Looking for tutorial

I am learning how to set up LED circuits and looking for some understandable tutorials which show me every step in detail. If you guys know of any source, please let me know. Thanks a lot in advance.

In essence, for standard LEDs on low voltage DC circuits:

Subtract the LED forward voltage (taken from its data sheet) from the supply voltage.
Divide the result by the required current in amps.
That gives the value of resistor needed to set the LED current on that voltage; use the nearest standard value.

eg. For a red LED to run at 20mA with a forward voltage of 1.8V on a 5V supply:
5 - 1.8 = 3.2
3.2 / 0.020 = 160

So for readily available resistors, you could use either 150 Ohms and get a slightly higher current, or 180 Ohms and a slightly lower current.

If you want several LEDs running from the same circuit, you can series them and use the total of the forward voltage drops for the calculation, as long as that leaves a reasonable voltage across the resistor, to stabilise the current.

And with anything working from batteries, remember the voltage drops as the battery discharges.

High power LEDs or LEDs working from high voltages tend to need more complex switch-mode power circuits.

There is a huge amount of info on web.....google is your friend. LED manufacturers
very helpful.


Regards, Dana.