Power Supply to thes LEDs

[Leef]

Greetings. I need a power supply to test LEDs. It'll need 120vac input, constant current or constant voltage outputs, in the 0-12vdc and 0-3 amp range.

I have an MPJA HY1500 series supply, but was told that, on occasion, it can cook an LED at first connection. I suppose this is because it doesn't have OCP or OVP (does it?).

I don't know much about these things. Anyone have any confirmation of the hazard, or other advice? Thanx!

[999999999]

Re: Power Supply to thes LEDs

I know a fair bit about LEDs and about PSU, but am not clear on exactly what you're trying to do.

How do you want to test LEDs?

How many LEDs?

Why this complicated setup to test LEDs?

What is an HY1500 exactly? MPJA's search function is horrible, I saw an HY1803 for sale but their search couldn't even find that! Were there any more details about the supply cooking LEDs, like what the scenario was including the supply settings? Perhaps it is only a matter of setting the voltage low then tweaking it after the LED is hooked up.

What kind of test on these LED are you trying to do? Light output or output per mA or live/dead or ? It might influence your choice, I don't know what your ultimate goal is or how adjustable the result needs to be.

What you might be encountering is that some supplies float high before the load is attached, if this is the case then you need to have a load on the output already or another means of current control. You could start out with such a supply and put a series resistor or another method of control after it, but it might just be a convenience, in general such a supply might be overkill.

What I propose for a basic LED tester is to take any generic wall-wart of at least 9V DC rating, (or that HY1500 will probably do fine too though I don't know exactly what it is yet), followed by an LM317 linear regulator set up in constant current mode (see National's LM117/317 datasheet, page 16, "1A current regulator" example circuit, and in that example the resistor "R1" is that of the values I list below.

Get a multi-throw switch with as many positions as you want current levels, and each position has a different resistor to select the current limit you want.

For example,

120 Ohm = 10mA
47 Ohm = 27mA
4.7 Ohm = 266mA (only for high power, Luxeon Stars/etc)
(or do your own calculations per target mA)