Fan?



  • If I have the expansion dock for the Omega2 is it possible to run a 3.3v 0.2A fan using the 3.3v header on the dock? I might be a little shy because I don't want anything to go bang.



  • Hi Jessica, generally you can't run "loads" even comparatively small ones like that directly from a GPIO pin.

    Also you probably want to use a unique power source for the load with just a common ground, since the Omega modules can already put quite a stress on their power supplies.

    Options you could consider for a relatively modest (3.3v, 200 mA) load:

    • a small electromechanical relay, though this is excessive for a load of this type

    • an N-FET switching the negative side of the supply to the load, while the positive side is permanently connected to the supply. For example DMN2041L FETs are commonly used in small quadcopters with 3.3v gate drive for loads on the order of 5-times as heavy as yours.

    • a high side USB power switch chip like an RT-9701 that would switch the positive side of the load, while the negative side remains connected to ground.

    If you are not trying to control the fan but simply have it on all the time, then you don't need any of these switching elements but just a unique supply for the fan, or else a more capable supply for the fan and the system (but beware of the fan backfeeding motor noise to the logic).



  • @Chris-Stratton That tells me what I need to know! Thank you! :D


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