CO2 power supply

[Hemlock_Mike]

Unless this is a high impedance RF excited CO2 tube, stay with a balasted DC driver. RF is a different world as some here have found.

HMike

 

[Pontiacg5]

American Radio Relay league?
The ARRL handbook for radio communications 2010 [Book]

 

[cistercian]

American Radio Relay league?
The ARRL handbook for radio communications 2010 [Book]

Yes.From transformer turns ratios to building a transistor driver for the transformer, the raw data you need is there.2 big transistors being driven by a simple PWM circuit( pulse width modulation) would allow you to control output power of the system nicely.It is relatively easy to incorporate current limiting to the output as well.There will not be explicit plans, but the theory you need is there as well as enough practical applications to allow you to design and build what would otherwise be either unobtainable or prohibitively expensive.
Commonly available parts and some time should pay off nicely.

I hope this helps.If it is too much, an inverter running a commercial supply would work, but it would be bulky and heavy too!

Good luck with whatever method you choose to feed your tube with.

 

[Hemlock_Mike]

The ARRL is the "voice" of ham radio like the NRA is the "voice" of gun owners. Both are very important for freedom but not always related to laser science.
If your laser tube is a long water cooled style with electrode connections, it is driven by HV DC power with current control. If it has copper foils on the side of the tube, it is likely RF excited with 27 Mhz or 50 MHz input.
There may be driver circuits in the ARRL handbook if yours is RF excited but impedance might be a problem.

HMike

 

[Pontiacg5]

Mine isn't RF excited, but I would still like to learn to run one that is. Anyways I don't think cistercian is recommending running the laser off of RF, I think he is recommending this book for circuits to drive a flyback transformer to get HV DC.
Correct me if I'm wrong, but pulsed DC is what powers a flyback right? If you hook up regular batteries it wont do anything. Right?
There is a power supply on ebay for around 200 bucks, but its 110AC. I guess I could get a power inverter, but I want to build this one myself from scratch. Minimalist for portability

 

[cistercian]

The ARRL is the "voice" of ham radio like the NRA is the "voice" of gun owners. Both are very important for freedom but not always related to laser science.
If your laser tube is a long water cooled style with electrode connections, it is driven by HV DC power with current control. If it has copper foils on the side of the tube, it is likely RF excited with 27 Mhz or 50 MHz input.
There may be driver circuits in the ARRL handbook if yours is RF excited but impedance might be a problem.

HMike

Power supply design is basic.And the Handbook covers it very well.It would certainly be good enough information for him to choose the proper solution for his application. I had not even thought of the tube needing rf drive, but achieving a decent impedance match once it was lit would not be that hard.
The Handbook is a good reference for any electronic/science enthusiast.And it has the particular advantage of being in many librarys.
If the tube requires HV DC, the safety precautions alone may save his life.Voltage multiplier strings are incredibly dangerous when the capacitors are charged...no second chances.

 

[Pontiacg5]

Funny you should mention that, I've got a story from a ways back...

I was playing with 2 CRT monitors trying to wire them in parallel to run a tube (don't laugh, I was just tossing crap together!) I got one hooked up, but it would only pulse the tube at really low frequencies (probably around 1Hz) so I tried to hook the other up. I was bringing the ground towards the tube for the second monitor and the HV arced about 8 inches through the air to my hand. That dropped me on my buttox extremely quickly, I walked around for a good hour tingling and twitching pretty good. I guess some people call that seeing the HV ghost, well I know I don't want to see him again

After that incident, I became a lot more cautious with what I was doing. I can't believe I didn't kill myself, I guess I'm just lucky.

 

[cistercian]

Mine isn't RF excited, but I would still like to learn to run one that is. Anyways I don't think cistercian is recommending running the laser off of RF, I think he is recommending this book for circuits to drive a flyback transformer to get HV DC.
Correct me if I'm wrong, but pulsed DC is what powers a flyback right? If you hook up regular batteries it wont do anything. Right?
There is a power supply on ebay for around 200 bucks, but its 110AC. I guess I could get a power inverter, but I want to build this one myself from scratch. Minimalist for portability

You are right, if you put DC into a transformer, output only occurs at first connection or when you disconnect the power.Transistors turn the dc on and off and that will give you output.Try Google for really specific recipes for 12 volt powered current limited hv supplies.A neon sign transformer of the correct voltage would work, and they come in various current ratings.Driving one with an off the shelf inverter would work too.
Remember, If your tube has to see dc and not ac you have to rectify whatever you use.An HV transformer would need a HV rectifier...not cheap.
A lower voltage transformer needs a higher parts count in the multiplier string, but those parts are rated for lower voltages, so they cost less.What you ultimately decide to use will probably be driven by what you can obtain easily, and inexpensively.
Neon sign transformers are constant current designs....and choosing one that will provide the requisite current while not cooking the tube may be easy.It would certainly be easier than calibrating the current control scheme of a multiplier approach.
Either one provides voltages and current capable of killing you instantly.
Read up on fatal current paths in the human body.I am serious here.
Charged capacitors can stop your heart before you know you made a mistake.The Handbook deals with how to "dress" HV leads and safety precautions you should follow.If you have any doubts about it, buy an off the shelf solution or ask for help, IN PERSON, from an expert.It is literally impossible to overemphasize this point.
Also, never work on HV alone...and make sure your friend knows CPR.

