Hello,
I have been working my own scratch built r/c system from quiet some time now and it is almost complete. The progress has been very slow due to a number of reasons. The system is a 3 channel proportional system that will have a frequency of 27mhz (legal) and a range of about 500m. The picture below shows the working encoder and decoder. The system works but needs some refinement, if successful then it could drastically bring down the cost of a complete rtf r/c model and make it available to the masses ! I am also planning to add features like transmitter battery indicator, and failsafe for the receiver I have built several r/c gadgets like esc's and v-tail mixers... etc before. I plan to build a complete scratch built r/c airplane (even servos) !!!


regards

Cool... Now, I see some real intersting stuff in the forum. I am hooked to this thread.

Could you please post more information on your design?

-Ismail

Great work buzz.
Keep it up .
We need DIYer like u.
Keep us posted on the
progress ..

Are some LHS's listening?

Keep the good work going.. Why don't you check out some of the opensource projects like arduino.cc for control logic, pwm control and transmitter integration?

thank you  , what sort of information would you like to know?

i have seen many of the open source designs, but for some reason i wanted to put my own knowledge to the test and make something and since i love this hobby, i decided to build a complete r/c system.

Preferably the circuit diagram showing the ICs used would be better. However, its upto you to disclose the level of details.

-Ismail

Kudos     


The transmission part would be pretty challenging, especially supporting multiple channels etc.  Not sure how much can be done without access to spectrum analyzers and so forth. 

Here is a link
http://home.nordnet.fr/~fthobois/anglais/engl-index.htm

This is a DIY project though the TX is more complicated, the different RX's are worth a look at.

They have documentation and schematics. The best part, the  Motorolla MC3362DW  FM receivers chips are available in the surplus market from vendors like futurelec and chinese suppliers. You can also use MC13135.

Could be used for your reference build.

I have used the 12Fxxx and 16Fxx series of microcontrollers from microchip, the code is written in pic basic, sorry I would not like to disclose the ckt diagrams, but more technical details will be posted soon.

what coding protocol are you using ? PCM/PPM/BCD or your own ? sounds intersting! are you using 3rd arty RF modules as the board in the pic more seems to be the Codec modules.

Great Job!! so planning to hook up with a 'force feedback' Game pad ?

The whole project is a big challenge, lack of availability of components, testing equipment, funds & time have been some of the major obstacles. the current system is for 3 channels only but will support upto 7-8 channels in the future. This is just a prototype for test purposes, I will have to find an enclosure for the whole setup which will allow me to add more channels and other features also !

Out of curiosity, how much time (in hours or days) have you spent on this so far, and across what time span (over how many weeks / months) ?

I was referring to "channels" as in multiple concurrent users without interference, did not realize that channels could mean two things generally in RC radio land

As I am building the entire system from scratch, I would prefer to stick to the basics. The current system uses amplitude modulation. Frequency modulation is a bit advanced, I will be building a system that uses FM but that would be for later. As I am a student, I cannot afford to buy the IC's you've mentioned in surplus quantities. I do have a pair of the MC3361 NBFM chips though which i got from an old cordless telephone. Most of the components that go into the construction of RF systems like tunable inductors are really hard to find in the market. Moreover I have limited access to equipment like oscilloscopes, LC meters and spectrum analyzers.

I am using ppm. No,I have made the rf modules on my own, the picture is of the encoder and decoder only. I will be posting some more pictures of the boards in some time. I am planning to make an enclosure for the system. I will start work on that as soon as I manage to find joysticks .

On average I have spent about an hour every day for the past year to make this system......
I thought you were referring to no. of channels the system will support  well after I finish building the complete system, I will work on the different frequencies the system can use (27,35,40 and 49 Mhz). The prototype uses 27Mhz.   

I was thinking about handling 27.010 and 27.060 (just sample values) as channels where multiple transmitters (all in 27Mhz) can co-exist.  Then you begin to run into adjacent channel interference and so on, and more and more sophisticated testing instruments are called for.

Here are some more pictures
in sequence:
1.Encoder (old)
2.RF module
3.Encoder (new)
4.Decoder

Man, You got patience  I mean it

Some more........
In sequence
1.Some of the previous failed attempts.
2.Servo tester
3.lithium polymer charger
4.Photo of my home made PCB (encoder) with my name etched on it    !

  . Ujjwal, You got a brother. 

Awesome work! We need more guys like you in this hobby.

BTW, your RF module seems to use a simple TO-92 package transistor. I doubt if that would be adequate meet the power levels. May be the transistor is running warm. If you need a good RF power amp transistor, then try a 2N3866. Its very good for RF amplification and can dissipate up to 4W of power!!  . Thatz hell a lot of power for RC use.

