How to power NSPW500BS ?

Slick

Flashlight Enthusiast
Joined
Apr 24, 2002
Messages
1,264
Location
Nor Cal
What's a "NSPW500BS"??? This sounds like a Lumiled's part number.
 

sunspot

Flashlight Enthusiast
Joined
Aug 22, 2001
Messages
2,707
Location
Graham, NC
Well crap. nobody has given any answer yet to the main question. Here is my quick and dirty method. Hook up a LED to 4.5v with a ampmeter and get a reading.Start adding resistors untill the amps drop tp 20-30ma. Thats all I do. I hope the experts chime in here and give you a more exact method.
 

McGizmo

Flashaholic
Joined
May 1, 2002
Messages
17,290
Location
Maui
Saaby, the BS refers to the type of leads; in this case they have the PCB stops on them. The color and intensity rank is indicated with letters and numbers beyond this part number. The LED's probably have a voltage requirement between 3.3 and 3.8 to achieve a current draw of 20 mA. With a voltage drop in this range across the LED, I believe you will be driving the LED in spec. Any voltage above 4 volts should have a resistor in series with the LED to protect it or some other method of current control, IMHO.

EDIT: I just reduced the Vin figures from a quick bench test.......

- Don
 

Saaby

Flashaholic
Joined
Jun 17, 2002
Messages
7,447
Location
Utah
rolleyes.gif
Well I was close anyway
grin.gif
 

Minjin

Flashlight Enthusiast
Joined
Sep 21, 2002
Messages
1,237
Location
Central PA
I just found out that I work about 20 mins away from Nichia's headquarters! I'll definitely have to stop down there. Maybe they'll have dumpsters full of LEDs that are factory seconds...
wink.gif


Mark
 

EMPOWERTORCH

Enlightened
Joined
May 1, 2002
Messages
743
Location
Coalville, Leicestershire, England
back to the original subject...I "calibrate" my LEd's in Btgx's to achieve maximum output without overdriving the LED's. I look up the current rating, set my constant current source to give me the rated current then measure the actual voltage drop. The actual voltage drop can vary from LED to LED even of the same colour, manufacturer and type. With brand new batteries, EMPOWERTORCH BTx run slightly over the current rating without seriously heating the LED. For a 30mA LED I might be running 32 mA on brand new batteries. On AAA's this soon drops to below the rating due to voltage drop across the cells' combined resistance.
 

CM

Flashlight Enthusiast
Joined
Sep 11, 2002
Messages
3,454
Location
Mesa, AZ
Originally posted by iam_dznutz:
I am really wanting to know about this ZETEX chip I have seen this chip mentioned on this site and at http://www.5thcolumn.org/zetex/project/ . I however want to drive a nichia led and not a luxeon star led.
<font size="2" face="Verdana, Arial">The zetex is a constant current DC-DC step-up converter. You can buy these from digi-key. You also need a suitable switching transistor, also a zetex, and an inductor. Most people also use the rectifier and capacitor in their circuits, I leave these out, it's up to you. You set the bias current using a resistor. I like the driver since it is straightforward and doesn't require a ton of parts. It's also easy to layout the circuitry.
 

iam_dznutz

Newly Enlightened
Joined
Sep 28, 2002
Messages
11
Location
Salt Lake City Utah
I finally recieved my 10 nspw500bs leds in the mail today. I immediatly noticed they take more power to drive them than any others I have used.
These are the first white ones I have ever had.

Please explain to a novice how I should go about powering these leds without blowing them up.
 

Hemingray

Enlightened
Joined
Jul 2, 2002
Messages
380
Location
New Hampshire
For 4.5 Volts (3 AA alkies in series), use a 33 to 47 ohm 1/4 watt resistor, or for 4.8 to 5V (4 AA NiMH in series) use 68 to 75 ohms 1/4 watt in series with each LED. They can be direct driven from 4.5V, and will be brighter than normal, but this can shorten LED lifetime. A lot of the cheaper LED flashlites do just this. Resistors are the cheapest and simpleist, but not the most efficient way. For running off 1 or 2 AA cells, there are various step up circuits, the simplest of them being the "SATCUR" circuit discussed elsewhere on the forum. One NPN transistor, a resistor and a small toroid with two 20 turn windings. Then there is the "Brinkmann" 2 transistor circuit, also discussed elsewhere on CPF.

/ed brown in NH
 
Top