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LED wiz - which LED's?

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PL1:

--- Quote from: tony.silveira on May 08, 2012, 10:42:24 pm ---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

--- End quote ---

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:

--- Quote from: PL1 on May 08, 2012, 10:48:57 pm ---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

--- End quote ---

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:

--- Quote from: tony.silveira on May 08, 2012, 11:37:28 pm ---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)

--- End quote ---

Sweet! ;D

PL1:

--- Quote from: Mysterioii on May 08, 2012, 11:17:00 pm ---
--- Quote from: PL1 on May 08, 2012, 10:48:57 pm ---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

--- End quote ---

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.

--- End quote ---

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

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