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Old 01-29-2007, 05:09 PM   #1
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Default Why use a Power Capacitor, Why not a Schottky Diode??

I am looking to find out what applications you use a power capacitor for? And what applications do you use a schottky diodoe for?
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Old 01-29-2007, 05:18 PM   #2
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Power Capacitors stop ripple current from damaging the ESC.

Schottky Diodes stop voltage generated anytime the motor free spins from damaging the ESC.


Always Use Both for forward only racing ESC's of any time. They cannot hurt, only help keep the ESC cooler and running better.
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Old 01-29-2007, 05:28 PM   #3
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from what I understand a power capacitor is used to smooth out a pulsating voltage into a steady voltage. a schottky diode act like a one way check valve, allowing current to flow only one way ( forward bias ), and blocking it in the other (reverse bias ). so the schottky diode stops voltage flow to speed control coming out of the motor, because the motor acts as a genorator when it is just free spinning.
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Old 01-29-2007, 08:47 PM   #4
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In a nut shell,

first of all, they are TWO DIFFERENT THINGS, DO NOT CONFUSE THE TWO!

caps smooth current, protect esc by keeping esc temp low. if you want to know more, search this forum.

diodes protect protects the braking fets and the esc from voltage generated when the motor free spins.

my definition anyway haha
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Old 01-29-2007, 10:56 PM   #5
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Quote:
Originally Posted by Charlie
Power Capacitors stop ripple current from damaging the ESC.

Schottky Diodes stop voltage generated anytime the motor free spins from damaging the ESC.


Always Use Both for forward only racing ESC's of any time. They cannot hurt, only help keep the ESC cooler and running better.
question added to this thread.

are all power caps the same? does it matter what kind of power cap you use on different esc's. can you get them from your local electronics outlet?

for example, a GM V12, or a Novak Cyclone...
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Old 01-29-2007, 11:18 PM   #6
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Not all Capacitors are the save they vary by capacitance (farads) and Voltage. You can get capacitors from you local electronics's dealer just be sure it's the same voltage and capacitance as the one recommended by the ESC manufacturer.
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Old 01-30-2007, 12:15 AM   #7
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Quote:
Originally Posted by subman
Not all Capacitors are the save they vary by capacitance (farads) and Voltage. You can get capacitors from you local electronics's dealer just be sure it's the same voltage and capacitance as the one recommended by the ESC manufacturer.
*scratches head* now what cap was for the gmv12.. eep.

now, are all schottky diodes the same =)

Last edited by RCMits; 01-30-2007 at 12:35 AM.
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Old 01-30-2007, 10:49 PM   #8
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Quote:
Originally Posted by subman
Not all Capacitors are the save they vary by capacitance (farads) and Voltage. You can get capacitors from you local electronics's dealer just be sure it's the same voltage and capacitance as the one recommended by the ESC manufacturer.
OK.. here is a question.

All the caps that came with my GMv12 say 820uf 16v, but the GMV12 Worlds Edition came with a 1000uf 16v. I cant find in the manual what it wants. I have emailed GM about it, and they havent responded.

So........ is it safe to say, if I buy:



or



ill be ok? some say 85c some say 105c (i presume its max temp).

but even MORE confusing now is:

http://www.shopatron.com/product/pro...=NOV5673/135.0

Novak has a 8200uf 10v power cap for "any FWD esc".

Maybe I should just buy that?
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Old 01-31-2007, 06:42 AM   #9
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Quote:
Originally Posted by RCMits
OK.. here is a question.

All the caps that came with my GMv12 say 820uf 16v, but the GMV12 Worlds Edition came with a 1000uf 16v. I cant find in the manual what it wants. I have emailed GM about it, and they havent responded.

So........ is it safe to say, if I buy:



or



ill be ok? some say 85c some say 105c (i presume its max temp).

but even MORE confusing now is:

http://www.shopatron.com/product/pro...=NOV5673/135.0

Novak has a 8200uf 10v power cap for "any FWD esc".

Maybe I should just buy that?
Looks like any you've listed will be OK.
My MRT uses a 1200uf

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Old 02-22-2007, 02:15 AM   #10
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Hai,

My reply probably too late.
But looking at your pics .....
I don;t know about the blue one ... but the brown is totally useless.... It's a common / general capacitor..... Whether you use it or not, doesn;t give you any effect.

The brown one made by United CHemicon old model (new one is SMG series)

Rgds,

Quote:
Originally Posted by RCMits
OK.. here is a question.

