Designing LED displays may be fun, but very often we are just left thinking how to wire led lights? Learn through a formula how simple it is to design your own LED displays.
We already know that a LED requires a particular forward voltage (FV) to get lit. For example a red LED will need a FV of 1.2 V, a green Led will require 1.6 V and for a yellow LED it is around 2 V.
The modern LEDs are all specified with 3V forward voltage irrespective of their colors.
But mind you, at these voltages the relevant LEDs will just begin getting illuminated and be hardly visible. To get an optimum light output from them, you have to at least apply a voltage which is 25% higher than the FWD voltage of the particular LED.
But since LEDs are very “current sensitive” may just blow off and get permanently damaged on doing the above explained method of illuminating them.
Using Current Limiter Resistor
This problem is very easily solved by just adding a series resistor to the LED. It may be connected either to the positive or the negative line of the circuit.
The value of this resistor may be simply calculated through the below given formula:
R = (supply voltage VS – LED forward voltage VF) / LED current
For a series connection the total forward voltage will be required in the formula, by multiplying FV of each LED by the total number of LEDs in the series.
A 20 mA of current is enough for most of the purpose.
How to Connect the LED Lights?
To understand this let's read the following discussion:
· If for example you want to design a LED display using 90 red LEDs with a supply power of 12 volts, begin the procedure of construction first by dividing the supply voltage by 3 volts (Forward voltage of red LED for optimum brightness).
· The answer will be obviously = 4. This is the number of LEDs required for each series of LEDs.
However we won't connect 4 LEDs in series, because that would make the light pretty dim, Let's make it 3 for getting optimum brightness.
· Now dividing the total number of LEDs (90) by 3, we get an answer that's equal to 30. So you will have to make 30 numbers of series, each consisting of 3 LEDs.
· All the 30 series will naturally have a positive and a negative free ends.
· Now just connect the common positives ends of the LEDs and the resistor negatives ends of each series and apply 12 volts supply to these terminals.· You will instantly find the whole design glowing up brightly with an uniform intensity.
· You may align and organize these LED series as per the design of the display.
· A situation may arise when your designed display may contain LEDs in odd numbers.· For example if in the above case instead of 90 if the display would consisted of 101 LEDs, then we could have made 33 series of 3 LEDs each, but still there would be 2 LEDs remaining to wire.
· The problem is easily solved by just changing the resistor value for the remaining smaller series. This can be again done using the formula already explained in the article.