-Ismail

This is just a preliminary version of the prototype, will use the 2sc2314 with a heat sink in the final design!

Good. That should work as well.

I have a bunch of these RF ICs lying around 3361 (SMD too), 3371, 3362, 3363 SMD from my abandoned projects. If you need any, it is yours.

Here is a video of the system being bench tested. It works !!!!  . I have to still work on the RF front end though, it needs to be tuned. I'll have to find a spectrum analyzer for that. Ill also have to find joysticks and a suitable case for this as it is a little difficult to test like this.

Thank you for the kind offer, I have built a receiver using mc3361 before, but I din't have a transmitter to test it with, I have only one tx on 72mhz and the receiver was built for 35mhz. MC3361 in not so good for 72mhz and the 35mhz version required fixed value and easily available inductors, therefore I built it but could not test it. I will let you know if I require the chips and may be even send you a complete rx (i.e. if i get it to work)   !!

try to contact your local HAM guys, should help u out with RF stuff easily !

No need to send me an Rx, I'll be glad to just see them getting some use than gather dust here with me. I don't see myself doing any RF project on these frequencies in future.

On the 3361 there are versions from other manufacturers (Toko if my memory is correct) that works at higher frequencies.

yes the toko tk83361 works at higher frequencies !

hey buzz_rc

which compiler are u using and how are u reading the pots (i.e A/D-voltage or Resistor-Capacitor mode) ?

http://www.elektor.com/news/mcus-feature-integrated-wireless-interface.1220375.lynkx?utm_source=UK&utm_medium=email&utm_campaign=news

http://www.atmel.com/dyn/products/product_card_mcu.asp?part_id=4692

this can be a good way to implement RC transmitter/receiver for indoor to parkflyers range !

sahil

hello sahil i'm using PBP complier from the link below:

http://store.melabs.com/prod/software/PBP.html

i'm reading the pots using A/D voltage. I'm planning to make a very light weight rx using surface mount components n use it for indoor flying purpose also.I just need to find a way to put the entire system together so that I can test it properly !

okay,also what tools are u using for testing RF stuff ??

build yourself a simple sound card based PC-Scope if you don't have one already !

sahil

I have made a simple rf detection probe using two diodes .It can detect RF strength and display the readings on a multimeter.I have a soundcard scope (see my video). I am now trying to make an LC meter but cannot locate the reed relay required. Once I have an lc meter I will be able to wind my own inductors.
I did see your thread on a similar project as well (the one in which you've used the micro star encoder), how's it coming along ??

the micro-star thing is a huge ocean in itself, i still need to do lot of work,wiring etc also have a look at Frequency counter/meter 50Mhz range unit (this is the simplest unit i know)

http://freenet-homepage.de/dl4yhf/freq_counter/freq_counter.html

http://www.hamradioindia.org

you can get the reed relays in cordless phone base and are you by chance building an LC meter using 16F84A and 16X2 LCD display ?

http://electronics-diy.com/electronics/lc_meter.php

sahil

Thanks for the links Sahil, I have a relay (I took this out of a cordless phone base), but am not sure if it would work. Yes I am planning to build the LC meter using pic16f84a and 16x2 LCD.

here is a link to the relay I have:

http://www.daiichiparts.com.hk/product/reed/rl108n_700.htm

if I'm not wrong that guy is using reed relay because it can be driven directly by the PIC !
all you have to do is make sure it matches with current ratings !

assume the 3volts relay is a 3volt led and you are applying 5v supply with a limit resistor in series

R-limit = supply voltage - led drop voltage ( 3 volts ) divided by current consumed by led (relay)

now you can calculate the current consumed by reed relay by V = I X R

the value of R/V will be printed on the relay from that get "I" now from the "I" you can get R-limit which u can use to replace  10kohms resistor in the circuit and please beer in mind the current limits of pin (PIC)

sahil

oh i think i might have one of those 700ohms stuff let me check !

i have been reading your postings it seems you are using an Bit-char circuit for the TX stage and what about the receiver system ?

sahil

hey if you need any partners let me know I'm getting bored doing stuff alone  

we can share results n resources and i'm particularity interested in the Radio Frequency part!

here is a link to my project    http://www.indiarc.com/forum/index.php?topic=2242.0

Its a standard AM ckt that I made using the reference circuit given in the book 'principles of communication'. it consists of an oscillator, a mixer and an amplifier stage. The receiver is a superregen.

