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ArcticMyst Security by Avery

Homemade CO2 laser power supply

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Feb 28, 2011
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After seeing the price of an average 40w CO2 laser power supply i decided i could probably make my own for much less.
Took about a week of messing around with components, a day of putting it in a box and about a month of getting round to actually doing it ;)

It runs from about 24VDC at 12 to 15A and gives out (hopefully) ~15kv at ~18ma.
Features no output regulation at all...

Heres a few pics:
Top down view:
img0355ds.jpg

Side view(shows HV out):
img0356yn.jpg

Front view (input):
img0358a.jpg

Back view (HV ground):
img0359y.jpg

Case open (Yes, that is the top of the transformer sticking out the side):
img0360bb.jpg

Pulling an arc from 12V input:
img0363e.jpg

Just thought i'd share this with you guys, let me know what you think :)
 





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Mar 7, 2011
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Looks very similar to a SSTC I built when I was ~ 18 years old. I wish you well and look forward to pictures of the completed laser.
 
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Thanks :)
I'm going to leave it running for a bit to see if anything melts/explodes, if all seems good i'll connect it to my laser and post some pics here as soon as i can.
 
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Getting about 8ma through my laser, driver might need some tweaking.
Then again, i'm using an ATX PSU and a 12v SLA to make 24v or so to run it. The battery is a bit low and the 12v rail of the PSU sags to about 10v under this type of load...

Some pics anyway:
Lighting up a ceramic tile from incandescence:
img0366e.jpg

Same thing but with the lights off:
img0367je.jpg

Just a note; the laser has a nice pink glow in real life, my camera doesn't seem to pick it up all that well so it looks a lot more blue.
 
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Verry nice stuff man :)

And can i ask you what you payd for the tube ?

+rep :)
 
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cheers :D
The tube cost £60 (just under $100) from ebay. Unfortunately, it was coming from china so postage was £50. Although it did arive in one piece within a few days, so i can't really complain about the cost.
 

Arayan

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Nice PSU :gj: +1 Rep :)
there is also a potentiometer to regulate the output voltage?
 
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Thanks a lot :)
Unfortunately not, right now i regulate the output by adjusting the input voltage. It uses a ZVS driver for the transformer, i can't find a way to easily adjust the driver with somthing like a potentiometer to change the output voltage. If anyone knows of a way to do this please let me know.
 

Arayan

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If anyone knows of a way to do this please let me know.
I asked this just to know if there is a way :(

...unfortunately i'm not able to spread other rep to you :cryyy:
 
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Seems we have the same problem :(
The only things i can think of is a very large ballast resistor on the output/input but this would waste lots of power, or some form of variable power inductor (if such a thing exists) as from what i can tell the ZVS driver output current and voltage can be adjusted by changing its inductor.
 
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The usual way of regulating that circuit is to put a buck converter on the input and use a voltage divider to sample the HV output and feed that into the feedback input of the buck converter. Something like the LT1074 would probably work well, can do 10A with a tapped inductor.

DC flyback transformers usually fail when run for long from a push-pull driver though. Also the very small wire in the secondary will limit your output current and cause heating in the transformer. When it burns out you can wind your own HV secondary for better results.
 
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Hmmm... They only take 18mA to run. The wire would have to be microscopic to burn out at 18mA. Are you sure it is not because of insulation failure or something like that?
 
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18mA at 20kV is 360 Watts, that's quite a lot of power. Consider that the max beam current in a CRT display is typically 1-2mA and consumer goods are rarely made with much of a margin. Some flybacks are more robust than others but I have burned out several of them. Some suffered insulation breakdown from pushing them too hard, others overheated and burned out in plasma speaker experiments and Jacobs ladders. I've only ever cut open one flyback and the wire was about the smallest I've ever seen, it looks like a strand of hair.
 
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I've had this one for quite a while, it's lasted much longer than any others i've played with. They all seemed to arc over internally and die from that.
I've pulled thick white fire-like arcs from it for a few minutes continuously multiple times before i decided to use it for this and it didn't seem to get all that hot. I don't plan on using it to power my laser for more than a few minutes at a time anyway. After all, who needs a 40w beam of 10600nm radiation flying around their room for any relatively long period of time.

DC flyback transformers usually fail when run for long from a push-pull driver though. Also the very small wire in the secondary will limit your output current and cause heating in the transformer. When it burns out you can wind your own HV secondary for better results.
I agree running it push-pull can't be doing it much good. I was tempted to wind my own before i used that one but i decided to use the original secondary and get the most use out of it before it dies, then wind my own.

Oh and on a side note, am i right in thinking that if i wind my own and use a bridge rectifier it will give me almost double the possible output? Considering i'm driving the core push-pull DC it will have an alternating magnetic field as if i was driving it with AC.
 
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Sounds like you found yourself a good one. It may indeed hold up for a while, who knows? Some are certainly much better than others, but usually I end up frying them eventually. I built a mains powered driver which is a bit like a turbocharged engine in that you can turn the power up and up and just keep getting more and more output until something breaks. Takes some restraint to recognize the limit and not push it beyond.

This is not my design, but it works great.
_-= Uzzors2k =-_ Project Site

He also has a variable bench supply using a very similar design which would be a good basis for a regulated HV supply.

Yes, if you use a transformer with an AC output and a full wave rectifier on the output you will get much more as well as it greatly reduces the problem of core saturation since you no longer have DC in the winding.
 
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I have the same problem, I always end up pushing things that 1 step too far...

Hmm, i'll have to look into that. I always find myself needing a decent reliable HV power supply for one reason or another.

Great, i'll look into HV diodes and magnet wire next time i order parts.
Thanks +1 Rep :)
 




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