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[rathikrishna]

Good morning Friends..when i was started to make RC crafts in all means,the speed controller was my ever nightmare.at begining i was using a simple on and go type controls like any cheaper RC cars.but as i progress i started to use my knowledge in electronics to my applications. as a result i made several types of speed controllers still working nicely after years of gruelling service.i am posting this article here because i know many of my friends are need it..when i asked for a speed controller here at Chennai Town,they gave me a price list.and was
shocking while looking in to it.for a single channel speed controller, the price was Rs 4500/00-!!!!  (a Dollar is 45 Rupees now)..with that money,i can buy a good quality DVD player, or a 20 inch CTV, or a Dual Core Mother board, or a good digital camera.!!!!...

So again..see the instructional video here....http://www.youtube.com/watch?v=SS3gkDgQSz4

[rathikrishna]

   and if you ask for a two channeled one its 6000/00-almost...and for a motor differential one..9000/00..ohhhh...and can only work as the home made one..so i decided to make my controllers even better than before.now all it works nicely and flawlessly...

[rathikrishna]

   to make a good quality solid state speed controller, you need heavy and expensive equipents and ample of money and ultimately a good knowledge in electronics..?  sure..? rethink..NOOOO....you need nothing, but some patience and mechanical mind with some time to spend. here we are...you need only some handy things from around you...and sure a soldering iron in to 25 watt, a three pinned one to avoid leakage. soldering flux and good solder wire.you need not even a multi meter  !!!!!!!...


   
   first of all find a sliding or rotating type volume controller can found at scrapyards or can buy at any electronics shop within  half a dollar.if you are taking it from an old source the value of the potentio meter is not an issue...any value will work.so if you are buying one try to get it within 50 Kilo Ohms, and Linear type one.if you are using a conventional servo, the sliding one wll be the best bet.and if you are using a toy RC a rotating type will be best.but you can use either for either use.

[rathikrishna]

   i took this old tape recorder main board to take needed parts to me.here you can see some good sliding controller looking at me.."hey Rachu we are waiting for you"...hi..hi..


   desolder it from base carefully...now its free...now we got the main part of the controller..the variable resistor, or a potentio meter...its value here is 50 Kilo Ohms.

[rathikrishna]

   now we need a power transistor to drive our motors, lights, or anything you need...here some inexpesive but ever classic silicon, and Germanium transistors, from, MJE 3055 up to 2 Amps..TIP 3055 up to 5 Amps..and 2N 3055 for 30 Amps or more as you can bridge it. the TIP 3055 also can be used instead of 2N 3055 to save space. you can place these or this transistor anywere you like so you can save space and weight.and a heatsink is a must for higher amps.no fan is needed to cool it as most of these PTs can withstand temperature up to 180 degree of heat..

[rathikrishna]

and here you have a second alternate for PT, is Darlington pairs..means two transistors in one..with this you can achieve a good soft start and stop..good for light crafts..

[rathikrishna]

   now its fixed and wired..you can see how simple it is..here i have wired it in a rough way..but you can simply place and wire neatly as you can...so everything will be tidy..a 470 ohms resistor is used with controller to protect the transistors from stalling current,when a stalling of motor occurs.as the TIP 3055 is employs a thermal protection inside you need not worry about burning it out while a short circuit happens...no worry...reverse polarity is not a matter here as we use a diode in series with this circuits.there is nothing to go wrong
 with it so you need not worry about splashes of water..if this goes to water nothing happen..wait untill dry..and then works again..no money loss...

[rathikrishna]

   now i glued a piece of aluminium sheet on to the arm of servo, with many holes on it to adjust the stroke length of the actuating arm,as we need...

[rathikrishna]

Make a hole at the tip of the controller..carefully..dont tear it....

[rathikrishna]

   now yo can simply fix it as shown,all with foam boards,because it can absorb excess throw and shock,made out of servo if you switched of the transmitter first...no steel or plastic structure is needed...i used a brass rod here..its only for a guidance..you can simply do on your way with your own ideas...

[rathikrishna]

   now our controller is ready for the ordeal..but still lack one thing..a reverse switch..here i used a DPDT switch, can foud any land  phones, or can buy at any electronics shops..much cheaper..here it costs only a 5 Rupees..(45 Rupees a Dollar).

[rathikrishna]

now wire a second line in reverse with wires from transitor out..and place the switch at the neutral position of the arm, after checking the play of servo arm..place the main throttle stick at this position as neutral...mark it or keep it in mind..



   Now its ready...with a motor..this motor was actualy a toy motor, for 3 volts..and i reworked on it for 9 volts and 700 ma..and in to 6000 Rpm..for my KAAKKA..means the Raven,from strw board and bamboo sticks..a flying model of my own..have to compleate it..

[rathikrishna]

   And here i am adding some useful proven circuits , all tested and with me now,is first one is simple but effective inexpensive but works almost same as professional one.its much simpler , and using the ever basic principle of transistor biasing.here the base voltage is controlled via a variable resistor, our volume controler in this case,so the out put will remain as constant untill we alters the base voltage.

   Second one is based on MOSFET( Metal oxide semiconductor field effect transistor),for greater amperage handling.you can simply fix a RS 500 or more powerfull motor to it.if feel bad can bridge same one with exsisting one so it will handle your load nicely.here you can see that the circuit is more complicated, because this unit is based on PWM, or pulse width modulation. so it may generate some SAW, (Surface Accoustic waves)means some radio disturbances, so we must use good quality wires, and must use a shielded wire to connect
the variable resistor.


