Electronics > Beginners
Capacitors don't work like I thought, please help me understand.
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Wimberleytech:

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But now I can't get the gate to open at all. :(

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What do you mean?
Try this:  http://tinyurl.com/y5w5ybl6
james_s:

--- Quote from: gilligan on April 14, 2019, 08:49:17 pm ---I'm only working with DC, so I assume that it will just not let current pass.  No?

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It's a little more complex than that, any time you have a changing voltage you have something like AC. In a steady state, a capacitor will charge up to whatever potential is across it and then it will block the flow of DC once it reaches equilibrium, but then what? In order to do something useful you have to have a way to charge and discharge the capacitor. What are you trying to accomplish? What do you want the mosfet to do?
FriedMule:

--- Quote from: gilligan on April 14, 2019, 08:50:01 pm ---
--- Quote from: alsetalokin4017 on April 14, 2019, 08:30:05 pm ---If you want the mosfet to turn off you have to provide a path from Gate to ground somehow, usually through a pull down resistor.

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But now I can't get the gate to open at all. :(

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An easy way to understand why your circuit is not working, is thinking of power as super lazy. If you follow your path from the battery and to ground / negative, you'll see that the power can run trough your switch via the lower 10K and trough to ground, totally avoiding the obstacle your mosfet and upper 10K is making.

EDIT: Also, if you look at your circuit. You have positive on booth sides of your cap, so nothing is going on there. You only get a flow if you go from positive to negative.
Am I right in guessing that you are trying to make a delay, so when you switch off, the mosfet stays on for a short while longer?
FriedMule:

--- Quote from: james_s on April 14, 2019, 09:13:02 pm ---
--- Quote from: gilligan on April 14, 2019, 08:49:17 pm ---I'm only working with DC, so I assume that it will just not let current pass.  No?

--- End quote ---

It's a little more complex than that, any time you have a changing voltage you have something like AC. In a steady state, a capacitor will charge up to whatever potential is across it and then it will block the flow of DC once it reaches equilibrium, but then what? In order to do something useful you have to have a way to charge and discharge the capacitor. What are you trying to accomplish? What do you want the mosfet to do?

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You are perfectly right but I thought that a simply but not totally correct explanation was better, for later to learn more about what is in reallity is going on. Like the flow of electrons, resistance, conductance, heat and much more do in his circuit. :-)
gilligan:

--- Quote from: Wimberleytech on April 14, 2019, 09:08:06 pm ---
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But now I can't get the gate to open at all. :(

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What do you mean?
Try this:  http://tinyurl.com/y5w5ybl6

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Ah, I blew my capacitor and didn't notice... you'd think I'd learn as i've done that a hundred times now. ;)
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