I just wired two LED's in series for a BLI F7 lightboard install using one 750 ohm, 1/8 watt resistor.
I have some standard LED's that are 20 ma max. I just checked with a 12.2 vdc battery. I use 1/8 watt resistors. There is a little difference in light intensity.
1000 ohms 9.0 ma
750 ohms 12.45ma
680 ohms 13.12 ma
510 ohms 16.25ma
Ohm's law will be a benefit.
Rich
If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.
Wiring the LEDs in parallel would be best. Wired in series, if one fails they all go out. And each LED should have it's own resistor.
The value of the required resistor depends on the amperage draw, usually measured in milliamps (ma), and operating voltage of the LEDs you use, and the output voltage of the power supply. A general rule of thumb that works nearly every time with most LEDs is a 1KOhm resistor for a 12 Volt DC power supply.
If you don't know how to calculate resistor or other values using Ohms law, here is a very handy product to have on your computer:
http://www.stanstrains.com/SoftwareHandyConverter.htm
I usually use a 1000 ohm resistor in series with each LED. They are cheap enough. A couple times I have put two LED's in series with one 1000 ohm resistor. Have never dome more than that in series.
I think the max for 12 volts DC is six LED's.
Since most LED's for our use are rated at 20 ma max, only need one resistor for a bunch in series but the voltage has to be hight enough for the amount of LED's in series.
Normally, running them at 9 ma with a 1000 ohm resistor gives plenty of light.
Others will comment with calculations if you like math.
I am building a structure in which I want to install 4 LEDs in overhead lighting fixtures. Do I want to do this in series or parallel? Do I need a resistor before each LED or how many in a series circuit- how many in a parallel. What gauge wire should I use?
Is there a written resource- either on line or in a book- that would be a useful reference for these types of questions?
Thanks in advance for any assistance.