Let's Make Robots!

Wiring up a brushless motor


So I was in awe at jklug80's "cheater" pinewood derby car and this year my son's pack is doing an anything goes class for the dads.  My thought was to use a ducted fan to push the car but I can't figure out how to wire it up.  

It's a brushless ducted fan for rc planes and it requires an esc that receives a signal for how much "throttle" to shoot to the motor.  So how would I wire it up on the same set of switches he used?  Basically I want it either off, or all in.  I completely understand Jklug80's use of switches, I just don't know how to wire the esc up to it.

Also, do you guys and gals have an idea on a cheap, lightweight batter to supply either 11.1 V, 29.8 amps or 12.6 V, 35.3 amps?

Or am I asking for a miracle?

Thanks for all your input in advance, this site is awesome.





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So I have gotten a Ti Launchpad ($4.30 is awesome for the kit!) and have programmed it in C to generate a PWM signal with the 2ms on followed by 20ms off...but I still can't operate the motor. 

A little recap:

DC brushless motor


LiPo battery

and i am sending the output of the chip to the signal wire of the ESC (that would come from the RC reciever)


Any ideas?


If you're needing a PWM frequency of 1/20ms, you're off time should be 20ms minus your pulse width of 2ms, or 18ms.

Some of them need an arming sequence. It's a safety feature to keep your from chopping up your fingers while wiring. Usually that is some period (a second or so) of lower frequency pulses. Many of the ESC units (probably most at the voltage/amerage you are working) will beep when armed.

I just re-read my post. I used the wrong word, which is a big mistake there. Try 1 second of 1ms pulses to arm. If that doesn't work, try 1.5ms and then try 500 microseconds...

Probably the smallest, easiest way is to use a picaxe 08M and the servo command. Arduino also has a servo command. Otherwise there are simple circuits on the internet that use a 555 timer to generate a suitable signal.

Google "servo 555" and you will get links like this:

So could I use a PWM hooked to the ESC?  

If so, how does that work?  Are they programmable or do you order the one with the right pulse?  I assume that the switches would turn the PWM on and off?


Thanks for your help!

P.S. - That trike is awesome, I hope my fan sounds as mean as yours did!

The ESC will need an input signal the same as a servo. Full throttle would probabbly be a 2mS pulse every 20mS.

I don't know about cheap, you will really need a LiPo battery capable of delivering the power you need.

You will end up with something like my Drifting Turbo Trike.