Hi, newcomer here and a total newbie when it comes to circuits / electronics.
I've tasked myself to build a circuit using the Arduino to control 3 sets of fairy lights. A lot of research and advice later, I've managed to get a working prototype for one set of lights with a switch, but now I'm moving on to all 3 and want to make sure that it makes sense for others.
The idea is that all 3 fairy light sets are turned on at their respective power sources (batteries), but are off. The Arduino waits for the switch to be closed. Once it's closed, it sends output through pins 9-11 into the MOSFETS which then effectively close the fairy light circuit, turning them on. In reality, each set of lights is timed to turn on at different intervals and at different speeds using PWM to fade them in. This is why they're separate.
This circuit was based heavily off of two tutorials. First, the switch is based off of the debounce tutorial offered by Arduino (Arduino - Debounce), and the second is based off of an N-Channel MOSFET/Arduino Tutorial on bildr (bildr » High-Power Control: Arduino + N-Channel MOSFET). My work is simply combining these together.
My main concern is how everything is connected to one ground (on the schematic). Would not using diodes to regulate the flow cause problems here?
Generally though, is this a valid solution? Are there any issues that I should probably know about? As mentioned, I'm still super new to this, so any feedback would be hugely appreciated.
Apologies in advance for the images if they're messy. This is my first real time prototyping and using the Fritzing tool. I've tried to reflect the colored wires between the breadboard and the schematic. Note that the LEDs shown in both images represent the fairy lights.