Hello Sahil,
I did see the link of your project, your encoder circuit seems to be the one given here:  http://users.picbasic.org/projects/RcEncoder/radio_control_encoder.htm, and also you've used standatd RF modules available in the market. My approach is different, the current prototype uses low powered basic version of the tx and rx, this is only for test purposes and to Check whether the concept works or not. a lot of tuning will be required and also amplifier design will have to be modded for the final version. Once I find an old radio case with joysticks, I will assemble the entire circuit on a new pcb and test it further...

yes the circuit part of it is correct but there code is wrong and i have modified the circuit to work with my own code plus one can use different pots/range not just 5kohms and planning to add a LCD display with voltage indicator/trim options !

regarding the RF stage there are two main reasons one simpler to implement and two i was more interested in indoor/light weight RX system ! hence off the self stuff.

and you are planning to build any FM systems ?

After finishing this project, I definately have plans to build a FM system. In my previous post I have mentioned building a FM receiver but I could not test it. I have also ordered Xbee pro modules for my final year project, so after i'm done with that, I might end up experimenting with 2.4 Ghz also !!

great 

do help...me....

pls share ur knowledge..

Hi Buzz_rc,

Try with relaytronics, mumbai for the relay, i'm sure it should be available with them.
Last year I had built a PIC based LC Meter with 16*2 LCD Dispaly & I hope I have a spare PCB of it with me.
Let me know, if you need it.

Sanjay

Hi buzz
how is ur work on
the tx rx going ?

Hello,

I am still working on it, The other day I blew up the rx circuit while testing. My power supply had developed a fault that caused it to output a higher voltage. A couple of other circuits also stopped working due to this. I need to find a convenient way of testing the system. I am looking out for the following stuff, can anyone help me out ? I will pay for it.

Old/unwanted/broken radios (will use this for the case and joysticks + to salvage hard to find components+ for testing the receiver)
A pair of tx/rx crystals on 27mhz band.

Hi Buzz,

Since i couldn't locate the spare PCB, I have got it fabricated again, but with a new circuit.

http://ironbark.bendigo.latrobe.edu.au/~rice/lc/index2.html

It seems to be better than the earlier one (not tested by me). PCB is ready with me.

Please PM me your address.



Sanjay

hi sanjay

although this is off topic, can you post some pictures of your builb here. I'm also interested in building one !

sahil

Hi Sahil,

I built one last year & a local HAM  > took it from me & never thought of returning it back. I had made some spare PCB's at that time but unfortunately got misplaced  . Now I have fabricated with a new design  & I have not assembled / tested it yet. Go through the link, If interested, PM me your address for the PCB.



Sanjay

lucky guy 

okay let me first try my skills on PCB itching, if it turns out bad i know whom to refer for a PCB

Dear friend..a great effort..but you need not to go to this extreme, to make an R/C proportional system. now you can use RX2B and TX2B integrated chips respectively for reciever and transmitter. with very simple transistorised circuits, and two 5 Kilo ohms POT, you can simply make an R/C system.if you are not willing to make your R/C in to proportional, its again too easy to do..so you think how can you get the controlls..?.its easy by using small toy gear boxes.with this setup, you can freeze the steering of a car at a certain point, or a rudder of a boat, or a throttle of any vehicle,or a stabilizer of an aircraft.with proper RF power amps at end you can pump out your signal up to your need as the voltage and the number of transistors increase.i was making whole R/C systems from 1990s.all in to legal freequencies.i always make individual R/C systems for my each and every crafts.its too easy..

Hello mr.Krishna,welcome to the forum..U made ur own tx n rx for ur models?

Tx2B and Rx2B Chips do not provide proportional control...........I have built a system for 27mhz and am now making one on 2.4 ghz...(both legal frequencies in India).Time and lack of resources are the only limiting factors here, otherwise I would have completed it by now....With the RF amp I am using, It is possible to control a model upto 4.5 miles away, provided that there is a proper heat sink on the final transistor. Its good to know that you have been making your own rc systems, please do post some pictures here....and yes ,with the proper knowledge it is easy and fun to build and fly your own rc airplane...

Buzzz..who told you that RX chips will not controlls at your hands..?..to get a proportion, you must add a 4 transistorised circuits for each lead of the IC.and must take output from NON OSCILATING pin. to increase the range of an home made R/C system,you need not any costlier things,but you need some general purpose transistors,costs only 8 Rupees for one.with three final stage you can control your model from 6 KMS away, and with a five stages and a complimentary system at end i got enough range far about 30 kms directional.for that i need only around 300 rupees....i was making all rcs withis legal range, and i started my own r/c making after getting my HAM RADIO lisc:.

Hello Roopesh, Great to hear that you are using proportional controls using rx chips.
It will be great if you could post in more details with some circuit diagrams pics etc.
Also please share some details and pics of your DIY radio controls

Thanks
spitfire

SURE..but Spitfire i do not know that i break the codes by posting whole circuits related to the R/C systems here..if not i am too happy to share my all proven circuits here..now i am in my work shop to make an rc system for my new fire craft, a wide bodied boat designed for my fire dept.its based on RX TX 6B for five functions.

