what are assymetrical capacitors? - Page 1
Forum section: electronics / beginners

author: Capernicus
author_rank: Frequent Contributor
timestamp: October 09, 2021, 08:25:33 pm
content: I always knew about them, but what are they, capacitors crossed with diodes?

author: bob91343
author_rank: Super Contributor
timestamp: October 10, 2021, 02:13:23 am
content: I presume they are capacitors in which one plate/electrode is considerably larger than the other. It could also refer to polarized capacitors, but that's unlikely.

author: Capernicus
author_rank: Frequent Contributor
timestamp: October 10, 2021, 02:16:34 am
content: i see. That would be hard to get to happen considering youd only get capacitors on the AND of the plates, what does it do exactly, because maybe u could make a rectifier with them, but I have to work out what they actually are yet.

author: bob91343
author_rank: Super Contributor
timestamp: October 10, 2021, 03:47:36 am
content: Perhaps it would help if you gave the source of this term.

author: Capernicus
author_rank: Frequent Contributor
timestamp: October 10, 2021, 03:50:20 am
content: I just always heard about it. apparently electrolytics are polarized, but does that mean they are assymetrical - they still seem to charge the same either way.apparently super caps can be ionicly assymetrical, but I've never heard of ppl putting super caps in circuits much, so no-ones gave them much attention.Maybe because not many people can actually design circuits, they just copy them!What does assymetry bring? Carlsons Lab actually showed it on one of his videos, But I cant remember where it is now!!!

author: Zero999
author_rank: Super Contributor
timestamp: October 10, 2021, 08:13:52 am
content: Electrolytic capacitors don't charge the same direction either way, except perhaps at very low voltages. An electrolytic capacitor behaves like a poor diode, with a lot of reverse capacitance. It will conduct with a relatively fixed voltage drop, when connected in one direction and act as a capacitor, in the other.

author: Capernicus
author_rank: Frequent Contributor
timestamp: October 10, 2021, 11:48:59 am
content: Thanks for that.So the charge graph is different either direction?? That means u could possibly get some rectification to happen?

author: Terry Bites
author_rank: Super Contributor
timestamp: October 10, 2021, 04:48:37 pm
content: Where did you get that term from? Often supercaps are symetric or asymetric in their internal structure. That affects performance characteristics and manfacturing complexity.If you make a capcitor with unequal areas or inconsistent dielectric or spacing there is only one capacitance value , so from an electrical point of view it will always be symmetric.seehttps://physics.stackexchange.com/questions/302875/what-is-the-capacitance-of-a-parallel-plate-capacitor-with-different-areas

author: Capernicus
author_rank: Frequent Contributor
timestamp: October 10, 2021, 05:34:31 pm
content: Look at this video.Its about how to do outer-space propulsion with a hi-voltage asymmetric air capacitor. (but works in vacuum as well.)WTH?? what is that 6 watts?

author: CaptDon
author_rank: Super Contributor
timestamp: October 10, 2021, 07:02:30 pm
content: Isn't that lifter just more or less electrostatic attraction/repulsion???

author: Capernicus
author_rank: Frequent Contributor
timestamp: October 10, 2021, 07:16:15 pm
content: Im not sure! its definitely a bit of a show stopper, all my knowledge up to seeing this were just the hasel actuators for robots.these things->

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 10, 2021, 10:09:15 pm
content: It's just ionic flow. High voltage is required to ionize the air.Tim

author: Raj
author_rank: Frequent Contributor
timestamp: October 12, 2021, 06:18:43 am
content: Quote from: Capernicus on October 09, 2021, 08:25:33 pmI'm assuming you're talking about varicap... They are diodes, who's junction capacitance and it's variability, you exploit as a variable capacitor.

author: Gyro
author_rank: Super Contributor
timestamp: October 12, 2021, 08:40:43 am
content: Quote from: Capernicus on October 10, 2021, 05:34:31 pm"Asymmetric air capacitor" is a very poor way of describing a lifter, or it's mode of operation. Its all about ion flow and nothing to do with capacitance.It also doesn't work in a vacuum without an Ion source.https://www.eevblog.com/forum/dodgy-technology/ionic-lifters-has-anyone-else-around-here-build-one/

author: Zero999
author_rank: Super Contributor
timestamp: October 12, 2021, 09:57:19 am
content: Quote from: Capernicus on October 10, 2021, 11:48:59 amYes, an electrolytic capacitor can be used as a poor rectifier, but a proper rectifier diode is much cheaper and more reliable.Interestingly, the electrolytic capacitor was developed from the electrolytic rectifier.https://en.wikipedia.org/wiki/Rectifier#Electrolytic

author: Capernicus
author_rank: Frequent Contributor
timestamp: October 12, 2021, 11:14:55 pm
content: hi-voltage seems to give capacitors more power/versatility for design than they have otherwise.hi-voltage also makes voltage dividers more contrastive.

