# Good capacitor?

Discussion in 'General Electronics Chat' started by Geronimo42, May 10, 2014.

1. ### Geronimo42 Thread Starter New Member

May 7, 2014
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I made a thread several days ago because I was working on a project where I was trying to charge devices with a generator and a micro USB (bare with me, I'm new at circuitry). I recently contacted the company to ask about the voltage of their generator, to which they replied it was ~3v. They had also said that the source had to have a higher voltage than the battery to be able to produce a charge, which I did not know. I researched capacitors as they increase voltage, however I'm not sure as to how much they increase voltage by. If i needed roughly 1-2 more volts would 1 capacitor be enough? (I also think the measurement for capacitors is mf, correct?)

Would 1mf (or whatever) be enough to increase voltage by 1-2 or would I need stronger? There isn't a lot of space on the board, but a very good friend of mine who worked as an electrical engineer told me that I could solder the capacitor to one of the diodes that are already soldered onto the board, is this possible?

Thank you guys again! I'm really learning a lot

Apr 5, 2008
15,799
2,385
Hello,

What kind of generator are you using?
It looks like a very small power one, if it is only giving 3 Volts at the output.
Is the output AC or DC?

Bertus

3. ### #12 Expert

Nov 30, 2010
16,665
7,314
Start with a drawing of the circuit. Capacitors don't create voltage, they only store it. Where is this extra volt coming from? (I'll be able to see that on the drawing.)

4. ### Austin Clark Active Member

Dec 28, 2011
409
44
Capacitors don't boost/generate voltage. In fact, their only real job is to reduce the CHANGE in voltage. Kind of like a buffer, it keeps voltage stable by releasing it's charge when the voltage drops, and storing charge when the voltage rises. If you like the whole water analogy, a capacitor would be a tank, it's pressure rating would be the voltage rating, and it's volume/size would be it's capacitance rating.

5. ### Geronimo42 Thread Starter New Member

May 7, 2014
15
0
I actually can't get a hold of a drawing as the company doesn't offer one

The voltage is DC and yes, it is a very small generator. Roughly 10cm board in length.

Apr 5, 2008
15,799
2,385
Hello,

Do you have a link to the companies page for the generator?
Or can you post a foto of the generator?
How much current can the generator give at this 3 Volts?

Bertus

May 7, 2014
15
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8. ### wayneh Expert

Sep 9, 2010
12,378
3,231
It takes about 3400mWhr to charge a single AA battery. At 0.5mW, you'll never get there. You'll need ~1yr.

Step back and tell us what you are hoping to do.

9. ### Geronimo42 Thread Starter New Member

May 7, 2014
15
0
I'm trying to use said generator to power a small battery, I was testing out smartphone batteries as it seemed interesting and small enough, but I suppose not. I thought voltage was what dictated a charge, it says he output is 0.5mW but the voltage of it is around 3v as said earlier. How is there a difference in these things and what dictates how fast something will charge?

EDIT: Is there another component I can solder to the board to increase power output?

Last edited: May 10, 2014
10. ### #12 Expert

Nov 30, 2010
16,665
7,314
No. There is nothing besides a different generator that you can solder to the board to get more power.

It's like volts are pressure, current is mass flow, and those multiplied is wattage.
P=IE
Power = current times voltage
.0005 watts = .0001667 amps time 3 volts.

Just guessing, a smart phone might use from .01 amp to .1 amp.
That's going to require 100 to 1000 hours of charge per hour of use.
You need a bigger horse to get that horsepower.

11. ### Geronimo42 Thread Starter New Member

May 7, 2014
15
0
Well thanks guys, I suppose that type of technology doesn't exist yet, however. I'll just use this generator to mess around with. Thanks again!

12. ### MrChips Moderator

Oct 2, 2009
12,624
3,451
You cannot get extra energy from nothing. If the generator max output power is 0.5mW that is all you are going to get. You cannot boost that.