I still don’t have access to my Pi(s), but I decided to work on the electronics a bit so that I could hit the ground running when I do get access.
I’m thinking about using PWM (pulse width modulation) the LEDs from my Pi. I really don’t know how the stability will be affected with the pins running PWM for hours at a time, but I guess I’m going to find out.
Quick tangent about PWM. PWM basically turns the pins on and off really quickly to output a signal that isn’t 0% or 100% power. I will most likely be using the WiringPi or the pigpio libraries to pull this off with the Pi. However, the Pi only outputs 3.3v with it’s GPIO pins (not the 5v rails), which is not nearly enough to power the LED strip.
I decided to use 3 transistors, this allows me to still use the Pi’s PWM, and also let it deal with higher voltages. I could have gone with solid state relays, but I’m not really pushing that much current to justify the choice. I’m also aware of the added “lag” when using more parts, especially transistors, but I seriously doubt that this “lag” will affect the LED’s performance, or affect enough that the human eye can sense that something is wrong.
With all of this in mind, my current idea for the LED light controller is as follows:
I’m trying to do some research on whether or not I will have to cool the transistors, as they should theoretically be getting very hot. Also, it should be noted that the protoboard will be cut to be smaller than shown, I just didn’t know the size before hand. Hopefully I can get the parts ASAP and start building soon!