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Old Oct 29, 2012, 02:48 AM
inside joke, inside my head
GySGT Fenix's Avatar
New Zealand, Canterbury, Christchurch
Joined Jul 2012
31 Posts
Help!
Running brushless motor without r/c gear

I was thinking of making a long range dartgun that propelled the darts by pushing them through multiple flywheels. I was thinking of using brushless motors because i can get cheap ones with more power than brushed motors of the same price.

my question is can you power a brushless ecs without the transmitter/reciever thingy and is it possable to to remove the ECS completly.

After looking round the forums i have found out that it is not advised to run more than 1 motor of a single ECS so that kinda sts on the idea of only one ecs for the 10 or so motors i want to run.

any info would be helpful.
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Old Oct 29, 2012, 04:40 AM
Registered User
Georgia
Joined Jun 2007
682 Posts
It's not possible to do without an electronic speed control. A servo tester can be used to generate the control pulse that goes to the speed control(s). The brushless motors are basically an a/c motor operating at a frequency much higher than 60Hz. It can be possible to operate more than one motor from a sufficiently sized speed control. There is a relationship between the number of poles and the motor RPM. (More poles, less rpm from the same drive frequency/pulse rate.) Both the motors and the speed control should be lightly loaded. Anything like a flywheel would have to be sized such that the particuliar motor represents sort of an equal load to the other motors.

Separate speed controls are really preferable.
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Old Oct 29, 2012, 04:58 PM
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United States, MD, North East
Joined Apr 2011
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To add to the above post, you can use an arduino board to control your esc's (arduino uno is the cheapest, ~ $30) and write a simple program that will trigger your ESC's to make the motors spin with a button push or something like that. Could be a fun project and you will learn a lot...
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Old Oct 29, 2012, 05:09 PM
Wake up, feel pulse, be happy!
C₄H₁₀'s Avatar
United States, AK, Fairbanks
Joined Aug 2009
12,455 Posts
You can use one of these to control the ESC and motor.

The motor cannot be run without an ESC, though. The ESC handles the task of commutation for the motor. A brushed motor performs its commutation internally by means of brushes and a commutator, which allows it to run straight off a source of DC voltage. The brushless motor simply replaces the mechanical commutator with an electronic one (the ESC).
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Old Oct 30, 2012, 03:09 AM
inside joke, inside my head
GySGT Fenix's Avatar
New Zealand, Canterbury, Christchurch
Joined Jul 2012
31 Posts
so i need the esc but how do you create the signal pulse with a microcontroller like a picaxe chip or the arduino thing that was mentioned.
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Old Oct 30, 2012, 04:28 AM
Wake up, feel pulse, be happy!
C₄H₁₀'s Avatar
United States, AK, Fairbanks
Joined Aug 2009
12,455 Posts
The $2.26 servo tester in the link I posted will generate an appropriate signal pulse for the ESC. You CAN use a microcontroller or some other clever way of doing it, but if you just want simple manual control of the system, the servo tester is really all you need.
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Old Oct 30, 2012, 07:59 PM
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Australia, VIC, Melbourne
Joined Feb 2010
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Quote:
Originally Posted by GySGT Fenix View Post
so i need the esc but how do you create the signal pulse with a microcontroller like a picaxe chip or the arduino thing that was mentioned.
The signal is a 1-2ms pulse repeated 50 times a second. 1ms is ~0% and 2ms is 100% (this varies a little, but you can calibrate ESCs to match). Pulse should be 5V but there is a good chance 3.3V will work too.

You can easily generate this signal using PWM libraries for uCs you just use a very short duty cycle on a very low frequency signal (50Hz with a 2-4% duty cycle). I have done this my self, no need to use HW PWM units as it is a very slow signal.
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Old Oct 30, 2012, 09:13 PM
The Prez....... again
kenh3497's Avatar
United States, IA, Rockwell
Joined Jul 2011
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wrong thread
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Last edited by kenh3497; Oct 30, 2012 at 09:25 PM.
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