Any comments from our electronic experts?

Coan Gerber
Anyone know what brushed esc will handle a 36volt brushed motor? Wil run it on 4s but have no clue if there is an esc that will handle it brushed?
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James Garvin get a brushless esc you can put a brushed motor on it just use 2 of the wires
12 hours ago · Like

Coan Gerber thanks
12 hours ago via mobile · Like

Vikramaditya Chaudhury James - seriously - will that work? If that be the case, I am learning something new. Something that will save a LOT of woriies in future. PLEASE CONFIRM.
11 hours ago · Like

James Garvin yes i have done it and i know someone that has their scx10 like that right now you just have to figure out which wires to use
11 hours ago · Like

Sanjay Rai Wonder why Hobby stores sell brushed ESCs then
A few seconds ago · Like

Won't work - a brushed motor is a DC motor where as a brushless motor
is a ac motor - maybe Kalyan can chip in with a more technical explanation - I
would be happy to be proven wrong.

There are car ESCs that can run brushed and brushless but the highest rated one I know of can go upto 6s.(Not really useful when you have a motor rated for 36V)

A brushless only ESC cannot run a brushed motor.

I thought that the motors that we use are DC Brushless. Now I am confused, and after reading this: http://www.rcgroups.com/forums/showthread.php?t=609591 - I am completely nonplussed. Beware, it is written mostly in Greek and Latin..........

Brushless ESC will not power Brushed motors. BLDC motors (explains they're DC motors - detailed explanation below) need their coils to be activated in a sequence and voltage difference between two 'active' wires to work, brushed on the other hand only need a voltage difference in the two wires to run, both the wires are always 'active'

In the case of Coan, the gentleman will not get adequate rpm. The motor runs at a highest voltage of 36v which means, it will get best speed at 36v and enough torque. 4s will only amount to 14.8 v which is less than half of 36v.

Here's my explanation at demystifying the AC/DC confusion:

In simple words:

1. All motors are AC.
2. AC motors - the current alternates automatically so no conversion required
3. Brushed - batteries provide dc; To run from battery, the current must be converted to AC, conversion done mechanically
4. BLDC - batteries provide dc; To run from battery, the current must be converted to AC, conversion done electronically, since nothing is moving to change the contacts, there need to be more than one coil that can take care of in-between positions.

Further Explanation:

Magnets repel magnets or magnet attracts another magnet. magnetism of a coil depends on the direction of current. So if a coil is revolving, it is changing orientation and once it reaches 180 degreees, to maintain the magnetic polarity the current must be reversed. Due to the nature of Alternating Current (AC), this inversion happens automatically. This is an AC motor. current is automatically switching  (due to its alternating nature) so the motor goes on and on. Conceptually, a motor can only work on AC

But since batteries provide DC current, someone brilliant decided to attach the battery contacts to the commutator in such a fashion that  when the commutator revolves 180 degree, the brushes get inverted, mechanically alternating the current. The source current is still DC but what the motor sees is AC (and hence runs). DC to AC conversion is mechanical.

Brushless motors do not have a rotating commutator, only free magnets that start rotating due to attraction/repulsion, so mechanically contact switching is not possible. Again, someone brilliant thought of keeping the contacts fixed and have more than one coils inside, and wired up an electronic circuit (friendly name: ESC) that would electronically switch on and switch off current in the right direction to the coils so the magnets rotate. The source is still DC, the motor sees it as AC. The conversion is electronic.

Like all disciplines know to man, the story does not end here, other factors settle into the equation. but I feel this should satiate the introduction

Kalyan da, request your inputs.

Well, Brushless motors (standalone) are essentially AC motors as they work on PWM signals from ESCs.

There is a design differentiation aspect here, "brushed" DC motors have rotating winding and the commutator contacts keep changing the magnetic field as they rotate, hence creating the inertia and further movement. hence, ideally the current with the 2 inputs (+ve & -ve from DC source), which the commutator passes these to the "moving" rotor acts as changing the field forces enabling the motor to move.

