this might be fast enough and supply the current you want.  50 cents  
in 1000s.
http://www.clare.com/home/pdfs.nsf/www/CPC1822.pdf/$file/CPC1822.pdf
Cedric
> On Jul 5, 2007, at 7:16 AM, Mike Harrison wrote:
>
> On Fri, 06 Jul 2007 00:32:30 +1200, you wrote:
>
>>
>>> Any ideas?
>>
>> Run away ?
>>
>> I've tried to do something similar for a project and gave up. Went
>> with a non-light mechanical option, but I could do that
>>
>> The problem, as you probably gather, is that the sensor needs to
>> be on all the time. And not only that, be discriminating.
>
> There is a lot of scope to be clever in reducing power, but it does  
> depend entirely on the
> characteristics of the signal - i.e. how long is it going to be  
> there for, and what is the
> worst-case response time.
>
> If the signal is long enough you can save a lot of power by only  
> looking for it periodically, but
> issues like startup settling time of the detector need to be kept  
> well under control.
> Another approach is to split the discrimination task - wake up when  
> you see something 'plausible'
> then stay awake a little longer while you validate it.
>
> I recently used a vishay IR remote sensor in an app that had to run  
> on about 10uA - fortunately I
> could arrange that the transmitted signal lasted for about half a  
> second, and this allowed a
> sufficienlty low duty cycle on the receiver to get the current low  
> enough.
>
>
this might be fast enough and supply the current you want.  50 cents  
in 1000s.
http://www.clare.com/home/pdfs.nsf/www/CPC1822.pdf/$file/CPC1822.pdf
Cedric

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