Electronics Questions & Answers ← browse Q&As

Hi. I am hoping you can help me with this.

I purchased a LED light string. The kind that are on a roll that has a sticky side that enables you to stick the LEDs to a surface.

My goal is to cut off a small piece of the strip and stick it to my guitar, so that the LEDs make the guitar "flashy" pardon the pun ;-)

The roll i bought can be seen here:

https://www.amazon.ca/gp/product/B07XXQD5PG/ref=ppx_yo_dt_b_asin_image_o00_s00?ie=UTF8&psc=1

I have two questions:

The roll is connected to a power adapter by way of a tiny four prong pin connector. The LED strip operates on 12 volts. I am trying to cut a little strip and rather than using the pin connector, solder wires to each of the four connection terminals.

But I don't know how to connect the terminals to power. Why are there 4 pins? Do they both go to a positive and negative power supply? How do I know which into connect to which?

Once I figure that out, i have the folling question:

My goal is to power bu this a battery. Since the battery has to be on the back on my guitar, it cannot be too big. So I was thinking of using a battery pack made up on a 9 volt and 2 1.5 volt batteries. Or two 9 volt batteries with a resistor to step down the voltage to 12 volts from 18v.

Would their be more nbattery life, if I used the 2 9 volts with a resistor?

If so, how do i know what strength the resistor should, have?

Thank-you kindly

What I think you are doing worries me a bit. The reference you give refers to "RGB 5050" LEDs but the 5050's I'm working with are rated 5 volts, not 12. This reference also shows a small white or grey box in the pictures with no mention of it in the text. This box (I think) will reduce the 12v to 5v for the pixels and will also contain a processor which will build a command word defining brightness for each colour of each pixel and send it to the "Din" port for the pixel string. As for the 4 pins puzzling you there will be one +5v for the pixels, one gnd (-) for the pixels, one data line for the Din and one gnd for the data. The +5 is usually red, the data line some other colour and the two grounds black. They are tied to-gether at the pixel.
I've been doing quite a bit of work with this stuff for microscope illuminators and the neopixel strip in your reference sure looks much like what I'm using. If so it needs a processor of some sort to talk to it.

Take a look at https://learn.adafruit.com/adafruit-neopixel-uberguide

This tutorial gives a lot of information on these things