Fieldlines.com || Make your electricity from scratch!

Front Page - [Homebrewed Electricity-- (wind) (solar) (hydro) (steam) (controls) (storage) (mechanical)] - Classifieds - Site News
Everything - Newbies - [Remote Living-- (housing) (heat) (light) (water)] - Reviews - Diaries - Our Products

caps n more caps
By spinner, Section Controls Posted on Thu Oct 29, 2009 at 10:02:37 AM MST
caps in a voltage multiplier

i have seen many different mfd size caps used in voltage multiplication schemes without really knowing the reason for, say 470 mfd vs 1800 mfd caps, for example.
what is the actual result of using size one or another in a voltage multiplier circuit?
thanks,
spinner

caps n more caps | 15 comments (15 topical)

Re: caps n more caps (3.00 / 0) (#1)
by Flux on Thu Oct 29, 2009 at 11:57:11 AM MST

Voltage multipliers are charge storage based things. If you just want volts then low capacitor values will do. If you want a low impedance multiplier that can handle amps then you need big capacitors. For serious power transfer you need monsters in the 10,000 uf and upwards.

I just don't find these multipliers very useful for other than tiny power levels there are better ways that don't use very expensive capacitors.

Flux

Re: caps n more caps (3.00 / 0) (#2)
by ghurd on Thu Oct 29, 2009 at 12:05:19 PM MST

The larger the capacitor, the more current you can get out of it.
The cap limit is "how many amps" it can hold before it is "full".
Naturally, you can't get 12V amps after the cap is "empty".

From my testing, I'd say it takes BIG caps to do much, and the charging current decreases with every step, so unless the charging current is small (tiny?), it is not worth the effort.
G-

Re: caps n more caps (3.00 / 0) (#3)
by imsmooth on Thu Oct 29, 2009 at 12:59:38 PM MST

I've made a few. I find the 1900uf caps (2 of them) for a voltage doubler work well. Make sure they have the proper voltage rating for your application. I double my wall voltage to 340dc and my caps can handle 900v.
Jonathan

Re: caps n more caps (3.00 / 0) (#15)
by spinner on Wed Nov 04, 2009 at 02:47:43 PM MST

my doubler has 1800mfd caps(2) and always seemed to work well til today (naturally its cold and windy outside!)

i could not see anything wrong when i was outside shivering and looking for my problems cause without much success.

it just now, as i am posting this, dawned on me, yesterday I added a circuit that disconnects my homemade controller that is located outside, from the batteries and
xantrex located inside.

problem i saw was the doubler was not doing much until wind speed begin to come up (took more than normal) and that it seemed prone to move up and down, output wise, more than wind speed changes could explain.

with the caps no longer seeing battery voltage with the unit at rest,& thus staying charged, i wonder if i need to go to, maybe 470 mfd or smaller caps instead?

hmm always something new to mull over<grin>
maybe it will be warmer tomorrow

tks
spinner

[ Parent ]

Re: caps n more caps (3.00 / 0) (#4)
by wooferhound on Thu Oct 29, 2009 at 04:31:24 PM MST

Capacitors are my favorite electronic component, They are so useful for many things and behave differently depending on the application or frequency. I think the most fascinating thing about capacitors is their similarity to batteries except for the instant charging and ease of use.

W o o f -={(
Huntsville Alabama U.S.A.

Re: caps n more caps (3.00 / 0) (#5)
by terry5732 on Thu Oct 29, 2009 at 09:32:49 PM MST

The instant discharge is cooler

[ Parent ]

Re: caps n more caps (3.00 / 0) (#6)
by DamonHD on Fri Oct 30, 2009 at 03:42:43 AM MST

See my doubler here:

http://www.earth.org.uk/wind-power-pilot-autumn-2007.html

http://www.earth.org.uk/CW-voltage-multiplier-for-small-3-phase-turbine-full.gif

I calculated the capacitor size from the AC frequency (guessed initially and wrongly to be one cycle for each turn of the rotor) and the current flow at the rated voltage and power; I chose the capacitors to have the right impedance to allow that current at the speed that the rotor was observed to turn.

Anyhow the tiny turbine seemed to be multipole (if I use the term correctly), ie multiple AC cycles per rotor turn, therefore my caps were conservatively over-sized.

I may be talking out of my beast-of-burden, but the circuit worked for me.

