CL1B power distribution

david at david at
Fri May 1 14:22:45 EDT 2009

On Fri, 1 May 2009, Benjamin M. Schwartz wrote:

> John Watlington wrote:
>>> the LED trick has the advantage of not requiring a change to the case,
>>> just a single additional drive pin to be able to run it as a detector.
>> And where would you place said detector LED, without modifying the
>> case ?
> While we're bikeshedding this to death, I'll put in my vote for reusing
> the camera activity LED.  It's well isolated from other light sources, and
> it's rarely on. Whenever the camera is off, it can be used a
> photodetector.  To retain the security guarantee that the light is on when
> the camera is on, it might be necessary to put a diode across the camera's
> power supply, so that they can be reverse-biased together.

my understanding is that currently the camera and mic LEDs are hard-wired 
to those devices, not controlled independantly (to make sure that it's not 
possible to activate those devices without activating the LED)

the power LED is well seperated from everything else, has a fairly large 
opening in the case to let light in, so it would seem to be a good option.

at least one article indicated that this could be done with an LED that 
was otherwise on without the user noticing (comments were made that in the 
dark the delay could become noticable, but that could be solved by setting 
a max count to wait for)

David Lang

> If only we could get another hole in the case.

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