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Options on Capacitor install location
#1
I have had success with using a low esr cap on the battery leads of a quad for cleaner video.  All the sources say do this where the battery leads attach to the pdb.  Can I just put the cap on any open pads of the PDB?  I would like to move it away from the battery leads for better packaging.  

What's better - putting wires on the capacitor leads and attaching at the battery tie in, or shorter leads on the cap but mounted elsewhere on the PDB?  or does it matter at all.  It seems like it should not matter electronically.
#2
In theory the best placement of the capacitor is as close to the noise source as possible which in our case will be on the escs. But if you are using just one cap, you can put it on whatever pad you want on the PDB as long as it is on one of the main pads (esc, battery etc)
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  • Oscar
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#3
Hello, I have a question, would adding 4 smaller 25v caps to each ESC be better for reducing the noise going into the 5v and 12v BECs from the battery? Or would it be better to have one big cap on the battery before it connects to the BECs?
Also, in the case of 4 smaller caps, would they're voltage protection add up to 100v (25v each) like they're micro farads add up?
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#4
If you have the room on your build, you're better to use 4 smaller caps on the ESCs so as to be as close to the source of noise as possible.  These are what I use
https://www.readymaderc.com/store/index....ts_id=6526


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#5
(07-Jun-2017, 12:25 PM)RazzMtazz Wrote: Hello, I have a question, would adding 4 smaller 25v caps to each ESC be better for reducing the noise going into the 5v and 12v BECs from the battery? Or would it be better to have one big cap on the battery before it connects to the BECs?
Also, in the case of 4 smaller caps, would they're voltage protection add up to 100v (25v each) like they're micro farads add up?

Capacitors in parallel add together, so 4 x 250uF is 1000uF.
The voltage rating of the capacitors does not as the rating applies to each individual component.
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#6
Thanks for the info, is it still benificial to add caps to my mini quad even if im getting absolutely clear video on fpv? Does it help with quad stability and PIDs to function better?
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#7
(08-Jun-2017, 09:47 PM)RazzMtazz Wrote: Thanks for the info, is it still benificial to add caps to my mini quad even if im getting absolutely clear video on fpv? Does it help with quad stability and PIDs to function better?

It won't hurt anything and might save your video camera from any voltage spikes generated by the ESCs and motors during active braking.

It has nothing to do with how the quad handles or how the PIDs should be tuned, it's only about controlling some of the incredible electrical interference that can be generated in a quad.
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#8
(08-Jun-2017, 10:05 PM)unseen Wrote: It won't hurt anything and might save your video camera from any voltage spikes generated by the ESCs and motors during active braking.

It has nothing to do with how the quad handles or how the PIDs should be tuned, it's only about controlling some of the incredible electrical interference that can be generated in a quad.

Sorry to bug you so much, was wondering if you could clarify this, i have this PDB :
http://www.aliexpress.com/item-img/QAV25...96872.html

It seems to have some sort of LC filter on it already although im not really sure if its on the 12v line or 5v line. I use the camera on the 5v line. also i use another LC filter on the 12v line between the PDB and vtx. Would adding low esr caps on the esc's still be benificial to me?

Edit: Boaterguy over at rcgroups.com says it will increase the response speed of the motors?
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#9
(09-Jun-2017, 04:20 AM)RazzMtazz Wrote: Sorry to bug you so much, was wondering if you could clarify this, i have this PDB :
http://www.aliexpress.com/item-img/QAV25...96872.html

It seems to have some sort of LC filter on it already although im not really sure if its on the 12v line or 5v line. I use the camera on the 5v line. also i use another LC filter on the 12v line between the PDB and vtx. Would adding low esr caps on the esc's still be benificial to me?

Edit: Boaterguy over at rcgroups.com says it will increase the response speed of the motors?

An LC filter removes high frequency noise from the power. It is great for getting rid of noise on your FPV video.

A simple capacitor on the ESC helps to suppress high voltage spikes that can be generated by the motor during braking.

Fitting them is entirely optional and many people fly without problems without adding low ESR capacitors to the ESCs.

I have no idea how adding them would increase the response speed of the motors and I have not seen any testing that would support that theory.
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  • Drone0fPrey
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#10
Thanks very much for clarifying the difference between the lc filter and a low esr cap Smile i think ill put some on it just to be safe Smile
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