Drive a rc brushless motor. at DVinfo.net

Lau Ho Ming · June 8th, 2008, 04:52 AM

I'm planning to make a spinning adapter using a small rc airplane brushless motor. I know it requires some kind of circuit to drive it. So can I just buy a cheap brushless esc to drive it?
I wonder how the receiver give signal to the esc to spin the motor. If we could provide a constant "Drive" signal to the cable connecting to receiver. Then the esc will spin the motor.

Rich Hibner · June 8th, 2008, 03:40 PM

lau, i'm not sure what DC motor you're referring to, but the ones i have experienced with, all move when just hooking the recommended battery up to it. no circuit to drive it.

that's a servo i believe you're thinking of. that only moves 90 and 180, sometime 360 degrees.

check some of these out:
http://www3.towerhobbies.com/cgi-bin...3p?&C=CKA&P=ML

Bob Hart · June 8th, 2008, 05:53 PM

Brushless motors for scale aircraft can be made to work but it does require an extra box to be made up. I had one hand-made up over here to drive two of the larger scale motors to spin gyros.

Operating the controller is not as simple flicking a switch and it does not start instantly. It has to calibrate itself on power-up. Once you are powered up, then the controller works instantly.

I would favour staying with the CD motors for home builds.

Lau Ho Ming · June 8th, 2008, 07:47 PM

Yes. That's why I'm thinking about cheap brushless esc(Cheap one. Since we don't need all those fancy function). And find some way to mimick the signal from the receiver. Then the motor will spin continuously.

I'm aware of the quality of CD motors. Does it provide enough torque and speed? And how to mount the non-CD GG disk on the motor?

Rich Hibner · June 8th, 2008, 08:33 PM

I have no idea what motors you guys are used to, but this motor here, will spin freely with just a battery....it's rpm's are at 6000 and plenty to spin a disk. same make as habuchi, the disk motors.

what motors are you guys talking about where you'll need to mimic the signal?

Lau, how fast do you need the adapter? I'm going to post a video tutorial, hopefully at the end of the month for a spinning 35.

http://www3.towerhobbies.com/cgi-bin...&I=LXSR92&P=ML

Lau Ho Ming · June 9th, 2008, 06:22 AM

The motor I'm talking about is a brushless motor. Like the one in the picture. The one you are refering is a DC brushed motor.

But anyway. Is it a good idea to spin the GG with a high quality brushless motor than using a simple DC brushed motor?

http://www.kanamx.com/uploadpic/20084162211266513.jpg

Rich Hibner · June 9th, 2008, 08:43 AM

don't know if there's a difference besides the price.

Take Vos · June 9th, 2008, 11:12 AM

An brushless ESC for radio controlled models receive a PWM (pulse width modulation) signal from the receiver. You also have ESC (not for RC-models) which has a voltage input to control the speed, here you could simply use two resistors in a voltage divider circuit.

You could also control it yourself directly using a AVR or PIC controller:
http://www.atmel.com/products/AVR/mc...?family_id=607

A brushless motor is basically a stepper motor with only three steps. They run much cooler, use less power and live much longer (no sliding contacts).

Lau Ho Ming · June 9th, 2008, 11:58 AM

Wow.Where can I get a ESC that use voltage input then?

I can get a rc brushless motor for airplane with a very cheap price here.

Ben Winter · June 10th, 2008, 11:32 AM

I don't think there's a need for a brushless motor in this application. You're not driving airflow here--you're just spinning a piece of glass which is a pretty simple load for something like a typical brushed motor.

Good luck if you do take this path, but if I were you I wouldn't want to overcomplicate things.

Rich Hibner · June 10th, 2008, 01:20 PM

You said it Winter.

Lau Ho Ming · June 11th, 2008, 01:59 PM

You are right. Another question is that how to mount the GG perfectly on that motor shaft? I can't really figure out how to mount it. I'm not worrying about the centering problem. I just want a way to stick the GG firmly to the shaft.

Bob Hart · June 11th, 2008, 05:34 PM

Brushless RC motors comonly mount the props to a plain shaft with a compression collet arrangement which takes care of both centering and alignment of the propellor.

These motors are loaded along the shaft axis in tension as well as torsionally in their normal application. The collet sits well out on the shaft. An adaptor disk loads the motor shaft torsionally only. A loaded prop pulling forward, to some degree wil dampen an out-of-balance state. Slight aerodynamic differences in each blade will introduce forces which behave like an out-of-balance state. The airframes are built to take it.

Combined 35mm adaptor/camera structures are not.

If you have a disk that is not true for centre, it will run out of balance and sitting well forward, gives it a lot of leverage over the motor mounts.

At best it will only run out across the focal plane and soften the focus. More likely it will do this AND shake the whole appliance-camera combination. It takes little vibration to introduce a vibration artifact to an interlaced imager or a rolling shutter imager.

Centering is important.

Some of the RC motors are called "outrunner" motors. Some of these have a shorter shaft on the opposite end and a flange face with axial screw holes which might make for easier fit up.

Whichever way you go, there is some custom machine work to do.

June 8th, 2008, 04:52 AM	#1
Lau Ho Ming Regular Crew Join Date: Nov 2006 Location: Hong Kong Posts: 81	Drive a rc brushless motor. I'm planning to make a spinning adapter using a small rc airplane brushless motor. I know it requires some kind of circuit to drive it. So can I just buy a cheap brushless esc to drive it? I wonder how the receiver give signal to the esc to spin the motor. If we could provide a constant "Drive" signal to the cable connecting to receiver. Then the esc will spin the motor.

