Tinyg: Powering Leds using J11 pins?

Started by Hamill on Sep 19, 2015 in TinyG Support. 2 replies, last activity Sep 20, 2015.

Hamill Sep 19, 2015 #

Hi everyone,
I would like to use J11 pins for powering some leds (35/40 centimeters or 14 inches in total of common white led stripe) I have installed on my spindle.

I have been looking for the max current J11 pins can deliver, but I can´t find any information regarding this.

As I´m using a 24v power supply and set the jumper to deliver 12v (I have two small 12v fans, 0.7w each), I was wondering if J11 pins has power enough for some leds too. That would be much easier than having 2 different power supplies.

Thanks in advance!

cmcgrath5035Staff Sep 20, 2015 #

Here is the applicable schematic page:

https://github.com/synthetos/TinyG/blob/master/hardware/v8schematics/v8h/tinyGv8h%20-%20schematic%20page2.pdf

The regulator device is a 7812 device, using the board ground plane as a heat sink.

Assuming the fans you already have are cooling tinyG, it is a bit difficult to guesstimate where on the power dissipation curve for the 7812 your implementation will lie.

With no heat sink, the 7812 is rated at 2.5W at 50C.
So you are currently drawing 1.4W, my guess is you'll be safe with LED's added to load.
I'd suggest a before and after finger tip test; if the 7812 feels hot to the touch, perhaps consider an alternate solution.

Hamill Sep 20, 2015 #

Thanks for the information. I will make a test and see if the regulator is not hot to the touch. Will post the results here.

Thanks!