In case of brushless motors, as the electrical contact is static (winding is static) i.e. no moving of winding or changing/switching of current through the windings take place, this is acheived electronically using ESCs which are essentially PWM current signal generators, the switching rate (hence the width of PWM wave) changes when we throttle up & down.

I have tried a bit to explain this using one slide. Sorry about my creativity here in limited time, I have drawn a line to explain the AC & DC part in the attached picture.

Actaully it depends what you consider an motor to quality as AC & DC, the line seperates the AC & DC part.

PS- ideally brushless motors are always associated with external circults (PWM) to run, hence if we consider a "Bushless motor unit" (comprising of Motor + PWM circuts) as one entity, certainly its "DC Brushless motor" then, if we consider this as standalone entity (without PWM circuit), its an AC then.

Thanks.

They are called DC Brushless because it is run using LOW voltage DC batteries, unlike AC motors which are designed to run on AC.

However they can run only with a ESC without which it cannot run on DC supply. ESC in effect is supplying AC to the Brushless motors. Most of the RC Motors are with 3 phase windings which runs on non sinusoidal three phase AC supply produced by ESC.

You can run the Three contact Commutator DC motor using Brushless ESC. if you are able to remove the rotor which has the windings and three contacts and fix it as stator. Solder the three wires of ESC to the three contact of the commutator. Put the outer Can with magnet on the same axes on a bearing fix load shaft to it. Then with the brushless ESC you can run the same DC motor.

In case of a Brushless DC motor commutation is done by ESC. Even in DC Motors the current inside the coils of the rotor is AC which is achieved by commutation with help of brushes.

Typical three contact commutator cross section where the rotor is in the center with load shaft. Make the rotor as stator. fix three wire of ESC to the three contacts of the commutator. when you supply through ESC the Outer Can with Magnet will rotate as rotor.

DC cannot run motors which changes rotation by 180 degrees with every 1/2 rotation. which is a phase change in itself.

DC can only produce a electromagnet with fixed poles in one direction. To change the direction of Poles of electromagnet, the direction of DC has to be changed for every 180 degrees of rotation, then it becomes a AC. Its no longer a DC.

Hi ..

I am sure people know the fundamental principle that AC current can be very easily converted to a DC using a couple of DIODE or a diode bridge while this can not be done so easily the other way round, to convert DC to AC we need more complex circuits..

so...

the thing is mainly if you are able to run a DC (brushed) motor on a regular ESC ..

and that is the concern of flyers if they are able to do so or not.. 

DC Brushed motors on Brushless ESC?

Not without modifications.

Food for thought for all.

If the ESC is producing AC. If it is given through  6 diode Rectifier Bridge. Can it run a DC motor?

 

Hmmmm. A lot of theory and jargon flowing here. Unfortunately, the conversation is not meant for idiots - so I can't participate constructively. However, before we shoot James Garvin, Esq., no matter how implausible it may sound - has anyone tried it practically?

Probably, I being the least educated, will try it. Keep you all posted.

VC Bhai    yes you can 

It looks like I've stirred up a hornet's nest here! 

VC sir! Just do it!

After all you have nothing to lose but your motor......and you have plenty DC BMs 

"If ya ain't got the ejucation - make Google yer best pal........." VC 2013

Check the first and last replies on this page:

http://www.rctech.net/forum/radio-electronics/458618-brushless-esc-brushed-motor.html

So the ejucation finally says it may, or may not 

We don't need no ejucation
We don't need no thought control

VC sir no offence but when i hear ejucation something awkward comes in my mind.
So if you know what i mean i think plain education would be a lot better .

Dirty mind.........

Nothing awkward about it laddie - its all about growing up. Perfectly normal at your age - the wonder of it is, that these awkward moments will 'arise' well past middle age and perhaps, well into old age..................hopefully..........

Amazing things these raging hormones in teenagers. Even a dry subject like ESCs.....

It might be coz im a teen but education is better its like if you put mandatory as mandatery
its a bit awkward. 
Well anyway its after all you saying. Pink Floyd just rocks!!!
Sanjay sir the subject was esc but my point was on vc sirs saying
No offence anyone

 

Before the effects of raging hormone distracts our no so young teenagers   away from the subject let me get all of you back to the topic at hand.

