Just got a little super cap to work! - Page 1
Forum section: electronics / beginners

author: Capernicus
author_rank: Frequent Contributor
timestamp: October 07, 2021, 11:59:30 pm
content: Just dip a couple of copper strips into carbon paint, wait for it to dry, put a square of toilet paper between and then give it all a liberal coating of salty water, make sure u keep the volts down, and bang! finally got it to work!I think I got about 200-300 uf into a small dc motor?? hard to say, but I bet I couldve got more but I need to stabalize the setup more, its all falling apart.Its definitely easier to get a phantom charge than actually getting a true discharge out of it, it was leaking real bad, but I managed to just get it working for a little while.If I had about 20cmx20cmx2000 layers I could get 10,000 farads out of it, its quite amazing what you can do with fish-tank charcoal.I think id prefer to make a dry unit, u put the electrolyte in a glue and then it solidifies onto the carbon, so thats what we are going to try when we make our big one.The exact mechanism behind it I cant fathom it, its something to do with how the electrolyte is fully connected to the carbon paint, and the resistance ratio between the electrolyte and the electrodes.Does anyone have a better idea how this phenomenon of super electric fields is working?

author: Dubbie
author_rank: Unknown
timestamp: October 08, 2021, 12:03:33 am
content: Sounds kinda doubtful to be honest. I want to see some measurements!

author: Capernicus
author_rank: Frequent Contributor
timestamp: October 08, 2021, 12:37:03 am
content: np dude, maybe these things are best left possibly a secret, because it blows the industry away completely.Thats why everything from Ali Express costs 1c a piece, basicly, everyone in china and their skinned cat knows how to do it.

author: gcewing
author_rank: Regular Contributor
timestamp: October 08, 2021, 05:45:10 am
content: It's like an electrolytic capacitor, except there's no dielectric layer formed on the electrodes. To prevent current flowing between the plates and the electrolyte it just relies on the voltage being kept too low to cause an electrochemical reaction.Layers of opposite charge collect at the surface of each electrode, as shown in this diagram:The distance between the layers is very small -- about the width of an atom -- and the carbon particles give it a very large surface area, leading to an extremely large capacitance.It seems you can do even better by using graphene. Robert Murray-Smith has done a lot of experiments with this sort of thing and got some impressive-looking results:https://www.youtube.com/user/RobertMurraySmith

author: Capernicus
author_rank: Frequent Contributor
timestamp: October 08, 2021, 06:44:33 pm
content: yeh its pretty amazing I first saw them about 3 years ago (From RMS too.) and just couldn't even believe it at first, so did other things. But I just got one working they are pretty good, if u can get electrolytic performance off about 4cm^2(which is about i got.) thats totally shocking to me, just using ordinary capacitors all up to now, and its well under what RMS gets by a fair mile.I agree with that theory, its the self discharge of the connection through the conductive water! definitely it. Its half electrochemical, with those hydrogen and hydroxide ions in there up against the plates, they haf to have something to do with it.thanks! =)

author: Just_another_Dave
author_rank: Regular Contributor
timestamp: October 08, 2021, 08:12:32 pm
content: Although I suspect that its performance would be rather disappointing (I wouldn’t expect that super capacitor to stand high enough voltages for that application without catching fire), I’d love to see an e-bike powered with toilet paper rolls

author: hendorog
author_rank: Super Contributor
timestamp: October 09, 2021, 10:58:26 pm
content: It is good fun playing with these.I had good results with Grafoil, the RMS carbon felt, ethylene glycol (old, toxic antifreeze), water and salt.I think the term super cap - although correct - can mislead people a little.My experiments didn't behave like a commercial capacitor, because the internal resistance is higher so the short circuit current is much lower.