MMM to power Robostix

[BrianG]

Sounds good, but I would suggest adding something to the BEC if you plan on using a switching one. Switching BECs can fail and if they do, will send full battery voltage to the brain.

Depending on the optimum brain voltage, main supply voltage, and brain current draw, you could either use a linear regulator running off the battery (but the current would have to be around 100mA tops for ~15-20v main supply).

Or, attach a low dropout type set to 5v at the output of the MMM BEC. The BEC would be doing the majority of the stepping down, but the LDO linear reg would serve as a protection device if the BEC went bad. To keep current to a minimum, you could just feed the brains through this, and leave the MMM's BEC as-is to power other things.

good to know, I'll look into that

On a positive note, the battery source I am using with the robostix is 7.4, which is within the limits of the robostix. So, if the voltage did run away, I'd only have to worry about other devices on the PWM headers, but it's good to know I should think twice about plugging in a 6S LiPO ;-)

I have a 1800kv motor in my Slash so I can fly at 6S, and putt putt at robo speeds on 2S.

Originally Posted by BrianG

Sounds good, but I would suggest adding something to the BEC if you plan on using a switching one. Switching BECs can fail and if they do, will send full battery voltage to the brain.

Depending on the optimum brain voltage, main supply voltage, and brain current draw, you could either use a linear regulator running off the battery (but the current would have to be around 100mA tops for ~15-20v main supply).

Or, attach a low dropout type set to 5v at the output of the MMM BEC. The BEC would be doing the majority of the stepping down, but the LDO linear reg would serve as a protection device if the BEC went bad. To keep current to a minimum, you could just feed the brains through this, and leave the MMM's BEC as-is to power other things.