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Solid States Devices => solid state devices => Topic started by: magnetman12003 on July 10, 2015, 01:20:06 PM

Title: Capacitor charge questions
Post by: magnetman12003 on July 10, 2015, 01:20:06 PM
I have a 20 farad audio capacitor.  It's capable of 20 volts as a charge.
My questions are as follows.  I have a power source that delivers 13 volts with a tiny .0000181 amps.
If I direct that power source into the cap is it the voltage or current that charges the cap?

Title: Re: Capacitor charge questions
Post by: Void on July 10, 2015, 01:41:04 PM
Quote from: magnetman12003 on July 10, 2015, 01:20:06 PM
I have a 20 farad audio capacitor.  It's capable of 20 volts as a charge.
My questions are as follows.  I have a power source that delivers 13 volts with a tiny .0000181 amps.
If I direct that power source into the cap is it the voltage or current that charges the cap?

Hi magnetman12003. It is the current (flow of charges) that charges the cap. The voltage on the power source acts as the
electromotive force that 'pushes' the charges and causes the current flow into the load that is connected.
All the best...
Title: Re: Capacitor charge questions
Post by: MarkE on July 10, 2015, 02:20:11 PM
Quote from: magnetman12003 on July 10, 2015, 01:20:06 PM
I have a 20 farad audio capacitor.  It's capable of 20 volts as a charge.
My questions are as follows.  I have a power source that delivers 13 volts with a tiny .0000181 amps.
If I direct that power source into the cap is it the voltage or current that charges the cap?
20 farads does not sound like an audio capacitor.  Are you sure it is not 20uF?
All real capacitors look like low impedances to any step voltage:  IE closing a switch to a pwoer supply.  If your power source is limited to 18.1uA, then the voltage will collapse and the capacitor will charge at 18.1uA/C.  If it were a 20F capacitor, the leakage would probably exceed the charging current and nothing would happen.  If not, it is going to charge at 3.5mV per hour.   A 20uF capacitor would charge at about 1V/s.
Title: Re: Capacitor charge questions
Post by: Temporal Visitor on July 12, 2015, 06:49:25 AM
Quote from: MarkE on July 10, 2015, 02:20:11 PM
20 farads does not sound like an audio capacitor.  Are you sure it is not 20uF?
All real capacitors look like low impedances to any step voltage:  IE closing a switch to a pwoer supply.  If your power source is limited to 18.1uA, then the voltage will collapse and the capacitor will charge at 18.1uA/C.  If it were a 20F capacitor, the leakage would probably exceed the charging current and nothing would happen.  If not, it is going to charge at 3.5mV per hour.   A 20uF capacitor would charge at about 1V/s.

Hi Mark,
You really need to get out more. Time to play in the Forest you wrote didn't exist will do you good.

He wrote 20F and that is what it IS. Many of the younger people use huge caps on their car stereo systems - not in them: ON THEM, on the power input.
Some even have cool looking LED's, it is a marvelous world outside of the computers, "in reality".

You might like to see the WORK 66F at 120v can do do in my work in the Forest I play in "off screen" known as REALITY.

Remember what I am "playing with": "Mass Particle Accelerators" which; BTW two are used WORKING in "Stereophonic" or four for "Quadraphonic" ENERGY DEVELOPMENT. For the most part I am already moving past caps, they are just too expensive for the average home ower/tax slave stuck in "this reality".

Michael Frost

http://www.backgauges.com/Gen-E-Sys%20II/

Title: Re: Capacitor charge questions
Post by: TinselKoala on July 12, 2015, 01:30:19 PM
66 Farads charged to 120 volts is E=(CV2)/2 = 475200 Joules, which is a fair amount of work. What do you do with this work, TV?

And you, TV, might like to calculate how long it would take to charge 20F, or 66F, of capacitance from 0 to 13 volts with a peak charging current of 0.0000181 amps.
Title: Re: Capacitor charge questions
Post by: MarkE on July 12, 2015, 05:43:43 PM
Quote from: Temporal Visitor on July 12, 2015, 06:49:25 AM
Hi Mark,
You really need to get out more. Time to play in the Forest you wrote didn't exist will do you good.

He wrote 20F and that is what it IS. Many of the younger people use huge caps on their car stereo systems - not in them: ON THEM, on the power input.
Some even have cool looking LED's, it is a marvelous world outside of the computers, "in reality".
An "audio capacitor" refers to a series coupling capacitor applied at audio frequencies.  A capacitor applied across a power supply of an audio amplifier is not an "audio capacitor".  So, maybe you should get out there and learn something.
Quote

You might like to see the WORK 66F at 120v can do do in my work in the Forest I play in "off screen" known as REALITY.
I am quite aware of how much energy can be stored in a capacitor, linear or otherwise.  If you had done the trivial calculations you would see that the 18.1uA quoted would only charge an ideal zero leakage current 20F capacitor by 3.5mV every hour (actually 3.3mV).  Any leakage current from a real capacitor would reduce that charging rate.  That means in the ideal case it would take over 166 days to recharge the capacitor.
Quote

Remember what I am "playing with": "Mass Particle Accelerators" which; BTW two are used WORKING in "Stereophonic" or four for "Quadraphonic" ENERGY DEVELOPMENT. For the most part I am already moving past caps, they are just too expensive for the average home ower/tax slave stuck in "this reality".

Michael Frost

http://www.backgauges.com/Gen-E-Sys%20II/