Lightmaster 5000

It all started when I found a cheap “stack-light” while browsing AliExpress… Back then I had no idea what to do with it but I wanted one. Just for fun. Because I can…

Way too many of my projects start like this…

When it arrived a few weeks later I started thinking where I could mount it and what to actually do with it. Since those lights are usually controlled by some machinery I needed my own controller for it. The light is rated for 12V to 24V DC – Some playing around and blinding myself later I decided 12V is definitely enough. Each of the five lights has its own voltage regulator but they still change brightness a lot when run on different voltages. I also tried running it with PWM and that actually worked so I wanted to make use of that as well to be able to dim them further.

Top to bottom: 1206, 0805, Resistor Network
(Next to metric ruler)

My circuitry is actually quite simple since most work is done by the ESP-12F and I am using a buck regulator module to provide the 3.3V for that one. Five of the GPIOs each control a Si2302 MOSFET to run the lamps, the other four available GPIOs are used to control the LEDs in the case – When I designed the circuit I wasn’t sure yet what to use the LEDs for. Since I needed quite a lot of resistors I decided to try something new: SMD resistor networks, with 4 resistors in a 1206-sized case. Soldering them worked quite well with a heat gun and lots of flux, but I am not sure yet if it’s worth the effort for future projects. It definitely saves a lot of space though!

I decided to mount the light to the fusebox that’s running my server rack so the whole device had to fit into a DIN rail case. I also got a fitting 12V 15W power supply (Mean Well HDR-15-12) and already had a slim switch to be able to cut the power if needed.

As always the board was designed in KiCad though this was the first time it let me down – at first the footprints for the resistor networks didn’t seem to work correct since the soldermask wasn’t applied correctly in the gerber files. Apparently that was working as designed though since I found a solution online: The minimum width for the solder mask has to be changed for such a small footprint. After that everything worked fine and I ordered the boards. Just a pity that KiCad has no function that warns you. If I had not spottet the missing solder mask between the pads, the boards would have been useless.

Once I got the boards and I had everything assembled I installed the software, added the new hardware to the fusebox, connected everything and it worked! Now I just need to find things to display with my new lights.

Oh… and while at it I also added a proper earth connection to the fusebox, too…

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