Aloha DH

Kinda waitin' 'til you have the LEDs in hand and can use the variable supply to label them with the actual Vf, at the current you want.
You can use the variable voltage function and increase the voltage until you reach the target current. Or you can use CC mode if you turn the voltage all the way up and adjust current up to the target and, in either case, just record your meter readings.
Should come out the same regardless of the approach, ya?

Theory is lots of fun, but, once you have actual facts in hand, design kinda handles it'self.

Once we know what is, we'll know what needs to be.
No wasted speculation, now mind be mo' free.
Once you've whittled many paths down to 2 or 3.
'tis then, the path that you will choose, seems obvious to me.

Sorry!
It happens.:jointsmile:

Weezard
Weezard Reviewed by Weezard on . Calling out to Weezard for LED advice My friend, I've read your stuff here and at Steve F.'s site. I want to build a dedicated flowering lamp using Ledengin 15 watters. (4 reds, 1 blue, and possibly 1 warm white; LM 317's so I can tweak the ratios.) Essentially, a copy of your 4+1 cake pan lamp but built on a 4 x 18" finned heatsink so I can see what's going on under it.) If I were to post my picks for power supply, resistor ratings / values, etc., would you critique and perhaps offer some guidance? I have already purchased Rating: 5