+- Blue Plastic Tracks (https://www.blueplastictracks.org)
+-- Forum: General (https://www.blueplastictracks.org/forum-35.html)
+--- Forum: General Forum (https://www.blueplastictracks.org/forum-7.html)
+--- Thread: LED Wiring Question for Our Experts! (/thread-2814.html)
Pages:
1
2
LED Wiring Question for Our Experts! - Super - 11-12-2017
I have a wiring question for our experts...
I have many prewired LED lights that already have the resistors soldered in...
Can I wire these in Series as is or do I have to remove all the resistors except for the first positive one or can I just use them as is without removing the resistors?. A 9 volt battery to be used. I suppose I could run them in Parallel and leave the resistors but I thought that wiring them in Series would reduce how much wire there will be in a small space. Is any of this possible?
RE: LED Wiring Question for Our Experts! - Nigels - 11-12-2017
You can probably re-wire them by removing the resistors, but you'd probably need to re-calculate the resistor needed (if any) depending on the number of LED's you want to use.
The main thing you need to remember is that the current will drop across each LED, so for example if your current LED + resistor is calculated to provide say 100ma, by putting two in series with the resistors in place may drop the amount of current getting to each LED to between 50 to 10ma as the effect is likely to be cumulative. This will result in the LED losing brightness and eventually may drop below the threshold to light them at all.
The other thing to remember is the connections are polar (i.e. negative and positive) get it round the wrong way and they won't work at all lol!
RE: LED Wiring Question for Our Experts! - Super - 11-13-2017
Bummer....math...
I wouldn't remove the resistors on the ones I already have, it would be much easier to just buy wired ones without resistors as they really aren't that expensive plus I am also thinking of projects using Nano or Pico Chip LED's already wired for other projects run in series so info will go with that idea too. I do admit I can't grab on the sizing of resistors & LED's when looking into them before.
RE: LED Wiring Question for Our Experts! - plarnold - 11-13-2017
@Super,
The concept is:
- In series, you can only have around 11-12 (standard) LEDs turning on with a 9V battery. With any more, they are probably not going to turn on at all. With high-bright LEDs, you won't even get 4 lighting up in series. Even if these LEDs in series do light up in series, they will be so dark that you might as well not have them.
When in series you can have just one resistor with entire chain.
- In parallel, you MUST have one resistor for each LED. All the LEDs will be the same brightness (assuming the resistors and LEDs are all the same) and will actually light up. You can have as many LEDs you want in parallel. The more you have, the faster your battery will be depleted. You can control the brightness of each LED individually by changing the resistor for each. A larger resistor will make the paired LED darker and a smaller resistor will make the paired LED brighter. Don't make the resistors too small though! A good resistance is roughly 500 Ohms to 1k Ohms for a nice bright LED (assuming standard LEDs).
-plarnold
RE: LED Wiring Question for Our Experts! - Super - 11-13-2017
Thanks Plarnold
Do you know if the Nano or Pico Chip LED's use less and therefore can use many more in Series with a 9volt battery?
I find this interesting "A larger resistor will make the paired LED darker and a smaller resistor will make the paired LED brighter" Would this also be the case with more than a pair? I have always thought that regular LED's are too bright for this scale and being able to dim them this way is interesting.
RE: LED Wiring Question for Our Experts! - plarnold - 11-13-2017
@Super,
A rule of thumb (or variations of this) for LEDs in series:
Number of LEDs that can be used in series = Supply Voltage divided by 0.8
This is assuming standard LEDs (non-high brightness).
Yes, a larger resistor will make the LEDs shine darker.
If you have multiple LEDs in series, the same applies. A larger resistor in series with those LEDs will make the LEDs darker. The LEDs in series will always have the same brightness and you can't control them independently.
I recommend LEDs in parallel with one resistor each. That allows you to control each brightness independently and you can have as many LEDs you want. Note that more LEDs will make the battery run down faster!
-plarnold
RE: LED Wiring Question for Our Experts! - Super - 11-13-2017
I kinda was hoping that wasn't the case as creating a harness running Parallel uses much more wiring and soldering. So even the Nano chipped LED (not bulb type) will still be limited in the same way in numbers run in series?
RE: LED Wiring Question for Our Experts! - plarnold - 11-13-2017
Yes, the tiny ones are still limited in the same way.
-plarnold
RE: LED Wiring Question for Our Experts! - Super - 11-13-2017
Many thanks Plarnold, time for me to put my big boy pants on and learn a bit more about using my new Multimeter and to learn more about the available sizes of Resistors.
RE: LED Wiring Question for Our Experts! - Nigels - 11-13-2017
Super,
If you want to keep the wiring to a minimum why don't you just use the strips of surface mounted LED's - you know similar to the ones you get in those 'Lego LED' sets we been buying. You can get those LED's in the form of a long strip on a reel, these are marked so you can cut them to the length you require (typically they are marked to cut every 3 LED's).
Then all you need is the two fly wires to the solder pads on the end of the strip you have cut off. As to how many you can power from a 9v battery, that is something you'd have to play around with
