Powering a 12v HeNe PSU? Update: Adapter built

Re: Powering a 12v HeNe PSU?

Yeah, sorry. Fixed

All of the power supplies for hard disk enclosures have 12V at 1.5-2.5A, and most of the older ones have 5V at 1.5-2.5A as well. So if you have an old one you don't need any more or know where to get one cheap, you can use that. I use one to power a 445nm laser. You could also put two 12V 1A ones in parallel.

You could even make it portable. SLA batteries are on sale. 7Ah for $13 is pretty good I think.

Re: Powering a 12v HeNe PSU?

oo. Good thought on the external HHD power supply. i think I have one I could tear apart to at least test with. I did find this on Amazon that along with a standard 4 pin extension cable and a P4 extension cable will make the permanent power supply.

Amazon.com: CG 110v AC to 12v DC 4pin molex Power Adapter: Electronics


edit: found the same thing at newegg (diff brand). I'd rather pay a dollar more and order from a company I've dealt with many times in the past.

Re: Powering a 12v HeNe PSU?

Ok hate to double post again but the suggestion to use the PSU from an external HDD case worked perfectly. I put my DMM in series with it and it's drawing a steady 2.12A which I should be able to get out of that adapter fine. The 543.5 green it puts out is nicer than the 532 DPSS IMO. I metered it three and got 2mw twice then 5mw. The last measurememt was after it had been running for a good 15 minutes and I suspect it was either picking up the heat of the tube or from my hand which resulted in the extra 3mw. I suspect 2mw is pretty accurate because that's just a hair above the 1.9mw that the seller told me it had been measured at.

Re: Powering a 12v HeNe PSU?

Pleased it works. Little hene lasers are great fun

Re: Powering a 12v HeNe PSU?

Good deal on the GrHene! Let me know if you need one of those little female quad connectors, I might have one in my parts bin.
- Robert

Re: Powering a 12v HeNe PSU?

I ordered the parts to build the 12v supply for my GrHeNe's PSU since the PSU in my external HDD case isn't self contained. They should be here mid week. I'll update this or post a new thread once they get here.

Re: Powering a 12v HeNe PSU?

vk2fro said:

In that case you connect the TTL lead to ground to turn the laser on.

If the TTL Line has 2 wires (what I call a seperate TTL), short them together

If the TTL has only one wire (common ground TTL), short the TTL wire to your ground (12V negative) connection.

Whatever you do, dont connect the +TTL line to +12v, you will probably end up killing the brick.

Click to expand...

With the Laser Drive PSUs (which most of them are even if they are branded by the laser manufacture) wiring the TTL enable wire to +12V damages the regulation circuit. The PSU still appears to work, but the current is too high and will damage the laser tube. Why they made the enable wire yellow instead of black, green, or some other color that would imply negative is beyond me but almost all of them are. I've been fixing a lot of these potted bricks lately so it can be done but it can be tough to get into them.

I've seen a lot of HeNe lasers incorrectly matched to power supplies. People see that the Alden connector fits and assume that means it's ok. Look up the specs on your head and compare them to what's printed on the PSU, then measure the current. I usually insert my DMM in the cathode (black) side of the circuit set to DC mA and measure directly, but it's safer to put a 1k resistor in the cathode side, measure the voltage across that, with 1k each Volt equals 1mA. Most of the green HeNe heads I've seen are spec'd at 6.5mA but work ok at 6mA.

As for powering the brick, most are rated 10-16VDC input but it's best to use a regulated power supply. You can find regulated "wall wart" types or as someone else mentioned, a computer or external HD power supply will work well.

Re: Powering a 12v HeNe PSU?

My parts arrived Wednesday and I whipped up an adapter.

First the test supply I rigged up from an external HD case as suggested by Cyparagon. Worked fine. Yu can see the PSU is pulling2.12A. The draw was very constant never varying more then +/-.01A over a period of 15-20 minutes.


2010-12-08_04-05-02pm - Version 2 by ltkernelpanic, on Flickr


The parts I used. A 12v 2A power supply mostly used to power 12v devices such as DC fans in equipment cabinets and entertainment centers. I also used a P4 extension cable, a standard 4 pin to SATA power adapter.