Rgds

Damon

Re: caps n more caps (3.00 / 0) (#7)
by spinner on Fri Oct 30, 2009 at 05:20:50 AM MST

thanks for the reply
part of the reason for my post IS what i saw on the site you posted links to.(my email does not allow me to contact that site, for whatever reason)

I was floundering around, frustrated, trying to visualize what that circuit schematic would look like, if one were to use two block rectifiers instead of separate diodes, when it dawned on me that there are lots of people on this site that would easily be able to do what they always so kindly do: point me in the right direction.

spinner

[ Parent ]

Re: caps n more caps (3.00 / 0) (#9)
by DamonHD on Fri Oct 30, 2009 at 10:52:00 AM MST

If by block rectifiers you mean bridge rectifiers than yes, after mentally jumping through hoops myself I found out that actually it's quite simple: the bridge rectifiers are just 'stacked' as it seems in the diagram: the AC comes into the 'AC in' pins via the various taps in the stack of caps on each side, with the centre stack of caps caps capturing the DC from the + and - outputs of the rectifiers, and these are connected like cells in a battery + output to the - output of the one above, to add the voltages together and get the multiplication effect.

Actually ended up being simpler to build than describe!

BTW, I'm sorry that you couldn't get through to me: did your mails bounce with any sort of helpful error message?

Rgds

Damon

[ Parent ]

Re: caps n more caps (3.00 / 0) (#11)
by spinner on Tue Nov 03, 2009 at 06:25:36 AM MST

yep
message was "non deliverable"
i run into that whenever i try and email a site that uses outlook express and/or similar services
tks for the reply
spinner

[ Parent ]

Re: caps n more caps (3.00 / 0) (#13)
by DamonHD on Tue Nov 03, 2009 at 10:47:54 AM MST

Hi,

FYI: I don't use any M$ code at all. My mail system is sendmail on Linux.

I reject mail for only one of two reasons: either SPAMHAUS.org has noted SPAM coming from your IP address or ISP, or you are trying to send email directly from your machine rather than via your ISP's mail system and your IP address has no reverse lookup.

If either of those is happening then I'm afraid that no one should accept your mail at all, and if you can get any through then it is luck, and insecure recipient mail systems.

May I strongly urge you to check how your mail system is put together, and if your ISP is the culprit and has been marked as handling SPAM, take your custom elsewhere.

Rgds

Damon

[ Parent ]

Re: caps n more caps (3.00 / 0) (#14)
by spinner on Wed Nov 04, 2009 at 02:30:53 PM MST

I think it may possibly be how email2me.net handles email from my machine; it is not thru my isp.
the problem only seems to occur when i try to email someone with outpost or aol mail.
no doubt, as you say, problem is on my end; did not mean to infer anything else.
tks for the reply
spinner

[ Parent ]

Re: caps n more caps (3.00 / 0) (#8)
by spinner on Fri Oct 30, 2009 at 05:34:18 AM MST

thanks to one and all for taking the time to reply to my ?

i have spent nearly a year, when time, money and knowledge didn't get in the way, experimenting with various ways to improve the overall operation of my somewhat odd genny setup.

i have managed to, via lots of experiments, run up against the speed vs torque wall with my dual-helix and its chain driven genny. The latest much simplified controller (relays of course) hehe
seems to be a step in the right direction, however.
like so many others of you, i deal with what geography gives (or takes away) wind wize, it is a great experiment, ain't it?
thanks again
spinner

Re: caps n more caps (3.00 / 0) (#10)
by oztules on Sat Oct 31, 2009 at 02:43:31 AM MST

For the last word in cap loading with windmills (and it is worthwhile sometimes) see this:
http://www.thebackshed.com/windmill/articles/GordonsCapMod.asp

..........oztules

[ Parent ]

Re: caps n more caps (3.00 / 0) (#12)
by spinner on Tue Nov 03, 2009 at 06:29:17 AM MST

tks OZ

bit over my head initially, at least...looks like something i could very much benefit from after spending more time studyin' on it!
spinner

[ Parent ]

caps n more caps | 15 comments (15 topical)

Menu

� create account
� How to use the board
� FAQs
� search the board
� Google search the board

Login

Make a new account

Username:

Password:

Total Views

��97 Scoop users have viewed this posting.

Related Links

� Also by spinner

You must be a registered user to post here. It's easy and free, and the link is on the upper right side of your page.
All trademarks and copyrights on this page are owned by their respective companies. Postings are owned by the poster, but may be deleted or moved at the ADMIN's sole discretion. The Rest � 2009 Forcefield.
You can Email the board ADMIN here. PLEASE include the username you signed up with!