[chbot] noob mosfet/transistor question

Mark Atherton markaren1 at xtra.co.nz
Mon May 24 00:43:53 BST 2021

Hi Andrew,

Please tell me more about your 12V load.

Is the 0V or the 12V power rail common to all of the devices you are 
driving ?

If you use a common 0V rail, the whole issue is much easier using an 
N-CH FET with 5V (min) gate drive.


>     Short version: What transistor/mosfet / resistor would you use to
>     switch 9-13v 100-300ma from an arduino?
>     Long version:
>     I’ve had great success with a “prop hub/master controller” I
>     designed, but keep running into a mental wall trying to make the
>     next generation.
>     In a nutshell, its a breakout for an arduino with a dozen rj45 jacks
>     to power and control remote props.    I have been trying to put a
>     transistor inline with the 12v output to each remote prop so I kill
>     power to each remotely.
>     I have the free pins on the arduino and I know basically how I’d use
>     the transistor/mosfet to switch, but I’m lost as to exactly what
>     transistor/mosfet to use.
>     The switched voltage would be between 9 and 13v, and I reckon the
>     maximum draw from any device would be maybe 300ma?
>     Does anybody have a favorite transistor for this application (where
>     the gate is 5v and the throughput is 12v, and the 5v from an arduino
>     would saturate the gate)?  I was thinking maybe the transistor would
>     be “closed” when the arduino went high, and switch off when low… but
>     it could easily be the other way around if that’s a simpler circuit.
>     Any wisdom appreciate!

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