Why do my LED strip lights only work if I reverse the connection polarity?

Couple of questions for you.

Are the pads on the pcb accessible with meter probes?
Can you probe each pad and find out which wire it goes to?

It looks as though the pads I am referring to are labeled "+12, G, R, B"

Now are you saying that the controller is set up for a common cathode and the led strips are set up for common anode (which it appears they are)?

I cannot clearly see what the input is on the controller but the output seems to be labeled "VCC, B, G, R" which makes me think that the controller is a common anode. So I guess I don't know what the problem really is.

edit: Okay I saw the other pictures. So the board should work with the led strip as configured but you say it doesn't unless you change the polarity of the input power to the controller...

0 0

I’m sure you already know that LEDs are polarity sensitive. If you didn’t know this basically means that they will not light up if the power and ground are connected backwards. So if you plug in you new V-LEDS and they do not light up, try flipping them around and plugging them back in and they should work. I want to go over some other polarity issues where flipping the connection over will not work.

Here is the classic example. Your car, truck, or motorcycle uses an 1156 style bulb and you have replaced your blinker or brake light and it won’t light up. The filament bulb that was installed before worked just fine, why is the LED not working? Simple answer is polarity. The problem here is that you can’t just flip this bulb around to make it work. The metal base is the main contact and there is a center pin in the bottom of the socket that is the other contact. The problem here is associated with the wiring on your car. The wires going to the socket are backwards. The...

0 0


I just received the starter kit today. I'm new to Arduino and I'm having problems getting the first project to work. I'm supposed to press the button and the LED will light up, but when I press the button, nothing happens.

I used my LED tester to make sure the LED was working. I tried swapping to a different LED, and to a different resister. I am having a hard time telling the difference between the colors in the book and on the resister, so I'm not even sure that I'm using the 220-ohm resister.

It looks like I have everything hooked up the correct way-it looks the same as the book image as far as I can tell, except, I'm using orange wires instead of brown, because I didn't get any brown wires with my kit for some reason.

I also sent a test program and modified the Blink program to make sure that the Arduino board was working.

I swapped the switch with a different one to make sure that wasn't broken.

I took a picture of my setup. Can...

0 0

I'm trying to build a preamp for a piezo pickup in acoustic guitars. The project is a mash-up of Mr. Tillman's preamp and Mr. Keen's polarity protector. I plan to build two versions of this project. The first will be powered exclusively by a 9V battery with a polarized snap. The only time the polarity should ever be reversed is when a new battery is being installed and then it would be very brief and obvious that the snap doesn't fit onto the battery. I've considered just using a diode to protect the preamp in that version.

The second version of the project will use a battery compartment that does not prevent accidentally inserting the battery backwards. It will also have the option of a wall wart. That version will definitely need the polarity protector circuit.

The problem is that if the assembly doesn't work, I cannot distinguish between a dead battery and blocked reverse polarity. I came up with what I think is a solution using a two-color LED but being far from...

0 0

I'm working on project with RGB LED strips with my arduino and a ATtiny84. Basically, what I plan to do is attach the strip to my display cabinet and attach the strip to an ATtiny84 microcontroller which will program the lights. Doing this I have encounter a few problems. As I haven't receive my ATtiny84 chip from the store yet, I'm testing everything on my arduino first. I first attached a normal single RGB LED to test all my programs and it works almost fine.

My first problem was when I attached 3 potentiometer(pot) to the arduino to control the intensity of each pin(red, green, blue). It did as it suppose to. When I turn the knob the brightness increase but as I'm reaching its maximum it drops back low again. So basically as I turn the knob gradually increasing, the brightness increase gradually from zero to it brightest then drops. I have attached a screenshot of this program below. I think it may be the connection between the pot and the arduino as they...

0 0

When I inspect houses where an amateur has been doing electrical work, there’s a good chance that I’ll find outlets with reversed polarity. This happens when the hot and neutral wires get flipped around at an outlet, or upstream from an outlet. Reversed polarity creates a potential shock hazard, but it’s usually an easy repair.

