Sir

I am working on a project for which i need to make a radio controlled vehicle. The vehicle was earlier designed to run using wired controls. But now i need to convert in RC.
So, is it possible run simple ordinary DC motors using a 72 Mhz receiver or any other self designed circuit?

Regards
Vaibhav

'Ordinary DC Motors' = Brushed Motors. If RC circuits can use simple brushed motors then where is the problem?  After all, the Chinese made RC cars are using "ordinary DC motors" aren't they?

Go ahead, I'm sure they will work.

All the best!

VC

Guess you are aware of the need for using a proper speed controller (ESC), in addition to a receiver.

Hi
if u plan to make a simple rc car (just like wired one) u can make ur own tx n rx using rf modules.u will also need encoder n decoder.
In these set up the rf link take the place of the wired connection.
If u use a hobby radio set then u will need the electronic speed controller ( ESC ) which is plug into the throttle channel of the rx.than u can control the speed motor using the transmitter.

Hi Vaibhav,

What is the application you are looking for? what is the size (ampre rating of the DC Motor)?

You are looking at unidirectional rotation or bi directional? Do you need speed control also for the motors?

DC Motors can surely be used with the RC 72 Mhz receivers which you are using. depending on application you are looking at electronic components are available which can control the DC motors through RC receivers. Electronic Brushed (DC) motor ESC are available for various capaicty with GWS, marketed by many LHS in India.

agree with all
u need an esc for that motor of the ampere ratiing and u cant  directly connect the motor to the reciever

It is possible to connect a DC motor to connect a radio receiver by using relays. But since im not an electronics student so i cant tell the circuit..

..just try this out take ur dc motor wires (two wires) and connect it to vcc(+) and gnd(two of the 3 pins .the 3rd pin is coded signal which you cannot use for motors)of the receiver channel and see it  is working or not, the channel might act as a relay ..or better do one thing  all the normal lowlevel  rc cars(27 mhz) rs300 to 500 uses twochannels one for steering and one for engine ALL OF THEM NORMAL TWO WIRE DC (+VE,-VE)..so take it out and use it directly for your project...

"Oh No........!!!!!!!!!!"    please don't try this. Your motor will constantly run without any control. +Vcc and -Neg is the BEC Direct connection power supply for the servo.

even the receiver may get fried if the current requirement of DC motor is higher.

oops.....my bad....i'vent tried it actually ..

but if it is for project then he can try 27 mhz receivr..on toy cars those are relly cheap and easy JUST TWO WIRE STUFF....



i've drawn a easy block diagram...buy a toy car with 27 mhz receiver and take it out and connect to ur motors

true,it will constantly run as the reciever power in a 'always on ' state when battery is connected[since because of that when the plane is powered on the control surfaces are stiff as the servo is powered on but in centre position
the 3rd coded pins send signals which are proportional to ur tx and they gives u the control of the planes throttle and control surfaces

well this thing also experiences many problems i have been trying to do it from a long time[provided u take a rc car and dismantle it]

http://www.rcindia.org/beginners-zone/coverting-a-low-cost-chinese-rc-car-into-an-rc-plane/

taking it out of the car would be a good idea ..because ...for his project he is just converting wired remote car to wire less so the easier thing would be to just connect the two wires of the dc motor
to the receiver ....the reason is u dont have to buy a tx as it will come with the toy.......but if u want to design and build a tx and rx on your own  i can give u a block diagram but components you have to find them (i struggled to get the components when iwas in my 2 nd year )(considering the time and difficulty in getting components and the difficulty in understanding what does each components exactly do i would prefer  a 500rs car) but if are really intrested in understanding what exactly happens in thhose circuits when you press the button,how electricity flow inside ,how those ac currents getting converted into electromagnetic waves and how those waves are used as signals ...trust me it gives u one hell of a joy .....the kind of components you get these days you can create ur own 100 channel transmitters in a very cheap price ,anyways it is not about money ,just the fun in doing those things ....so never stop learning and to add learn just for fun ...a hobby should alwas be fun 

