# Choosing resistors for an LED lighting panel [duplicate]

I want to build an LED lighting panel (something like this: https://manioscinetools.gr/en/product/fv-z180-ultracolor-5600k-led-light-panel/). To do so, I am thinking of an implementation with LED diodes placed in parallel.

I wonder if the two schematics above are equal. The first one is a classic schedule solution, while the second is an alternative one in order to avoid non necessary parts (The total resistor has a value multiplied by the number of the single resistors.)

I should note that the LEDs will be turned on/off all together, and that they have the same characteristics concerning the forward voltage.

Any suggestion would be appreciated.

• Nov 19 '20 at 17:40
• A question on this topic has already been asked and answered at Why exactly can't a single resistor be used for many parallel LEDs? generally it is more efficient to search existing questions before posting a new one, as this both provides you with an answer immediately and saves the community effort to dig up duplicates and close unnecessary questions against them, and also to write unnecessary new answers... Nov 19 '20 at 17:41
• Even if it was a good idea to replace all 7 resistors with a single one (which it isn't), a 7R resistor does not replace 7 resistors of value R in parallel. Nov 19 '20 at 17:47
• Since LEDs' luminous intensity is related to current, large panels like these generally have parallel groups of (several LEDs in series with a resistor.) For instance, 3 LEDs in series might consume 20mA at 10V, so a 12v supply is used and suitable resistors. Nov 19 '20 at 18:04

... and that they have the same characteristics concerning the forward voltage.

They don't.

Figure 1. Variations in Vf for a typical white LED. Image source: Variations in Vf and binning.

I wonder if the two schematics above are equal.

Nope.

The first one is a classic schedule solution, while the second is an alternative one in order to avoid non-necessary parts.

The LEDs with lower Vf will pass more current and glow more brightly.

I should note that the LEDs will be turned on/off all together, and that they have the same characteristics concerning the forward voltage.

Check the datasheet for the LEDs and look at the tolerances.

My linked article may be of interest.