hi, I´m a physicist from argentine, cordoba.

I like aeromodelism. and I want to build a 4 channel radio control.

i´ve seen around in the www a dtmf based radio control. but this scheme does not
apply to servomotors.

any one has some circtuit diagram of an 4 channel radio control ??

sorry, but my english is not a good one :P

thanks
rayo

 

Your best bet is to buy an off the shelf radio like these: http://www3.towerhobbies.com/cgi-bin/wti0093p?&C=JEJ

I'm not sure how you would go about getting them in Argentine though.

 

but i want to build one...

i can deal with electronics, the main problem is that I does not know about standards, a circuit diagram could help a lot !!!

i was thinking in attach some FM transmitter to a laptop... but the main problem is the receptor

i´veen read some where that servomotors decode a pulse length between 1ms and 2ms into its position, if they are sent to the servo periodically at 20ms.
so I think about a receptor that fragment a train of pulse lengths of 2*4 = 8ms of length (each pulse needs 2ms, and 4 channels), into 4 pulse lengths of
a maximum of 2ms each, and sent each pulse to the respectively servo ( rectified from the transport FM signal ). in the jerga PWM.

look:

http://www.seattlerobotics.org/guide/servos.html

so the laptop do all the complex work by mean of software, constructing the pulse train. the complexs part of the receptor, are the FM receptor, and the
pulse fragmentator. mainly because it must work in coherence with the transmitter. so some kind of reset signal must be transmitted as well. but i think in
the remaining 12 ms to do that.

also i think a microsoft window crash in the middle when flying a model jajajaja

best regards
rayo

 

You generally can't buy the special chips required, and it's not a good idea to make your own radio control for aircraft, far too dangerous.

Commercial gear is cheaper than you could make it, and likely to be far more reliable.

__________________
PIC programmer software, and PIC Tutorials at:
http://www.winpicprog.co.uk

 

yes, i know that, but the scheme that i talk about seems not to expensive. (the laptop its the expensive one, but i already have one)

anyway, i want to build one. it is about the challenge.

can some of u, give to me a FM transmitter and receptor diagrams.
and diagrams about pulse fragmentors as well ??

best regards

 

You can buy Zigbee modules from Maxtream and connect the two and build the circuitry around the transceivers.

 

ohh, that´s nice, but everything is solved there...

i want to construct a simple FM receptor. (the transmiter can send pulses by mean of switching it on and off) and to the output of it connect a device, that cut a train pulse of DC current of 8ms (plus 12ms of _ signal) into 4 channels of pulses of 2ms (in it respective location).

for example:

--__ -__ ---_ --__ (and 12ms of _ signal)

fragment it to:

--__ ____ ____ ____ (and 12ms of _ signal) to the first servo

____ -___ ____ ____ (and 12ms of _ signal) to the 2° servo

____ ____ ---_ ____ (and 12ms of _ signal) to the 3° servo

____ ____ ____ --__ (and 12ms of _ signal) to the 4° servo


here ____ or -___ or --__ or ---_ are pulse trains of 2ms

best regards
rayo

 

I'd suggest searching for R/C model sites with Google.com. Pretty sure there are a few complete transmitter/receiver diagrams. I remember seeing the stuff when I was looking to decode PPM (PWM) signals, at least you will get a better understanding of how it's encoded/decoded to drive servos, or other things. Don't have any links, and kind of busy to go searching. I know there are several sites out there, not sure about 4 channels though, wasn't what I was looking for. Use 'PPM decoder' for a search, should find a site with that, and the rest. Pretty sure I used something like that, when I was finding the tech stuff. Been a few months...

 

I´ve donde that, and I havent found something clear about... just dispersed parts...
from that i must do a lot of work to ¨assemble¨ those parts...
if this is the case, I prefer start from the begining...

anyway... thanks for u time...

best regards
rayo

 

Hi rayo,

Most modern sets are microcontroller based, so the design is for the most part software. Here is a group that is working on a high-end, open source transmitter:

http://groups.yahoo.com/group/beyond4000/

The draft schematic was posted early on, so you can search on it to see what I mean. Whatever you do, I would suggest buying a pre-made RF module. That not only helps address some of the license issues, but possibly more important, if someone crashes when you turn your transmitter on, you won't be the immediate focus for the blame.

I am pretty sure that in my files I have some hobbyist designs from years ago. I will post them or the links when I can. John