   
   Third one is even more complicated because here we are using a CMOS Ic for making pulse.(Complimentary Metal Oxide semiconductor).the Ic is easily available, and cheap.



   The next circuit is based on Darlington Pair transistor means two PTs in one.here is the circuit. its too easy to make and an ameter is connected in series to output, so you can simply determine the load current in output.this circuit is meant for only under 2 Amps.you can also use this circuit as a battery charger and voltage eliminator for electronics service...its based on BD679, a cheap PT to buy.




   so..now its on the way..woooommmmm....try it...and you can save ample of money...and you can do many other things with those saved money...the main job that to do is...buying some good ice creams for me...and send me...hi..hi...ommm yummy..yummy...

[rathikrishna]

you can see a red marked potentiometer in all circuits, is meant to fix on the servo...you can also try with various value in the first basic circuit, from 470 Ohms, to 1 Meg Ohms, and can get various results with your SC. and one main thing is to remember that, all speed controllers consume some voltage itself..here in the basic circuit, the PT will drop a .7 volts as its junction barrier current. we cant eliminate this here as we need a brake or stop to our used motor. so if you need a 6 volts output, you must connect a 7.2 volt battery pack to the circuit.so it will work nicely...so try it...save money...and never forget to give some icecreams to me....ha..hi...so have a nice day...Merry Christmas...Happy new year...this New year may a good year to you all...with this speed controller...


    Any suggestions , corrections and advice will be great , for this article, so we can simply upgrade our speed controller to a even more great extent...and i will post a MOTOR DIFFERENTIAL CONTROL, means controlling two motors with to servos as FWD, REV, LEFT, RIGHT,while first moor spins at CLOCKWISE, while second one is to ANTI CLOCKWISE...so we can control our crafts even more simply....

[david j]

hi rashi,  (SUPERWOMEN) this is fantastic what you have shown many thanks,
i will try this in the new year, merry xmas

davidj

[tugmad]

Onw word Rathi     BRILLIANT!!!!!!!

[barryfoote]

Stunning. You are a genius, to come up with such gear from old stuff just lying around. Brilliant..

[rathikrishna]

Thank you all...but you must try such things yourself..its only a simple idea..and all you can make even better things..because making a craft from own idea will be more satisfying..indeed..and i know all you are veterans by all means..thanks once again..

[roycv]

Hi Rathi, love to see these circuits, I used to use them and they are very satisfying to operate as you have made them yourself.  Still have a small pilr of 2N3055's etc.  I would make my own battery chargers etc.
I then got lazy although I would build from published circuits, but soon the technology started to pass me by.  With surface mount and proms etc.
Still like to put a circuit together though, although I now need the magnifying glass to get to some of the small stuff.

Do you have vero board available?
I also used to use a small construction board where you can plug in integrated circuits and then do a try out of a circuit by plugging in the components and seeing if it worked.
Carry on the good work,
many regards Roy

[rathikrishna]

Hai Roy..all we know electronic, components are shrinking a lots now..and its so superb..sure..but here we can see all used components are big enough to se with naked eye..and very inexpensive to buy..if i buy all things from shop here, i can simply buy all components with a money of  a cup of coffee with two cutlets.and all it works for a lifetime. and more satisfying..we know again, if any SMD, or COB accidentally drops on water...!!!  it will be a mess  but here nothing will happen..i have veroboards with me and bread boards..but no usage..i always make my own PCB s by chemical etching...thanks for the interest in this article..i hope i can expect a good posting from you, so many of our friends will arise from the laziness...and never forget to send me some icecreams with saved money...hi...hi...

Roy..we know we can also use these circuit to dim and bright a light source...or can change the pitch of a horn...so never be lazy...please post usefull circuits and goodies here..we all are waiting for such innovations...with great hope...rachu.

[Roadrunner]

Just outta curiosity how much amperage can one of these home made esc's actually cope with?

Its a great idea making one with the parts you have but the motor you have been using have been on the small size compared to some that we have available here.
What suggestions would you have, to say build an esc that can can support up to 20A's since this is the typical size most 'regularly' use here, or is the esc the mechanical type that can support anything you throw at it?

When it comes to esc mechanics i have no clue. I have always purchased mine with little regard for they construction.

[rathikrishna]

Friend..we can get all details about the parameters of used components at an electronics shop, or from the DATA MANUAL..i will post a video for your question...to night...i have tested my basic (shown) circuit with 30 amps load, along with a bigger heatsink, and a small fan from an old grapix card...only thing that we have to listen is the gauge of the wire...and if you are too nervous about your circuit, you can simply add on this circuit..that i will post tomorrow, as i do not have with me now..i am not at home now..but in a cafe..sure i will post the new video with a big motor, and short circuit protection.

The over load and short circuit protector can be made easily by two methods.one of the ever simplest possible method is using a thermistor.we can fix a thermistor on the heat sink of the PT, so it will acts as a sensor.you can decide it as PTC or NTC. and can simply wire accordance.basically its function is controlling the base bias of the given transistor, so the output.we can simply alter it again with simple PCB PRESET.so wait until tomorrow...i have to shoot the video tonight..after my parents sleep..sure..good night..

[Martin (Admin)]

Topic name changed...... shortened   

[cos918]

very good and well explained

John

[Corposant]

Rathi,

Are there no limits to your talents?!!

Mike