well i will be pleased if u give me the block diagram of the tx.
Cheers
-ANkur

sure ...give me ur email id or something ......
but before i want to know weather u know any thing in designing amplifiers and oscillators ..in ur labs or some where because thy are very important ...the block diagram will be simple and it has AN OSCILLATOR then AN AMPLIFIER then a CHOPPING circuit aVCO ,using some TIMERS (555 ur wish) ..and all channel selection working it out and components are design problems  u have to face....i can explain u the principle simply ..but i want to know about ur technical ability so that i can explain you in some what simplified and best possible way ...c'omon u cant learn every thing in a computer ..could you ...hey but good to see that u are intrested....don't forget ur ID i'll compose a word file or something with block diagram and explaining u somethings in the way i know and from very few things i know when im really free and send u and hey remember u have to put in a lot of work and understanding and make it really work ...as they say u can't reap ,if u don't bend ,so bend your back....   u know the thing is u dont have to know communication electronics digi communications PCM ppm PWM....bla...bla ..bla.. etc all u need to have is intrest ..and with that u can learn all those things ...ok

my id is ankurgr8on@gmail.com
it is visible under my profile
and i m a beginner to electronics/robotics however know/can use the things
just give me th plan as detailed as possible

cool ..then i'll send u a word file ...preferably whem i'm free of work saturdays.. sundays....ru i scool ,collg working or somethng ...done any thing with transistors resistors 555s ics amplifiers because once once again its very basic in electronics..if you are an electronics student my job will be very much reduced ..but if u don't know then let me know for those i can give you a jist or some links regardin...but you have to learn them ..

"a beginner in electronics is completely different from a beginner in rc" cos if electronics is ocean then rc is like coral reef (the appealing and beautiful part but there are  lot more things in the ocean.....)

well i m a student in class 9th but know the basics of these electronics [spent hours on surfing the net and reading the books for the knowledge of these things]
so i will be comfortable with using transistors ICs etc[made a 1s lipo charger and a led flasher using 555 IC (plan found somewhere on the net) during the past few months]
so as i said i want the plans as detailed as possible

9th standard....??...hey i don know how to put things.....
.i belive it ill take you some more time to do things in this level of electronics
..you would have hardly started knowing things in electronics may be PN junction diode (it'll be in 10th)..
.but electronics is a huge subject.to the level of desigining oscillators ,amplifiers you should atleast have a couple of semesters in u'r side(may be even two years)
it is not because you need to have that much knowledge or subject to do these it's just the things you learn  from handling things practically just for the know how of things....you know if u were in my town i would've taught you all those things in a matter of months... but...you know thats how life is
...not all things happens as we wish ..hey don't think im discouraging you or something...you've got intrest (that's the most important thing)
..i'm not saying you are not good enough it is just you would'nt 've known certain things at this point ....
..hope you'll have a good physics teacher just go and pest him ask how remote works ,ask wats a oscillator,wats a amplifier ,wats this wire wats that wire ,,just keepon asking questions untill you understand every thing ...because i've always belived (it's a fact) thatTRUE KNOWLEEDGE IS OBTINED ONLY WHEN IT IS PASSED ON and it takes a real good person to teach (or give you that knowledge)
every other way of obtaining knowledge watever it may be reading books studying from magazines ,reading from the net ,getting a circuit diagram and copying it everythings has got their LIMITATIONs you wont learn things completely....the reason i gave you this boring lecture is ,you are a kid and you got time on your side and you should learn  where exactly to look for,for the  things that you want ........and also for apersonal reason that it would'nd've been
 possible for me to explain such a complex stuff to suit you  in just a word document...i'm really sorry (you kno i really thought you were in hr sec or in collge...just now i'saw that u've mentined 14 below your  name ..i'should've seen it...)...hey you just carry on doing the application part of electronics it is really inresting ...the fabrication design part and all are boring (but good )....you can do them when you are in college or sometime...
and if you are good in the application part of electronics..you can understand the fabrtication part very easily......

I think you can simply use L293D motor driver IC for this purpose....it will give a signal input for driving the motor which i believe can be connected to the Rx signal pin of throttle.