author: tooki
author_rank: Super Contributor
timestamp: October 13, 2021, 02:14:19 pm
content: Quote from: Capernicus on October 12, 2021, 11:14:55 pmThey're more flexible in that you can always use a higher-voltage cap at a lower voltage. But they're less versatile mechanically, in that higher-voltage capacitors are physically larger than otherwise-equivalent lower-voltage ones. A project I'm working on at work uses 10KV capacitors, and they'remassive. You wouldn't want to use them for low-voltage stuff for that reason alone. But even among "normal" components, the space savings between, say, a 16V 1000µF and a 50V 1000µF electrolytic capacitor is nothing to sneeze at, it could easily be the difference between fitting in the housing you want and needing to go bigger. So you wouldn't want the 50V cap if you're only running it at, say, 10V.And of course a corollary of size is cost, since larger components are typically more expensive than smaller ones. (Down to the point where the cost of miniaturization exceeds the materials savings.)Quote from: Capernicus on October 12, 2021, 11:14:55 pmSay what? Capacitive (or resistive) voltage dividers are linear circuits: they divide a voltage according to a fixed ratio. There's no "contrast" involved.

author: Capernicus
author_rank: Frequent Contributor
timestamp: October 13, 2021, 04:55:15 pm
content: With the voltage divider, the higher the voltage going into the divider the more range you get out of it. If you use a potentiometre in voltage divider mode its not an ohms range anymore, it converts it into a volt range, and hi -voltage would be a higher range.Hi-Voltage lets you use spark gaps in your capacitor circuits, and makes more things possible.Capacitor based mech actuators dont work unless its hi-voltage, and static electricity in general is hi-voltage.Hi-voltage seems to go with electric fields to me.

author: Gyro
author_rank: Super Contributor
timestamp: October 13, 2021, 05:15:22 pm
content: I have no real clue what this thread is actually about... I still don't understand what the OP is looking for.

author: Capernicus
author_rank: Frequent Contributor
timestamp: October 13, 2021, 05:36:02 pm
content: Quote from: Gyro on October 13, 2021, 05:15:22 pmI was wondering if theres some way to make a recifier using polarized caps, and it seems to be its a yes, but it doesnt work as well as a diode.Im wondering if I can make a rectifier without a diode.

author: Gyro
author_rank: Super Contributor
timestamp: October 13, 2021, 06:03:05 pm
content: Ah, ok then. Yes, electrolytic rectifiers used to be a thing, back in the '20s / 30's. If I remember correctly from my old electrical engineering books, they actually used to be available in quite large sizes. There are a few references on the web if you search 'electrolytic rectifier'.eg.https://physicsmuseum.uq.edu.au/electrolytic-rectifierTrying to do the same with modern sealed electrolytic capacitors is a recipe for disaster - far too much capacitance and internal dissipation. It's all about electrolytic action, not capacitance.Somewhat related was the electrolytic surge suppressor which used the breakdown of a (self re-forming) aluminium oxide layer for protecting transmission lines from lightning strikes.

author: Capernicus
author_rank: Frequent Contributor
timestamp: October 13, 2021, 06:12:39 pm
content: I think I made an electrolytic rectifier by accident! Believe it or not, I used 2 wet sponge-cloth (chux wipes) with a plastic separator and it acted like a slow acting diode, it took charge before it shut off like a capacitor except it was only 1 way. it passed current the other as normal. But if I ever tried to get a discharge out of it, there was nothing there, it had a phantom charge one way but no charge to speak of inside it. Water IONS do funny things!!I went on the internet, and I found another guy doing the same thing as me coincidentally, heres the page->https://halestrom.net/darksleep/blog/021_more_diodes/

author: Gyro
author_rank: Super Contributor
timestamp: October 13, 2021, 06:19:39 pm
content: From my copy of 'The Modern Electrical Engineer' published by Caxton 1927.....

