How To Calculate and Connect LEDs in Series and Parallel

Read this article to briefly understand how to calculate LEDs, and design circuits with them, through simple series, parallel connections.
In this article you will know the basic tricks to calculate LED in series and parallel and learn how to design a large numerical led display.

Led lights have always fascinated us since childhood. These lights are known not only for their dazzling color effects, but also because of their durability and least power consumption. Moreover LEDs can be wired in groups to form large alphanumeric displays which may be used as indicators or advertisements.

Young electronic hobbyists and enthusiasts are often confused and wonder how to calculate LED and its resistor in a circuit, since they find it difficult to optimize voltage and current through the group of LEDs, required to maintain an optimum brightness.

In this article we will discuss regarding a simple construction of a small LED numerical display and try to understand its design and functioning.

As an example we will build a number display “8” using LEDs and see how it is wired.

Parts Required

You will need the following handful of electronic components for the construction:

 RED LED 5mm. = 56 nos.

RESISTOR = 180 OHMS ¼ WATT CFR,

GENERAL PURPOSE BOARD = 6 BY 4 INCHES

How to Calculate and Construct LED Display?

The construction of this number display circuit is very simple and is done in the following way:

Insert all the LEDs in the general purpose board; follow the orientations as shown in the circuit diagram.

Initially solder only one lead of each LED. After completing this, you will find that the LEDs are not aligned straight and are in fact fixed in quite a crooked manner.

Touch the soldering iron tip on the soldered LED point and simultaneously push the particular LED down so that its base is pushed flat on the board. Do this for all the LEDs to make them aligned straightly.

Now finish soldering the other unsoldered lead of each of the LEDs. Cut their leads cleanly with a nipper.

According to the circuit diagram common up the positives of all the LED series.

Connect 180 Ohms resistors to the negative open ends of each series. Again, common up all the free ends of the resistors.

This ends the construction of the LED display number “8”.

To test it, just connect a 12 volt supply to the common LED positive and the common resistor negative.

The number “8” should instantly light up in the form of a large numerical display and can be recognized even from long a distance.

Circuit Functioning Hints

 To clearly understand how to design a large numerical led display it will be important to know the circuit functioning in details.

Looking at the circuit one may notice that the whole display has been divided into 7 LED series “bars”.

Each series contains a group of 4 LEDs. If we divide the input 12 volts with 4 we will find that each LED receives 3 volts enough to make them glow brightly. The resistors make sure that the current to the LEDs is limited so that they may last long.

Now by just joining these series LEDs in parallel we can align them into different shapes to produce a huge variety of different alphanumeric displays.

Readers must have now easily understood how to calculate LED in different modes. Its just a matter of connecting LEDs first in series, then joining these in parallel connections and applying a voltage to their common positives and negatives.

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