A brief definition of Hot and Neutral wires: On a standard outlet, which is technically called a ‘duplex receptacle’, there are two wires that carry electricity. One of these wires is connected to the earth, or ‘grounded’, so this wire is called the grounded conductor. This wire is commonly referred to as the neutral wire, and it should always be white. The other wire doesn’t get connected to the earth, and it’s called the ungrounded conductor, or hot wire. This wire can be any color besides white or green, but it’s usually black or red. Because the hot wire completes a circuit by coming in contact with the earth, if you touch a hot wire and...

0 0

A bad pin connection also includes a backwards connection or reversed polarity. Typically one side of the strip light carries a positive charge, noted by a single dashed line, and the other side has the negative charge, usually noted with the manufacturer logo. The arrow on your connectors should point to the plus sign on your strip lights. RGB or color-changing LED strip lights are particular susceptible to this reversed polarity problem. If your RGB strip lights won’t change colors try flipping your strip light around and reconnecting it.

Incorrect Power Source – Make sure to double check which power source your lights require. LED strip lights are available in 12 or 24-Volt versions. A 12-volt strip light is typically used for short runs, such as for automotive vehicles or motorcycles, which is how many people are able to skip installing an LED driver and hardwire the lights to a 12-Volt DC battery. 24-volt strip lights are better for slightly longer runs, commonly in...

0 0
This tutorial covers wiring up any old LED strip to your computer's power supply in a number of ways, but also to an independent power supply for use outside your case or on the back of your monitor or something else.

First of all if you can't be bothered with all this faffing about with bits of wire, connectors and the potential to damage your power supply or PC then you should really be looking at OcUKs extensive range of LED strips, which come with modular connectors that can be connected together to create full case lighting.


Anything you decide to do with LED strips from this guide is your responsibility. I accept no responsibility for anything you do so don't even think of blaming me for something you've done wrong. None of the voltages inside a PC case (PSU excluded) can actually hurt you.

Things you will need:-

1) Some sort of mating half for a PSU or...

0 0

Originally Posted by


Take a multimeter and check the polarity of the power

I don't have a multimeter at the moment but do these images help determining the polarity or do I still need a multimeter ?

This is a "K" tip, with the - symbol on the back of the white plastic and the + symbol on the side where the metal tip protrudes

what it reads on the adapter plug (these are also called transformers, correct?)

What does "6A Max" mean?

btw, someone on youtube commented saying to try an L or M plug here is what he said:
Some devices require "tip to negative" which might be why it partially works when flipped. If you look at a Radio Shack universal power adapter it shows the symbols to follow based on the device.
Or try a "L" or "M" plug, I've seen devices act weird with really close tip sizes that fit the...

0 0

Using a AA battery, two pieces of speaker wire and an LED, I am trying to make a simple circuit. I am meeting with complete failure. Help!

I read books for a living. I do not program computers, wire electronics, play with oscilloscopes, or regularly work on projects that require modulating a radio frequency. That said, I'm bored for the summer and looking for new projects. Choice A is a neat LED nightlight, and so I find myself (once again) trying to teach myself simple electronics, and (once again) meeting with middling levels of success.

Basically, I'm trying to wire an LED to a battery. I am following this instructable. I am using a 1.5V AA battery and a 1.7V LED, using a lower-level power supply on the assumption that I don't yet have to learn how to wire a resister. I realize that there are TWO steps to this process - making the connections, and putting the LED in one of two orientations. And yet...my LED fails to light.

I realize that this is...

0 0

Most, if not all, of the drivers in our flashlights are switched/regulated on the negative side, with the positive side taking a mostly unobstructed path from Batt+ to LED+ on those drivers. I’m wondering if there’s a simple way to make the driver do its switching/regulation on the positive side instead. From my (very limited) understanding, the ATtiny sends out a positive signal to either the 7135(s) or FET. Both of those components take the PWM on the positive input and use that to regulate the negative output. That regulated negative is what goes to the LED.

Obviously, the LED doesn’t care which side is switched/regulated. It will be “on” only when both sides are connected, and “off” otherwise. But, the switching/regulation components themselves DO care. So, for instance, if you want to add a slave board to your driver in order to add more 7135’s without stacking, you normally must run three wires from the driver board to the slave board. You can’t just connect it to your...

0 0


Last week, I was wiring up a demo with a three colour RGB LED, and accidentally wired the pin for the red component straight to 3V3 (plugged it into the wrong port). It went “crackle” and then turned black. Ooops. Now it’s a GB LED, the red’s a gonner. :(

“Dammit. I wanted to shoot a video with the Quick2Wire Interface running the RGB LED. It’s 7pm and if I order some they won’t be here for two days.”