Sir,its really good to hear about your accomplishments ........ do post some pictures of your work.

Wow.. good to see some interesting things happening on the electronics side. Would love to see your developments on these.

-Ismail

sure..indeed..i will post all things that usefull to all..i have a lovable little sister, Rathikrishna.she is also a model maker and doing many stuffs by herself. i will share all things that we used and using now..happy...

Roopesh sir, please post some circuit diagrams of your RC systems.. It will be very helpful.. Also you could start a new thread on how to build your own radio.. This would help many people who are staying away from this hobby due to the high cost of buying a radio..

Hai medicine..its sure..but i do not know that can i post all my circuits here, because of legal issues.i started playing with electronics from the age around 8.all things was related to valves on that time.but soon i mastered in transistorised circuits and chips.i was using my own rc systems from 1988, onwards as i passed my first HAM RADIO lisc:.but now i do not know about the related legal issues of RC. i started making usefull circuits for me because of my helplessness...to me all needed stuffs was only a dream..cost was only the second criteria to me.but before 1995, even the internet was only a dream for most of us..so i stared to build all my need things myself..its not a miracle.my first RF transmiter was a small, based on 3 volts, to send audio and video signals without wires.it gave me a range of 100 meters around.then accidently i got a book from my father's library, a russian book,authentic,THE BASICS OF RADIO.it explains the whole needed things esp about antennas.it was a shocking discovery to me...then i tried to follow its rules..then with a tuned antenna to my circuit i got more than 500 meters with my 3 volt circuit !!. from that point i started my pioneering journey in radio. i know many reputed companies are keeping all secrets of circuitary to keep their monopoly.you have to understand that , you can simply make 100 channel radio controller, (IF NEEDED),without interfering others, all with..PWM,PPM,PLL,LMP,PPL and RFS...NOOOOO....nothing we need..we need only an audio oscilator, means an oscilator produces audio range freequencies (FROM 20 Hz to 14000 Hz) for a control.then we need an local oscilator one oscilates in your desired RADIO FREEQUENCY, and in final an RF power AMP. then you need an RF RECIEVER, (along with rf local oscilator in same freeq, that you used in transmitter), and a simple DECODER of this carried signal.means, a particular audio signal is modulated with your carrier freequecy and changed in to MODULATED CARRIER FREEQUENCY.   

to make a proportional srvo you need two CD 4060 ics along with LM series ics,all within a range of 50 rupees.a simple toy, (WALK MAN MOTOR IS THE BEST BET) motor,and a 470 Ohms pot will do the job nicely..all around 300 rupees..you can also make a full fledged R/C system by using all transistors, digital proportional, not by any costlier stuffs but all with BC 148, BC 547 along with SL, and SK 100.you can wire an RF amp around any general purpose HF switching transistors like S 8050,8550 for low power, and can do high power transmiters by 2N 3056 or in extreame case 2N 2219, or 2N 2222 metal case transistors.while using these moderately powered transistors you must use all resistors in 2 watt range, and all coils must be in good quality in winding and wire, as the BJT drops an high current while in operation.a heat zink also provided.for even more extreame case you can use complimentry type amps or bridged amps in final stage.such circuits only works with a car battery.now you can also use N channel mosfets for final stage.i still use a four channel full proportional system,that i made in 1996, still works nicely..a 4x4 inch vero board and some transistors with an audio oscilator.i can change its freequecy to any desired range just turning a GANGED CAPACITOR from a pocket radio,in local oscilator stage. its better to make an R/C system based on SUPERHETRODYNE method, as it increases selectivity of freequency.

after verifying to some local authorised persons i will post all of my proven circuits here...and more...its not a fun...its a science to enjoy..i know making and operating a model from an entire KIT is not much creative. imagine that one of  your aircraft or a ship or a train or a robot is entirely made out of scratch inc radio...!!!its worth a live gold medal.my sister is a crazy one, and was spending ample of money on radios.i adviced many times her..but she continued to buy..untill once i opened a professional system,a four channel,from a reputed comapny, and she shocked...it was truely based on my basic circuits except one thing. there wasnt any part number on any component, and all was SMD to avoid servicing,just like a mother board of a DVD player.the layout of the circuit was almost same except they used a mosfet instead of transister.so think again. and i have seen many professional systems interfers each other even with various crystals. means the basics are the same..but you can avoid all such mal functions by using your own RC by tunnig your system with tuner circuits.so you must buy a professional system,yes sure its a pleassure , now i am looking for a second hand one a two channel,but only for a realisation of my old dream.but i will not use any of them on my crafts as i can make world class RC systems my own...my extreame creation was a 12 channel multiport continious RC system, for a robot.so have a nice RC system to you...