I had to do this project for many of my young friends who are interested in LED’s but do not know how to go about it.
I also had the same problem but was fortunate enough to get HELP from my friends at www.Instructables.com.
This is not about any calculation or study but a set of proven rules to follow and get results,
which anybody can do if he has the mind to.
Here I have shown you many types of power supply which can be used to glow a LED.
I have also shown here how different types LED's can be made to glow and use it in you project.
Step 1: KNOW YOUR LED
A 15 mm LED has two legs, the long one is the Positive and the short one is the Negative.
It consumes 15 milli Ampere of current and can glow on 3 Volts DC Current, or a 3 volt battery.
LED’s are Diodes and the current can only pass through the POSITIVE side.
Always remember to maintain the POLARITY of the LED, that is (plus to plus) and (minus to minus) otherwise it will not work.
LED is a one way street. Now you know how to connect an LED in your circuit.