I have a VBus of 12VDC. I would like to take 14 discrete inputs and Light a single LED for each input that is active.
I was planning on just doing a simple current limiting resistor and having a common anode and allowing the inputs to switch ground.
A new requirement was added: If any of the inputs are active they want to switch on a 500mA load on. (ie a buzzer or light). I would most likely do this with a NFET.
I would like to try and do this as cheaply as possible.
If i use a micro then I need to generate 5v. I could probably do a micro / powersupply / and either optos or resistor divider for the inputs this would cost around $8.00 per board.
Can anyone suggest any easier / cheaper way to mux the LED inputs together?