Step 2: [CALCULATIONS]
Now, like any project with electricity, certain calculations are necessary. Although the equations might look a bit threatening, I can assure you that it's quite simple. Before starting your calculations, make sure you have your LEDs' detailed specifications from your supplier.
FV (Forward Voltage) - This is the voltage used by each separate LED. It is expressed as a range, so a minimum and maximum value is present.
AC MAX/MIN - AC Mains are not always at a constant voltage and are not always the same across a whole house. There is actually a range present. In the US, the range is 110-125VAC. In other nations, the range is 220-250VAC.
[AC MAX] X 1.4 = A
A / [FV MAX] = [# LEDs]
[AC MIN] X 1.4 = B
B / [# LEDs] = C
C represents the forward voltage and must be within the range.
Your final result represents the number of LEDs you can put in each series. Think of this as a basic unit. The total amount of LEDs on the light bulb must be a multiple of this number. In each "unit," the LEDs connect positive to negative in order to distribute the voltage. All the series may then be connected together, positive to positive and negative to negative. Below is a sample of my calculations.
125 X 1.4 = 175
175 / 3.8 = 46
110 X 1.4 = 154
154 / 46 = 3.3478
C is in range. (exhale)