Welcome to a new voltlog, today we’re going to assemble some prototype PCBs for different constant current LED Drivers. I’ve designed and ordered these pcb’s a while ago, the goal is to test different constant current led drivers I have ones that are switch mode and ones that are linear and I wanted to see if I can get away with using the linear ones, because there is a significantly lower part count at the expense of burning energy away and generating more heat.
I haven’t ordered a steel stencil for these pcbs, I’m gonna hand assemble them, I’m gonna use some of this mechanic leaded solder paste which comes in a syringe and then I’m gonna reflow the boards over a hot plate. One hint here about the paste, if the syringe is very old, the paste might get dry which will make it unsuitable for the job and not to mention hard to push out of the syringe so try to keep the paste fresh by storing it in a fridge and replacing it when it starts to dry up or separate inside the syringe.
These two boards will be powered from 12V current through LEDs will be 25 mA and the total string voltage is 10 V calculated with a typical led forward voltage of 2V. That means the difference of voltage will be dissipated on our regulator and that can be calculated 12V-10V we have 2V dropping on the regulator times our current 25mA and is equal to 50 mW.