can use my 12 v 2 amp adaptor for my current design for lamp please tell me suggestions as sketch including all necessary resistors or buck convertors or please add required things I am a starter in electronics people willing to help highly appreciated thanks... no other talks needed please tell me anyone can do help to complete this small project?

 

Hi I4,
When connecting LED's in series, each LED forward voltage drop must be included in the total voltage drop of the LED string

What is the forward voltage of one your LED's.
E

Example: if each LED is White light, that usually means a Vforward of 3.2V
So that means 16 Led *3.2V = 51V, you have a12Vdc power supply, it will not work.

a LED forward current of 0.7A, times 3 LED strings = 3 * 0.7A= 2.1Amps.

 

With a 12V supply the maximum number of white LEDs you can have in one series string is three. So if you wanted to use all 48 LEDs you would need 16 such strings in parallel. That would require limiting the current in each string (hence in each LED) to 2A/16 = 125mA.

 

Dear pros... Please check my power module and connection diagram i am using UV LED 390 TO 400 nm, Enough cooling Fans, heat sink, heat paste is also ready to heal the heat shock.

LED Power: 3000 mW (milliwatts),
Forward Current of one LED : 700 mA,
Number of LEDs = 48
Input Voltage = 12V

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Personally I wouldn't run the LEDs at their rated 700mA maximum. Perhaps ~500mA?
Your post #4 pic shows no series resistors, and the + and - connections are shorted together!

Edit:
If the post #1 datasheet is accurate and I'm interpreting it correctly, 3000mW power at 700mA implies a LED forward voltage of 3000mW/700mA = 4.28V. If that is indeed the case then a 12V supply could not drive 3 LEDs in series at that current.

 

hmmm... i do not see the datasheet... just screenshot of a very small part of a datasheet. most likely those are the Absolute Maximum values...
in this case 700mA is a breaking point at which those LEDs get damaged. and they can only sustain that with a MASSIVE heatsink and using water cooling or cryogenics.... therefore such value is therefore unrealistic for any application. i would say 50% of that is more reasonable (and still require cooling!).

the next part is expected current draw.... suppose one does connect 3 LEDS in series and one such series connection does draw 0.7A at 12V. 12V supply rated for 2A can only power two such strings (total current 1.4A) or total of 6 LEDs. as soon as 3rd string is added total current is 2.1A which exceeds PSU rating. that is 9 LEDs... strip shown in post #4 has 14 strings. combined current draw would be 14*0.7A = 9.8A. clearly a bigger PSU is needed.
also LEDs are notoriously nonlinear devices. even slight change in forward voltage makes huge change in drawn current... this is why LEDs are normally operated in a way that limits (controls) the current and not the voltage. one way to handle current limiting is to user resistors for each series string.
then by limiting current for one tring to 500mA (Assuming LEDs can handle that, ie. they have proper cooling), then 2A PSU can power4 such branches or total of 12 LEDs.

 

clearly a bigger PSU is needed.

That's what the TS is showing in post #4.

 

true, and that can work for 48 LEDs....

 

No issues running perfect 2 fan, 48 LED, 12V 5 amp - write down and you can test it , I am not electronics guy, but still it's working perfectly. No issues