[dread240]

Nope..

I don't remember max current on the dimmer circuit atm but it was north of 350ma. The only 16 channel multiplex chips I could find were surface mount and only capable of handling 150ma-200ma. I'm going off the top of my head, but I think long term we would fry a multiplex without isolating it.

N channel mosfets are dirt cheap, and can handle the current. By building the gate with voltage from the arduino, I can then conduct the dimmer circuit through the mosfet. One mosfet per channel for the 16 channels of the multiplex ic.

You would basically have 2 lines for the circuit... Both +VDC (straight line from the LED Driver and an inline resistor on the arduino supply before they join, otherwise you would need a resistor on every base leg) will be on a shared bus so to speak. The collector of the mosfets would all be off this bus. The base of the mosfet would go through the mux to arduino ground, and the emitter of the mosfet would go to a tap position of the resistor array.

The resistor array will simply be .1 ohm resistors in series. The -VDC of the driver will go to the front of the array, and you will tap the emitter's to various points within it. Once you command a channel on the mux to energize the gate of the mosfet, the driver circuit will flow from the common bus, through that mosfet to that tap in the resistor array, giving you the variable resistance you'll need to control the dimming.

The reason I typed it all out. That's what the guy that does not do electronics for a living has come up with. I thought of relays as well too but they're too expensive for this project imho. Once you reach a certain point you may as well opt for a pwm driver as you're not saving any money if there's too much cost in components. You on the other hand, may have a few people around work or yourself for that matter that might find some better components for this... like mainly a controllable chip (I went with the multiplex setup as it gave me 16 steps for only 4 wires, which was pretty smooth transitions). I haven't been able to dig too much on all the various mux chips. Ideally if we could find one that could handle 350ma then no mosfets are even needed whatsoever and it simplifies it greatly. Or if we could find cheap chips that may only be 8 channels but are 2 wire capable with higher current they'd work too.

That's just some of the few things other people could look into and try. I know my plan will work and give the end results I want, but I don't know all the various semiconductors and IC's out there, if it's the most effecient cost wise, or if there are just flat out better options for this low and tight of a resistance range.