When using the calculator I provided it is assumed that the actual forward voltage is measured and not a guess or estimation.

Any minor variations in the supply voltage, will have little or no affect, if the voltages are measured and the correct resistor is chosen.

If a user cannot do the proper calculations and take the proper measurements, then an over the counter CC supply should be used.

And the idea that adding 3 more volts to the supply to protect from burnout is a joke, under the possible scenarios provided.

 

You can still use the set up I posted in #19. If you plan on operating the LEDs at max drive a 3 ohm-10 watt series resistor is required, based on a forward voltage drop of 2.25 volts from the specs.
SG

 

Even with the resistor having to drop something like 3 volts, using a 12 volt supply I come up with only 1 watt or so on the resistor…are you saying you need a 10 to 1 safety factor?

 

3 volts at 1 amp = 3 watts....safety factor of 3....10 watt
SG

 

i am not understanding how to calculate the power supply. for example for powering 4 CXB3590-0000-000N0HCD35G i am using a
HLG-185H-C1400B power supply without any resistors. im confused

 

3 volts at 1 amp = 3 watts....safety factor of 3....10 watt
SG

1 amp...he said 350mA.

 

i am not understanding how to calculate the power supply. for example for powering 4 CXB3590-0000-000N0HCD35G i am using a
HLG-185H-C1400B power supply without any resistors. im confused

The HLG-185H-C1400B power supply has high voltage output not recommended for just 4 LEDs as in your set up. Just use a separate 12 volt supply and dimmer as in post #19. Series resistor value will depend on how much drive you need.

SG

 

1 amp...he said 350mA.

See post #20

SG

 

im totally confused at this point. for the driver i should be looking for the right Voltage and it doesnt matter the amps. as the amps would be the amount of leds i can connect. right?

 

Hello,

I found here the datasheet of the COB that is mounted on the star plate.



Bertus

 

Specs say 2.1 volt forward voltage at 350 ma forward current on the Mouser link.
SG

And that is a TYPICAL forward voltage. The one thing that you can pretty much count on is that the ACTUAL voltage will be different.

 

Hello,

You can not use the mentioned driver for the leds you got.
The current and voltage are to high:



The leds will be blow in a matter of seconds when you connect them or the driver will refuse to work, due to to low output voltage.

Bertus

 

I actually changed the led setup i want. It will still be 4 leds . What i dont understand is how to pick the right power supplies. This are the leds i want to get. And the spreadsheet. Maybe somone can help me figure out what meanwell i need?
XPEFAR-L1-0000-00701
https://www.mouser.com/ds/2/90/XLampXPE-221789.pdf[/QUOTE]

Look at page 3 and you will see that, at 350 mA, the typical forward voltage is 1.9 V and the maximum is 2.4 V. No minimum is given.

 

Hello,

You can not use the mentioned driver for the leds you got.
The current and voltage are to high:

View attachment 144143

The leds will be blow in a matter of seconds when you connect them or the driver will refuse to work, due to to low output voltage.

Bertus

Yeah I've already told him this twice. BTW he switched to a different LED in post #20.
SG

 

im totally confused at this point. for the driver i should be looking for the right Voltage and it doesnt matter the amps. as the amps would be the amount of leds i can connect. right?

Voltage and amps matter. Below is the set up I recommend using the components in post #19.
SG

 

See post #20

SG

Oh, he changed the LEDs…my bad…well I sure hope he knows how to heat sink them, if he wants to run them anywhere near max.

 

i am not understanding how to calculate the power supply. for example for powering 4 CXB3590-0000-000N0HCD35G i am using a
HLG-185H-C1400B power supply without any resistors. im confused

There are basically two ways of driving a string of LEDs -- constant current and constant voltage. At the end of the day, you want to control the current, so if you use a constant voltage source then you need to use a current limiting resistor to set the current. But if you use a constant current supply you don't as the supply will adjust its output voltage to what ever is needed (within its control range) to achieve the specified current.

If you want to use a constant current supply, then the rated current needs to be what you want and the rated voltage needs to be at least what you need. But some supplies (and it looks like the ones you reference fall into this category) can only maintain proper current control as long as the output voltage is between a minimum and maximum value. For that unit you gave the part number for, that's between 71 V and 143 V. I didn't see an indication of what happens if you try to operate it below 71 V. It's current range is also adjustable only down to 700 mA. It is not suitable for driving just 4 LEDs or trying to drive any LEDs down in the 250 mA to 350 mA range.

 

so basically you are saying that i could get a 12-24V power supply as longas i dont exceed the 1000mW as its 250mW*4 ?
Confused=!"="!£

 

so basically you are saying that i could get a 12-24V power supply as longas i dont exceed the 1000mW as its 250mW*4 ?
Confused=!"="!£

Where's this 250 mW value coming from?

What current are you planning to operate the four LEDs that you want to use now?

 

i want to operate them at their max current. from what i see on the sheets their min is 250mW and max 350mW so yeah sorrry
it would be 1400ma.
i got it from here https://www.mouser.com/ds/2/90/XLampXPE-221789.pdf
for the XPEFAR-L1-0000-00701 cobs