Cottage lighting system. Would appreciate general guidance/problem solving.

Hey everyone, another noob here, diving too deep into something I don’t know enough about. But I gotta learn somehow. :slight_smile: Thanks everyone in advance for taking the time to read this.

So the general outline of the project: I am installing lights in an off-grid cottage. Power source is 12v, Lights are 12v Led strip lights, some 9 volt led pot lights, and some 12v outdoor lights.

All light feed wires are run back to the utility room to minimize line loss. A cat5 runs from each of the wall switch boxes to the utility room. There are 11 circuits so far.

My Ideal vision for the finished project is this: Each light switch will have a switch(for turning the light on) and a pot(for dimming) in it. When the switch is turned on the light will fade from off to on, to the current position of the pot.

My current control board(yes, its actually a wooden board) has an Arduino mega, and 12 irlb8721’s on it. Pic attached. (Go ahead and laugh, I did).

Any advice or criticism is greatly welcome and appreciated. And on to the problems so far…

  1. The code. Not quite sure how to write code that monitors all the pot’s at the same time and can fade multiple lights on at the same time. Not even sure if it is possible with one arduino? I read through the sticky at the top of this forum(the one about doing multiple things at once), and am trying to understand it. Any help or links to help would be great.

There is a few other current problems but I gotta hit the hay now. I hope my post is fairly readable, because I suck at grammar. Thanks again

Hi,
Layout looks logical, but have you got 10K resistor across each gate-source, to make sure that the MOSFET does not turn on if gate signal is not present.
I'd be putting sleeving over all three leads of the MOSFETs too.

The choice of MOSFET is not quite right unless you are going to have a driver transistor, it is not a logic input type, so 5V on the gate will not turn the MOSFET completely ON.

Tom... :slight_smile:

IRLB8721 seems to be a logic mosfet.
Leo..

couple ways to dim.
pwm is the most common.
using a shift register and turn the lights on and off quickly to let them ramp up.
use a mega for more pwm is an option.

I would offer that if you are 100% off-grid that you will want an energy management plan that shut down the most power hungry and then only leave on the most essential.

You are not seriously going to use CAT5 to reticulate power, are you?

TomGeorge:
Hi,
Layout looks logical, but have you got 10K resistor across each gate-source, to make sure that the MOSFET does not turn on if gate signal is not present.
I'd be putting sleeving over all three leads of the MOSFETs too.

The choice of MOSFET is not quite right unless you are going to have a driver transistor, it is not a logic input type, so 5V on the gate will not turn the MOSFET completely ON.

Tom... :slight_smile:

Hello Tom, thanks for the reminder. I forgot I had to put resistors in. And I have 2 of the leads on each FET shrinktubed but I should do all 3.

My understand from the data sheet for the FET's is that they are saturated at 4.5 volts. Am I wrong in this? The few projects online that I've seen them in have used arduino's.

dave-in-nj:
couple ways to dim.
pwm is the most common.
using a shift register and turn the lights on and off quickly to let them ramp up.
use a mega for more pwm is an option.

I would offer that if you are 100% off-grid that you will want an energy management plan that shut down the most power hungry and then only leave on the most essential.

I had planned on using pmw, and a mega because I need 11 analog inputs. Unless there are better options.

Absolutely, the whole place is run off solar so one of my primary concerns is saving energy.

Paul__B:
You are not seriously going to use CAT5 to reticulate power, are you?

Thanks for reading. The cat5 is only for carrying signal from the light switche buttons and pot to the arduino. Do you think cat 5 is not thick enough for this?

myt30:
I had planned on using pmw, and a mega because I need 11 analog inputs. Unless there are better options.

Yes there are.
Use one Adafruit 16-channel PCA9685 breakout board near your mosfets.

Then a two-wire interface can drive 16 mosfets.
Any small Arduino with enough program memory for your needs can drive 1000 LED channels.
With smoother 12-bit PWM.
Leo…

edit
I went one step further, and made my own constant current LED driver boards with that PCA9685 chip.
Two of those boards are running 24/7 from one Arduino, driving 12watt LED downlights.
No mosfets needed. Just power in and LEDs out.