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1. MaxikC+(OP)[view] [source] 2024-11-27 21:16:48
A capacitor can hold enough charge to power led for noticable amount of time even if powered for a brief moment, no logic needed
replies(3): >>RA2lov+53 >>square+Rd >>HeyLau+uB
2. RA2lov+53[view] [source] 2024-11-27 21:39:12
>>MaxikC+(OP)
The trick is to keep using the camera until that capacitor is discharged. I'm pretty sure most cameras can run at voltages below a LED's forward voltage nowadays.
3. square+Rd[view] [source] 2024-11-27 23:10:02
>>MaxikC+(OP)
I don't think they would waste a high value capacitor just to keep a led lit for longer, also a led directly lit by a capacitor would be noticeable by slowly dimming when the capacitor discharges. It's more likely that the signal driving the led comes out of a monostable implemented in code: pin_on() drives the led on; pin_off() waits n secs then drives the led off.
replies(1): >>altair+vu
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4. altair+vu[view] [source] [discussion] 2024-11-28 02:12:21
>>square+Rd
This is Apple, so that assertion isn’t guaranteed valid like it would be for non-enterprise HP or Lenovo. They absolutely would invest in a capacitor if that’s what it takes, as they are maximally focused on camera privacy concerns and have made a point of that in their security marketing over time; or else they wouldn’t be allowing hardware security engineers to brag about it, much less talk publicly about it, at all.

EDIT: It’s not just a capacitor, it’s a full custom chip, that can’t be software-modified, that keeps the light on for 3 seconds. >>42260379

5. HeyLau+uB[view] [source] 2024-11-28 03:34:06
>>MaxikC+(OP)
Logic on an already existing ASIC is going to be cheaper than a capacitor.
replies(1): >>MrDrMc+RS
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6. MrDrMc+RS[view] [source] [discussion] 2024-11-28 07:28:12
>>HeyLau+uB
This is counter-intuitive enough to warrant further explanation.
replies(1): >>ale42+qa1
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7. ale42+qa1[view] [source] [discussion] 2024-11-28 11:04:07
>>MrDrMc+RS
If you are designing an ASIC for the camera, you can include all the required logic gates to control the LED for a cost that is close to zero. It wouldn't impact the production cost of the ASIC, whereas a capacitor is an additional item in the BOM (and to be charged it requires current, more than the LED, so the driver in the IC must be bigger).
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