My home capacitor experiment

[avicenna]

TL;DR Summary

aluminum foil capacitor with paper dielectric

Say I build a parallel capacitor from two 10cm x 10cm aluminum foil with one sheet of writing paper in between as dielectric. I press the foils together with a weight and a flat piece of plastic/glass.

I can power on a 6VAC incandescent bulb with a 6VAC power supply. Now if I connect my capacitor in series with the bulb, will the bulb light up.

 

[Baluncore]

Now if I connect my capacitor in series with the bulb, will the bulb light up.

The capacitance will be about 200 pF.
Reactance, Xc, will be about 16 MΩ at 50 Hz.
Current will be less than 6 V / 16 MΩ = 0.4 uA
That current will be insufficient to light a filament lamp.

 

[avicenna]

The capacitance will be about 200 pF.
Reactance, Xc, will be about 16 MΩ at 50 Hz.
Current will be less than 6 V / 16 MΩ = 0.4 uA
That current will be insufficient to light a filament lamp.

Thanks.

 

[avicenna]

Thanks.

The capacitance will be about 200 pF.
Reactance, Xc, will be about 16 MΩ at 50 Hz.
Current will be less than 6 V / 16 MΩ = 0.4 uA
That current will be insufficient to light a filament lamp.

My estimate:
capacitance = 200 - 400 pF.
reactance(1/(2πfC)) = 16 MΩ

This site, All About Circuits has an online calculator:
https://www.allaboutcircuits.com/tools/capacitor-impedance-calculator/

Gives impedance to be 1591 Ω ; I think wrong.

Bad website?

 

[avicenna]

Is there a simple way to build a home 100 - 1000 μF capacitor?
Best as a parallel plate capacitor with small area plates.

 

[Baluncore]

Gives impedance to be 1591 Ω ; I think wrong.

I think you left out a few powers of ten or did not specify the frequency.

Is there a simple way to build a home 100 - 1000 μF capacitor?
Best as a parallel plate capacitor with small area plates.

I do not think so.
You would need too many layers, with molecular thickness insulation and an electrolyte with a high dielectric constant.

 

[avicenna]

I think you left out a few powers of ten or did not specify the frequency.

I think you left out a few powers of ten or did not specify the frequency.

I do not think so.
You would need too many layers, with molecular thickness insulation and an electrolyte with a high dielectric constant.

I do not think so.
You would need too many layers, with molecular thickness insulation and an electrolyte with a high dielectric constant.

Yes, I think no way for super capacitor this easy.

About the site, I think really bad. My entry was 200pF, 50Hz only

 

[Baluncore]

About the site, I think really bad. My entry was 200pF, 50Hz only

It works correctly for me, 200 pF at 50 Hz = 15 915 494.3092
I note that 2 uF at 50 Hz gives 1591.5494
Did you click on the calculate button?

 

[avicenna]

It works correctly for me, 200 pF at 50 Hz = 15 915 494.3092
I note that 2 uF at 50 Hz gives 1591.5494
Did you click on the calculate button?

OK. The display box in my linux system is only 4 digits wide; I have to use the right arrow key to get the rest of the digits!

I reduce the font size and got the full value!

 

[Baluncore]

Maybe start with a bead of tantalum or titanium powder, electrically bonded and sintered on a wire lead. Next, oxidise the entire surface of the bead, inside and out. You then have an oxide insulator with a high dielectric constant. Plate the outside of the oxide with a metal and attach a second lead.
https://en.wikipedia.org/wiki/Tantalum_capacitor

Look at the materials at the bottom of this list.
https://en.wikipedia.org/wiki/Relative_permittivity

Alternatively;
Get two rolls of aluminium foil, and two rolls of cling-film, from the supermarket. Roll the four layer sandwich tight onto a cylinder. Make connections to the two foil layers.

To solder aluminium, wet the area with cooking oil, scrape the Al oxide surface through the oil, to make it shiny, bare Al, then solder coat the Al surface through the oil. Solder the leads onto the plated patches. Practice that technique with scraps of foil, before rolling the capacitor.

 

[avicenna]

Maybe start with a bead of tantalum or titanium powder, electrically bonded and sintered on a wire lead. Next, oxidise the entire surface of the bead, inside and out. You then have an oxide insulator with a high dielectric constant. Plate the outside of the oxide with a metal and attach a second lead.
https://en.wikipedia.org/wiki/Tantalum_capacitor

Look at the materials at the bottom of this list.
https://en.wikipedia.org/wiki/Relative_permittivity

Alternatively;
Get two rolls of aluminium foil, and two rolls of cling-film, from the supermarket. Roll the four layer sandwich tight onto a cylinder. Make connections to the two foil layers.

To solder aluminium, wet the area with cooking oil, scrape the Al oxide surface through the oil, to make it shiny, bare Al, then solder coat the Al surface through the oil. Solder the leads onto the plated patches. Practice that technique with scraps of foil, before rolling the capacitor.

Thanks. But I am not at the level to try this yet.

 

[Baluncore]

Thanks. But I am not at the level to try this yet.

You might try to make the alternative foil and film capacitor using kitchen commodities from the supermarket. Stagger the two foils so they hang out at opposite ends of the roll, then use clips to contact the foil.

 

[avicenna]

You might try to make the alternative foil and film capacitor using kitchen commodities from the supermarket. Stagger the two foils so they hang out at opposite ends of the roll, then use clips to contact the foil.

I realize my idea about my capacitor experiment wrong. So I don't need my capacitor for now.

Thanks for the advice.