red-orange superflux LEDs

[1-3-2-4]

unless i screwed up someplace i have a 33 ohm 1/2 W resistor with 8 Superflux LED's if I recall they are vf 2.5 and I'm driving them at 60 mA my power supply is 14.4 V

The LED's don't light at all but the resistor is too hot to touch after about 10 seconds

I should be able to run 8 at once right?

 

[KJ6EAD]

That's an unusual supply voltage. What could produce such a voltage? You should show a schematic of how you've got your LEDs wired. Are you saying that your LEDs are each rated at 60mA and 2.5V?

 

[strantor]

if you've got them all in series, 8*2.5 = 20V. So not enough voltage. 14.4V sounds like a laptop power supply or cordless tool NIMH battery charger.

 

[strantor]

and 14.4v/33Ω = 436mA, not 60mA. Probably burned em all up.

 

[audioguru]

A car battery charges at 14.4V.

Philips Luxeon Super-Flux LEDs have a detailed datasheet. The forward voltage of a red-orange one is 1.83V to 2.67V or 2.19V to 3.03V at 70mA. There are two versions which explains the two ranges of forward voltage.
They get extremely hot at currents above 50mA and the pcb tracks help carry heat away from their 4 legs.

(14.4V - 1.83V)/33 ohms= 381mA. The resistor dissipates 4.8W.
LEDs are NEVER connected directly in parallel unless they all have EXACTLY the same forward voltage.

 

[1-3-2-4]

and 14.4v/33Ω = 436mA, not 60mA. Probably burned em all up.

I've already got the 3rd brake light with 4 with a vreg with a 33 ohm and it works fine that puts it at about 60 mA

I wanted to see how might brighter 4 extra LED's would be over just having 4.. It would make it a bit more uniform if that.

Here is the pictures I took last week when i completed it

Using a low dropout voltage regulator.

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[KJ6EAD]

Are there any other circuit elements you neglected to mention before we continue? Post a COMPLETE schematic.

Just a guess here. Your circuit is supposed to use an adjustable voltage regulator in constant current configuration with a 33Ω resistor to program the current to 38mA but you've got it wired wrong so the resistor is in series with the LEDs and the regulator isn't regulating the current.

 

[1-3-2-4]

^ in which post are you referring to? The one where about adding 4 other LED's or the current 4 LED setup? I did not make a schematic because it was simple enough the 4 LED one you see works fine as it is I left it on at the bench at home for over 30 min and the resistor maybe got 1-3F over ambient temp.

I'm talking about the 8 LED version I did on the bench something can't be right.. I might rewire it first and keep all the LED's in the same direction just to make the wiring less of a hassle and less errors for a screw up.

 

[strantor]

Are there any other circuit elements you neglected to mention before we continue?

like this one:

Using a low dropout voltage regulator.

You should show a schematic of how you've got your LEDs wired.

Post a COMPLETE schematic.

I did not make a schematic because it was simple enough

When the technical experts on the other side of the internet who you expect to help you, repeatedly ask you for a circuit despite the pics you've posted, that's how you know when your circuit isn't simple enough to get by with pictures and half explanations.