LED wiz - which LED's?

[tony.silveira]

hey guys,

i have a 32 port LED wiz lying around and have an idea for my CP.  basically, i want to drive 32 standard red LED's (not RGB).  Red LED's on GGG's site say:

"Includes appropriate resistor for 5v connection"

if i read that correctly, that resistor is needed when driving the Wiz with a 5v connection from my power supply.  So here are a few questions i have if anyone can answer:

Will the LED's need this resistor if the Wiz is being powered only thru USB? 
Can the Wiz even drive 32 LED's solely with USB?

i'm looking at flush mounting the LED's with the top of my panel and am looking at these flat top LED's:

http://www.allelectronics.com/make-a-store/item/LED-167/4MM_Red_Flat-Top_LED/1.html

so, not sure if i have to have that resistor on these or not

any help is appreciated!

[BobA]

Whether it is USB 5V or your molex connector you will still need a resistor to run it so it does not burn up.

32 LEDs require approx 20 ma x 32 = 640 ma or .64 amp.  This is over the max draw for a USB outlet so you should wire with the molex providing external power.

If the LEDs do not mention 5 or 12 V then they are probably provided bare without the resistor.

[Mysterioii]

Yeah that's just a plain ol' LED, you'll need to provide current limiting resistors for each one.

[tony.silveira]

thanks guys!  if i did my math correctly per the LED wiz instructions, here is what i just bought:

LED, FLAT TOP, 3MM, RED; Bulb Size:T-1 (3mm); Forward Current If:20mA; Forward Voltage:2.25V

RESISTOR, METAL FILM, 140OHM, 400mW, 1%; Resistance:140ohm; Resistance Tolerance:± 1%; Power Rating:400mW; Voltage Rating:250V

[PL1]

Red LED's on GGG's site say:

"Includes appropriate resistor for 5v connection"

if i read that correctly, that resistor is needed when driving the Wiz with a 5v connection from my power supply. 
...

i'm looking at flush mounting the LED's with the top of my panel and am looking at these flat top LED's:

http://www.allelectronics.com/make-a-store/item/LED-167/4MM_Red_Flat-Top_LED/1.html

Tony,

Electronics is like plumbing: Voltage=water pressure, current=how much water flows through

Most LEDs are designed to work with up to 3.2 or 3.3V. If the voltage is too high, it will be like connecting a garden hose to a fire truck--It won't be long before it bursts. Use the resistor with ANY 5V connection.

As for the Flat LEDs: No manufacturer + no manufacturer P/N + no specs = avoid like the plague unless you get help from someone with a good background in electronics.

If your heart is set on those flat LEDs, I recommend using the LED calculator to design your circuit.  http://ledcalc.com/#calc

If you want to check/test the circuit before building it into your CP, you can use a solderless breadboard to test brightness, current flow, etc. Amazon has one for under 6 bucks.
http://www.amazon.com/Solderless-BreadBoard-tie-points-power-rails/dp/B005GYAIES/ref=sr_1_4?s=electronics&ie=UTF8&qid=1336530277&sr=1-4
You'll need some test leads and jumper wires to go with it.  I use the USB power tap cable from GGG to power my board, but you can tap into the power+ground from your computer power supply if you like.

Under the plastic exterior, the breadboard has connections like the attached picture of a solderable breadboard.

Scott

[PL1]

thanks guys!  if i did my math correctly per the LED wiz instructions, here is what i just bought:

LED, FLAT TOP, 3MM, RED; Bulb Size:T-1 (3mm); Forward Current If:20mA; Forward Voltage:2.25V

RESISTOR, METAL FILM, 140OHM, 400mW, 1%; Resistance:140ohm; Resistance Tolerance:± 1%; Power Rating:400mW; Voltage Rating:250V

Tony,

Next common size up for the resistors will be 150 ohm, get ones with a power rating of at least 1/8 watt--1/4 watt would be even better.  Each LED+resistor should draw 18.3 mA.

------------5V------------>
|       |      |       |      |
LED  LED  LED  LED  LED 
|       |      |       |      |
R1    R1    R1    R1    R1
|       |      |       |      |
-----------Ground-------->

Scott

[Mysterioii]

As for the Flat LEDs: No manufacturer + no manufacturer P/N + no specs = avoid like the plague unless you get help from someone with a good background in electronics.

If your heart is set on those flat LEDs, I recommend using the LED calculator to design your circuit.  http://ledcalc.com/#calc

Eh some specs would be nice but the 140 ohm resistors should be fine, some people go 150 to be on the safe side, but in a pinch you can even go to like 100 ohm and it'll probably work ok, just might shorten the lifespan a bit.  Never had one blow outright with anything in that ballpark.  