Naatu..i am too sad with you, because you are burning your brain for an easy matter, a lots..here your problem is this..now you have a ground vehicle, and at present it is controlled by wires..so, from now, you want to run it by wireless method. for that, you have a professional radio set..means, a hand held Tx and a receiver..yes..? so, surely, it is not possible to connect a motor directly on such receivers..because, a professional radio system is based on pulse principles..means, a 1, 1.5, 2 micro pulses will generated by a circuit in Tx, as all to your stick inputs. means, when the stick stays in '0" position, the pulse generated by the Tx will be 1.5 m/s..and the servo motor gearbox, is designed to work with the same pulse bases..means, when a servo gets a pulse of 1.5 m/s, the arm of the servo will stand at "0" degree, as we already programmed the working base of a servo, to that. then, when you apply your stick, to any position, the pulse from, 1.5m/s, changes to, either 1 or 2m/s..so, when the integrated circuit of a servo motor gearbox, attain a signal, to 1, or 2, the chip, or circuit corrects the error signal, generated by you..to understand the error signal, there must be a potentio meter within the servo motor gearbox.so, briefly, to operate a servo, you do not need any Rx or Tx..we can make a pulse generator, with simple circuits..so, why we use a Tx and Rx..? yes, we have to control the servo, remotely..from a distance, in wireless mode..so, we must transmit the generated pulse, to the AIR, to the servo..but servo is not designed to receive any wireless signals..so, we need an interface, that must convert the incoming wireless signal, to an apropriate working signals..(1, 1.5, 2 m/s)..

so, we made the signals from Tx..now we want to send it towrds the servo, staying away from us..so, wee need a wireless interface..so, for that, we must choose a medium, to carry the generated pulse from Tx, to servo..for that we have many options..easiest and coolest way is for that, is using the invisible RADIO WAVES..you can also use LIGHT, SOUND, HEAT..and more..but, radio wave is very easy to use, and versatile for this purpose..so, we goes to, AM,(Amplitude Modulation), and FM (Frequency Modulation)..in AM, there must be lots of disturbances from SAW.(Surface Accoustic waves)..so, the servos always get an unwanted signal errors..so, even with a slight sprk, from some where, servos started to works its own..but we can eliminate this by narrowing the band..and aby adding SAW filters..but still AM, is suseptible to signal disturbances..still we can afford SW..(Short Waves)..and one of the coolest option is to use FM..as in FM, there is no amplitude variations..so, the distuirbances affected by all SAWs are almost negligiable..so, we choose FM, for wireless transmission..here..and still we are using the FM..most of us, will run for a TX, and Rx, if it is in to 2.4 GHz..it makes us smile..while we ignores the modern 2.4 Tx and Rx system uses the same FM transmission principles..still you can see on modern sets..as operation mode: FHS( Frequency hoping system)..MODULATION:FM..so, even now we are still on FM..i mentioned these things to clear one thing..you can use any radio set to any RCying purpose..it may be 26, 27, 32, 35,38, 40, and 72..Band..no issues..

Now you have the radio set..install the all respective batteries, in Tx and power the Rx, and always make sure, while powering Rx, that please make sure at least one servo is connected to Rx..if not, in some time, a surge from a fully charged battery pack can kill the protective zener diode within the Rx..in such case, you never notice the malfunctions happening inside the Rx..eventually this can lead to a full scale malfunction, it may happens in mid flight, or in mid run, as all needed srvos drops a high current from the Rx protected power line.., ok..make sure all things are working..means, if you have a 4 channel radio, connect 4 servos to rx and make sure all servos are working in proper order..and keep it aside, as switched off..now we have the fully functioning radio set, and a vehicle to operate..with it..cool..now we must drive the motor of the intended vehicle, in to both directions, as FWD and REV..and same while, a second servo, must alter the steering mechanism..ok..? done..

