Tell us about yourself!
Are you aware that the LM39 series are no longer in production and there are no alternatives for the 3915/3916 either? So a PIC or Arduino solution may be needed these days (2020)
Assembling the Board
Which end? The header end, use a soldering iron. The LED end, they came like that (prewired).
Not blade-less, but this Dysons fault as they call theirs blade-less when it uses the same principle! Well done on a recyclable version.
the 3 batteries are in parallel. Each is 3.7V at 2200mAh. This gives 3.7V at 6600mAh, so a larger capacity and not a higher voltage. To increase the voltage with the same capacity would require 3 extra batteries not 1. Also, how would you charge the extra batteries from a 5V USB input? This current solution is the most elegant and compact.
Yes, a very nice module that still only takes a 3.7V LiPo battery and not the 7.4V that was being suggested. Does anyone produce a battery charging circuit that runs on both series and parallel connected batteries that is cheap? The circuitry involved would be too complex for series and parallel operation. There is also the issue of parallel battery seesaw drain when connecting multiple batteries in parallel. There should be a 3 pole switch to disconnect each battery when not in use or they will self discharge.The battery seesaw effect is when the very minute difference in terminal voltage causes the higher battery to discharge into the smaller and overshoot the terminal voltage, then the cycle reverses to the new higher voltage until all batteries discharge.
the 3 batteries are in parallel. Each is 3.7V at 2200mAh. This gives 3.7V at 6600mAh, so a larger capacity and not a higher voltage. To increase the voltage with the same capacity would require 3 extra batteries not 1. Also, how would you charge the extra batteries front a 5V USB input?
Preparing a Schematic
PCB Concepts and Materials
Laying Out the Board
Circuit Board Design Class