RE: LEDs

[steve.cooper@xxxxxxxxxxxxx]

The comfort board is supplying 12v on it's outputs which means there is a
fair amount of voltage to drop across the resistor to get to the supply
down to the approx. 3-4v the led needs, which is why the values are so
high.  So either go with high values of resistor or try putting a standard
diode or two in serial with the led to help drop the voltage down a bit.

S.



"Paul Gale"
<groups@silicon        To:     <ukha_d@xxxxxxx>
pixel.com>             cc:
Subject:     RE: [ukha_d] LEDs
11/05/2004
09:01
Please respond
to ukha_d





Ta Frank.

There seems to be little difference between 4K7 and 10K - even 33K is still
very bright - might even try something higher.

Paul.



> -----Original Message-----
> From: Frank Mc Alinden [mailto:fmcalind@xxxxxxx]
> Sent: 11 May 2004 08:35
> To: ukha_d@xxxxxxx
> Subject: Re: [ukha_d] LEDs
>
> Hi Paul
>             Do you need to go up to 33k...??? I would have thought
> 4k7...to
> ...10k would be suffice...
>
> >Are there any disadvantages to using such a large resistor value?
>
> Just not as bright........On my Probe Zone Monitor i use 1k on the bi
> coloured leds @ 5v and they seem bright enough.....
>
> Frank
>
>
> ----- Original Message -----
> From: "Paul Gale" <groups@xxxxxxx>
> To: <ukha_d@xxxxxxx>
> Sent: Tuesday, May 11, 2004 5:30 PM
> Subject: [ukha_d] LEDs
>
>
> I've just fitted a couple of waterproof LEDs to an external alarm
keypad
I
> bought the other day. The LEDs are 12V, red and green. They're not
> intensity
> matched though unfortunately so the green LED is significantly
brighter
> than
> the red. I'm going to drive them both from a Comfort output.
>
> I was thinking of using a high value resistor on the green LED (33K as
> opposed to 1K for the red seems about right). Are there any
disadvantages
> to
> using such a large resistor value?
>
> Paul.
>
>
>
>
>
>
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