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Apr 29, 2009, 10:33 AM
just Some Useless Geek
Quote:
Originally Posted by richgraf
I plan to use three of the 220 uf Panasonic part# EEUFM1E221
Good choice. Those are 25V, 220 uf, low ESR caps. Panasonic makes good stuff component-wise. There are lots of other choices out there; you just need to search for ["low esr" electolytic capacitor] to find 'em all over the place.
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May 02, 2009, 04:21 PM
Registered User
Quote:
Originally Posted by A Useless Geek
TSK06, the difference is that the motor windings are on the switched, or output, side of the control devices. Back EMF is contained and damped by circuitry within the output stage. The long battery leads create EMF pulses on the input side, which is the power supply for the entire unit. There is no built-in dampening for that.

You'll notice that all ESCs have electrolytic capacitors on the input to dampen some of that inductive pulsing. But as has been previously pointed out in this thread, you need to add more capacitance if you add more lead length.
Thanks for the answering, that makes sense.

Edit: Misunderstood slightly originally.
Last edited by TSK06; May 02, 2009 at 04:41 PM.
May 03, 2009, 12:39 AM
BEC
BEC
Registered User
BEC's Avatar
Good stuff....

Having seen input capacitors explode, I know what the result of ignoring this is.

Thanks for pulling all that info together, Ron.
May 07, 2009, 06:03 PM
Fantasy Scratch Builder
HanW's Avatar
Oke Ron some picts.



















May 08, 2009, 09:20 AM
homo ludens modellisticus
Ron van Sommeren's Avatar
Thread OP
Nice clear pictures Han, dank je But I still don't understand the reason behind the two printed circuit boards. Why not this way, with one pcb?

Vriendelijke groeten Ron
edit: picture/drawing not made by me

Last edited by Ron van Sommeren; May 08, 2009 at 02:28 PM.
May 08, 2009, 10:08 AM
jrb
jrb
Member
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Yes, nice photos!
May 08, 2009, 10:11 AM
just Some Useless Geek
Quote:
Originally Posted by Ron van Sommeren
Why not this way, with one pcb?
Because of the huge conductor planes from using multiple boards. Your layout has a relatively thin copper path with built-in inductance from the length. Using a plane removes some of this and increases the surge current capability quite a bit.
May 08, 2009, 10:22 AM
Registered User
ricoalonso's Avatar
Gentlemen (and ladies):
Is it really 'a must' to use a low ESR capacitor? What would happen if I use a standard electrolytic capacitor?

Thanks,
Rico.
May 08, 2009, 10:28 AM
Magicsmoke maker
Inflexo's Avatar
Rico,

Low-ESR caps allow for handling higher ripple currents, eg a 2200uF 25V low ESR might have about 22mR of "resistance" and handle 2.7A of ripple current. Where's a 'standard' cap can only handle about 1.4A ripple.
May 08, 2009, 10:52 AM
Registered User
ricoalonso's Avatar
pldaniels,
Thanks for the explanation.

Rico.
May 08, 2009, 01:00 PM
Here's a good one for you... (I need to buy some more capacitors...)

The Nitroplanes (Art Tec) F-18 RTF package deal comes with a LOOOOOOONG extension between battery and ESC. 18 inches of extension.

I'm sure its fine at full throttle (which is where you have to fly the palne 100% of the time its in the air the way it comes out of the box)

The supplied ESC is also 30 amp rated... and the motor only pulls 15 amps at full throttle. They may have made up for the capacitance issue (somewhat) by using the oversize ESC.
May 17, 2009, 09:42 AM
homo ludens modellisticus
Ron van Sommeren's Avatar
Thread OP
Measurements by RCGroups user Peter D Rieden
www.rcmf.co.uk/4um/index.php/topic,50366.msg569630.html#msg569630

Vriendelijke groeten Ron
Last edited by Ron van Sommeren; May 17, 2009 at 09:55 AM.
May 17, 2009, 05:08 PM
Registered User

Long Battery--> esc leads


Reading this with interest.
-
I am just about to cobble together 2 x 3s, and 2 x 2s packs to effectively form a 5s2p 4.4Ah pack.
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I will be using the following:-
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http://www.hobbycity.com/hobbycity/s...llel_Pack_lead
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and:-
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http://www.hobbycity.com/hobbycity/s...ries_Pack_lead
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ie...parallel up the respective pairs of like batteries, then series these.
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I will obviously take precautions (ie...close voltages before paralleling etc)
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Having read this post, my situation will be as follows:-
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a) Considering this will be in a hotliner, the throttle will very rarely be anything other than off, or full.
b) You can imagine the sheer amount of wire involved in connecting together all 4 x batteries together, although this will consist of a mixture of series/parallel cables, branching topologies etc, and not just a straight 2-wire run to a single battery.
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Do these points reduce my need for these extra capacitors at all?
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Your input would be much appreciated.
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Many Thanks, Steve
Jul 01, 2009, 01:35 PM
Registered User
sparkie624's Avatar
Subscribe - Good info here.. Thanks to all who have posted.
Jul 01, 2009, 05:00 PM
just Some Useless Geek
"After witnessing the tests the customer withdrew his claim. As a gesture of goodwill the importer decided not to bill the customer for the cost of the controllers consumed, and I then felt that I had to waive my previously agreed fee for the four hours of work."

Out of his mind. Sorry, man -- I gots to eat too, y'know?


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