electronics newbie here and looking for a bit of advice on a project.

I’m trying to build an LED light panel that will serve as a light source for a 4x5 large format enlarger. After being let down by a commercial product I waited for over 3 months to arrive only to find it didn’t even fit never mind work properly (I won’t mention any names).. I’ve decided to try and build one myself. I’ve done a few Arduino projects with various components, so I would say I have a basic understanding but having read loads recently on LED circuit layouts I must admit I’m still thoroughly confused!

So what I’m trying to build is an array of R,G and B LEDs with the 3 colours on individual dimmable channels so I can mix the colours (to be honest it’s only the blue and green that are critical as only these are needed for black and white negatives). Also, I’ve gone for individual colours rather than a combined single LED as the wavelengths (especially of the blue) has to be fairly specific in order to be able to use multi-contrast paper, so I’ve now got my LEDs which are fairly typical values:

Red: 2.2v drop @ 20mA

Blue and Green: both 3.3v drop @ 20mA

One other thing is that the panel would be powered by an external timer (not from an Arduino) so a transformer of some sort would be involved, my main timer outputs 240v AC - I’ve put 9v in the circuit below as I think this should be enough, but could be changed if not.

I’ve considered various options, but the one I’m leaning to at the moment is to build it in clusters with each cluster having 2 of each R,G and B LEDs in series, then linking then all the clusters in parallel (see below)

Ignoring the fact that there’s no dimming ability in the above, does this approach seem right or would there be a better way of doing this? With 20 clusters (so 40 LEDs on each channel), my thoughts/calculations would be that 9v would be supplied on each channel and the total circuit would use 1.2A. I may be barking up the wrong tree here and got it completely wrong.. apologies for the very long question but any advice of thoughts would be greatly appreciated!

Electronics newbie here and looking for a bit of advice on a project.

I’m trying to build an LED light panel that will serve as a light source for a 4x5 large format enlarger. After being let down by a commercial product I waited for over 3 months to arrive only to find it didn’t even fit never mind work properly (I won’t mention any names).. I’ve decided to try and build one myself. I’ve done a few Arduino projects with various components, so I would say I have a basic understanding but having read loads recently on LED circuit layouts I must admit I’m still thoroughly confused!

So what I’m trying to build is an array of R,G and B LEDs with the 3 colours on individual dimmable channels so I can mix the colours (to be honest it’s only the blue and green that are critical as only these are needed for black and white negatives). Also, I’ve gone for individual colours rather than a combined single LED as the wavelengths (especially of the blue) has to be fairly specific in order to be able to use multi-contrast paper, so I’ve now got my LEDs which are fairly typical values:

Red: 2.2V drop @ 20mA

Blue and Green: both 3.3V drop @ 20mA

One other thing is that the panel would be powered by an external timer (not from an Arduino) so a transformer of some sort would be involved, my main timer outputs 240V AC - I’ve put 9v in the circuit below as I think this should be enough, but could be changed if not.

I’ve considered various options, but the one I’m leaning to at the moment is to build it in clusters with each cluster having 2 of each R,G and B LEDs in series, then linking then all the clusters in parallel (see below)

Ignoring the fact that there’s no dimming ability in the above, does this approach seem right or would there be a better way of doing this? With 20 clusters (so 40 LEDs on each channel), my thoughts/calculations would be that 9v would be supplied on each channel and the total circuit would use 1.2A. I may be barking up the wrong tree here and got it completely wrong.. apologies for the very long question but any advice of thoughts would be greatly appreciated!