MMM UBEC option

[BrianG]

Well, I'm not going to argue with an expert. I'm just going by the reports I've read. I've had one UBEC die (not yours) and it just stopped working by outputting 0v (actually, closer to 0.5v). I just figured a switcher "IC" had various disaster compensation built-in (overload, thermal, etc) compared to a discrete design like the one in the CC BEC. At any rate, this mod was to prevent the MMM BEC from powering any external load to [hopefully] prevent it from dying.

[lxmuff]

I have 2 MMM that I have been doing some hard racing every weekend since they came out. The fan worked for one qualifier. The blades broke or got hung up. I modded the fan to not hit the shroud and have been powering the fan directly off the main battery while the internal bec powers the rx and servo. They both still run fine on the truggy and the buggy.

[BrianG]

Patrick, I just re-read your post, and want to add that the KoolFlight UBEC does not use an external FET. The entire circuit (minus input/output caps, coil, main diode, etc) are all on one IC. To be specific, the LM2596 switching IC. It's the same chip many UBECs are based on, but it works very well. Some of the cheaper UBECs that use this same chip tend to overheat and are noisy, but they are smaller and use a smaller coil, so obviously choice in support components makes a difference even with the same basic circuit. I haven't heard where a BEC of this type fails by sending full batt V...

I'm not trying to rag on the CC BEC. I use one in my Hyper8 and like it a lot. Small, powerful, and programmable. I just didn't have an extra when I did this mod, or I would've probably used it for size alone.

Speaking of this type of failure; are there any plans to release a version that contains a circuit to disconnect the output if it exceeds, say, 9v? I know it can be an add-on circuit, but I don't have the resources to make a small surface mount one. Just curious...

[magman]

Brian...took your advice about rewiring the fan to run off of the rx. Also I am running a ccbec so hopefully, that should help w/the bec issues for now.....we shall see. Thanks for you help..

[BrianG]

Added a note to the original post about programming via the Castle Link...