Star LED 230826

[AllenPitts]

Hello EOT forum,

Working on using LEDs in residential architectural
lighting.
In 2013 it was discovered that the first
LEDS that were encountered in the electronics
domain, 5 mm thru hole light emitting diodes,
were indicators not illuminators.
In search of LED illuminators the 1156 was
exposed which is quite bright. There are a
lot of components that cater to the 12 volt
automotive universe. The 1156 is very
efficient at 200 lumens per watt.
For instance, a 60 watt incandescent bulb
is twelve lm/w.

As is oft the case in the world of electrons,
smaller and brighter is sought.
Have stumbled upon a couple of LEDs that
are superior in lumens per watt.

Received several of these yesterday. Have looked
for schmetics and hook up guides
with no luck.

Have tried powering these LEDs
as shown in these test schematics.

Tests 1 and 2 results are negative,
that is, nothing happens.
Test three is also negative.
In Test 4 I think I may have fried
the component because the LED
came on briefly and then went
off. A test second Test 4 yielded
no results.
The conjecture is that a driver
is required for the Voolong
star LEDs.

CCPSD series 36W Constant Current LED Driver - DiodeDrive® - 1800mA - 12-20 VDC - IP65 Waterproof - CCPSD-36W-1800

CCPSD series Constant Current Driver from DiodeDrive is a reliable power solution for LED lighting systems. Durable construction maintains an IP65 rating for indoor or outdoor application. High efficiency of 86% and fanless design allow this device to operate with in a wide temperature range.

www.superbrightleds.com

Have searched at the
distributor and the Chinese
manufacturer and queried the
state-side disributor with no result.

Has anybody ever powered one
of the Voolong or other star LEDs?

Thanks.

Allen Pitts

 

[danadak]

That LED V rating is :

V is 6.8 to 7V

And you need to insure you are current limited and bolted to a heat sink
if you try to drive it and full power, even moderate power. it will fry in milliseconds.
Max I = 800 mA. Set your power supply with a dead short on it .1A, eg. set it
into current limiting, then do the test ramping V.


Regards, Dana.

 

[AllenPitts]

Hello danak and the ETO fotum,

The reply from dananak is much appreciated.

It must be admitted that I am a bit red-faced because the
table provided in dananak's post from

5W High Power LED-High Power LED-Vollong Electronics Co.,Limited

was read but was not really sure what was meant
by 'Drive Voltage(V)'.

If the voltage to be supplied is 6.8-7 volts
it seeems that the configuratuion marked
'VL-H01WW30003180 Test Circuit 1', in the
original post. should have
worked. Unless the difference between 6.8
volts specified and 5 volts used in the test
(1.8/6.8 = 26%) is too great
to cause the LED to light. Or perhaps the
resistor value was too high?

Thanks.

Allen

 

[audioguru]

The LED must have a voltage of at least 6.8V for some of them to conduct some current and make some light.
But since they are not a Name Brand then I do not trust their specs.

 

[danadak]

Unfortunately the vendor does not tell you if thats wrost case V
to turn on the LED, and same for current, if thats operating max
and there is an eroror in their table versus operating charatceristics -
the pused current rartin doe not make sense for blue/green/white....


I would take it 800 mA is max, and that drive V is just the min V needed
to get the LEDs to turn on. So operate them as contact current, dont
drive them with a V source dfirectly, rather use a R to insure 800 mA
is not exceeded.

Better yet contact them ......


Regards, Dana.

 

[For The Popcorn]

Your best solution is a constant current power supply module rated for the wattage of the LED you're using with a voltage range encompassing the forward voltage of the LED.

 

[Jverive]

Luminous intensity of LEDs is very closely related to (forward bias) operating current, so for these devices it is common to specify a minimum intensity at a given current. Then, at this current, a range of typical forward voltage is given.

LEDs - particularly the high-power types - can be extremely difficult to drive reliably with constant voltage power supplies, and as a result almost all high-power LED drivers operate in constant-current mode.

Finally, it IS possible to do a quick go/no-go test with a battery or constant voltage power supply, but it's essential to characterize the internal resistance of the power source at the desired current. Very large voltage drops can occur inside these power sources, and can leave you scratching your head!

 

[AllenPitts]

Hello dandak, for the popcorn, Jverive and the ETO forum,

Because I am an architect who has stumbled into the world of lighting using LEDs, not an electrical engineer, my ignorance of the terminology makes it a little difficult to understand some of the replies,
It is written: 'The recognition of ignorance is often the beginning of knowledge.'

Specifically Jverive's excellent post:
'Luminous intensity of LEDs is very closely related to (forward bias) operating current, so for these devices it is common to specify a minimum intensity at a given current. Then, at this current, a range of typical forward voltage is given.'

It has been read that forward bias current refers to the flow of electric current through a semiconductor diode when a voltage is applied in a specific direction, known as forward bias.
Often the watts are specified on the data sheets.
G4-WWHP21-DAC specs
In the case of the G4-WWHP21-DAC G4 LED the device works with a 12 volt supply at 3 watts, so the LED draws 250 milliamps. This is the forward bias operating current, I think.

Another term that is a bit fuzzy is 'forward voltage'. It is surmised thru research that forward voltage is the voltage at which the diode starts to allow a substantial flow of current in the forward direction.
Perhaps this is the same as Drive Voltage (V) shown in the multi-colored table posted by Danadak in post #2 which is for VL-H01WW30005 which is 6.8-7.0 for the AVG Luminous flux.

Finally, another term used is 'constant voltage power supplies'. The power supplies being used for design and testing are
XP Power VEL24US120-US-JA

https://www.xppower.com/portals/0/pdfs/SF_VEL24.pdf

Would these be considered constant voltage power supplies?

Thanks.

Allen Pitts

 

[For The Popcorn]

Often the watts are specified on the data sheets.
G4-WWHP21-DAC specs
In the case of the G4-WWHP21-DAC G4 LED the device works with a 12 volt supply at 3 watts, so the LED draws 250 milliamps. This is the forward bias operating current, I think.

I think you have some basic understanding problems, mixing up essentially "LED bulbs" for replacement in standard fixtures and "raw" LEDs. In the first case, like shown in your quoted link, this bulb replacement contains the necessary circuitry to drive it directly from 12V AC or DC.

In the second case, like the Luxon star shown way back in your first post, it's a raw LED without any drive circuitry. The LED is mounted to the aluminum circuit board, and it's up to you to limit current to the proper range.

An aluminum circuit board may contain one or many LED elements and may be configured in various ways. This type of LED is where you need to know maximum current and Vf (forward voltage).

If an LED array is rated for 12v, 120VAC or 240VAC, it should include the necessary circuitry to power it directly from a fixed voltage source.

In every case, heatsinking is critical and must be provided. Excessive temperature is the enemy of LEDs. Also, operating LEDs below their rated current will extend their longevity.