2010-12-08_04-09-10pm - Version 2 by ltkernelpanic, on Flickr

I didn't take pics of the actuall building part but it was pretty simple. I cut both cables in half since I needed the male end of the standard 4 pin power plug and the female end of the P4 extension. Next I plugged the P4 cable into the the PSU and labeled which cables were what. Then I soldered them together, tested the completed cable and finally slid the heat shrink over the joint and shrunk it.

The final cable. I decided for now not to cut off the red 5v wire coming from the power adapter or the unused yellow wire in case I needed 5v for something down the road. I did wrap the end of the 5v line in some tape to stop it from shorting. The clear tubing was from the SATA adapter. I put piece on to help protect the solder joints.


2010-12-09_09-45-52pm by ltkernelpanic, on Flickr

Powered up and working.


2010-12-09_09-45-34pm by ltkernelpanic, on Flickr

And of course a beam shot. I left the camera on auto and let it do it's thing. Ended up with a 6 second shot. Oddly enough except for 2 dimmed LCD computer monitors it was pitch black in the room. Looks like all the lights were on in the picture. The texture of the chair really scatters the beam.


2010-12-09_09-47-06pm by ltkernelpanic, on Flickr

Re: Powering a 12v HeNe PSU?

Hmm. Hate to bump this thread again but I noticed last night that the 12v PSU put out a high pitched whine when running off the 12v adapter. I plugged my adapter into the external HD's PSU and the whine is gone. Looks like the extra .1A it was able to draw from the unregulated 12v supply. So now a question? Would running the PSU off a 2A source instead of 2.1A harm it? I don't run it for more than a few minutes at a time so would it be a problem other than the irritating whine?

I may just try to put the PSU from the external HD case into a rat shack project box after Christmas if the Dremel I want is under the tree. :san: I might also see if I can find another one of these 12v supplies that puts out 3 or 5A which would be more than enough to power it.

Re: Powering a 12v HeNe PSU?

LtKernelPanic said:

Hmm. Hate to bump this thread again but I noticed last night that the 12v PSU put out a high pitched whine when running off the 12v adapter. I plugged my adapter into the external HD's PSU and the whine is gone. Looks like the extra .1A it was able to draw from the unregulated 12v supply. So now a question? Would running the PSU off a 2A source instead of 2.1A harm it? I don't run it for more than a few minutes at a time so would it be a problem other than the irritating whine?

I may just try to put the PSU from the external HD case into a rat shack project box after Christmas if the Dremel I want is under the tree. :san: I might also see if I can find another one of these 12v supplies that puts out 3 or 5A which would be more than enough to power it.

Click to expand...

Does that power supply have a 5V output too? If so, it's likely that it requires a certain minimum load on the 5V output for the 12V output to be stable. I've used small power resistors and incandescent lamps in these situations.

A power supply rated at 2A ought to be fine indefinitely at 2.1A. I don't advocate overloading things in general, but you're talking a 5% increase, which should be well within the safety margin. Switchmode supplies will shut down if overloaded and the transformer type have a thermal fuse that will blow if they overheat.

Most of the "lab style" HeNe supplies use PacTec instrument enclosures which can be ordered from them directly. I used a similar enclosure from Teko for the PSU for my 1145P and it came out really nice. You could get a really clean professional look by mounting the brick and the 12V PSU in one of those. Electronic Goldmine has a great deal on some key switches perfect for laser PSUs at $1.29 each. When it comes to cutting openings for connectors and switches I use a nibbler tool, file and a step drill bit. Dremel tools tend to make a mess of plastic.

Re: Powering a 12v HeNe PSU?

Sorry I misread that, I thought it was whining off the HD power supply.

Have you measured the voltage under load from the power supply that makes it whine? You may need to add a filter capacitor to stiffen it a bit. Whining is bad news, the 12V input power bricks are somewhat fragile and repairing them can be very difficult since they're potted.

Thanks for the input. It pulls 1.99-2.01A off the adapter. I haven't measured the voltage yet though. I found the same type of 12v supply that puts out 12v at up to 5A which I'm gonna pick up after Christmas.