BTW do you have to use high-side switching?
Unfortunately, yes. The lamps are in an assembly which grounds through the body..
Is this an automotive application.?There are robust high side switches designed for this , although i am not sure if they are suitable for PWM.
probably not with a 28vdc supply,,, but it might be a lorry...Allan
Not many modern small aircraft have a metal fuselage - they're usually composites.... so do you really need a grounded load? And if this is for Boeing or Airbus, I take it you should know what you're doing, and would be unlikely to be using arduinos..just curious.Allan
And I'd replace the zener with a pull-down resistor - say 10k - to ensure the mosfet is off when arduino power is removed.
Hi,Why you do not install the mosfet instead supply voltage provide the ground to the light bulb.