## Lasertube Preset circuit...

Electronics related to CNC

### Lasertube Preset circuit...

I had found a simple circuit on the internet with two potentiometers to set the presets of a fresh installed lasertube, but i can't find it anymore..
Let me explain:
Say, your lasertube will start firing at 13% and will reach its maximum current at 92%.
This preset-circuit makes the spread from 13-92% equal to 0-100% of the controller, so 0.1% on the controller will be 13% at the powersupply and 100% from the controller will become 92% at the powersupply.
This presets only have to be set once, when the tube is installed.. After that you can program 0-100% full scale..

Has anyone find this too and know where it was? Ofcourse i can develop my own circuit, but better "stolen" good than though out bad..

Kees
Techgraphix

Posts: 102
Joined: Fri Feb 24, 2012 8:37 pm
Location: Appelscha, NL

### Re: Lasertube Preset circuit...

I haven't seen this before but please post here if you find it.
greenvandan

Posts: 59
Joined: Mon May 28, 2012 1:41 am
Location: Baltimore, MD

### Re: Lasertube Preset circuit...

It was this thread I believe:

http://www.lightobject.info/viewtopic.p ... ing#p12236

It's really just a voltage divider so that as you say, 100% stays within the current limit for your particular power supply/tube combination. The author talks about "trickle current" which there really isn't. All it's doing is scaling the 0-5v PWM signal so that it's really 0-Xv instead. You have to be a little careful because not knowing what the low pass filter on your power supply looks like, your results might vary.

Scott
sshwarts

Posts: 93
Joined: Tue Apr 22, 2014 6:37 pm

### Re: Lasertube Preset circuit...

Hi Scott,
Yes, that was the article I was looking for... I knew he had tried several ways to connect the potentiometers..

Kees
Techgraphix

Posts: 102
Joined: Fri Feb 24, 2012 8:37 pm
Location: Appelscha, NL

### Re: Lasertube Preset circuit...

I'd be interested to see how this works if anyone else tries it.

My laser has a smaller window of operation. The tube is only useful between ~10%-35% of the laser PSU's power.

Rich
rsm5178

Posts: 119
Joined: Tue Jul 23, 2013 9:57 pm
Location: 19425

### Re: Lasertube Preset circuit...

I looked pretty closely at this and didn't really see an advantage (unless there's something I'm missing). With our DSP's (AWC and ilk) the biggest downfall I see is that they don't, I believe, do PPI the way that others do it. The pulse length is not constant but varies with the PPI.

Scott
sshwarts

Posts: 93
Joined: Tue Apr 22, 2014 6:37 pm

### Re: Lasertube Preset circuit...

I was thinking in terms of engraving. Not sure how the awc lo-x7 or laser cad works when dithering an image. Normalizing over 100 values would seem to have a better grayscale range than trunkated 35 values?

Rich
rsm5178

Posts: 119
Joined: Tue Jul 23, 2013 9:57 pm
Location: 19425

### Re: Lasertube Preset circuit...

Thank you for sharing this with us.. its very useful..

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g4ngst3r

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