So, Naatu, we are almost near to our aim..so, here we need to operate your vehicle with a wireless radio set..!!..so, a little about Electronics..the Science of Electronics is vast as 7 seas..no one can learn it wholely, or entirely, even with a span of 10,000,000,00 births..!!! because it is vast as our unknown universe..but still we can adopt all thins for our needs, as we fetch a pial of water from a big river..you cant drink the whole water in a river yourselves..it will flow endlessly..but you can take water from it for your needs..you may take a bowl of water from that river for, may be to make a cup of tea..but for an other woman, your neibhour, she may take water from same river, in a big bucket, to make rice and curry..so, the need of the water is differ..still the source is same..like that, whenever, we hears about Electronics, we instantly thinks about a PCB (Printed Circuit Board), with ample of components on it as a messy thing to look..and scratches our head..!! but, it is all because of the ignorance..you do not need to scratch your head, while thinking about an electronic circuit..because its all CIRCUITS..means, a path, or a highway, to travel for ELECTRONS..in a controlled manner, as our rail road systems..so, while considering an electronics circuit, do not worry..but whatever may be the circuit desgned for, there must be only two things to consider..a VOLTAGE PATH, and a SIGNAL PATH..voltage path is means, the wires connected betwwen components, to carry the battery currnet to all components..and signal path means, a wire network, to carry all intented signals..for an example, your radio Tx must need a battery current to work..so, for this there must be a circuit for that..and it must also send radio signals to Rx..for that it also must be eqipped with some related circuits..i said this all, beacuse of nothing, but, you must need some electronics to make your crafts.. :thumbsup:so, do not scratch your head..its all easy..follows..

once again we are on the move..so, we are going to propel our vehicle by our radio set..here, we must consider the RX..the question was, can we add a motor directly on a Rx terminals..it is not possible to control any motors with Rx itself..because most of the Rx are not designed to drive a motor..usually, an Rx will be equipped with three terminals each, for each servos, as, Gnd, (battery negative), Supply,(battery positive), and a Signal,( from 1, to 2 m/s) to the application circuit of the servo..most of the cases, the red wire, ( battery positive) will be at centre of the connector, is because, to avoid any circuit failiure, by a wrong polarity connection..if you insert the pin of the servo, in Rx slot, either in any direction, the battery supply wire will be in its original position..this eliminates any wrong polarity problems..and, most of the time, the + and - supply from Rx to a servo will be directly from BEC ( battery elimination circuit)..so, connecting a motor to this terminals is a waste..means, when you connect the BEC, to Rx, the motor will rotate freely..untill you removes battery..and yes the signal terminal is also, not intended for to drive a motor, as its output will be milli volts, and in pulse base, while even a micro dc motor needs a 1 Volt, 200 mA to work..and connecting a powerful motor to the rx terminals can burn out the Rx terminals from inside..

now please do not disturb your Rx setting as it is poor innocent one to work with..
we have ample of ways to drive a DC motor in either directions..may be an ECM, ( Electronically Commutated Motor, or Brush Less), or an MCM,( Mechanically Commutated Motor)..to drive a DC or AC motor, we must need a speed controller, more clearly a motor controller and it must not be an ESC..( electronic speed Controller)..we can also control of the speed and torque of a motor by means of mechanical methods..so, here we have two ways to choose..one mechanical and one electronical..at first easiest way..the mechanical..i told you, at present, you have a Tx, Rx battery packs to operate it, and yes at least two servos..surely, wee need one servo, for steering control, while one left..so, we will connect the steering servo, to one desired channel of Rx..the second one will be connected to the throttle channel..now fix a servo drive arm to the srvo drive shaft..switch on your radio set..centre the trimmer..and make sure, the arm of the throttle control servo is straight..then fix the servo, on a piece of platic sheet, foam board, or on a common PCB, and you can attach two smaller switches in to the two sides of the servo arms as shown..

each switch have 3 terminals..and one of the terminals for each switch will be the pole..connect two wires from motors to pole..and connect the battery + and battery - to the Nc No contacts of the one switch..and connect the same wires in opposite to the second switch..so, at present, when the servo arm stays at centre, two sitches will be as in OFF position..because the motor will get same two terminals from battery..so it wont turn..but when the servo arm pushes a swithc, the motor will get one polarity, through switch, and start to turn to one side..and yes in opposite, when servo arm pushes the second switch..we can also add a compound switch for more compactness..see here..

from here you can see its morecompact and versatile..this switch can hold up to 15 amps at 12 volts dc..now we can drive our motors with ease in clock and counter clock directios..and any heavy motor..but still have a infermity..is cant control the speed..while cruising..it will works only on a predettermined voltage..as switches..here comes the importance of a ESC..is Electronic Speed Controller..