June 9th, 2008, 11:12 AM	#8
Take Vos Major Player Join Date: Mar 2007 Location: Amsterdam The Netherlands Posts: 200	An brushless ESC for radio controlled models receive a PWM (pulse width modulation) signal from the receiver. You also have ESC (not for RC-models) which has a voltage input to control the speed, here you could simply use two resistors in a voltage divider circuit. You could also control it yourself directly using a AVR or PIC controller: http://www.atmel.com/products/AVR/mc...?family_id=607 A brushless motor is basically a stepper motor with only three steps. They run much cooler, use less power and live much longer (no sliding contacts). __________________ VOSGAMES, http://www.vosgames.nl/ developer of Boom Recorder and Mirage Recorder

June 10th, 2008, 11:32 AM	#10
Ben Winter Trustee Join Date: Jun 2005 Location: Hollywood, CA Posts: 1,675 Images: 1	I don't think there's a need for a brushless motor in this application. You're not driving airflow here--you're just spinning a piece of glass which is a pretty simple load for something like a typical brushed motor. Good luck if you do take this path, but if I were you I wouldn't want to overcomplicate things. __________________ BenWinter.com

June 11th, 2008, 05:34 PM	#13
Bob Hart Inner Circle Join Date: Dec 2003 Location: PERTH. W.A. AUSTRALIA. Posts: 4,477	Brushless RC motors comonly mount the props to a plain shaft with a compression collet arrangement which takes care of both centering and alignment of the propellor. These motors are loaded along the shaft axis in tension as well as torsionally in their normal application. The collet sits well out on the shaft. An adaptor disk loads the motor shaft torsionally only. A loaded prop pulling forward, to some degree wil dampen an out-of-balance state. Slight aerodynamic differences in each blade will introduce forces which behave like an out-of-balance state. The airframes are built to take it. Combined 35mm adaptor/camera structures are not. If you have a disk that is not true for centre, it will run out of balance and sitting well forward, gives it a lot of leverage over the motor mounts. At best it will only run out across the focal plane and soften the focus. More likely it will do this AND shake the whole appliance-camera combination. It takes little vibration to introduce a vibration artifact to an interlaced imager or a rolling shutter imager. Centering is important. Some of the RC motors are called "outrunner" motors. Some of these have a shorter shaft on the opposite end and a flange face with axial screw holes which might make for easier fit up. Whichever way you go, there is some custom machine work to do. Last edited by Bob Hart; June 11th, 2008 at 05:40 PM. Reason: error

June 8th, 2008, 03:40 PM	#2
Rich Hibner Major Player Join Date: Jan 2006 Posts: 218 Images: 1	lau, i'm not sure what DC motor you're referring to, but the ones i have experienced with, all move when just hooking the recommended battery up to it. no circuit to drive it. that's a servo i believe you're thinking of. that only moves 90 and 180, sometime 360 degrees. check some of these out: http://www3.towerhobbies.com/cgi-bin...3p?&C=CKA&P=ML

June 8th, 2008, 05:53 PM	#3
Bob Hart Inner Circle Join Date: Dec 2003 Location: PERTH. W.A. AUSTRALIA. Posts: 4,477	Brushless motors for scale aircraft can be made to work but it does require an extra box to be made up. I had one hand-made up over here to drive two of the larger scale motors to spin gyros. Operating the controller is not as simple flicking a switch and it does not start instantly. It has to calibrate itself on power-up. Once you are powered up, then the controller works instantly. I would favour staying with the CD motors for home builds.

June 8th, 2008, 07:47 PM	#4
Lau Ho Ming Regular Crew Join Date: Nov 2006 Location: Hong Kong Posts: 81	Yes. That's why I'm thinking about cheap brushless esc(Cheap one. Since we don't need all those fancy function). And find some way to mimick the signal from the receiver. Then the motor will spin continuously. I'm aware of the quality of CD motors. Does it provide enough torque and speed? And how to mount the non-CD GG disk on the motor?

June 8th, 2008, 08:33 PM	#5
Rich Hibner Major Player Join Date: Jan 2006 Posts: 218 Images: 1	I have no idea what motors you guys are used to, but this motor here, will spin freely with just a battery....it's rpm's are at 6000 and plenty to spin a disk. same make as habuchi, the disk motors. what motors are you guys talking about where you'll need to mimic the signal? Lau, how fast do you need the adapter? I'm going to post a video tutorial, hopefully at the end of the month for a spinning 35. http://www3.towerhobbies.com/cgi-bin...&I=LXSR92&P=ML

June 9th, 2008, 06:22 AM	#6
Lau Ho Ming Regular Crew Join Date: Nov 2006 Location: Hong Kong Posts: 81	The motor I'm talking about is a brushless motor. Like the one in the picture. The one you are refering is a DC brushed motor. But anyway. Is it a good idea to spin the GG with a high quality brushless motor than using a simple DC brushed motor? http://www.kanamx.com/uploadpic/20084162211266513.jpg

June 9th, 2008, 08:43 AM	#7
Rich Hibner Major Player Join Date: Jan 2006 Posts: 218 Images: 1	don't know if there's a difference besides the price.

June 9th, 2008, 11:58 AM	#9
Lau Ho Ming Regular Crew Join Date: Nov 2006 Location: Hong Kong Posts: 81	Wow.Where can I get a ESC that use voltage input then? I can get a rc brushless motor for airplane with a very cheap price here.

June 10th, 2008, 01:20 PM	#11
Rich Hibner Major Player Join Date: Jan 2006 Posts: 218 Images: 1	You said it Winter.

June 11th, 2008, 01:59 PM	#12
Lau Ho Ming Regular Crew Join Date: Nov 2006 Location: Hong Kong Posts: 81	You are right. Another question is that how to mount the GG perfectly on that motor shaft? I can't really figure out how to mount it. I'm not worrying about the centering problem. I just want a way to stick the GG firmly to the shaft.