How to make a 2nF capacitor

Is this a question? Is this schoolwork? Did you check your textbook? Did you google it?

Hello anita

Your Duplicate Post has been advised to Admin.

Is this a Class or Homework Question?

Kind Regards....

Hello Del the cat

With grateful Compliments

Kind Regards....

Correct DK, but I think he is talking about using paper as the dielectric and for some reason he has called 'electrolyte' for something else.

When this question came up last (it is homework!!) I made one about a year ago and I found it much better to use a thin film of oil to hold the separate 'plates' together.... Also I wound mine up onto a cardboard tube to make it stronger.

It worked very well!!

John.

Hi, anita!

Welcome to CR4! It's really great to have you in here, and I hope you enjoy participating over time in a great many areas where you will see engineers from a huge number of disciplines asking questions to which you can contribute ideas and suggestions. It goes both ways. And that's what makes this forum so unique...all these engineers from a wide variety of disciplines sharing information together across the entire engineering realm.

As to your inquiry, I remember having fun in electronics class building a capacitor using aluminum foil sheets and two pieces of cardboard as the dielectric. It's a bit dusty, but what I thik we did was simply as tightly as possible roll two sheets (not touching) of foil on either side of a piece of shirt cardboard and a second piece of cardboard lying on the top foil sheet, ending the outside sheet of aluminum foil just before the inner one, connecting an insulated terminal to each, and putting the resulting roll in a good-sized tubular plastic medicine bottle with insulated posts from each tinfoil piece sticking out through separate holes in its lid.

Using insulated alligator clips extending from the two posts to 'charge' our home-grown capacitor from a car charger for a brief interval (you have to experiment to see how long it takes), we 'loaded up' the 2 tinfoil sheets (actually just changed the overall charge of each via the charger's influence) and then used the combined charges through an LED to light it up. To get the correct capacitance check the unchanged capacitance on a meter and adjust your in-line resistance accordingly to see if you have created the 2nF capacitance you want.

The result? Shocking! If my memory is too dusty and I've forgotten (as I'm more likely to do than I'll admit...) something important.

Have fun, and keep a fire extinguisher handy!

BTW, we have an "Education" section for inquiries such as this...and I'm sure that somebody in here is going to direct me to it after this foray into my distant past...

Mark

I had a brainstorm a while back and decided to make a capacitor from some aluminum foil run through the laminating machine. Me and my math teacher buddy took a whole roll of aluminum foil (one half at a time) and ran it through. Then we ran the two laminated pieces through. In theory, it should have worked great, in reality it wasn't nearly as much capacitance as I had anticipated. The best part part was the looks from the rest of the faculty...truly priceless!

Another easy capacitor is a Leyden jar (spelling?) Fill a plastic cup with water, wrap with aluminum foil...presto! A fantastic storage device for shocking your friends. This can also be modified by wrapping the inside with foil.

Enjoy...and be careful!

You have two conductors (foil) with a layer of dielectric in between (for example, wax paper)

Here are the three parameters you have to work with:

Area of capacitor A, dielectric constant of dielectric Er, thickness of dielectric d

C=Er*e0*A/d

or

A=C*d/(Er*e0)

C is capacitance in picoFarads, (2000 in this case)

e0 is permittivity of free space = 8.854 pF/m

Er is dielectric constant of dielectric (no units)

d is thickness of dielectric in meters

A is area in square meters

Look up dielectric constant, Er, for dielectric. Measure thickness of dielectric, d, with a micrometer. Calculate area you need for 2000 pf.

Please check:

http://cr4.globalspec.com/thread/8426/2nF-Capacitor-Design?frmtrk=CR4digest

25 comments in discussion

Regards !

As I referred to an old link for exact the same question:

Capacitor-Design-2nF

Extract is as:

Just get one polyester/polyestreen capacitor 10nF or near about.

Open it carefully to get the aluminum foil and insulator,

This will give you a good insight of how it is made,

Unroll the aluminum foil and insulator carefully.

Measure its length. Workout how much length for 2nF is. Assemble in reverse to when you opened it.

You may need to try. You will get ultimately

Wish you best of luck

Hi, anita!

Looks like you got the same professor as 'maydayrocks' had last year. Follow the link in #15 above!

And get hold of some of last years' student notes because this professor seems to repeat assignments.

Mark