# Wiring a bunch of micro LED fairy lights to a single power source in parallel

I want to create a cascade effect using the wire fairy lights, like in this photo .

What would I need to accomplish this? I can find the coils of lights for cheap online that use battery packs, but I'm looking to wire this so it can be plugged into our central lighting hub that is powered by our light control board.

I'm a complete amateur in the electrical realm--I'm very handy and mechanically inclined, I've followed a lot of youtube tutorials on wiring small electrical projects, but only understand the bare basics of electricity.

How do I create a string of LED's and switch them on and off?

• Would icicle LED lights be suitable? These are sold as Christmas outdoor decorations, and plug into a standard 120V AC wall outlet. Oct 17 '17 at 17:49
• What is the type of battery? What kind of physical distances are we talking about here? Feb 11 '18 at 18:09

Since you are looking to string the LED's together, you will need to first choose a type of light. We will assume until otherwise that your lighting option is 12volts, since that is fairly common in cars. What you will need to find is the amperage rating of each string of led lights, then you will need to add it together.

simulate this circuit – Schematic created using CircuitLab

Each Led represents each string and is simplied here. Red is positive + and black is negative -.

Then you will need to find a wall wart that is both suitable for voltage as well as the total amp draw for the combined strings. Since you are in a church setting, the cheapest option for one of these is probably a flea market or something similar.

Once you get the wall wart, you will want to cut the end off. Be sure to mark the negative and positive sides of the wire ( + and -) so that you can match those up with the plus and minus on the led strip. If you are not sure, you will need to take a multimeter and determine negative and positive while it is plugged in. Don't worry it won't kill you, just be careful not to touch both ends together.

You will then need to solder or crimp the ends together, depending on the skill and worry you have for burning yourself. Make sure to take care to match up the positive to positive and negative to negative.

Note that if the voltage the lights run at is not a standard amount, you can always use a variable buck converter (or similar) to take the voltage from high to low, but you will need solder and multimeter for sure. The plus of this is that you have more control on how bright the highest setting is, which may be useful in some of the cues you want to run.

• Beware: when designing the battery-operated lights, they will have allowed for the internal resistance of the batteries. Power the same lights from a mains adaptor, and they may blow, even if the voltages are supposed to be the same. Dec 7 '17 at 12:02
• I've seen that with LED path lighting, I swap their NiCD for a NiMH for longer runtime, and they burn brighter and shorter due to lower internal resistance. Yes, you may need a right-sized power resistor. Trick would be to package it into the battery's form factor. Feb 11 '18 at 18:08

The pictured leds look to be multiple strands of parallel leds. Each string may have a resistor, or a single resistor is used for all of them. The image may be misleading and there may be loops at the bottom that are cut off, but that doesn't change that they are wired in parallel.

These are not addressable leds, and are not wired in a way that allows individual control. If you control power via the translucent cable/power supply, then it will be an all or nothing setup. Unless you control multiple strings independently. If it's AC and controls an outlet, then power the strings from an AD to DC adapter.

To control them, you can use a relay, or a solid state setup like a mosfet or transistor. The specifics depend on your lighting controller and voltage.

I think the way these LED strings are wired on each strand of copper wire are that the LED's are soldered in Parallel and are also bunched in groups (say a strand of 100 LED's will be bunched in groups of 25 x 4 groups- with 3V & 500mA across each group- so you get 12V and 2A across each strand) I guess they add a resistor at the beginning to limit the voltage.

You have to know for your project - how many LED are there on each copper wire strand that you are choosing. You have to know what is the resistor value that is there at the beginning of the copper wire. Most of these run on 12V DC. According to the number of LED's on each strand you will require that much amperage.

I had done a similar thing- Took around 4 of the LED copper wire strands (each had 50 LEDS / string) Those ran on 12VDC. So i connected it in Parallel (before the resistor) and powered it with a 12VDC 2A AC-DC drive.