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[on:]

I have found a rgb strip given in this link
http://www.sirs-e.com/st/strip-meters-p-2920.html?cPath=67

It is 12V, 24W, 2A strip.
but again at the last he has given that 20ma per color. Both are not matching. With 20mA/color it needs 9A.

How it is possible.

pls give me sollution...

[Reply #1 on:]

The 20mA per colour is the specification of the individual LED.

With a 12V supply it is likely that there are some LEDs in series and so the currents are not cumulative. That is if you have 3 LEDs in series with 20mA flowing through each the total current is 20mA not 20 * 3 = 60mA.
It is only when the LEDs are in parallel that the currents add.

So it is safe to assume that this product takes 2A per strip.

[Reply #2 on:]

k but in the strip 3 red leds are in series, 3 green leds are in series, 3 blue leds are in series and each series combination connected in parallel. so that we will have 150 series combinations(each color) in parallel.

2A current must be devided in to each parallel branch then what may be the current in each branch ?

[Reply #3 on:]

If you have 150 identical circuits in parallel taking 2A in total then you have an individual current in each circuit of 2 / 150 = 13.3mA.

[Reply #4 on:]

can you give me the internal led connections of rgb strip ?

[Reply #5 on:]

Sorry I don't have that. It's simple enough to trace it if you have one to hand.

[Reply #6 on:]

what may be the max current required for a rgb strip ?

i have 12v rgb strip but i dont have its manual, how can i know the current required for that strip ?

[Reply #7 on:]

The Strip is divideable.
Every "3LED"-part takes 3x20mA per color.
A whole meter/inch/kilometer/lightyear takes the 2A.

EDIT: 5m take 2A It's written on your link.

[Reply #8 on:]

On my commonanodestrip it's all 3 LED in series (per Strip)
every kathode (each color) has a corresponding resistor. (150/330/330).
If you dont divide the strips, every 3-led-strip is parallel.
So assume 60mA per element

[Reply #9 on:]

if 3 led strip element takes 3*20=60mA. for 5m, 30LEDs/m strip will take
60*50=3A only. Is it right ?

[Reply #10 on:]

I have a similar strip. The red leds have a fwd voltage of 2, and use the 330 ohm resistors per 3 leds. Blue and green are 3V and each use a 150 ohms resistor. Use http://led.linear1.org/led.wiz to tinker with this. Now, about the amperage I made same calc as you did to arrive at 60mA*50 = 3A. Either the supply is beyond max or it isn't lighting the LEDs properly. In any case, it's a shame they didn't make the strings twice as long, in which case they could have left out the resistor on the red leds. Now, how do drive these with my arduino ?

[Reply #11 on:]

*bump*

Had any luck on driving these with the arduino, yet?