Naatu..now our vehicle is running..you can simply increase or decrease the speed and power of the vehicle by adjusting battery numbers..
so, now about ESC..when we thinks about an ESC we think some thing big..its all nothing but some simple circuit..what we need to make an ESC is a signal streacher, or a pulse expander..   ?   ..yes..i told you, the out put from the Rx will be 1.5 m/s at stick at centre, and 1 at stick at one end, and 2m/s at stick at other end..so, we will get the same signal pulses at the out put of the Rx staying far away from Tx..so, we must need a circuit, that circuit must gives us a positive voltage as ouput, when the signal from Rx reaches to 1m/s..and there must not be any voltage from it, as the signal from Rx reaches 1.5 m/s..but again this circuit must gives us a negative voltage when the Rx signal reaches 2 m/s..and it must be all proportinally..means, the voltage, from the circuit, must be in positive or negative, not instantly, but it must increase gradually to maximum, as we pushes or pulls the Tx sticks to desired levels..to achieve this we have ample of integrated circuits in markets, and such ICs are leberally used in DVD, VCD player boards..this kind of Ics are far cheaper, costs about Rs 20/- and works well..for an example, M 51660 L is one of the beast Ic, i ever used, that can drive a 800 mA DC motor rated at 7.2 volts..in either directions..

now we have the motor driver..still this one is not capable of driving a heavy motor..so, with this IC, we can use a H bridge circuit, that you can simply attain from any Hobby electronics Books, from any good book stall..costs about a 30 Rs/-..remember..buy some circuit books for you, as books are far beyond explanations than looking in to a web site..make sure the purchased book is from a reputed publisher, like BPB,ITE, EFY...those books will lead you ample of good stuffs..because we can simply place the book in front of us, while working and can go for many repeated readings and references in realted subjects..that you need not any power source to switch on it..and instead of wandering behind some thing, make a clear idea about needed circuits..follow some strict rules while assembling an electronic circuit..sucsess guranteed..

if you feel a H bridge circuit is far complicated, you can simply make an ESC with a micro servo, and a MOSFET, in IRFZ48..this MOSFET can hold a current up to 40 Amps at 12 Volts..and costs about 20 Rs/-..how to make it..? easy..remove the back cover of your micro servo, de solder one of the motor lead from motor of the servo..attach a long wire to the same motor wire..this is your pulse ouput..cover back the servo..you can make an arrangement with an other or existing battery pack to MOSFET, and can feed it to motor, and can drive it with the pulse from servo..can also add reverse with the early mentioned switces, while adding it to an other channel of the radio..so, you can alter the speed from 0 to full in FWD and REV eaqually..

now even more easy way..take a standard or heavy duty servo..remove all thigs from it..except the PCB and motor..connect it to throttle channel of Rx..switch on..so, will find the motor of the servo running in any of the direction..be cool..turn the potentiometer of the servo, on it's PCB, to any of the directio..make sure the throttle stick of the Tx is at centre..so, after a particular point, the motor will stops spinning..now you can pull or push the Tx throttle stic to desired position..and can see the servo motor is running in either direction with respect to your stick inputs..and in proportional manner..so, do not try to remove the brass gear of the motor, as this can damage the motor..instead you can add a silicon drive grear by drilling it, and attching it on to the brass gear of the motor..so can drive any platic gear box, with it..if not, you can solder a new Dc toy, or a tape recorder motor, bgut sure not a RS series motors..and can add any motors rated within 1 Amps..so, can add a robotic gear box, toy car gear box..works well..in FWD and REV..without any extra ordinary materials..this also can be used in boats..and many otherapplications..if need more instructions tell me..Naatu, with this time, if you were near to me, we can make more than 3 vehicles..hi..hi..so, now time for my medicines..Mom shouting a lots..see once again..its all simple..make a lots of cars and vehicles..because even a HD servo costs a mere 450 Rs now..make sure it is in a good company..i found many standard servos with a bord of micro servos in it.. this kind of servos are for making us all fools..so, make sure the standard servo, or hd servoas are with a heavy PCB with a big Ic in it..or with transistors with it..so..dont be lazy..make cars..tanks..robots..boats..trains..planes..

Naatu..i will make a little RC car from two servos to clear your doubts..