led driver

[Boulebee]

first of all hello everybody.

i am completely new to electronics.

i want to connect about 20 leds so that i can light up my aquarium.

i have surf the internet for many informations and lately i have found led drivers.

my question is : is led driver very important. if i connect my led circuit directly to dc supply, what will be the difference?

tahnk you

 

[4pyros]

LEDs are current devices and need limiting. Thay are not like a light bulb in you house. Thay run off low voltage DC voltage with a current limiting device like a load resistor.
Do you have a DC supply already?
What kind of LEDs are you looking to use?
If you know nothing about LEDs maybe you should buy somthing off the shelf instead of trying to make something.

 

[Boulebee]

already have a dc supply.. 5mm led and resistors

 

[audioguru]

Your DC supply has a voltage and current rating that you forgot to tell us.
Your LEDs also have a certain color and voltage range and recommended current rating that you also forgot to tell us.
Your resistors have a certain resistance value and power size that you also forgot to tell us.

 

[Boulebee]

12 v dc supply 1000mA
white led ..31.-3.3v and 10ma
the resistors i have will not be suitable for the project
they are 820 ohm..i will have to buy new one

 

[4pyros]

white led ..31.-3.3v and 10ma

That does not look right.
So lets go with 3.2 volts at 20ma

Three in series would be 9.6 volts at 20ma.
12-9.6=2.4volts across the load resister.
2.4 volts divided by .02 amps = 120ohms.
2.4 volts X .02 amps = .048 watts so you can use a .125 or 1/8 watt resister.

You need a 120 ohm 1/8 watt resister for each string of 3 LEDs.
each string will draw 20ma.
With a 1000ma supply you could do 50 strings.

There is a online LED calculater here;
http://ledcalc.com/
good luck
Andy

 

[Boulebee]

thank you very much.

i dont need a led driver?

 

[4pyros]

i dont need a led driver?

No not with a fixed power sopply. The drivers are mostly for low voltage or varying power supplys and dimming.
The resister will be fine with your fixed voltage supply.
Andy