author: tooki
author_rank: Super Contributor
timestamp: October 13, 2021, 06:30:13 pm
content: Quote from: Capernicus on October 13, 2021, 04:55:15 pmA voltage divider is adivider. It stands to reason that the output voltage cannot exceed the input voltage.But "contrast" is not a thing here.Quote from: Capernicus on October 13, 2021, 04:55:15 pmNot all electronics is focused on spark-generating capacitive discharge.Quote from: Capernicus on October 13, 2021, 04:55:15 pmNo, it's just that low-voltage static electricity doesn't matter most of the time. But static electricity exists at low voltages all the time. An item being charged to a high voltage begins at a low voltage, after all. It's not instantly at the high voltage.Quote from: Capernicus on October 13, 2021, 04:55:15 pmElectric fields are the fundamental principle behind capacitors (and other electronic components) atallvoltage levels. They're inherent to electricity. So sure, high voltages involve electric fields. But so do all other voltages.

author: Bud
author_rank: Super Contributor
timestamp: October 13, 2021, 06:31:56 pm
content: "Asymmetrical capacitor" sounds an audiophoolery term to me. Audiophools must be pulling their hair out how come they could not think of it.

author: tooki
author_rank: Super Contributor
timestamp: October 13, 2021, 06:36:52 pm
content: Quote from: Bud on October 13, 2021, 06:31:56 pmTrue. But this thread is about "assymetrical" caps, i.e. caps involving donkeys or glutei. Just as applicable to audiophoolery I suppose!

author: Capernicus
author_rank: Frequent Contributor
timestamp: October 13, 2021, 06:39:06 pm
content: Thanks for that look at your cool book. I always thought I couldn't make my own home-made diodes, but maybe I can, I was always not putting diodes in my circuits because I couldn't make them myself, but that might change, but I think I'll always only use them if I absolutely have to.There seems to be no way to rectify ac with just a wire topology resistors and symmetric caps, because circuits built in this fashion respond identically with the polarity switched either way.It seems to take an assymetric component to get it, no other way.The diode I want to make I need to make just from carbon and electrolyte, (No metal and no metal oxides) I wonder if I can...TOOKI->Capacitive actuators wont budge an inch unless the voltage is increased, they depend apon hi-voltage to create the mechanical movement.Capacitors will store more charge, the more voltage you give them, and they generate a higher amplitude in the circuit, making things more visible, without touching the timing so much.

author: Gyro
author_rank: Super Contributor
timestamp: October 13, 2021, 06:47:05 pm
content: Quote from: Capernicus on October 13, 2021, 06:39:06 pmYou're welcome.QuoteCarbon would certainly work for one electrode, but you need something more reactive (like Aluminium or Tantalum) which can form an insulating chemical film according to polarity.

author: tooki
author_rank: Super Contributor
timestamp: October 14, 2021, 06:20:39 pm
content: Quote from: Capernicus on October 13, 2021, 06:39:06 pmI never claimed otherwise. I was disputing your claim that “static electricity in general is hi-voltage”.Quote from: Capernicus on October 13, 2021, 06:39:06 pmPractically nothing in electronics is visible to the naked eye; that’s why we have test gear.

author: Capernicus
author_rank: Frequent Contributor
timestamp: October 14, 2021, 06:38:21 pm
content: You think test gear is that good, how come quantum scientists keep going on about quantum uncertainty, that they cant even read their own instruments.

author: Gyro
author_rank: Super Contributor
timestamp: October 14, 2021, 06:39:43 pm
content: I though this was lack of understanding, but I'm beginning to smell troll.

author: tooki
author_rank: Super Contributor
timestamp: October 15, 2021, 04:20:21 pm
content: Quote from: Capernicus on October 14, 2021, 06:38:21 pmElectronics isn’t quantum physics. Electricity behaves according to well-understood rules with measurable quantities.Measurement error is a thing, and part of electronics (like any scientific discipline) involves learning when they occur and how to spot them.You aren’t evenremotelyat the point where that’s an issue.

author: tooki
author_rank: Super Contributor
timestamp: October 15, 2021, 04:21:04 pm
content: Quote from: Gyro on October 14, 2021, 06:39:43 pmYeah. My responses are largely for the benefit of any other readers who come along, not the OP.