stealing 5v for laser pointer

[jestah]

Hi Guys,

New to the forums but long time PMDX user!

I would like to install a laser pointer onto my new plasma cutter and wonder where the best place to steal 5v to drive it would be. The 5v DC SMPS (currently only feeding the Ethernet smooth stepper) or one of the PC 5v and PC gnd on the PMDX 126. I have a spare relay on the 126 that I can use to power the laser only when needed so it is also not running for any long lengths of time. I have attached a photo of the lifter but the laser is hidden behind the torch press fit into a hole in the magnetic brakeaway.

Was running a dedicated 5v supply over kill compaired to not using the 5v onboard the 126? also is my gut right to rob the 126 for the 5v and leave the ESS supply alone.

many thanks
Jestah

[Bob at PMDX]

It depends on what else you are powering from the "PC+5V" supply (PMDX-107, for example, or anything else tied to "PC+5V" or the "+12V" on J7). It also depends on the power requirements of the laser pointer.  How much current does it require?

Refer to page 37 (Electrical Specs) of the PMDX-126 manual and note the current limits on the "PC+5V" (350mA total) *and* the 500mA total from "PC+5V" and "+12V".

Bob

[jestah]

Apart from a few small resistors across my inputs and the outputs to the drive step and dir I don't think there is any thing else on the PC 5v.

I do have a PMDX 109 in the mix but I think I set that up to take 5v from PSU via the ESS so no worries there. The laser has 5mw output so sounds like i have a winner on the 5v pc line.

Cheers for the help!