[Elecraft] Leds for W1

[Doug Joyce]

Dave / Ken:

Further to the attached:

Gary provided the info on the Red LED as "the Digi-key part# is 516-1281-ND &  the Mfg is Avago Tech part # HLMP-S100."  

This part is listed in the Digi-Key T091 (Jan - Apr 2009) catalogue, page 2615.  The same section also lists two green LEDs, the brighter is Digi-Key part # 516-1285-ND (Avago part # HLMP-S501).  Interestingly enough the T081 catalogue (page 2455) also listed a "yellow" from the same series as Digi-Key part # 516-1284-ND (Avago part # HLMP-S301), but when I tried to get a quote, the minimum order qty was over 5000 units.  Orange is also made by Avago as part # HLMP-S401 (same Digi-Key part No.) with a minimum order qty of 3,000 units.  So green seems to be the only other LED from the same Avago family available in reasonable quantities.  (The Mouser part numbers for the Avago Tech LEDs are  630-HLMP-Sxxx etc)

For the "red" LED Luminous intensity is given as 7.5 mcd @ 20 ma with a fwd voltage drop of 1.8 volts; however for the "green"  (S501) the specs are 8 mcd @ 20 ma with a fwd voltage drop of 2.2 volts.  I suspect that this 0.4 volt difference may be the cause of the difference in intensity when installed in the W1. 

As for yellow and orange / amber LEDs from an alternate supplier, the same T091 catalogue, page 2557 shows LEDs from Lumex.
"Yellow" is Digi-Key part # 67-1050-ND (Lumex part # SSL-LX2573-YD).  Fwd voltage drop of 2.1V & luminosity of 10 mcd; and
"Amber" is Digi-Key part # 67-1045-ND (Lumex part #  SSL-LX-2573-AD).  Fwd voltage drop of 2.0 & luminosity of 5 mcd
(The Mouser part numbers for the Lumex LEDs are  696-SSL-LX2573xxx etc).

I ordered a qty of 
526-1285-ND (HLMP-S501) , green from Avago and
67-1050-ND (SSL-LX2573-YD), yellow from Lumex and
67-1045-ND (SSL-LX2573-AD), amber from Lumex

Connected to a 12V supply with a resistor to limit the current to 20 ma, the intensity seems to be similar in all LEDs (including the original red one).   When installed in the W1 however, it's a different story.  (See my comment in the email below.)  All of the other colours are significantly less bright than the original "red" ones.

Perhaps someone who has worked with the PIC microcontroller might be able to suggest a solution.

73

Doug,  VE3MV 
   
  ----- Original Message ----- 
  From: Doug Joyce 
  To: Dave Van Wallaghen 
  Sent: Friday, February 20, 2009 9:11 AM
  Subject: Leds for W1


  Dave:  I'm not sure the email I cc'd you on earlier got sent, so here is a resend.

  Ken / Dave:  Just to let you know, I did this with equivalent / the same parts (I'll provide the part numbers I used later this AM) and at 20 ma fwd current they do indeed seem to all have equivalent brightness.  The problem I found is that when installed in the W1, they don't light up with the same intensity as the red ones supplied.  I used other colours of green, yellow and amber / orange.

  I haven't spent a lot of time to investigate, but what I found so far is that the fwd voltage drop on the red LEDs is smaller than on the other colours, and in the W1 cct it is a smaller percentage of the supply voltage of 5 volts.  This results in more fwd current that available for the red compared to the other colours, hence the red appears to be brighter.  The next step I need to do is to actually measure the current provided by the W1 for these other colours.

  I got 10 of each when I  ordered then from DigiKey - Dave, if you provide your mailing address, I'll send you a couple of each and you can try then in the W1 as well.

  73 

  Doug,  VE3MV

    


    ----- Original Message ----- 
    From: Ken Kopp 
    To: w8fgu at comcast.net ; Doug Joyce ; elecraft at mailman.qth.net 
    Sent: Thursday, February 19, 2009 10:52 PM
    Subject: Re: [Elecraft] W1 LED Part Numbers


    I have a "set" of additional green and yellow LED's
    from Scott at Aptos.  He got them for me from the
    stock bins and didn't include their stock numbers.

    I'll light them with a PS and see if their all the same
    brightness and take a photo.

    They -should- be the same product line and therefore
    light equally, I'd think.  They're from the KAT-100
    tuner.

    Scott was at least receptive to making all the W1
    kits with three colors of LED's.

    73! Ken

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