Resistor or regulated 12 Volt WS2811 LED Pixel
A frequently asked question about 12 Volt WS2811 LED pixels is what is the difference between resistor and regulated pixels.
First of all the basic structure of LED pixels
LED pixels consist of two main components
- The LED
- The IC
Both the IC and the LED operate at about 5 volts. However, most installers like to use a higher voltage because this allows more pixels to be installed in a chain without a large voltage drop.
In order for the IC and LED to be driven at the correct voltage, the voltage supplied to the components must be reduced.
Here there are two common methods
- a series of resistors
- a voltage regulator
Now to the different methods
Reduction via resistors
Resistors work directly proportional to the input voltage and output current. If we have an input voltage of 12 volts and an output current of 0.3 watts, we select the appropriate resistor to regulate the voltage so that the LEDs light up without being damaged by overvoltage. However, since resistors work directly proportional to the voltage, you have the effect that the LEDs get dimmer when the voltage drops towards the end of the light chain.
The reason for this is that the appropriate resistors should be used with an input voltage of 12 volts. When that voltage drops to 9.5 volts at pixel number 130, the resistors still do their job, but instead of reducing the input voltage to 5 volts, they reduce it to about 4.5 volts. This might just be enough to make single colors glow at white, where all three LEDs should be on full, the voltage is no longer sufficient, which leads to the effect that the LEDs glow reddish yellow.
Basically, it's a bad idea to reduce the voltage from a high-voltage source to a low-voltage circuit, because if the components supplied with power need a higher current, the resistors will most likely burn out and fail.
However, in the field of LED pixels, each pixel consumes less than half a watt of power, so the most popular method via resistors is to reduce the popular 12 volts to about 5 volts. This is because a couple of resistors are much cheaper than a voltage regulator.
Reducing a voltage regulator
To reduce the voltage from 12 volts to 5 volts, "regulated" pixels use a linear regulator instead of resistors.
Unlike a series of resistors, the linear regulator reduces the voltage to a value set by the hardware (5 volts in this case). If less than 12V is supplied e.g. 9 volts then the voltage is still reduced to 5 volts.
But linear regulators also have a minimum voltage requirement, if this is fallen below, the regulator can no longer fulfill its task and the LED does not light up at all. This means that if, for example, the voltage drops to 8 volts, then from this point on the pixels do not light up at all, in contrast to the pixels with resistors.
If longer distances have to be covered, the regulated LED pixels are certainly the better choice, since less power can be supplied. However, they also cost more due to the built-in hardware,
One of the biggest disadvantages of regulated LED pixels is their susceptibility to errors. If you wire regulated pixels incorrectly, i.e. swap + and GNG, they will burn out and then need to be replaced.