[SOLVED] problem about LED to glow in parallel

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rahol

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how many ohm resistor is required for each LED to glow in parallel
i m using standard LED (white). which has 3.6v forward voltage drop and 20mA current
 

can I know which power supply voltage? & how many led do you going to connect it?
can I know the requirement?
 

power supply is 5V and i want to connects 5V in parallel
 

Hello rahol,

ask Mr. Ohm :wink:

R = (U - Uforw) / Iforw = (5V - 3,6V) / 20mA = 70Ω

Use 68Ω for each LED. It's better to use one resistor for each LED.

Regards

Rainer
 
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    rahol

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if you use 24v supply then you can connect 6 white led in series. which has resistor value of 150 ohm.
 

Hello madhusuthanan,

if you use 24v supply then you can connect 6 white led in series. which has resistor value of 150 ohm.
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You can do it, but you get trouble, because the fabrications tolerances of Uforw and Iforw are very large. So, for example, one LED glows very light and the other dark. Only if you select every group of LED to the same Uforw and Iforw it will be OK.

Regards

Rainer
 

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