We all know pulling the plug on a running PC is bad, bc the operating system could be in a critical process and interrupting it would corrupt the system.
But using a capacitor that holds electric charge couldnt we give the PC a couple of „grace seconds“ where the pc finishes its job and then starts the shutdown process?
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You end up needing a really big capacitor
There are already what I’d consider big capacitors in the power supply but they can only give you a fraction of a second to make it through a very brief power disruption
If you want to cover a system that’s running at a mere 35 watts for 5 seconds then you need a capacitor that holds 175 joules. At 500V that would be a 1700 uF capacitor. They make them but they’re about 2 inches in diameter and 4 inches long
If you’re really prone to abrupt power outages then get a UPS, that’s what their meant for and the lead acid battery in there will give significantly longer run time
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A capacitor has a few downsides. “A few seconds” of grace time may not be enough if a system is in the middle of an update that takes minutes. If you want to increase the amount of time, you’ll need a bigger capacitor which can be dangerous given the size and amount of power stored.
Instead of a capacitor, you should use a battery. Much like how a laptop can run on battery when the power cord is pulled, there are devices called uninterruptible power supplies (UPS) that have a large battery for backup power if there is an outage. This gives you a few minutes to save your work and gracefully shut down your system rather than everything shutting off instantly.
This is literally what a PC controlled UPS system does. So, yes, we absolutely can. But, as others have pointed out: those things are big. They are also heavy and sort of expensive. And they only provide between 5 and 25 minutes of power, so…hopefully your PC can properly shut down in that amount of time (usually not an issue, but Murphy rules all)
Aight, electrical engineer literally working on this exact task right now! Yes, you can do this with a capacitor. You will need a supercap or ultracap and a supercap management IC, and make yourself a small board. I recommend getting Eagle CAD or another cheap PCB software and making a real PCB.
Be careful. Supercaps have a lot of energy in there. Treat them like batteries.
Or you could use an uninterruptible power supply, but that’s expensive. Money vs time, though. Pick which one you’re more rich in.
Capacitors are nowhere near batteries when we’re talking about how much energy they can store. They’re used for really really brief dips in power, but not really for something that needs to run for a while.
There is an exception to this, and that’s ultracapacitors. Some devices like dashcams use them so if the power gets disconnected or the battery dies, it has time to shut itself down. That said, it’s still nowhere near the capacity of a battery. It’s a lot more than a normal capacitor though.
What you’re talking about already exists. They’re called UPS’s. It stands for uninterruptible power supply. they usually have capacitors in them too, and they’re used for two things. first, they help fill in the gaps for when the voltage coming out of your wall dips lower than it should, but more improtantly, if power goes out, it gives your relay time to switch to the battery. relays are fast, but the capacitors have enough charge to handle the brief time for it to switch
You could… but a UPS can already do that.
Plus… you know, you could just not pull the plug like a dummy. Instead, you press the “shut down” button in your OS and let the computer handle proper shutdown protocols, which includes the computer giving alert to any running processes and letting them find a quick but proper end and closing out before going through the shut down process overall.
Once the computer is fully shut down, you can pull the plug and move your PC as needed, or whatever you want to do.
And for extra safety, a UPS can surge protect and also has battery protection in case of a power outage so you can quickly shut down in the few minutes those UPS batteries allow you to run.
OP that’s not what capacitors are for. Capacitors store electricity for quick discharge not slow.
This is a batteries job I.E a UPS which most people should have for their PCs anyways
A 1 Farad supercap can provide 1amp for 1second at 1volt. It will exponentially decay to zero in that time. Don’t believe the above b.s. on keeping any pc alive. It’s suitable only for low powered and short intervals.
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