i'm now doing my final project. i need to attach a radio frequency circuit to my robot. i couldn't find any circuit about that. i need only the transmitter send a pulse, and the receiver just receive it and response to it. can any one help me??

 

search for Fm transmitter and receiver ckt

 

u mean search from the foeum of eletro-tech-online??
is it necessary for me to use fm?? or am??

 

Google or ETO , both will help

 

Schematics and kits for relatively simple transmitters are abundant for the FM broadcast bands. That might explain the recommendation. I see a lot of activity in this forum regarding the 433 mHz modules (transmitter and receiver) that are fairly common and inexpensive. Much of the hard work is done for you but that may not be allowed by your instructor. You also need to consider the rules and regulations that apply to your location. Your instructor may or may not expect you to comply.

If you have to build everything yourself give some consideration to lower frequencies such as AM broadcast. At higher frequencies keeping the transmitter and receiver on the same frequency will be a challenge with relatively simple circuits. More complex designs are out there however they can be a challenge to construct.

Lots of choices here. Share some of the rules with us. Maybe you are allowed to use a receiver that you have around - that would simplify things to a great degree.

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stevez

 

what i need is, the distance between the antenna of tx and rx should be very close to get connection. but i can't use ir, because i'm using my robot in dirty environment. the receiver is inside the robot, when the robot goes near to the tx antenna (less than 10cm if possible), once it receives the rf, it will change direction and so on. the rest is almost okay, my problem now is the rf circuit.

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in this case , u wont need the txs described above.

since the "ant" encircles the robot, just pass a low/medium freq current thru that line at low voltage(need to be experimented) , the robot shld tune into that freq .

 

oh!! thanks.. but, i don't know how to construct low frequency tx and rx as well.. can u show me a simple circuit?? i can't find the circuit from the net also.. thanks

 

u didn't find anything from net .. :shock: :roll: .. ur app doesn't need freq stability , use a 555 osc ...

 

use a 555 timer?? how it transmit the signal?? and how about the receiving part?? sorry.. i realy need helps..

 

Try this out. You may have to tweak the frequency and antenna current.

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that last circuit is good, except that the following should be done:

Instead of connecting the output of the 555 to a pull-down resistor, do this:

Connect the output of the 555 to one end of a large value capacitor. The other end is connected to a grounded tank circuit. Stick the antenna at the point where the two capacitors are connected (one being in the tank circuit).
Set the values in the tank circuit so that its resonant frequency is the frequency you want to transmit on.

I do advise the coupling capacitor in order to prevent the output from shorting to the ground via the inductor.

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"connect the o/p of the 555 to one end of a large value capacitor?, then how about the resistor between the o/p and the antenna? ignore it? and.. what is tank circuit?.. for the receiving part.. what is the triangle thing? and what is the mouser? sorry.. i really don't understand.. please show me the correct circuit design... thank you so much..

 

i don't think these modification have any advantage in the present context , apart from adding complexity .

 

it is a heart of an LC oscillator , where the oscillations start.
the 'triangle' thing is an 'operational amplifier' or simply opamp
and mouser is a company , the number shown is their catalog number for that part.