remote control using radio freq

[keile]

hello!

Our project has been approved and now we need to build our prototype.

As I research, our project is basically a radio controlled device. Push a button in the transmitter side and when it was received by the receiver it buzz or light.

I know it is quite simple compared to examples shown in sites. ???

Now I don't know how and where to get started. I'm thinking of using pulse modulation to send commands. Command to light or sound.


Thanks in advance

Note: I'm fairly new in practical electronics. As I have already studied
theories.. I think I can learn well.

 

[trigger]

Think of the followings:

1. Transmit distance
2. Transmit frequency
3. Transmit modulation (AM, FM, etc)
4. Bandwidth/ data rate of the commands

Hope these give you some insight... ;D

 

[MP1]

Keile,
Perhaps the attached will give you a start.

MP

4_Channel_UHF_Remote_Control_ck1616.pdf

 

[keile]

to MP
wow! that's one hell of an amazing device!! honestly, if I look and examine its every detail, its perfect for my project. With its security and features.. wow.. but the 433Mhz chip cost around $54 uhh.. but a whola thanks!!

to trigger
this is what I have tentatively decided:
minimum of 10m
around 2.45Ghz *same as bluetooth
PM (Pulse Modulation)
uhh.. i still don't have an idea

thanks! ill update to find more circuits

 

[trigger]

2.4GHz ISM band is a bit difficult for me esp. to build transmitter, because it involves a lot of matching problem.
Although you can build using simple LC+transistor circuit but if you don't have a spectrum analyzer or signal generator, it will not an easy job.

For me, I will start with 433.92MHz where it is simple and need lesser equipments esp. you can build a transmitter using saw resonator and a transistor based receiver.

 

[keile]

oh so a higher frequency has lots of difficulty in terms of building a transmitter...

do you have any idea how can i avoid interference if I use a lower frequency like 433Mhz? ???

 

[trigger]

higher frequency will have more interference esp. 2.4GHz band......
like microwave oven, DECT phone, wireless lan, Bluetooth etc.

For 433MHz, I think if you are in UK, the most problem will be caused by the TETRA (police RF communication ?? not sure, it is at 426MHz). You have to build a narrow band receiver to prevent jamming from it.

 

[MP1]

Keile,
You need to find a better place to shop for parts. You can get this whole kit for $40 or just the module for $13. This is a kit from electronickits.com
The exact link for these parts or the kit is here:
http://www.electronickits.com/kit/complete/elec/ck1616.htm

Hope it helps you along on your project.

MP

 

[keile]

hello I'm back!

btw, before I continue on.. I would like to give a lotta of thanks for trigger and MP for helping me on this project.. thanks a lot!!

Something strikes me while listening to my instructor bout 555 timer. And this what I think how my circuit should be (below)


and now i think there's a problem.. the two signals might not synchronize each other.. one might be low and one might be high.. i have to ditched the comparator i think..

my goal is to use PWM(pulse width modulation).. so i think the receiver would check the width of the pulse rather than compare it with the (same pulse width)--needs synchronization.. if there's only a way to measure the width of the pulse..

thanks in advance.. actually i'm happy if I could build the circuit by myself..

View attachment 35748

 

[trigger]

hmm......... you can use tone detector IC (LM567 ) after reciever for such application which will lower the complexity of building the comparator.

I haven't build circuits with this IC but I do think it may fit your needs.

 

[keile]

thanks trigger!

i have researched on the tone detector IC LM567 and found it.. uhh.. confusing ???

well, i have decided to take a look at my electronics book if I could find anything that would help my project. Phased-Locked Loop interest me. After reading all the explanation in the book plus a tutorial on the net, I found that this what I'm looking for, the PLL!!

Phase-Locked Loop (PLL) is an IC that synchronize two signals and output a voltage proportional to the phase and frequency of the input and self-generated frequency.

PLL IC's come in form of NE566, LM566, NE565 and LM565... I just noticed a similarities... LM567 is also a PLL! hehe.. sorry I'm so dumb to realize it sooner. Thanks again trigger!

I'll be back to post a circuit of my design.

 

[surajbarkale]

Check this out remove the IR parts & place RF communication link it might just work ;D
http://www.wimb.net/index.php?s=electr&page=7

 

[keile]

Check this out remove the IR parts & place RF communication link it might just work ;D
http://www.wimb.net/index.php?s=electr&page=7

thanks.. i'll check it

 

[trigger]

Check this link for some useful circuit

http://members.shaw.ca/roma/seventeen.html

 

[keile]

Check this link for some useful circuit

http://members.shaw.ca/roma/seventeen.html

wow! trigger I can't believe it!! You actually found it! oh thanks a lot!!
it's so similar that it only needs few customization or maybe not? hehe.. thanks again!!

 

[trigger]

You are welcome.
I just found the site yesterday where some of the circuits inside are useful to me too ;D

 

[keile]

hello!

so far this is the flow of my circuit:
555 timer(information,encoder) -> fm transmitter(carrier, modulator) ~~~
~~~ fm receiver(demodulator) -> PLL (decoder) -> output

i'm now in the process of testing transmitters and receivers..
i' ve come across this very nice fm transmitter: http://tacashi.tripod.com/elctrncs/smplfmtr/smplfmtr.htm

i'm planning to supply my transmitter and its receiver at 3 volts.

is there any 3v fm receiver that is simple enough for my project? Thanks!!!

 

[trigger]

Good to hear you have good progress ;D

And for FM receiver, you can try to use simple FM radio receiver ICs. They are served you well (for which your FM transmitter is within the broadcast band 88~108MHz)

ICs like TDA7000, TDA7088, MC3361, MC3362 may fit your needs..

Hope this help.

 

[keile]

yeah.. hopefully we can make a fully working prototype by next week..

I checked TDA7000 and TDA7088 IC's and looks like they're a complete fm receiver with no amp..

and I assume MC3361 and MC3362 is the amp right?

I wanted to run my receiver with 1.5V battery to reduce weight and I think these components would serve my needs..


As always, many thanks to trigger for your continuous support and help for my design project. May god bless you on your way

thanks,
keile