# VOXL2 J2 5VDC Fan Control overcurrent

Source: https://forum.modalai.com/topic/2026/voxl2-j2-5vdc-fan-control-overcurrent
Category: General Questions (https://forum.modalai.com/category/2/general-questions)
Posted: 2023-04-01 12:37:41 UTC by hmlow
Replies: 5 · Views: 608

## hmlow · 2023-04-01 12:37:41 UTC

Hi devs

What would happen if i sink more than 400mA on the FAN RETURN pin of J2?

Would i destroy anything on the board?

## Reply by Vinny (ModalAI staff) · 2023-04-01 14:30:28 UTC

@hmlow 
Yes, you can damage components in the control circuit, then the fan would no longer operate.
The fan we sell is rated for 110mA. You should not need much more than that anyway to have effective cooling.

## Reply by hmlow · 2023-04-01 16:02:38 UTC (in reply to Vinny)

@Vinny nah I'm trying to use J2 for smth else. Probably won't draw anything more than 250mA but I just wanted to be sure about what's connected to those pins

## Reply by Vinny (ModalAI staff) · 2023-04-03 14:44:53 UTC (in reply to hmlow)

@hmlow Please be aware that the fan circuit at the connector uses a switched ground technique with series resistor for monitoring fan speed/tach. The more current you use, the higher the ground offset you'll have. We have not validated that port with anything other than a fan. Using for anything else is at your own risk.

## Reply by hmlow · 2023-04-03 23:02:49 UTC (in reply to Vinny)

@Vinny may I know what is the value of that series resistor?

I'm using this to power a LED flashlight (only to fully turn on and off, nothing in between). I already have a current limiting resistor for the LED array, but I guess I have to factor in the one that is built directly onto the VOXL2 as well

## Reply by Vinny (ModalAI staff) · 2023-04-04 16:59:53 UTC (in reply to hmlow)

Sure @hmlow 
here is a schematic snippet of that section so you have all the info:
![7c56d0e9-6cd1-488e-9b30-a189e04b455a-image.png](https://forum.modalai.com/assets/uploads/files/1680627538383-7c56d0e9-6cd1-488e-9b30-a189e04b455a-image.png)