There is a thread dedicated in rcgroups on how to convert a coreless brushed DC motors to a brushless motors. I am still searching for it.



I deliberately planted this here to get you guys thinking, will it actually work knowing that all Brushless ESC of RC which are not dependant on sensors for timing, whose timing is controlled by the feedback from the back EMF of the motor.

I think one has to try it out to find out.

Woah so much happened here while I sipped on about 10 cups of coffee...mood for the coming weekend is already settling in.

Sandy sir, looks doable with a 6 diode bridge. Only my gut feeling is one would need high speed switching (fast recovery) diodes like FR301. simpler ones like IN4001 might not cut it.

Original point still remains, not without modifications.

What happens when we remove one wire of ESC out of the three. No reaction on motor since no feed back from motor. So will a Diode rectifier actually work?  >

Like you correctly said, one has to wire it up to see the effects. At the outset I feel latkas and jhatkas for the motor or motor stalls will occur. Btw, why would you want remove the wire if everything worked... pange, huh?  

I'm already smelling poofed up p-n junctions, or perhaps its the coffee

No you are getting me wrong. I was referring about one of methods to prevent a connected ESC from spinning motor is to disconnect one of the three wires. There will be no latkas or jatka. Motor will behave dead. But you can hear tones of programing 

Why do you intelligent big wigs have to rely upon the old idiot to show you the way? Now stop talking and get down to work:

Not without modifications  VC.  I watched whole video thinking its some method without modifications. There is a part -II and part -III also.   

VC sir,
Because we love grampa.

don't know about Sandy sir, but I totally have a receding hairline, so the wig is necessary...lol

I could barely hear any audio in the clip, but from the looks of it he is trying to make a ESC programming connector so he can reprogram it for brushed. The 6 diode suggested by sandy sir, is a generic solution which will not require one to mod existing ESC but will sit between the ESC and the motor

Sandy sir, got what you mean.

Girish sir cant we reflash the esc to run on brushed?
Anyway, a brushed motor needs DC power whilst brusless need ac to commute. With direct DC brushless motors have no way of commuting. While brushed motors have a mechanical commute. So direct current is used this is what i understood. So either we remove the FET's from the esc to stop switching or convert the ac back to DC with a bridge rectifier like sundaram sir said. Or if we could reflash it to run brushed.

Sandy sir's idea seems doable without any modding/opening ESC...I believe it's a much easier option and independent of other variables in the equation such as ESC freq, ESC has a microchip-firmware or not, can be reprogrammed or not, etc etc.

Seriously none of you guys tried till now any of the methods??.  >


Ok guys let me give you heads up. Unlike a brushless motor if you connect a brushed motor between two terminals of brushless ESC it will run but only at a very very slow interminant manner say 20% its full speed. This is  because ESC is designed to give drive pulse to motor timed by the back emf of the pole.  But if you re write the firmware with correct timings then you will be able to drive a brushed motor. Mind you the Brushless ESC is still not designed to run a brushed motor.

Even if you use bridge method with 6 diodes even then it run a shade better. But not at all to full capacity. However it will stop after some seconds for lack of back EMF.

Go on try it I have tried it.  

Yes if you able to supply commutator contacts directly with brushless ESC. It will run to full capacity.

Right.
I tried the 6 diode bridge now and the brushed motor doesn't really run that well. I don't know if its the diodes I used that were inappropriate, used 1N4007s. Also, the motor started stalling as I went above half throttle on the stick, not sure why.

When do you sleep Anjan? This post was at 4:30 am!

Brushless ESC don't have sensors for keeping the timing for the drive pulse generated by ESC and they are largely dependant on the feedback of the back EMF generated by the Motor. So if you connect the brushless to two wires of brushless ESC it will still run slowly but if you are going to connect it using a single diode then it will not run at all. when you are using a bridge rectifier it will run for some time and then stop due to lack of back EMF.

When your daytime wasn't productive enough, you make it up in the nighttime   

Alright, I'm waiting for a solution now, if there is one.

what about removing the back plastic cover and connicting 3 pads of the commutator to the 3 wires of the esc and set the esc timing to auto detect and save. that shall[or might] work as an outrunner brushless motor
there is one problem we can only use it as a pusher prop configuration .
until unless the bell is stopped to slip out by e ring lock or bearing lock .
thats what i  think . could it work ??

