Changing the max output power

I think this is more of a power supply question than a Ruida question, but maybe the Ruida can solve this as well, so here it goes:

My laser tube is rated for 25mA max. When my laser power is set to 70%, this power is reached. Right now I limited the laser power to 70% in the Ruida configuration to make sure I don’t kill my laser. So any job that is configured to anything higher will be restricted to 70% max.

Essentially this means my 70% is actually 100%. It would be much more convenient if 100% was actually 100%. Now I’ve seen a few posts of people with the same question that eventually ended up changing a potentiometer on their laser PSU to set the max power of their supply.

Unfortunately my PSU, a HY-Z80 does not have such a trim potmeter. So I guess my only option is to solve this in the Ruida (or in Lightburn).

Same goes for the minimum power, which is 13%. It would be great if that could be recalculated to 1%. But this is less of an issue.

Any idea if this is achievable?

I know that the manufacturer tells you not to touch it. But P1 sure looks like an adjustment pot to me. If it was me I would probably try adjusting it by recording the starting point so I could go back to it. Worse case is it might kill the power supply. then I would just but another PSU as they are $80, to me it would be worth the risk.

I thought the same. But unfortunately P1 is an indicator LED. :slight_smile:

Well sorry about that.

No worries. It’s reassuring that my first thought wasn’t that weird. :slight_smile:

You can limit power using either or both Lightburn or your controller. I not aware of a way to do that using your power supply, but I’m sure some power supplies have that feature. Obviously in Lightburn you can set max power in the cut setting editor. Controllers also have a max power setting which you should be able to access thru Lightburn. I would set your maximum amperage comfortably below 25ma, as long as it cuts well.

I had the exact problem with mine. It would drive the tube way over what you would expect the current to be.

My ‘China Blue’ has an 880mm tube and is 44 watts. The power supply is a 60 watt model.

Mine is in a very convenient position… lol…

My tube is placarded at 21mA max. 50% is about 10mA.

I set the power on the console to 50% and adjusted until I got 11mA of current. Granted I can run it ‘too hard’ but I want the ability. I have my comfortable max of 18mA and that is about 82% power. I have my controller set to 95% which should limit the max output to the tube to 21mA :pray:

I had to really crank it down.

@MichMich With that power supply can you set any limits via it’s control panel?

Seems to have ‘open’ circuit protection. Wonder if it’s a ‘smart’ supply…

Good luck


@Dean448 I’m well aware of these options. That’s how I’m currently doing it. But the thing is that in that case I alway need to use 70% if I mean 100%. What I’m looking for is to rescale the power percentage. That can be a software solution but it would be better if I can change the current output of the PSU.

@jkwilborn That control panel is only a display. Unfortunately it doesn’t allow you to set any current. Indeed it has open circuit protection and is “smarter” than an average supply. But there doesn’t seem to be a way to change the max current.

Just hoping it was an option. Guess it isn’t that smart…

Did you query Cloudray about the issue or the power supplies adaptability?

Looks like a nice supply, you would there would be something…


No Cloudray is my next hope. But usually if I ask Cloudray a question like this, the answer is something like “you can set your max power in your computer program”. :sweat_smile: love their shop, but never had a helpful answer from their support. :grimacing:

I guess I’m not following the problem. You have two percentages, one on the controller and the other on the cut.
Isn’t a matter of setting the cut at 100 and adjusting the controller percentage so that you don’t exceed 25ma?
My controller is set at 22% as to not overdrive the power supply which is lower than the tube. Obviously I’m not trying to get all the power my tube can generate

I really should get the unit you have but I’m kind of a wait until I have a good reason to spend $ guy.
Let us know if you see any issues with that unit.

@dean448 It is purely a convenience thing. With the way you describe it, the output will be as follows, given that I limited my controller to 70%:

50%: 17.14mA
67%: 23.9mA
68%: 24.2mA
69%: 24.6mA
70%: 25mA
71%: 25mA
72%: 25mA
73%: 25mA
74%: 25mA
75%: 25mA
99%: 25mA
100%: 25mA

In other words, anything above 70% will be limited to 70% which is 25mA. It’s safe for the laser tube. But It take the way the convenience of a real clean configuration range.

If you can set the max current of the power supply to 25mA, the range will be much cleaner:

25%: 6.25mA
50%: 12.5mA
75%: 18.75mA
80%: 20mA
95%: 23.75mA
96%: 24.00mA
97%: 24.25mA
98%: 24.50mA
99%: 24.75mA
100%: 25.00mA

Of course, this is only in theory because the PMW value will not be converted linear to the actual current. But it does make the range a lot wider 0-100% in stead of 0-70%. You want full power? You use 100%. You want half the power? You use 50%.

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Do you really know if your laser is cutting any different between 20 and 25ma? A laser amp gauge doesn’t operate like a speedometer on a car. I thought I read somewhere that laser power (in terms of energy going into the material) tends to flatten at the highest power.

In my opinion you only need to understand three settings for each material you cut. A cut power, a vector engrave power and a raster engrave power. And not to exceed power rating on the tube when cutting.

But…you can set it up how ever you like. Have fun and good luck. :blush:

You are right about the 3 settings. But those settings differ from material to material. For som materials I use 65%, for other 70% and that definitely makes a difference.

In most cases I prefer to use power below the maximum tube rating just to lengthen the life of my tube. But sometimes the full power is absolutely necessary.

And in case it’s 70%, what I actually mean is 100% of the maximum tube rating. That why I would like to adjust my PSU.

I understand you exactly and also wanted this option to “software scale” my tube, in order to work with the correct scale from 0-100%. But last time I have asked for it, I was told that it will be very complicated and I just had to adjust my power supply. Gradually, I have “accepted” the skewed scale (10-65% in LB), but a little annoying it is anyway.

Solving it in Lightburn shouldn’t be too difficult, but it gets messy because the Ruida will end up showing a different power percentage than what you typed in Lightburn.

Solving it in the Ruida firmware is pretty simple. But of course not something we can do ourselves.

Solving it by adjusting the PSU is extremely simple. But unfortunately not all PSU’s allow you to set the output power.

… even though it’s simple, I do not want to play with this power supply.

Doesn’t Amazon sell Magic Smoke in case it goes wrong?! :sweat_smile:

I monitor my hv when I’m running, along with current. Not sure I know what I’m look at yet as far as voltage/pwm/current relates when it’s operating.

I do know that a co2 is a ‘negative resistance’ device.

So an increase in voltage across the tube causes a decrease in current at some point…


AFAIK most (or maybe even all) Laser PSU’s are current controlled. So you only need to keep an eye on the current in regards to the supplied power. The supply automatically adjusts the voltage in order to reach the correct current.

I’m not sure if the PWM signal is converted by the PSU to a steady current driven power supply. Or that that actual high voltage power on the laser is also pulsed.