PWM for Laser on Rev 2 Acorn Board

[DY10CNC]

Help!
I have search for entries on this topic to no avail... maybe i used the wrong criteria so here goes..

I have a mill with a Rev 2 Acorn controller and after seeing the post by suntravel on using a laser on a mill i am looking to use the same laser module as Uve did ((Laser Tree LT-80W-AA Pro).

I have setup PWM in the wizard and run sample job (Centroid Logo)

With an LED connected to Pins 14 and common on the DB25 I get a a response (flashing LED) and the on board relay for output 2 clicking on and off as the output turns on and off.

My question is - If I de-solder the built in output 2 relay, will DB25 pin 14 work as it does on a Rev 4 Acorn board?

I have the laser module etc thanks to Amazon UK Black Friday reduction from £220 to £137.

Thanks in anticipation,

Edward

[tblough]

Perhaps this will help - https://www.centroidcnc.com/dealersuppo ... ds/326.pdf

[DY10CNC]

Thanks Tom,
I read the article in your link before posting.
However it does not mention older Acorn boards just rev 4 and Acorn Six.
My rev 2 Acorn has relays for outputs 1 and 2
soldered to the Acorn PCB, unlike Rev 4 Acorns with separate relays.
The relay on output 2 obviously can’t switch at the frequency needed for Pulse Width Modulation.
Which is why I am considering de-soldering and removing from the Acorn board.
Any further suggestions would be appreciated.
Edward

[Sword]

I have a rev3 board with the same relays, and I asked Centroid HQ the same question when PWM was in testing. The answer wasn't a resounding "Yes", but more of "you maybe could, but"....

I just left it as is and let it click and buzz like a telegraph machine, someday it will burn out the coil.

[DY10CNC]

I have a rev3 board with the same relays, and I asked Centroid HQ the same question when PWM was in testing. The answer wasn't a resounding "Yes", but more of "you maybe could, but"....

I just left it as is and let it click and buzz like a telegraph machine, someday it will burn out the coil.

Thanks,

That is encouraging - If it works with the relay left in place for you, I'll give it a go.

I was concerned that having the relay in might have a negative effect on the signal to the laser.

Probably an oscilloscope on the DB25 pin 14 and common would be worthwhile, but as I don't have one...

[tblough]

Just cut one of the traces to the coil on relay 2.

[Centroid_Tech2]

Proper PWM operation requires at least a Rev 3 Acorn.

[DY10CNC]

Just cut one of the traces to the coil on relay 2.

Hello TOM,
Thanks, that's my next move.

Today I've ben getting to grips Acorn and lasers in general.

I made DB25 cable and cables for PWM to laser and it's 24 volt power supply.

Plan to get laser to fire up with no table motion to see if one can really use a rev 2 Acorn board in a PWM application.

As you may have seen in SWORD's contribution he has a Rev 3 working.

As far as I can tell the main difference between Rev 2 and Rev 3 is the plug-in screw terminals instead of fixed screw terminals.

I don't use output 2 anyway so I have little to lose.

Thanks for the advice and encouragement.

[DY10CNC]

Proper PWM operation requires at least a Rev 3 Acorn.

Thank you for you input - I appreciate your expertise and time.

I am not ignoring you information but am somewhat encouraged by your phrase "Proper PWM operation requires at least a Rev 3 Acorn".

I have had my acorn Rev2 since summer 2017 and enjoyed great service from it

If the results of my laser experiment are unsuccessful I will have learned something, and hopefully not killed my trusty Rev 2 Acorn!

Disclaimer : All advice is appreciated but no blame will be apportioned to Advisors.

[DY10CNC]

Thanks to all who have helped me with this project - I now have a laser on my Mill with Acorn Rev 2 board!

Special thanks to suntravel for the inspiration and pointed me in the right direction and tblough for reminding me of the importance of reading the drawing!