From: "Frank Bemelman"
Subject: Re: battery operated PIC board.
Date: Thu, 2 Jan 2003 12:28:58 +0100
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NNTP-Posting-Date: 02 Jan 2003 11:29:39 GMT
"Jonathan Kirwan" schreef in bericht
> On Mon, 30 Dec 2002 15:56:16 -0000, "joe"
> >I need some help running a simple circuit board with a PIC controller
> >(16f628) , 3 x 74hc393's and 24 led's. The 393's drive the leds and all
> >works well, however the battery life is very short due to high current
> >consumption. Only 2 leds will be on at any time therefore total current
> >consumed at the moment is 40mA. The PIC is already operating in low power
> >mode. Are there any leds available that can be used below the mA range ?
> What batteries are you using? What kind of battery lifetime do
> you need to achieve? There are high efficiency LEDs which look
> fine to me at 2mA or so, are are claimed to provide "usable"
> levels of light at 500uA, though I think 1mA is more like it --
> but it depends on what you need, I suppose. Another factor to
> consider, which may help, is the required viewing angle for the
> LEDs. You can improve the apparent brightness by narrowing the
> emitted cone angle, but by sacrificing brightness outside that
That's right. I once choosed *clear* high efficiency leds, these
look brighter compared to diffuse ones, as the 'spot' is smaller.
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