Here's a video for the eager beavers



This is a half wave rectifier scheme. My observations:

- Response time is not great, much like a nitro engine running rich
- One will lose 0.7v due to the p.d of the diodes.
- Use fast switching dioides.
- Use diodes that can handle current and temperature. They will get really hot with higher currents, and poof if go beyond thermal/electric tolerance.
- Could use MOSFETs but it would lead to unnecessary complexities
- Proportional control is not too good .  The range or proportional control aint great either. 10% and 40% sound similar but yea i was using crappy 1.5v motor so can't complain. May get better results with a full wave
- No reverse without added circuitry, use an H-bridge but yes then getting hold of a brushed is easier

Why people are knocking your head this much. There is simple method of doing this with arduino. Just calculate incoming pulse width using pulseIn and accordingly drive a mosfet using a GPIO pin on MCU. If not interested in arduino The pulse width can be measured using interrupts or pin change interrupts and then according program PWM to a MOSFET. If you want to add more features then try to merge them with it.Its lot more easy.

Agreed Bala, in fact even an Arudino is an overkill, a PWM to PAM converter is all that is required (can be wired with a 555 and a few opamps). Here is a PDF http://www.elektro.undip.ac.id/sukiswo/?download=PT2_4_%20PWM%20Demod.pdf&usg=AFQjCNFzdSLgQFMepFrGfrfgqFASziTCpw&bvm=bv.117868183,d.c2E that talks about PWM to PAM conversion. Feed the output to a MOSFET and we have a basic brushed ESC. Use an Hbridge and we have reversal

There has been a discussion on this topic that warranted a video to demonstrate the concept that was being theorized amongst us tinkerers; The idea was to use a brushless ESC without modding or creating something new...   

i think every brushed motor have 3 poles/terminals/pads on the rotating stator , couldnt we connect it to bldc esc . And we will have a outrunner bldc motor ?

Yes we can connect it like that but you have to small modifications to it.
remove all connections connecting three poles is series such that you will have 6 terminals with you i.e cut the connections of wires internally on commutator.
Now this 6 wires are same as bldc 6 terminals join one end of three wires as neutral and remaining three to ESC will do the job.

I am not very much sure about this circuit because the PWM of receiver is only 10-20% duty cycle so when connected like that your motor won't rotate with full speed it will rotate at very less speeds so a micro controller just with one PWM pin and an additional timer will be very much efficient in using board space as well as we can add extra features such as throttle setting and configuring for min/max throttles etc.

could reversin possible in above setup without H bridge ?

For motor reversal the potential across it must be reversed. In order to do that we need a H-bridge only. The brushless esc can be made into brushed ESC by writing a small software to it because there is already bridges in it.

okay sir got you.
Whats needed to do if i have a atmega8s from a brushless esc and a l293 h bridge.
Schematics and circuit info

You dont need to have both ESC and l293 for brushed motor, one bldc ESC is enough if you have its circuit diagram to drive brushed motor. Else if you have an atmega8,l293 and if you know to program it then half of work is easy. First read pwm of receiver which will be at 10-20% duty cycle and convert to 0-100% duty cycle in your program.
First let the micro controller start
Now start two timers. One to calculate pulse width and other to drive motor.
using interrupts capture rising edge and falling edge of PWM signal and take the time of pulse width.
Now modify this time value to required output to atmega PWM pin which is connected to l293
if you want to have motor reversal connect 2 atmega PWM pins to 2 pins of l293
if you want one side rotation connect one i/p to ground and other to atmega PWM pin.

You could use an attiny85 or any microcontroller to convert the pwm to values between 0-255 and then run a high amperage motor driver with the outputs i have made one with an arduino pro mini and a dual 40 amp l293d motor driver.

I suggest using some attiny instead you can save a lot of board space and so does the power and weight of your total ESC.

But instead of going through all the trouble of foraging parts or moving around LHS it would be better to buy one unless you are a total diy junkie