# Capasitor bank

Discussion in 'Electronic Design' started by mark2006, Nov 6, 2006.

1. ### mark2006Guest

Hi.

This is the situation:
Constant DC source ( 1V ~ 1mA ).

Hardware:
400V ~ 20microF capasitor
I wait until capasitor is full, then i disconnect dc source.

Goal:
To power 12V DC motor for "unlimited" time.

Options:
To leave DC source connected to first capasitor

Questions:
1.) If i connect few capasitors together and if one capasitor will
recharge other then it is possible to make constant power output for DC
motor needs ?

2.) I was thinking to convert this 400V to 12 VDC on such way that i
slowly discharge capasitor so i can give neccessery power to the DC
motor. How to make this ?

3.) This project involves just capasitors and dc motor. How to
calculate power that is neccessery for dc motor to work ?

4.) How to convert this dc output to ac current ( transformers etc. )

2. ### John PopelishGuest

If this is the power source for the whole system, you have 1
milliwatt (volts times amperes) of power that can be
transformed into various combinations of voltage and
current, as long as you don't expect to have a volt ampere
product coming out to be higher than the 1 milliwatt going in.
I assume that by "full", it it has charges up to
approximately 1 volt and has stopped drawing any current
close to 1 milliamp.
You can do his only is the motor power is below 1 milliwatt.
That requires that the motor current be below 1/12th
milliamp. I am sure you have no such motor.
Your capacitor will not charge to 400 volts, but only to 1 volt.
Measure the motor current while it is connected to a 12 volt
source. Multiply that current (in amperes) times the 12
volts and you find out how many watts the motor requires at
that voltage. Whatever source you produce, it will have to
provide at least that much power to drive the motor with 12
volts.

3. ### MacgyverGuest

<snip>!

co-workers looking at me strangely>. This is not going to work at all.
You cannot charge up a 400V capacitor from a 1V source (failure of
understanding of capacitor theory).
You cannot use it to power a motor to charge up the capacitor to power
the motor indefinetly (faliure in understanding basics of efficiency,
and numerous other basic principles).

Lets start from the beginning. You really need (read as MUST) read up
on the basics of capacitor and electrical theory before you continue
any further. Don't even try and learn about stepping up the voltage
until you have done this. In fact dont try and think about doing
ANYTHING before you do this. I have also read your other posts and am
a little disturbed by your lack of basic knowledge and the complex and
potentially LETHAL areas you are asking questiions in.

Please go back and read up on basic electrical theory before you
continue.

4. ### mark2006Guest

@Macgyver
))). I know why i have asked this question. As you know, basic
questions lead to better understanding and to new ideas. But, one thing
is correct... you can not look at this at some general accepted level
and basic principles becuse this has nothing to do with basics.

Thank you guys for your replays !

5. ### MacgyverGuest

Do you expect to be able to charge up a capacitor to 400V from a 1V DC
source (ignoring the 1mA supply current for the moment)?
This comment, along with other mentions of capacitors recharging
capacitors, leads me to believe that you believe that this may be
possible. These two points mentioned above go against even the basics
of capacitor principles and energy conservation laws.

Now, from this post,
Yes I agree with this. BUT (and it is a very big BUT!).
foundation that everything else (including knowledge, understanding and
development) MUST be built on. Without even these you cannot know what
can and cannot be done. Years of experience have shown me (and a lot
of other people) this first hand. There is no way around this.
PERIOD.