“Oh I know. I’ve got an RGB LED in an old Christmas present that doesn’t work properly any more. I wonder if I can remove it and use that?”

So I took it out, desoldered it, added some longer pins and…

…it didn’t work. Oh **************. :(:(

Looking at it from the other way

After a few minutes I thought to try it on reverse polarity – just in case. The original had a common cathode (-ve electrode), so each colour had a separate anode (+ve electrode – a for add, +). This one was the opposite.

That’s nice, but now...

0 0

DO Use Stranded Wire

With stranded wire you get more intimate contact, thus reducing voltage drop and power losses. Poor connections can rob a system of a significant portion of the power being produced. Stranded wire will compress and flatten out which increases the contact area. This reduces the voltage drop and minimizes heating at the connection.

DO Use Clean, Straight Wire Leads

Having clean and straight wires is important to any LED installation. If your wires are clean and straight you will get the best possible connection and reduce voltage drop. If you want you can solder the ends of your wires to keep them together and know you are getting sufficient contact on your connections.

DO Heat Shrink or use Connectors

When connecting two wires together it is always best to use the proper wire connectors or solder your wire together and apply heat shrink to protect. There are a variety of wire connectors for different types of wires so it is...

0 0

1.) Determine the Specifications on your LED Lights

If you are having issues with your LED power supply the first place to start is to determine the voltage and power specifications of your LED Lighting Products. There are many types of LED products so it is important to know exactly what you have and one reason that we discourage people from "shopping around" for LED products because not all LED products are compatible with one another. If you do not have access to the specifications from the supplier then you can look on the product itself and usually there will be some type of marking or sticker on the product like you see in the picture to the right. If you do not know the wattage or voltage of a product you will have to purchase an instrument to read this. It is also very important to know whether your product is Constant Voltage or Constant Current LED, at Ecolocity LED we only sell Constant Voltage LED product, the two types are not compatible with one another.

0 0
Hi all,

I have a challenge for you, a problem for me. I have a circuit that uses a LED membrane, the LED's cathodes are all connected together and to ground on one pin. The anodes are all open for input. Each LED serves as a particular indicator. One of the LEDs was intended to be used as a reverse polarity indicator.

The challenge is how can I activate that one LED when there is reverse polarity?

I have been trying different ways with a bridge rectifier, mosfets, and transistors but to no avail.

Basically, I need it to light up with a voltage on the cathode or make it so that the cathode is somehow diverted to ground during a reverse polarity connection.

Please help me with your ideas!...

0 0

Investing into LED lights is a great way to save money, but sometimes those lights can cause a few problems. They are expensive to replace every time they flicker and those lights can flicker a lot! The good news is that this issue can often be fixed. Don't run out to buy a bunch of bulbs because there's a good chance they'll all flicker. Take a look at these issues instead to eliminate the flicker once and for all.

Check the Amount of Current In Your Home

The most common reason why LED lights will flicker, especially if it is only an occasional problem, is because there are voltage changes happening within the wiring of the home. This is because there is a current flow in the wiring and the resistance of each wire uses some of the voltage. If you turn on a washing machine while the refrigerator is running and this is when you see a flickering LED light, then there's a good chance you have loads turning on and off that change the voltage levels and this is causing...

0 0

SMD indoor and outdoor LED tape lights have quickly become an extremely popular linear lighting solution because of its high brightness, flexibility, small size and its ability to be cut and customized with easy to use accessories. LED Strip Lights are available in both single-chip SMD 3528 (standard output) and tri-chip SMD 5050 (high output) options. SMD 3528 LEDs are an excellent option for most lighting projects, while SMD 5050 LEDs produce the brightest light available in linear lighting technology. With an IP65 (120v) and IP67 (12v) waterproof rating, LED Strip Lights are perfect for both indoor and outdoor lighting projects. Installation of outdoor LED tape lights is easy using customizable track, mounting clips, or double sided tape.

LED Strip Lights are available in both 12v and 120v options and each has their advantages in certain projects. With 120v LED light strips you can easily create large scale projects because of their long maximum run of 164’, while 12v LED...

0 0