.5 mA at 3 kV I am willing to do the rest, for now.The ideal supply would be this:http://www.lambdaphoto.co.uk/lasers-photonics/lasers/helium-neon-lasers/power-supplies/lasos-san-7470-a4-he-ne-laser-power-supply.html

author: Gyro
author_rank: Super Contributor
timestamp: February 09, 2017, 01:03:10 pm
content: Yes, sure. You can use a capacitor discharge driven pulse transformer in series with the output to generate an ignition pulse.

author: Photon939
author_rank: Regular Contributor
timestamp: February 09, 2017, 02:52:34 pm
content: I have a few HeNe power supplies laying around, I'll check the ratings when I get home. Shipping to the UK may be prohibitive though.

author: Photon939
author_rank: Regular Contributor
timestamp: February 10, 2017, 06:19:06 am
content: I found the following:Melles Griot 05-LPM-379-11.15-1.77kV 5.5mAInput: 120vac4 Available, $20 each + shippingNot exactly what you were looking for but it was worth a shot

author: james_s
author_rank: Super Contributor
timestamp: February 10, 2017, 07:25:43 am
content: HeNe power supplies all have a starting multiplier built in, the starting voltage is not printed on the label.I've done quite a bit of reverse engineering and repair of these things, my schematics and information are in Sam's FAQ. There are a few common designs that show up under a number of different brands, with a multitude of different model numbers and ratings with little to no difference in the circuit. There are three common sizes, one that's good for small lasers up to about 2mW, one for midsized up to about 5mW, and one for up to about 10mW. The main difference is the current setting, which may be an internal resistor or an externally accessible pot.Anyway my point is that one brick may be labeled 2200V and another may be labeled 2700V when in reality they are identical internally. Sam G sells laser equipment and normally has a variety of HeNe bricks in stock if you don't find something here.The 05-LPM-379 mentioned above is a very common PSU manufactured by several different companies, it's one of the low power bricks for small lasers, 2-3mW is about the max that is likely to work on it, if your tube needs 3kV it's not going to cut it. $20 is a great price for one though.https://www.repairfaq.org/sam/laserhsc.htm#hscmg4

author: Alex
author_rank: Regular Contributor
timestamp: February 10, 2017, 12:08:22 pm
content: Very close photon, thanks for having a look.Hi James, yes I got in touch with Sam but also LASOS to identify the module I got. It looks brand new and it does lase. But it came from an OEM microscope, without a PSU, so it might have been replaced due to low output. In this case splashing $150 out or more does not make sense (from Sam, ebay, Mi-laser etc); need to test first.The search continues. I will be visiting colleagues at a university to at least test it with the PSUs from their HeNes. I really don't want to take out the x-ray transformer.Alex

author: james_s
author_rank: Super Contributor
timestamp: February 10, 2017, 04:46:44 pm
content: How long is the tube? That's a reasonable indication of the size of power supply required.Sam may still have one of the ones I repaired, I think he was selling those at lower prices because a potted brick is never going to be *quite* pristine after having been dug into. There's a common fault with those Laser Drive manufactured bricks that have a TO3 chopper transistor. The transistor is mounted horizontally floating above the PCB and thermal expansion of the epoxy under it eventually cracks the solder joints. I use a milling machine to cut a pocket right over the affected solder joints and then pick the epoxy out. I might have something suitable in my pile of HeNe bricks awaiting my attention, I must have at least 50 of them in various states of disrepair.

author: Alex
author_rank: Regular Contributor
timestamp: February 10, 2017, 05:48:59 pm
content: I am not entirely sure tube length as it is in a module. But I identified it with LASOS and it is a tad over 10mW. Spec-wise it is identical to the LGK 7654-8.Worth having a look through the pile I think.Alex