I recently read that in a series string of LEDs, it doesn't matter if the resistor is on the Vcc or Ground side.
My ( self appointed ) logic deduced from this was that the resistor just had to be in the string somewhere.
I have 15 LEDs, split into 5 series strings of 3 LEDs each.
Vf = 3.2v Current = 20mA Source = 12.43vDC
I am using a 150ohm resistor per set of 3 LEDs.
Due to the layout of the wiring connecting the LEDs, I chose to position the resistor on the Vcc line between the 2nd and 3rd LEDs. On power up, the first 2 light for a second, then die.
Did I have the resistor in the incorrect position ? Does the resistor position matter ?
oops, just realised, I have the 3 LEDs in each string connected in parrallel ( 3 Vcc connected, and 3 Gnd connected, with the resistor on the Vcc line of the 3rd LED. )
I guess that's why they died a spectacular dead as the magic smoke was seen escaping.
Would still like to know about the resistor position once I correct the wiring to 'in series'.
So is this correct : Vcc ..... LED+ .. LED- .. LED+ .. LED- .... R150 .... LED+ .. LED- .... Ground
or MUST it be either : Vcc .... R150 .... LED+ .. LED- .. LED+ .. LED- .. LED+ .. LED- .... Ground or Vcc ..... LED+ .. LED- .. LED+ .. LED- .. LED+ .. LED- .... R150 .... Ground