I have broken some of the rules in my youth.And I had to beat on my chest as the world began to gray out because of an arm to arm 1300volt dc hit from a charged cap bank.Just as I was sure it was over, my heart did some horrible squirming and then beat super fast, gradually slowing to a normal level for someone who was scared out of their mind.I was 15, and I still don't know what instinct made me hit my chest as hard as I could with my right hand.Doing so saved my life...but it was close.I have talked with 2 other men who did the same thing...one was hit by lightning, the other contacted a 440 volt bus.We all agree....it is very quiet when your heart is not beating , and the grayout starts really fast.I am 48 now...and have not had any repeats!
I tell you this so you can know, it happens.And most do not survive it.

 

[Pontiacg5]

Luckily my hit was only across my hand, I can't imagine what would have happened if I had grabbed the lead with my other hand. I guess I'm lucky I'm not left handed
I was 15 when I "rode the lightning" too, I don't know how you did anything. I couldn't move for a good couple of seconds.

HV is a different world, and I'll figure it out eventually. There are too many ways to do what I want, it just confuses me!

 

[cistercian]

Luckily my hit was only across my hand, I can't imagine what would have happened if I had grabbed the lead with my other hand. I guess I'm lucky I'm not left handed
I was 15 when I "rode the lightning" too, I don't know how you did anything. I couldn't move for a good couple of seconds.

HV is a different world, and I'll figure it out eventually. There are too many ways to do what I want, it just confuses me!

I was knocked on my back, and I remember it took an extreme act of will to strike my chest.It took 3 blows before the horrid sensation of a bag of worms in my chest, followed by the super fast beating.I was sore for 2 weeks in both arms and my chest.


You are right that there are a lot of ways to do what you want!You could copy a known good design.Schematics may only be a serious google session away!Also, Current controlled DC supplies are used in some giant copiers.I have a 10,000volt 11ma unit in the basement I salvaged from one.Use your imagination....blueprint machines might be good for parts too.
I think an inverter, a neon sign transformer, and a rectifier would work fine if the right size transformer is selected.Done carefully, it could be cheap too!
Good luck.

 

[Pontiacg5]

I have schematics for a 20k power supply, but they are only good for 10mA which is about a 10-15W tube. Not to mention they would be expensive to build. I'll probably end up running it with the neon transformer, I'm going to have to look pretty hard for one that pushes enough current. I think a oil burner transformer would work too, might have a bit more current with one of those.

HV diodes and caps are pretty cheap on ebay, that'll probably be how I do it.

Could I use 2 neon transformers in parallel to one multiplier to get more current? I ask because 2 of these with a multiplier would give enough current and no need for a inverter
http://cgi.ebay.com/ebaymotors/NEW-...ptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories

 

[cistercian]

I have schematics for a 20k power supply, but they are only good for 10mA which is about a 10-15W tube. Not to mention they would be expensive to build. I'll probably end up running it with the neon transformer, I'm going to have to look pretty hard for one that pushes enough current. I think a oil burner transformer would work too, might have a bit more current with one of those.

HV diodes and caps are pretty cheap on ebay, that'll probably be how I do it.

Most of the oil burner transformers I used were 10,000 volts @ 22ma.
They were actually 5000-0-5000, with zero(the center tap)being connected to the case.That gives 10,000 volts between the terminals.I used to connect 2 in parallel for 44ma.
I have seen 15,000 volt 60ma neon transformers.They were about like 3 oil burner transformers in size!

 

[cistercian]

You can parallel them for more current.They have to be identical, or they will burn out in short order.IE:2 of the same brand, part # etc.

 

[Pontiacg5]

I think I could get away with a 15kv 30mA transformer, but they are so damn big!!

I haven't seen a oil burner transformer with 3 leads, but 10kv at 44mA would be perfect. Probably pretty compact too. You don't remember what brand they were do you?

Ah sweet, I think I'll run 2 of these auto transformers in parallel

 

[cistercian]

I think I could get away with a 15kv 30mA transformer, but they are so damn big!!

I haven't seen a oil burner transformer with 3 leads, but 10kv at 44mA would be perfect. Probably pretty compact too. You don't remember what brand they were do you?

Ah sweet, I think I'll run 2 of these auto transformers in parallel

The case of the transformer is the center tap or third lead you are looking for!

 

[Pontiacg5]

The big iron core neon transformers have 2 HV out right? Because all of them that I'm looking at have what looks like 2 HV out standoffs.
The newer style transformers only have one HV out right? Because if that is the case I can't go full wave with one of those. I don't think using 2, one for each side of the wave would work either because there would be no way to tell if they are pulsing at the same time.

Correct me if I'm wrong, but half wave only has power 55% of the time. I want my laser to have power as much as possible so I would need full wave. So I don't think I can use the newer smaller neon transformers or the oil burner transformer because it doesn't push the current I need.

I'm thinking one 10kv 30mA iron core transformer through a 1 stage full wave cockroft-walton voltage multiplier. I only need one stage so that puts my voltage at 20kV and current at 15mA. But then I need a little more boost to kick the tube on, so I would need a extra stage, but not once the tube is on. That's what the parasitic part is for right? Is that just a resistor and a couple more diodes? I need a little more clarification on that step.

Well, do you think I'm on the right path so far? I think I almost have this figured out!