LED array - power source considerations

[82 chevy]

LED array

The information I am finding about putting together an LED array is not mentioning the output current of the power source I am using-should I take this into consideration. I am trying to assemble a 12 LED array using white LED's and a 12vdc 800mA wall transformer. Any help would be great. Thanks.

 

[Audioguru]

LED array

If you don't know the max allowed current for the LEDs then you need to buy LEDs that have a datasheet.

You also need to know the minimum and maximum forward voltage of the LEDs to determine how many can be connected in series and in series with a current-limiting resistor.

Most white LEDs are typically 3.5V. Then 3 can be connected in series and the current-limiting resistor will have 1.5V across it. Each string uses 25mA for most little ordinary LEDs. Make 4 strings like this. Their total current will be 100mA.
If your LEDs can handle 200mA each then the power supply will be at its max rating.

 

[82 chevy]

Thank you for replying. I found a website"LED Center" that if you plug in the values-it will design an array. It says that (for this one design) it will draw 80mA current. Does my power source have to be at that value or below,or can I use a higher current power supply(like a cordless phone transformer)? Or, does the array just draw what it needs?

 

[Audioguru]

The electrical power source for a car is its battery that can supply 600A to strart the engine. The car has a clock that is connected directly to the battery. Does the clock draw the 600A that are available? No!

An electronic circuit draws only as much current as it needs. But LEDs need a current-limiting resistor.

The "LED Center" assumes that you have cheap ordinary little LEDs that are rated at 20mA. But maybe your LEDs can survive a much higher current then they will be much brighter.
The "LED Center" asked for the forward voltage of your LEDs that you do not know. What voltage did you use for it?

 

[82 chevy]

I entered 3.5 volts. I've done a fair amount of reading. I knew the specs of the LED and my source voltage. But, I think you already answered my question. It is funny that you chose the example of the car battery and clock. I am an auto mechanic. I probably should have known that. I am building a model of the Starship Enterprise and I wanted to light it from the inside. It should be pretty awesome. Anything else you could suggest would be great . Thank You.

 

[Audioguru]

To light up things with LEDs you should select LEDs that have a very wide angle for their light beam. Some have a very narrow beam angle.

 

[82 chevy]

I can't thank you enough.