[BrianG]

Originally Posted by VintageMA

That's a logical and pretty simple design, but it's been a long time since I etched a circuit and would have to spend as much on chemicals and supplies as buying one of those linked ones. Also - wouldn't the transistor have to support the full battery voltage so that it doesn't burn out just from overvoltage across terminals?

yeah, etching is a PITA if you don't have the stuff already. I would just breadboard it with the pre-clad PCB found at radioshack. There is a minimum amount of components so it should be clean. If you start adding things like status LEDs, and other fancy stuff, the circuit gets bigger. Enclose the whole thing (except the switching transistor/FET) in epoxy or something for protection.

And yes, the output transistor/FET would have to be rated for the battery voltage you plan to use and the max current you plan to draw. The good news is that ratings for 40v+ and ~10A are not difficult to come by.

Originally Posted by slimthelineman

i have a dumb question for you guys, the MMM bec doesnt happen to have the same problem with passing input voltage through when it fails as does the cc bec?

It would depend on the design. IIRC, the MMMBEC also uses a discrete BEC design (as opposed to a BEC circuit IC like most BECs use). Patrick has said that ANY BEC that utilizes a discrete switching FET is subject to this type of failure. So, I would say that it is a possibility. However, we don't know exactly how the CCBEC fails to make it do that, so it's difficult to know if the same thing would happen to the MMM BEC.

Originally Posted by lincpimp

I may be barking up the wrong tree, but is there any way a fuse of some sort could be added to the output? If it blows then the ccbec is toast anyway. I have played with the small buss fuses (slow blow) in my Cerwin Vega tower speakers... would something like that work? I know that fuses are usually used for over current purposes, any chance they could be used for over voltage?

I only ask as I have about 10 of the ccbecs, and all run $50+ receivers and $110+ servos. I can only imagine the flame that I would produce if one of them cooked either component.

I am a die hard cc user, but may have to move these becs along if they are questionable.

A fuse is for over-current protection. We need over-voltage protection. The only way the fuse would help is if the CCBEC failed, sent full B voltage to the devices, and those devices pulled a lot more current. But, if that happens, the damage is already done. Many devices are voltage sensitive with little or no actual current flow. The only way I see to protect your expensive receivers/servos is to use an external voltage-sensing switch.