Using low ESR capacitors *with long leads* to reduce racing drone ESC noise

Hi,

Many people racing drones use low ESR capacitors soldered across the terminals of ESC boards to reduce electronic noise.

Unfortunately for me, owing to the physical layout I'm dealing with, I really need to add perhaps an inch onto the existing half inch capacitor leads so that I can locate the capacitor somewhere appropriate.

Is this acceptable? What about inductance issues? Any ways to obviate these issues?

Also, what should I use for the 'extension lead'?

Many thanks!

Hi,

without values nobody can do calculations for you. Thus you have to do it on your own.

* Decide which impedance you need
* decide the frequency (not the fundamental, but the max overtone)
* then use an online calculator to calculate your extension wire impedance (at the given ovetone frequency)
* then calculate the overall HF impedance (capacitor plus extension)
* then decide if this satisfies your needs.
* calculate the expectable resoance frequency and decide if this may harm your application

Hints:
* twisting the extension wires may reduce impedance.
* place a ceramics capacitor onto the PCB with wires as short as possible.


Klaus

Hi Klaus,

Thanks so much for your help. I have very little experience here, so I have to go by what I see other people using, namely low ESR, aluminium electrolytic capacitors, 35V, perhaps 560-1000 microfarads.

In terms of the type of capacitor, what is the best? You mention ceramic?

Thanks.

Hi,

I see other people using..

Click to expand...

* to see the solution .. you won´t find out the ideas behind it
* this does not mean "other people" do the correct thing

35V, perhaps 560-1000 microfarads.

Click to expand...

These are not the values needed for your first decisions. --> see post#2

in terms of the type of capacitor, what is the best? You mention ceramic?

Click to expand...

* ceramics capacitors provide very low ESR with high frequencies...thus they will have good effect to to reduce HF noise. But you won´t find 35V/100uF ceramics capacitors.
* Low ESR aluminum capacitors provide high capacitance values...but the ESR is way higher than ceramics capacitors.
Each has it´s benefits and drawbacks.

*************
Imagine you have to transport some goods for place A to place B.
What vehicle is best to use?
In your posts above you try to find the solution (aluminum capacitor, ceramics, 10uF ..) without knowing or defining the problem.
* a van (electrolytic capacitor) may be good to transport a ton of apples
* a motorcycle (ceramics capacitor) may be good to transport a letter (faster)
* but if there is water inbetween A and B, then none of the above vehicles is useful.

--> define the problem first, then do the calculations, then find the solution.

***
If you can´t define the problem. (Are you sure there is a problem at all?)
Then the only way is to "trial and error".

Klaus

Many people racing drones use low ESR capacitors soldered across the terminals of ESC boards to reduce electronic noise.

Click to expand...

This rather sounds as the lack of this part which was not originaly added to the board, afterward soldered anywhere close to the connector. Anyway, it is usual to place electrolitic and ceramic capacitors close to connectors which drive power to motors or any other inductive devices.