Not as fancy as a lot of the projects here, but... - Page 1
Forum section: electronics / projects

author: GadgetBoy
author_rank: Regular Contributor
timestamp: June 01, 2018, 06:23:28 am
content: I've successfully made a 297nF capacitor out of a pool noodle, parchment paper, aluminum foil, and packing tape. Feeling very MacGyver.

author: Karlo_Moharic
author_rank: Regular Contributor
timestamp: June 01, 2018, 06:26:23 am
content: Nice

author: mtdoc
author_rank: Super Contributor
timestamp: June 01, 2018, 06:28:59 am
content: Excellent, but you’re gonna need a big project box - even if your circuit only needs one of those caps....

author: GadgetBoy
author_rank: Regular Contributor
timestamp: June 01, 2018, 06:31:38 am
content: It's a one off for an educational video I'm doing on my channel. Sunday's video is about capacitors, I'm doing some small and large (pool noodle) scale practical demonstrations of how they work.

author: NiHaoMike
author_rank: Super Contributor
timestamp: June 01, 2018, 06:37:44 am
content: I remember when I would make high voltage capacitors from aluminum foil and lamination sheet trimmings from school. Charge one up with a flyback transformer and it would store a surprising amount of static electricity.

author: GadgetBoy
author_rank: Regular Contributor
timestamp: June 01, 2018, 06:44:01 am
content: I think the biggest I ever made was out of 1/16" aluminum sheets and 1/8" PVC sheets. It weighed about 20 pounds, was for a tesla coil.

author: knapik
author_rank: Regular Contributor
timestamp: June 01, 2018, 06:45:11 am
content: Now reverse bias it and watch it explode!

author: GadgetBoy
author_rank: Regular Contributor
timestamp: June 01, 2018, 06:48:51 am
content: Thankfully this one isn't polarized. Not sure how to make a polarized cap out of household materials.

author: DaJMasta
author_rank: Super Contributor
timestamp: June 01, 2018, 06:49:15 am
content: Is the pool noodle also the power source?

author: james_s
author_rank: Super Contributor
timestamp: June 01, 2018, 06:52:47 am
content: I've made accidental capacitors on a number of occasions. It's surprising the punch it will pack when charged to several kV, even a piece of coax or a couple of metal objects insulated from one another can form an effective capacitor.I've been meaning to try making an electrolytic capacitor sometime, IIRC aluminum foil and borax with a paper insulator are the main ingredients. I don't expect it would last very long but it would be fun to try.

author: GadgetBoy
author_rank: Regular Contributor
timestamp: June 01, 2018, 06:55:43 am
content: I guess you could generate static with the noodle....Anyone know the dielectric strength of parchment paper?

author: drussell
author_rank: Super Contributor
timestamp: June 01, 2018, 02:01:32 pm
content: Quote from: GadgetBoy on June 01, 2018, 06:55:43 amMost types of paper itself are usually about 200 volts per thousandth of an inch with a dielectric constant of about 3. Presumably impregnating it with silicone to make the parchment paper would change this somewhat. My guess is the dielectric constant would probably stay about the same (though it might go up a bit since some silicone compounds have higher values,) near 3 and the puncture voltage might go up a bit.If you can find regular paper exactly the same thickness as your parchment paper (measure multiple layers together to reduce your measurement error if you can't accurately measure very thin things easily), you could test the difference in dielectric constant by building two identically-sized capacitors out of the two kinds of paper and measure the difference in capacitance.

author: SiliconWizard
author_rank: Super Contributor
timestamp: June 01, 2018, 02:05:41 pm
content: Funky.I wonder what kind of capacitance you can get with toilet paper rolls.

author: drussell
author_rank: Super Contributor
timestamp: June 01, 2018, 02:15:36 pm
content: Quote from: SiliconWizard on June 01, 2018, 02:05:41 pmYou really don't need the pool noodle or the toilet paper roll.They're really just a form to roll things on for experimentation and actually just wasted space filler. You could make that capacitor much smaller, physically, by rolling it up tighter on a small dowel, for example. The pool noodle just looks niftier...