All the caps that came with my GMv12 say 820uf 16v, but the GMV12 Worlds Edition came with a 1000uf 16v. I cant find in the manual what it wants. I have emailed GM about it, and they havent responded.

So........ is it safe to say, if I buy:



or



ill be ok? some say 85c some say 105c (i presume its max temp).

but even MORE confusing now is:

http://www.shopatron.com/product/pro...=NOV5673/135.0

Novak has a 8200uf 10v power cap for "any FWD esc".

Maybe I should just buy that?
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Old 02-22-2007, 06:30 AM   #11
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Quote:
Originally Posted by akuhon
Hai,

My reply probably too late.
But looking at your pics .....
I don;t know about the blue one ... but the brown is totally useless.... It's a common / general capacitor..... Whether you use it or not, doesn;t give you any effect.

The brown one made by United CHemicon old model (new one is SMG series)

Rgds,
IMHO the brown one is NOT totally useless. Capacitors differ, while some give you more effect than others, any capacitor will give you some effect. The capacitor you buy needs to have low internal resistance.

About the diodes. Shcottky diodes are not created equal. Some are faster than others and we want the fastest diodes we can get. FYI I just replaced my shcottky diode with TV Damper diode (BY448). I costs more than twice as much but it works just as well if not better.
Other thing about diodes is that you can safely buy low amp diode, 3 amp shottky diode can withstand over 300 amps for couple of milliseconds.
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Old 02-22-2007, 09:09 PM   #12
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Quote:
Originally Posted by andsetinn
IMHO the brown one is NOT totally useless. Capacitors differ, while some give you more effect than others, any capacitor will give you some effect. The capacitor you buy needs to have low internal resistance.

About the diodes. Shcottky diodes are not created equal. Some are faster than others and we want the fastest diodes we can get. FYI I just replaced my shcottky diode with TV Damper diode (BY448). I costs more than twice as much but it works just as well if not better.
Other thing about diodes is that you can safely buy low amp diode, 3 amp shottky diode can withstand over 300 amps for couple of milliseconds.
OK every man has their own opinion. And you're right ... U still can use it but if you compare to power caps from branded product (Novak, LRP, etc) then your cap is nothing compare to them. For me, I always want the best for my electronics gadgets so I don;t deal with such general / common caps or components.

For some passing weeks I try to find some info and this what I've learn so far

1. About capacitor
Check out the capacitor supply by KO Propo ... ELNA RJF series 25V 2700 μF
See the spec and you'll know what I'm talking about.

Alternatively for comparable caps with those branded products (Novak, LRP etc) you can see this site :
http://www.badcaps.net/forum/showpos...44&postcount=4

Another info :
1. Higher volt will have lower ESR
2. Caps put in parallel will increase the capacitance (μF) and will decrease the ESR

About Diode
My reference for diode goes to this site :
http://www.teamnovak.com/tech_info/m...o/schottky.htm

It should be a schottky diode or schottky barrier/power diode, no others .....
The things you should care (as Novak said) is forward voltage (Vf) if you see in datasheet .... It should be close to zero (0,xx)

I've seen your diode spec here .... http://www.ortodoxism.ro/datasheets/philips/BY448_2.pdf
And it's in the range of common diode for Vf.
It works but it's not schottky type ....

Looking at the schottky diode which accompany the ESC (like GM Racing, Novak and others) usually it has a 30A and 25 - 40V. So I'm looking the alternative with those specs. And I found this inside my unused redundant (hot swap) PSU for computer : http://www.ortodoxism.ro/datasheets/...en/mXqwqqs.pdf
I think it's an overkill ... 40V 60A Schottky diode...and I get it for free
I'm happy with it.
I have installed and test it full-throttle unload, and so far okay.
Not try on the circuit yet (with load).... I want to know how's the braking effect

That's all about my experience for capacitor and diode... I hope it's usefull for everyone
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Old 03-16-2007, 01:51 AM   #13
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Due to many unknown brand / counterfeit / fake / re-badge capacitor products,
I've just got this device to measure the ESR of capacitor...

But this device also serve my other purpose as electrician .....

It really helpful to determine the good caps which has the lowest ESR within reasonable price (a.k.a. CHEAP)

You see in the pic... the reading is accurate ..... it's rubycon YXG 25V 680uF rated at 0.046 ohms in datasheet . While this device show ".04". Perfectly matched..

I also have found many interest thing things. Especially with the power caps sold together with the ESC or as optional one .....

Just watch my report ....

Enjoy .... !!!!

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