Are you planning to combine light bulbs with LEDs in the same circuit, or are you just referring to LEDs in general?
For LEDs, your source voltage may determine the best wiring. If you are feeding them off a 5v power pack then you will likely wire each LED with its own individual resistor. However if you're getting into higher voltage like 12V or 18V then you might need to consider wiring 2-3 LEDs in series with a single resistor, otherwise you'll have to use larger, more expensive 1/2-watt resistors. As an example of this, you'll find online a number of different LED light strips that are already set up for a 12V power source. These are wired with three LEDs in series to a resistor, which is why you have to cut apart those strips at increments of three.
Other than the resistor consideration, it is best to keep the set of series-wired lights or LEDs to a minimum. Eventually a light will fail, and if you wired 100 lights in series then you have to check them all to find the bad one (think of christmas lights!), but if you only have sets of three lights in series then it greatly limits the amount of troubleshooting needed.
@Rogue - It depends on your particular LED. The ones in the light strips are typically surface-mount devices which consume less current, therefore the resistor has to consume more (not quite accurate, but close enough for this discussion). A lot of the online LED resistor calculators will tell you how much wattage is required for the resistor.
If you already have something in place, let it run for a minute and then feel the resistor. If it is noticeably warm then you either need a higher resistance (which reduces the brightness of the LED) or a resistor rated for a higher wattage. If the resistor still feels room-temp then the 1/4W resistor is fine. I would add that sometimes you only need a minor change in resistance which may not produce any noticeable difference in the LED brightness but will prevent any warming effects. On the other hand if your resistor is way under-rated then it will get too hot to touch in just a few seconds and could create a fire hazard.
Your 1/4 resistors are fine. Your LED's are not running anywhere near the 20 ma max current with those resistors and a 12v source. I assume you mean that the resistor is in series with the LED. your 6.8k is probably close to reducing current below that needed to fire the LED.
Forgot to update that I’m running on 5v, my 12v crashes and I found a better/more appropriate cell charger. Love that trick. Should be good with 1/4. Working on the control panel for Tortoises and the LEDs were just way too bright. I want to light up the interior of some of my buildings, is it best to do that with a light strip or individual LED in series/parallel? I’m concerned they’ll get too warm and maybe melt the plastic... electrical tape??
If your LEDs are too bright, just use a higher value resistor. At a certain point the LED will stop working, but you can get them pretty dim before reaching the cutoff.
I mentioned in another thread, but if you want a flood effect rather than a spotlight effect with LEDs, rough up the outside surface of the LED with some fine sandpaper. Combined with a dimmed LED, you can get a nice glow. And it doesn't hurt to place multiple lights inside a structure to get more even lighting. You might also consider blacking out some rooms so the entire building isn't lit up. This can look good for houses. For a warehouse at night, you might only want to light up an office and leave the rest dark. You might even find extremely tiny LEDs to use as a desk lamp for a visible room with lots of detail.
Those are great ideas!! I’d like to set up outdoor flood lights for some of the industrial buildings, and I think I know how I want it to look which is the other half of the battle! On multi color auto changing LEDs does a resistor size change the color change rate at all? Probably not but that would be really interesting if it changed the rate.
Not sure what you mean by "multi color auto changing LED's". Once you get past standard single LED's the world becomes complicated. There are strip LED's that that the whole strip changes but all the same color. Then there are computer controlled LED's that come in singles, strips, matrix and host of other configuration. You've probably seen these used as computer controlled outdoor Christmas lights! They are wire with power in parallel and a data in/ out port so the data ports form a long string in series. The computer then sends a series of 24 bit commands that end up controlling individual RGB lights on the string. If you like to experiment and have an Arduino computer lying around its a fun project. Think of it as wiring up you're layout with these and then after you're all done, programming each light with color, brightness and any animation. And you can change it any time. The disadvantage is that the single LEDS are the bigger 5mm sized LED's ( larger), so it gets complicated to use tiny SMT LED's.
Hook up the bulb to normal LED power source and it changes colors without any other inputs. I have zero interest in programming but I will admit I love the look and flexibility/options. This girl is all about the options lol. What size wire would you use? I’m wondering if 22 gauge stranded is too big.