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: June 01, 2018, 02:43:53 pm
content: Today the nanofarad, tomorrow the entire Farad!

author: GerryBags
author_rank: Frequent Contributor
timestamp: June 01, 2018, 02:54:40 pm
content: Check out Robert Murray Smith on Youtube, he shows you how to make graphene-based super-caps at home with easily available materials. These are definitely polarized, and the NaCl electrolyte he uses for convenience has a low breakdown voltage, but they can store ridiculous amounts of charge. He also shows how to use deep eutectic solvents as electrolytes, which can get you a higher WV, but they involve chems that are a little harder to find.He also does some interesting work with batteries made from paper and carbon, including making a big one to run a Renault Twizy off. Well worth checking out if you like mucking about with materials. I got some high quality graphite from him, and some graphene powder, and was able to electro-plate a seashell in copper.... not a super thick coat (I had better results on a twig), but it did work.Anyway, check him out:https://www.youtube.com/user/RobertMurraySmith

author: SiliconWizard
author_rank: Super Contributor
timestamp: June 01, 2018, 05:04:07 pm
content: Nice.I tried making Al-Air batteries at some point, as I thought there was great potential with them. They worked but not for long. That's pretty hard to avoid aluminum surface oxidation, which quickly makes the internal resistance rise.

author: mtdoc
author_rank: Super Contributor
timestamp: June 01, 2018, 06:49:57 pm
content: This has provided an idea for some teaching I've been doing for my son's 6th grade maker space. I've been having them build 555 blinky circuits and teaching about capacitors - having them plot blink frequency versus capacitance.I think I'll build a couple of these and bring them to class, connect them to a blinky circuit and show them how capacitors are made.Thanks for the inspiration!

author: T3sl4co1l
author_rank: Super Contributor
timestamp: June 01, 2018, 09:23:36 pm
content: Come to think of it, pool noodle would actually make pretty good foam-loaded hardline, if copper or aluminum tube is slid into and over it.Doesn't matter much unless you're running an old school TV transmitter, though.Tim

author: james_s
author_rank: Super Contributor
timestamp: June 01, 2018, 11:03:41 pm
content: At that point you probably don't really need the noodle. Weren't those transmission lines made out of rigid copper air core coax? Seems like I saw a video about a TV transmitter once.

author: GK
author_rank: Super Contributor
timestamp: June 01, 2018, 11:55:20 pm
content: Quote from: james_s on June 01, 2018, 11:03:41 pmYes. I probably assembled several kilometers of the stuff back in my production assembler days. Man, I forgot that there was a time when my hair wasn't grey.

author: GadgetBoy
author_rank: Regular Contributor
timestamp: June 02, 2018, 01:35:12 am
content: Quote from: mtdoc on June 01, 2018, 06:49:57 pmMy video on capacitors goes up for patreon subscribers on sunday (and public release the following sunday), but I'll PM you the link if you wanna see if it's worthy of sharing with your class.

author: GadgetBoy
author_rank: Regular Contributor
timestamp: June 02, 2018, 01:36:12 am
content: Quote from: drussell on June 01, 2018, 02:01:32 pmI'm actually planning on making another with wax paper, and another with clear wrapping paper to test just that.

author: GerryBags
author_rank: Frequent Contributor
timestamp: June 02, 2018, 01:43:41 am
content: Quote from: SiliconWizard on June 01, 2018, 05:04:07 pmIf you coat the aluminium in activated carbon it stops it oxidizing. The Australian ultra-batteries, where they do the same thing to the lead plates in a lead acid battery, would be the source for a good glue/ink recipe. The carbon stops the lead plates oxidizing and producing gas, it should do the same to your aluminium electrodes, as well as increasing the surface area ten-fold, increasing the energy density.

author: JS
author_rank: Frequent Contributor
timestamp: June 02, 2018, 07:06:39 am
content: Quote from: drussell on June 01, 2018, 02:01:32 pmIt's funnier to measure the dielectric strength  (wear eye protection)And if you want to measure the dielectric constant do it before...JSEnviado desde mi LG-M250 mediante Tapatalk

author: SiliconWizard
author_rank: Super Contributor
timestamp: June 02, 2018, 03:29:39 pm
content: Quote from: GerryBags on June 02, 2018, 01:43:41 amThanks for the tip. I'm still interested in metal-air batteries. Is that what you're referring to?https://www.csiro.au/en/Research/EF/Areas/Energy-storage/UltraBattery

author: CM800
author_rank: Frequent Contributor
timestamp: June 02, 2018, 03:36:09 pm
content: I wonder how far you could go with making stuff using only household materials.You're allowed one thing extra: A vacuum pumpI'm curious if someone could go far enough to make a valve radio or similar, even a simple amplifier.

author: JS
author_rank: Frequent Contributor
timestamp: June 02, 2018, 03:49:55 pm
content: Quote from: CM800 on June 02, 2018, 03:36:09 pmPretty far, there are basement made vacuum tubes, given you need some tooling and materials but nothing way to special.There was a story about a guy ho did so in times of war and got some mad dudes checking what was going on. I can't remember who it was...JSEnviado desde mi LG-M250 mediante Tapatalk

author: VelOBor
author_rank: Contributor
timestamp: June 02, 2018, 04:34:52 pm
content: Nice!