Looking for a buggy project

[BrianG]

Good answer newe! :)

To add to what he said, the BEC in the ESC is "linear" and can generate a lot of heat depending on load (servos) and main cell count.

And the term "BEC" just means "Battery Eliminator Circuit". The "U" in UBEC is "Universal". Really, the terms BEC and UBEC are interchangable, but when the people here say "BEC", they usually are referring to the ESC integrated one, while if they say "UBEC", they mean the external switching one.

The capacitor is not required, but it does help filter noise out from the power lead, which may help stop potential glitching. And, it also provides a little extra current boost if the servo(s) need it (especially when they begin moving from a stop).

And thanks for the comments. :)

[skeeler]

Thanks for your replies. BrianG, now I see your (U)BEC explanation on your RC calculations site. I guess I needn't have asked. Here's a follow-up question: how does one determine the capacitance required? At what frequency do you find most of the noise?

[BrianG]

I usually just use a 1,000uF rated ~10v. If you are using a heavy duty servo, you could go up to 4,700uF, but the cap will be physically bigger.

Most of the noise will probably be at whatever the BEC switches at (I've seen anywhere from 20kHz to 250kHz) and will be most evident at higher loads. And since this BEC also supplies DC power to potentially sensitive receiver circuits, I take no chances. :)

[skeeler]

BrianG,

Thanks for the reply. What weight distribution did you strive for when assembling this buggy? I assume you wanted equal port/starboard, but did you aim for equal fore/aft, or did you want more weight on the rear wheels?

[BrianG]

I was shooting for almost perfect right/left distribution than fore/aft. But the amount of space under the canopy was a limiting factor in front as well. The ESC and receiver are about as high as I can go before it starts hitting the shell. I figure I can tweak the spring preloads for the weight and then compensate for less-than-ideal jumping attitude by tappign the brake or whatever.