[sdiy] LED Drops

[GRAHAM ATKINS]

The "DIE" BACK IN DIODE Ref is to the LED museum. See back down
the thread. Quite an interesting site.

Graham
On Dec 9, 2007, at 22:21, Roy J. Tellason wrote:

> On Sunday 09 December 2007 16:02, mike ruberto wrote:
>> Ok this is cool, the catalog has alot of good info.
>>
>> LOL "WE PUT THE "DIE" BACK IN DIODE" That website is a trip!
>
> I didn't run across that bit,  but the online rendition of the  
> printed catalog
> is really quite impressive!  Or was,  until my browser crashed for  
> some
> reason.
>
>> I want to build this circuit...
>> http://www.jlmaudio.com/JLM%20Hybrid%20Opamp%20circuit.pdf
>>
>> but all I have is a green LED.
>
> Oh my.  In that particular case I really wouldn't substitute...
>
>> It seems the green have a higher voltage drop than the red.
>
> Yes,  somewhat.
>
>> So it looks like I'll have to play around with resistors or a combo  
>> of
>> regular diodes.
>
> I acquired a whole bunch of (mostly red) LEDs by buying a couple of  
> assortment
> packs.  Years ago now, and I haven't come anywhere near using them  
> all up.  I
> also take LEDs out of stuff being scrapped,  and snagged a bunch  
> from a guy
> who was disposing of a lot of old computer cases,  which is handy in  
> that
> they have the leads with connectors attached.  Surely you can pick  
> some up
> somewhere...?  I don't suppose it would be that big of a deal to  
> drop one or
> two into an envelope?
>
> Most similar circuits I've seen had _three_ diodes in there,  not  
> two.  Two of
> them just compensate for the base-emitter drop of the transistors,   
> and that
> leaves the drop across the emitter resistors to overcome -- if you  
> don't have
> a bit more bias than two diodes would give you,  you'll end up with  
> somewhat
> more crossover distortion than what you probably want.
>
> -- 
> Member of the toughest, meanest, deadliest, most unrelenting -- and
> ablest -- form of life in this section of space,  a critter that can
> be killed but can't be tamed.  --Robert A. Heinlein, "The Puppet  
> Masters"
> -
> Information is more dangerous than cannon to a society ruled by  
> lies. --James
> M Dakin
>
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