LED Refresh – Indoor Lettuce

Well, my lettuce sprouts are dying. Of the four that spouted only one is left and is growing… straight towards the window. So, either the led modules are not putting out enough light or the light is the wrong color. To address this I designed a new module with almost double the LED density. The board will have 28 ultra bright blues in addition to 30 ultra bright reds. The chains have been reorganized into 6 in a row for red and 4 in a row for blue with an increased supply voltage of 15 volts. That reduces my future battery supply options, but to heck with it. I want growing lettuce!


Above you see two of the new modules being installed. With the higher supply voltage the old modules needed a change as they began to run at about 38mA, well above their 30mA maximum. So I put two blues into each chain of the old boards. That brought the current down to 15mA because the blues drop 3.2V each instead of the red’s 2.0V.

I have two more high density board toner-transferred and waiting to be etched, drilled and populated. Once they are on, I’ll give the lettuce a few more weeks before I try something new.