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Old 10-25-2013, 10:29 PM   #1
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Default BEC Stabilizing Capacitor Specs?

I am getting a high end servo and will be needing a BEC Stabilizing Capacitor, I don't want to buy one as I have hundreds of Capacitors at my house and can easily make one that out performs any I can buy, sadly I don't have a BEC Stabilizing Capacitor to test its capacitance to compare. Would assume its simply 6v, but was farad rating and watt rating are we looking at. Around 50watt is my guess as you want at least twice your expected watt usage and looking at 6v * 3a = 18watts, meaning wanting around 36watt rating, and its easlier to find one rated 50 than 40.
Sorry for rambling, thanks alL!
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Old 10-26-2013, 05:28 AM   #2
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The allowable range of load capacitance for a BEC will vary depending on the BEC design. In general, linear regulators will tolerate more output capacitance than switching regulators.

There is no wattage rating for a capacitor. The nearest equivalent rating would be for ripple current, and this application likely won't require anything special.

Try the BEC without any extra capacitance, then add some if necessary to eliminate glitching with your new servo. If extra capacitance is necessary, make sure you use a capacitor with a voltage rating at least as high as the BEC voltage, then increase the capacitance as necessary to achieve normal operation.
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Old 10-26-2013, 10:48 PM   #3
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Ok thanks!
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Old 10-26-2013, 11:30 PM   #4
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The target to hit by adding a capacitor to the receiver is to gain reliability.

That means that you select a cap that has a rated voltage of 1.5 to 2 times of the BEC voltage. This is a guidline used in engineering also found in the spec sheets of the cap manufacureres.

Next two values to look at are temperature rating and ESR (internal resistance).

I would go for a 105 C rated one with lowest ESR I can get hold of.

Thats something you usually will not find within those parts left over from DIY projects.
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