How to decide the size of the capacitor?
Ok, other than trial and error, I wonder if anyone has a suggestion on what size (rating) capacitor should draw from this? I have a cheap camera that uses SDRAM and I put in a capacitor can store in memory long enough so that the batteries can be changed. My measurements say that the camera is about 10-15mA @ 3V when it is not … and 100 mA at 3V when in if you are worried that … I also think you should get a non-polarized (as for audio) so it will not explode if the batteries are put in wrong (I do not want to change the camera insert a diode) The power supply is 2 AAA batteries
assuming that the current will not change significantly when the battery voltage is from 3V to 2.4V can be assumed that the resistance is around 3v/15ma OFF = 200ohms. If the battery replacement time is then T would capacitor size C = T / (200 * ln (3/2.4)) = T/28.6 for example, if you are fast enough to replace the battery in 10 seconds after millifarad capacitor 350, which is a big elco, but their maximum voltage is 3V should not be too hard to find 1F capacitor, which could operate
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