Capacitor variety

[Kevin Weddle]

Does anybody notice the variety of capacitor types that exist. I am sure there is a measurable difference, but it is subtle. Of course the value of the capacitors are different, given the same construction. My problem is my meter. It' doesn't measure low voltage AC very well. It's a radio shack autorange fit's in pocket.

 

[Kevin Weddle]

Actually my meter is fine. I just did not know that it would not measure an AC voltage when there is offset.

 

[Kevin Weddle]

I am in the process of making my own inductor. I used a transformer core and wound it using magnet wire. One can only speculate as to the equation of homemade devices such as these. Can you really expect a very simple homemade capacitor to obey a simple equation.

 

[Guest]

Yes you can make a homemade capacitor which will obey the equations.

I have read this in a small 'LEARN ELECTRONICS' manual.

Take a alluminium foil and paper.

The alluminium foil should act like the plates and paper as the dielectric. Then roll them up into shape of a cylinder. Simple.

A more complex way you can make a multilayered capacitor.

For eg:-

Take 6 alluminium layers and 6 that of paper.

Stack them up alternately.

3 aluminium layers should form one plate and remaining 3 the other plate.

Roll it up.

You could make a container for the capacitor.

The capacitors you make are quite large in size compared to the same valued capacitors of ceramic or paper capacitors but they do sometimes work perfectly .

I myself tried this once successfully but got irritated by its size.

But its a good try!

 

[MP1]

siddhu, this is interesting. What physical size was your capacitor and what Farad rating did it turn out?

MP

 

[Kevin Weddle]

I have a homemade inductor that I will use in a power supply circuit. It has a very high current rating, but it does not obey the equation very well. It is made with many strands of magnet wire, combined together, then wrapped around a transformer core. When I increase the frequency 10 fold, it should increase the resistance 10 fold, but it doesn't. I do, however, trust the high current possibilities. I have to wonder what the resonant frequency will be if I add the capacitor to it. The load would then be in parallel to the capacitor.

 

[Guest]

I do not know the value of capacitor(don't have a meter for it).But i had repalaced it in simple amplifier as coupling and worked very well in that case .

But when tried it in an oscillator and it worked just below good.

This was pretty long time ago(a year).

As for the size it was about 2 inch long and about 1/2 inch in diameter.

It must have had a poor tolerance level and hence must have not worked in the oscillator.

 

[MP1]

I was thinking about this in an audio type of set up. Car stereos need a large bypass capacitor on the 12 VDC power side to help deliver the good base response from the newer high power amplifiers. Usually a 1 farad capacitor is used. However, such large value capacitors are very expensive. If one could be made easy enough with aluminum foil plates and paper insulators but not require a trailer to carry it ;D, this would be a great alternative.

I can certainly see where a fuse would be necessary on this in case of a short in the home made device. Car batteries have a lot of current capability.

MP

 

[Guest]

Good.I been thinking to make a new one myself again.

 

[MP1]

Here is a link I have found regarding making your own capacitor. All done on a breadboard. It is very introductory but causes one to form other ideas as well.
Have fun!

http://www.doctronics.co.uk/owncap.htm

MP

 

[Guest]

Ever thought of making homemade resistors?

Well i am going to try to make one.

The graphite rod in a pencil wouldjust work fine.

 

[Guest]

I made the resistor.

Its fine.

Following things i found.

A HB pencil gives resistance of only 8-9 ohms.

A 2B pencil gives resistance of 11-12 ohms

An unknown pencil gave me resistance of 3.3 kiloohms.

All pencils(graphite rod) were 17 cms. in length(approx) and 2mm in diameter.