home made foil and paper towel electrolytic capacitor issues.

Thread Starter

realflow300

Joined Jul 28, 2023
124
So if water and baking soda aren't a suitable electrolyte what would be the next best thing (while still being as safe as possible)
I dont want a hazmat crew rolling up to my place to clean up a chemical mess.

update: im still forming the capacitor. 1.56mA at 9.19v
as I charge it higher it demands more current to form it (to get the oxide layer thicker or something?)
so it takes a while to form higher voltages.
 
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Thread Starter

realflow300

Joined Jul 28, 2023
124
I gave it a break just let it sit for a day then tried again and now it only requires 96uA of current to charge up to 7.35v!
Voltage still rising and current decreasing.
Trying with a 93.3k resistor/variable adjustable potentiometer to vary the current and resistance.

How would it change by just leaving it sit for a while? how would that improve the characteristics in allowing it to hold a charge with lower current?
Doesn't that sound unusual?
73 micro amps at 9.11v now! after just 20 minutes later.

if I just shove 16v to it with like a low current limit like 20mA
it reaches about 2mA-3.5mA and sits there fluctuating and jumping up and down quite erratically. is it generating bubbles/gas? evolving water?
how is it breaking through the oxide layer with a couple mA of current at 16v and is there any way to stop that from happening?
 
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Thread Starter

realflow300

Joined Jul 28, 2023
124
how about an option for getting more surface area?

Some way of scuffing up the surfaces without contaminating them.

an idea would be maybe a small fine-bristle stainless steel "paintbrush" to scuff the surface of the aluminum in one direction. then rinsing it well to remove the fine aluminum particulate matter. so its sorta like micro-heatsink fins and stuff. it should make the surface area way bigger.
I think that should be able to scuff up the surface pretty good to get a lot of surface area.
As long as I don't get too much stainless steel particles contaminating the aluminum it might work?
What are your thoughts? too much risk of contamination?
 

MrChips

Joined Oct 2, 2009
30,456
My thoughts are:

You have experimented with creating a DIY capacitor with rolled aluminum foil. You have discovered that it works but highly dependent on process and materials.

Your efforts were successful.

Now it is time to move on to something else.
 

Thread Starter

realflow300

Joined Jul 28, 2023
124
if I form my capacitor to higher voltages do I sacrifice capacitance? Say if I formed it to 20v instead of 6v I would have almost 4 times less capacitance at 20v than at 6v?
 

WBahn

Joined Mar 31, 2012
29,844
My thoughts are:

You have experimented with creating a DIY capacitor with rolled aluminum foil. You have discovered that it works but highly dependent on process and materials.

Your efforts were successful.

Now it is time to move on to something else.
@realflow300 Advice worth considering -- of course that doesn't mean you have to take it.

There is definitely a point of diminishing returns as far as what more you can hope to learn in exchange for further efforts. But when you have reached that point is for you to decide. But be aware that you are likely getting close to the limits of how much useful information you can realistically get from this forum's membership. There are probably forums out there more focused on chemistry and other more closely related fields that might help you go further.
 

MisterBill2

Joined Jan 23, 2018
17,774
At this point the TS, and the readers, probably learned what is to be learned. In most situations, for most people, the home-made electrolytic capacitor is not a practical item, except for learning.
So it is time to put it on the shelf and continue learning in other areas.
 

BobTPH

Joined Jun 5, 2013
8,659
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2.3 cents each. How much do your home made ones cost (including labor)?
 

joeyd999

Joined Jun 6, 2011
5,165
In his OP he stated the inntention of having fun not producing cheap capacitors.
And I've learned a few things. I hope TS continues this thread.

I'm in the middle of a chemistry/electronics investigation myself right now. Can't reveal details- except that it involves solid-state thermionic emission. This kind of stuff is fun, and there's always something new to be learned.
 

Thread Starter

realflow300

Joined Jul 28, 2023
124
Apparently adding epsom salt magnesium sulfate solution to the baking soda solution in my homemade capacitor has absolutely no appreciable effect. Neither to the leakage current or capacitance or voltage rating. its as if Ive not even added more distilled water or diluted the baking soda or anything.
Very peculiar
 

Thread Starter

realflow300

Joined Jul 28, 2023
124
Nobody is giving any suggestions on a better and still safe enough alternative. just telling me to "read some articles about it"
I need a direct example of something suitable thats safe enough to use without blowing myself up or setting the house ablaze or dissolving my flesh. or something that creates toxic gases. ect.
as well as suggestion about how to mix them in what ratio for a decent result.
my goal is lower leakage current rather than higher capacitance. to a point at least
 

LowQCab

Joined Nov 6, 2012
3,935
There is no "decent-result".
This is an interesting experiment that, may, or may-not, demonstrate the principles of a Capacitor.
So far it appears that You have succeeded only in creating some very poorly performing Batteries,
and nothing approximating an Electrolytic-Capacitor.

It is not feasible to build a DIY-Electrolytic-Capacitor at home.
There are highly complex Chemical-tricks that make an Electrolytic-Capacitor work.

And You are now complaining that nobody will
"divulge" the "secret-sauce-formula" for making a DIY-Electrolytic-Capacitor.
That's because it doesn't exist, not because they are "playing-games" with You.

Probably no one in any usual Electronics related Forum would even attempt such a project.
The BS that You see on YouTube is ~90% Click-Bait, and doesn't actually work in the real World.

But,
You can create other types of Capacitors at Home,
but it's not likely that you will ever achieve a capacity in excess of maybe ~1uF,
in a configuration and size that is actually practical to use in a DIY-project.

The reason that others are suggesting that You do further reading and research, is so that
You will quickly realize that making an Electrolytic-Capacitor is NOT a trivial-task for a DIY-Hobbyist,
and no proffesional would ever even consider the idea of building their own Capacitors.
.
.
.
 

joeyd999

Joined Jun 6, 2011
5,165
I don't understand why this thread bothers so many, including moderators of AAC.

If TS is boring you, or you think his quest is hopeless, ignore the thread!

Why keep harping on him about wasting his time? It's his time to waste.
 

Thread Starter

realflow300

Joined Jul 28, 2023
124
Charged up to 16v with a 1k resistor
I can get a good bright flash out of a 12v 5w LED out of my homemade parallel plate scuffed surface capacitor.
a standard 16v 100uF capacitor or so doesn't flash my LED nearly as brightly.
a 1000uF capacitor is a little more than twice as bright of a flash from the LED as my capacitor.
So it's not really a battery as its able to deliver all its potential energy instantly.
I should really have a capacitance meter to try to measure roughly what it is.
its about 5x5 inches square of foil with a napkin as a separator in between.
It holds voltage for a while when taking off the power supply. so the leakage isn't enough to completely overwhelm the capacitors capacitance. it only slowly drops from 16v and not instantly.
I think my baking soda solution or paper separator are the root cause of leakage current. Possibly contamination from being "standard grade" like not very high purity or something? Maybe even the foil isn't pure enough?
 
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