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CO2 Power Supply Schematic Help

upaa27

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Hello all,

I recently aquired a 50w co2 tube and have been designing a psu for it. I am pretty new to circuit design so I wanted to ask you guys for some help and suggestions on my current schematic. IT IS NOT DONE yet which is why some of the values have not been calculated yet. I am just wondering if I am on the right track as I am very much a newb to circuits.

Sorry for my chicken scratch handwriting. Been working on it :p


Click to enlarge. Host site wouldn't let me rotate for some reason.

Thanks
 
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ARG

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You should use imgur for posting images :p

If you're still new to circuits I wouldn't start with a high voltage project, that's just asking for trouble.
That 3125k ohm resistor on the 120VAC mains looks suspicious. I would recalculate that ;)

Edit: The bridge rectifier looks off as well.
 
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DashApple

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In the picture the rectifier bridge is shorted out ? .

For a simple co2 laser as long as the voltage is within range no starting pulse is needed just current limit the supply to the tube rating .
 
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upaa27

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You should use imgur for posting images :p

If you're still new to circuits I wouldn't start with a high voltage project, that's just asking for trouble.
That 3125k ohm resistor on the 120VAC mains looks suspicious. I would recalculate that ;)

Edit: The bridge rectifier looks off as well.
Sorry it is sopposed to say 3125 ohm not kohm. As for the rectifier I will look over that.

Thanks ionlaser. I think I might just voltage double a neon sign transformer I have with some resistors to keep the current at 22ma. Although this is a sealed tube and I tea somewhere that you need an inition voltage? Is this true? Just clarifying
 
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DashApple

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AFAIK all CO2 tubes require a startup pulse to start lasing.
The starting pulse is just to ignite the tube same as in argon lasers , small tubes will work without the start pulse as the running voltage is enough in most cases to arc though the tube

The peak DC voltage from the Rectified NST would be enough to start the tube

A 40W tube may run without the pulse when it's operating voltage is applied but a 100W tube would probably need the pulse to first ignite the arc ( high operation voltage too )


For a proper PSU it does the start pulse and then the voltage drops to the running voltage but that's to operation power as the start pulse is just to start but I think most low power supplies just supply the running voltage

Don't take my full word on this as this is mainly what I observed with my 15W and 60W tubes , but I would say the rectified 15Kv NST would have no issues running the tube considering people run 40W tubes on unrectifed NSTs
 
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Sigurthr

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Ditto on 555's comments. I've observed the same with 15W and 40W PSU's and tubes.

If you do voltage double a NST make sure you size your capacitors properly, the voltage sag under load for a greinacher cascade is tremendous. You'll also need to make the full-wave version, and not the standard half wave.
 

Things

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I've run a 40W tube straight off a 15kV 30mA NST .. just stick a chunky ballast resistor in series to limit the current a bit. CO2 lasers are designed to run off DC as it helps circulate the gasses through the outer tube (with the catalyst in it), but they will run off AC without damage too, just not as efficiently.
 

djQUAN

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why use multiple transformers rather than one with a HV secondary? If you plan to use off the shelf transformers and cascade them, then that will not work.
 

upaa27

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why use multiple transformers rather than one with a HV secondary? If you plan to use off the shelf transformers and cascade them, then that will not work.
Because I was planning to make the transformers and did not want to wrap 20000 coils of wire :p

I've run a 40W tube straight off a 15kV 30mA NST .. just stick a chunky ballast resistor in series to limit the current a bit. CO2 lasers are designed to run off DC as it helps circulate the gasses through the outer tube (with the catalyst in it), but they will run off AC without damage too, just not as efficiently.
Mine is 12kv. :cryyy:
 
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upaa27

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Just did some tests with my nst.

Nitrogen didn't ignite as expected. Need more powah! Just to wait on chinese shipping now...
 

djQUAN

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Because I was planning to make the transformers and did not want to wrap 20000 coils of wire :p
unfortunately, there is no easy way out.

To generate HV, you need many turns of wire. If the transformer will have to take in a HV input from the first step up transformer, you need even more turns on the primary and a lot more turns on the secondary to prevent core saturation especially if you plan to run it at 60Hz.

Still better to just wind 100T primary and 20000 turns secondary on a single transformer than wind 100T + 2000T on one transformer, 2000T+10000T on another transformer then 10000T + 20000T on another transformer. I hope you get the idea ;)
 




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