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Re: Anybody see a problem with this wiring change (DSP -> PS

Posted: Sat Nov 28, 2015 10:37 am
by Techgraphix
Carbon is even better as this has more linearity: a wirewound potentiometer (almost only used in high power applications) has a number of windings. In fact is more like a selectorswitch with many steps, one for every winding.
Kees

Re: Anybody see a problem with this wiring change (DSP -> PS

Posted: Sat Nov 28, 2015 11:46 am
by Tech_Marco
Just want to let you guys know that I already talked to the programmer about the % issue. So, the power output shows on the LCD will display 0~100%, regardless the Max_power (%).

Currently, if Max_power is set to 65%, the power output displays 65% even though the power level is set to 100% on the job's power setting
He will try to do it once the Baby DSP development is completed. Possible taking another month to finish

Marco

Re: Anybody see a problem with this wiring change (DSP -> PS

Posted: Sun Nov 29, 2015 1:39 am
by Techgraphix
Both trickle-current and max-current? Laser-power-scope-tuning-settings like these would be great.. a Zero-level-adjustment and a Hundred-percent-level-adjustment which can be adjusted when there is a new tube placed or when the old tube is degrading (ie draws more current) :mrgreen:

Kees

Re: Anybody see a problem with this wiring change (DSP -> PS

Posted: Tue Dec 01, 2015 11:02 am
by Tech_Marco
I talked to Li about that and he is willing to add that feature. For a while, he will add "trickle-current" say 4% or 5% (customer set it) and the max_power (60~98% usually). But on the work layer or the LCD, it will show 0~100%. That way, it is more linearly and easy to interpreted better. Should take less than a month to do it


Marco

Re: Anybody see a problem with this wiring change (DSP -> PS

Posted: Tue Dec 01, 2015 6:16 pm
by seeigecannon
Something I would like to point out: the trickle pot bypasses the water protection and safety interlocks. I am just about to make this same mod to my laser, but I have the flow switch and safety interlocks wired in series into the WP line of the PSU. This likely wont be a problem, but it should be something to be aware of from a personal safety standpoint because even at trickle powers that might still be putting out Class IV laser powers.

Disregard the above. I was wrong.

Re: Anybody see a problem with this wiring change (DSP -> PS

Posted: Wed Dec 02, 2015 1:02 am
by Techgraphix
seeigecannon wrote: the trickle pot bypasses the water protection and safety interlocks..
HUH???? Where do you see that in the schematics?????? Water protect is connected to the controller rather than the LPSU and the pot is nowhere in the neighbourhood of this waterprotect....

Kees

Re: Anybody see a problem with this wiring change (DSP -> PS

Posted: Wed Dec 02, 2015 1:19 am
by Tech_Marco
I think he was confused that a laser will not 'fire' without DSP approval. Even with current being pull up to 4% or higher, the laser won't fire unless the DSP send a signal to the TTL control.

BTW, most LPUS is having very low "trickle current" design. Even though no firing is engaged, there is a considerable high voltage, but low enough that would not cause current to flown in a tube. The reason is to minimize time delay from the laser tube.


Marco

Re: Anybody see a problem with this wiring change (DSP -> PS

Posted: Wed Dec 02, 2015 6:52 pm
by seeigecannon
Techgraphix wrote:Water protect is connected to the controller rather than the LPSU and the pot is nowhere in the neighborhood of this waterprotect....

Kees
Your right. My bad.

I implemented this design yesterday and it is looking better. I was thinking on it during a drive and I am going to try to make a version of this that uses a combination of a DAC and a MCU. When I get it working I will post the code and schematic somewhere. I am hoping that a true 0-5V (with adjustments to deal with laser current and trickle) will make my detailed rasters work better.

Re: Anybody see a problem with this wiring change (DSP -> PS

Posted: Tue Dec 15, 2015 6:02 am
by Telrad
Hey yaddatrance,

The pictures arn't showing up!! Can you please post the final wiring diagram again? I just got my potentiometers and now I can't wire them!! :eek:

Thanks!

Re: Anybody see a problem with this wiring change (DSP -> PS

Posted: Thu Dec 31, 2015 2:29 pm
by sshwarts
I'd like to understand what this actually does besides just act as a voltage divider. The schematic as drawn just has a resistor in series with the PWM output of the DSP with another resistor going to ground. So what would normally be a 0-5V PWM signal from the DSP is scaled to a 0-N V PWM signal. So for example, if the ratio of the two resistors were the same, it would be 0-2.5V where a 100% duty cycle PWM becomes 2.5V max.

The lowpass filter on the power supply input (where 5V = 100%) will see then 0-2.5V in the above example.

There's no "trickle current" because if the PWM signal is zero, so is the output of the voltage divider.

Now perhaps as someone commented, the software behaves better if it thinks it has a 0-100% range on power?

What am I missing?

Scott

Re: Anybody see a problem with this wiring change (DSP -> PS

Posted: Mon Jun 06, 2016 11:51 am
by jamesgates1000
Tech_Marco wrote:Just want to let you guys know that I already talked to the programmer about the % issue. So, the power output shows on the LCD will display 0~100%, regardless the Max_power (%).

Currently, if Max_power is set to 65%, the power output displays 65% even though the power level is set to 100% on the job's power setting
He will try to do it once the Baby DSP development is completed. Possible taking another month to finish

Marco
Hi Marco, was this feature added in the end?

Re: Anybody see a problem with this wiring change (DSP -> PS

Posted: Mon Jun 06, 2016 12:24 pm
by Tech_Marco
Still working on it.

He just finished ramping engraving and currently working on greyscale
U axis for rotary is also on his 'to Do list'

Marco

Re: Anybody see a problem with this wiring change (DSP -> PSU)

Posted: Tue Oct 11, 2016 12:41 pm
by jeckardt
It's been quite a while, so just wanted to bump this topic with a "I'm still anxiously awaiting this feature".

Thanks,
Joe