Would the 1k resistor help to light up the leds?
It is a function of the applied voltage and current used by the LED, and how they are wired, series or parallel, that determine what resistance is needed.
Check the specs of the LEDs you will be using.
In general red and orange consume 20ma and will reach this point with 1.5 to 1.7 volts applied, although some will get to 2 volts. Yellow and green requires a bit more current and will run at around 2.5 volts. Blue and white will use 30ma, sometimes more, and will achieve that at about 3 volts. Infra-red generally have a maximum of 1.5volts at 20ma. Ultra-violet will function like the blue ones although run as high as 3.5v.
Three red will run easily in series from a 5 volt source.
You need to be more specific, how many, what color, high brightness or standard, get the specs, and you may get a more appropriate answer.
There is no standard resistor value, it depends on the supply voltage. Use Ohm's law.
Say you are trying to drive a yellow LED from a 12v source. The LED draws 25ma at 2.5v. So you need to drop 9.5v. 9.5v / .025A = 380 Ohms.
Remember with series circuits current is equal at all points. 2 or more LEDs will draw the same current as a single one.
Also remember if you are doing this with a vehicle that the battery produces 12v while the alternator produces around 14.
You could build a driver circuit with a transistor or two, that's the best method.
* 1 day ago
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COLI
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