With regular old run of the mill LEDs like that you don't really need to sweat it all that much.  If you're designing a circuit for work then yeah you better know the manufacturer and P/N, but for personal/hobby stuff it's no big deal.  Definitely wouldn't say to avoid them like the plague.  I've gotten bags and bags of cheap LEDs off of ebay, most likely all from China, and while I fully admit that there's a huge amount of crap chinese electronics out there, I've never had a bad LED in the bunch with a reasonable current limiting resistor.  Don't know the manufacturers or P/Ns on any of 'em.  A better question would be, are you happy with the look of those LEDs?  You can get pretty much any color LED with a clear lens now, you don't need the LED to be molded in red plastic.  I like all of mine to be clear.  And I agree it's nice to see some specs, like brightness or viewing angle.  The better LED sellers on ebay actually give pretty thorough specs and show a picture of one lit up so you can confirm the viewing angle.  Of course, the specs could be made up, but I haven't been burned yet.  The superbrights were bright, the wide ange LEDs were wide angle, the narrow ones were narrow.  For my home use I've been very pleased.

[tony.silveira]

i do appreciate all of the input, parts are all ordered.  here are the full details on them

LED, FLAT TOP, 3MM, RED; Bulb Size:T-1 (3mm); LED Colour:Red; Luminous Intensity:1mcd; Viewing Angle:100°; Forward Current If:20mA; Forward Voltage:2.25V; LED Mounting:Through Hole; Lens Shape:Round; Wavelength Typ:700nm; Current If ;RoHS Compliant: Yes

LED HOLDER, 3MM / T-1 LED, BLK; Accessory Type:LED Holder; Holder Type:Holder; Holder Color:Black; No. of LEDs:1; External Length:4.8mm; External Diameter:5.9mm; For Use With:3mm / T-1 LEDs ;RoHS Compliant: Yes

wish me luck on getting them up and running!  i plan on mounting 8 around each joystick that i have on my panel.  then have the LED's light up per game.  i.e. 4 diagonals light up for q*bert (reminding me to spin my magstick plus to 4 way), horiz/vert light up for 4 way games, 8 lights around my two center sticks for twin stick games (robotron, etc)

[Nephasth]

i plan on mounting 8 around each joystick that i have on my panel.  then have the LED's light up per game.  i.e. 4 diagonals light up for q*bert (reminding me to spin my magstick plus to 4 way), horiz/vert light up for 4 way games, 8 lights around my two center sticks for twin stick games (robotron, etc)

Sweet!

[PL1]

As for the Flat LEDs: No manufacturer + no manufacturer P/N + no specs = avoid like the plague unless you get help from someone with a good background in electronics.

If your heart is set on those flat LEDs, I recommend using the LED calculator to design your circuit.  http://ledcalc.com/#calc

Eh some specs would be nice but the 140 ohm resistors should be fine, some people go 150 to be on the safe side, but in a pinch you can even go to like 100 ohm and it'll probably work ok, just might shorten the lifespan a bit.  Never had one blow outright with anything in that ballpark.  

With regular old run of the mill LEDs like that you don't really need to sweat it all that much.  If you're designing a circuit for work then yeah you better know the manufacturer and P/N, but for personal/hobby stuff it's no big deal.  Definitely wouldn't say to avoid them like the plague.  I've gotten bags and bags of cheap LEDs off of ebay, most likely all from China, and while I fully admit that there's a huge amount of crap chinese electronics out there, I've never had a bad LED in the bunch with a reasonable current limiting resistor.  Don't know the manufacturers or P/Ns on any of 'em.  A better question would be, are you happy with the look of those LEDs?  You can get pretty much any color LED with a clear lens now, you don't need the LED to be molded in red plastic.  I like all of mine to be clear.  And I agree it's nice to see some specs, like brightness or viewing angle.  The better LED sellers on ebay actually give pretty thorough specs and show a picture of one lit up so you can confirm the viewing angle.  Of course, the specs could be made up, but I haven't been burned yet.  The superbrights were bright, the wide ange LEDs were wide angle, the narrow ones were narrow.  For my home use I've been very pleased.

I agree that the builder being happy with the look of the LEDs is the important question.

The only reason I said to avoid those "unless you get help" was because he seemed to have limited electronics experience and was talking about modding his panel. I'd hate for someone to design a circuit that burns out LEDs regularly when knowing the specs and a little design tweak could leave it good for much longer.  Less fixing=more playing=good in my book.

I only mentioned the 150 ohm resistors because they are the next common size up and therefore probably easier to find and/or cheaper.

Scott

[matsadona]

32 LEDs require approx 20 ma x 32 = 640 ma or .64 amp.  This is over the max draw for a USB outlet so you should wire with the molex providing external power.

Just adding that the USB specifications set the maximum current to 500mA.

Nice idea to have LED's showing the joystick directions by the way.

[Mysterioii]

Just for future reference, these are a couple of ebay sellers I've bought LEDs from in the past and have been very satisfied...

http://stores.ebay.com/bestshop2008hk?_rdc=1

http://stores.ebay.com/Shop4leds?_rdc=1