It’s important to connect a LED the correct way in a circuit because LED shows the output in many of the circuit that we are going to discuss. LED is simple to connect – once you know how.
I thought that it is important for starters to connect a LED in the proper way. This post is only to show how a LED can be connected to batteries without damaging it.
Let’s look into three example of connecting LED. I took these three example because all three situation can happen when you start your electronic journey.LED not glowing. LED gets damaged connecting to some batteries. Don’t know which resistor should be connected to which LED and to what battery. This all happened to me when I was 7-8 years old. I hope you don’t have any problem connecting LED after reading this post. Let’s get started.
Before connecting LED you must remember that LED must have a resistor to limit the current. It does not matter if the resistor is connected above or below the LED. The circuits are the SAME. If you have problem in identifying the positive and negative terminal of LED check out my Light Emitting Diode (LED) post
The LED in the first diagram (A) does not illuminate because a red LED requires 1.7v and the cell only supplies 1.5v.
The red LED in the second diagram (B) is damaged because it requires 1.7v and the two cells supply 3v.
To connect a red LED properly, resistor is needed to limit the current to about 25mA and also the voltage to 1.7v, as shown in the third diagram (C) as a result LED glow.
Here is little something for clearing you doubts about what if I change the value of the resistor, LED and battery. Here I have given some common LED and how to connect it to different voltages.
Red super bright (1.85V 20mA)
9V – 360R
7.5V – 280R
6V – 210R
4.5V – 130R
3V – 60R
Red bright (2.0V 10mA)
9V – 700R
7.5V – 550R
6V – 400R
4.5V – 250R
3V – 100R
Green standard (2.2V 10mA)
9V – 680R
7.5V – 530R
6V – 380R
4.5V – 230R
3V – 80R
Super blue (3.6V 20mA)
White cool (3.6V 20mA)
9V – 270R
7.5V – 190R
6V – 120R
4.5V – 40R
Orange standard (2.1V 10mA)
Yellow standard (2.1V 10mA)
9V – 690R
7.5V – 540R
6V – 390R
4.5V – 240R
3V – 90R
Blue high intensity (4.5V 20mA)
9V – 220R
7.5V – 150R
6V – 70R
Remember this voltage we apply (Vcc) must be greater than voltage drop of LED, this is the reason why some LED won’t work on 3V.
If you want to know more about LED check out my Light Emitting Diode (LED) post.
Feel free to comment.
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