After the nice result of the Desk Lighting System project, my brother wanted me to do the same for some shelves in the basement. It quickly turned into a larger project than I was anticipating. This was honestly one of the most stressful projects I’ve worked on in a while as I spent 7 hours non-stop for two days getting it up. The lights we got was a 5 meter white LED strip. I had to go back the next day for two reasons: I bought the wrong power supply (had AC output), and I researched more and saw I would need a mosfet transistor (some explanations on this later).
The first day was literally spent cutting the strip and soldering them back together. It took a long time because the pads on the strip are really small when you cut them so they broke off or the solder gave me a hard time by refusing to flow on the pad. Once that was done, I taped them on all of the shelves. That was all of day one.Day two was another frustrating mess. I got the circuit working using an Arduino Uno board. The final project would have a standalone Atmega328p circuit and a voltage regulator. Before I move on, I want to explain exactly what the Atmega chip is for since I didn’t use it in my last lighting project.
My brother requested a dimmer. To do that, I’d need to use the PWM, or Pulse Width Modulation, pin on the Atmega microcontroller. Basically PWM is adjusting the duty cycle of the output signal so it changes the intensity of the light as we see it. To get a dimmer light, the duty cycle is decreased, or the time on becomes less than the time off in one cycle.
To make things more complicated, the LED strip runs off of 12v, which cannot be supplied directly to the Atmega chip. That’s where the voltage regulator and mosfet transistor comes in. The voltage regulator is a constant 5v regulator that is required for the microcontroller. The mosfet transistor is used in this case as a switch to open or close the ground connection of the LED strip. The positive connection of the LED strip goes to the 12v source. When a signal is sent to the mosfet [gate], the “switch” closes, turning the lights on. PWM still works as it’s basically opening and closing the switch really fast.
Now back to the pictures…I tried soldering it together. That failed. I don’t know if it’s a failure of connecting it properly or if it was because I had a wrong capacitor (which I discovered after, when I decided to just breadboard it).
So yeah, I took the easy way out on this one. My main worry is that something is going to fall off because it’s mounted sideways. I taped as many connections as I could so it should hold up. I’ll probably keep a close eye on it for the next few days to see how it works out in use… even though I don’t want to. I’m exhausted from this project.
The switch and dimmer potentiometer are solid in place. And yes, it’s another food container.
The final result.
Good riddance… I mean, it’s pretty amazing that everything came together in three days, but the stress was intense trying to get it to work. I have a fear that something will give.
On to the next one.