12v radio transmitter/reciever

[tdh1]

please help,

my knowledge of electronics is pretty limited; maybe someone could help me figure out how to put together the correct componets to do this experiment.

here is my idea: a 12v radio transmitter that would send out a signal to a remote 12v receiver.  the transmitter would be activated by a 12v automobile switch, and then output a signal; the time the signal is activated needs to be adjustable.  the receiever would then activate a flashing light.

transmitter componets:
    12v switch
      12v timer
      12 v relay
      12v voltage to frequency converter
      12v transmitter

reciever componets:
    12v receiver
    12v frequency to voltage converter
    12v relay
    12v flasher
    12v light

thank you,
have a good day...........

[Theatronics]

That’s a tall order.
  How far does this signal need to travel?

What you are describing is a CW signal.  A signal that is just a sine wave at a given frequency.  Morse code was sent using this method.  The problem with CW signals is that they are easy to fool and are prone to interference. 

Most systems modulate the Carrier frequency (Carrier Wave) with a second frequency or even a digital signal.  This insures that the signal can be identified from all the background noise an open CW receiver may pick up.

Building a reliable Transmitter / Receiver pair is not a project for someone unfamiliar with radio theory.  Not only are there lots of issues with the design, there are laws about the usage of the radio spectrum, if you mess up someone’s TV or phones they could complain and you could get fined.

My advice is to find a prebuilt pair and use them.  There are many such systems available.  Remote controlled cars and airplanes have good range and are easy to interface.

Look for Garage door opener retrofit kits.  Also there are home security systems that are used to detect mail boxes being opened.  All these are good prebuilt systems.  All you would need to add is the connection to the car and the signal at the other end.

Unless you really want to learn RF theory ? 


The basic method :
  Put together two tanks (a Cap and an inductor) that are tuned the same.
Using the tuned frequency, Calculate the length of the antennas needed.
(The distance an electron can travel at the speed of light in the time it takes for 1 cycle of the circuit)
Attach a wire that long to one end of each tank.  Ground the other end.

Then Inject a signal into one tank at the selected frequency.

The second tank will begin to oscillate in tandem with the first one.

(Magic but it only works over a few feet)

For longer ranges, additional parts are needed.

Here is a low wattage Transmitter for example.

-Mike

[Theatronics]

forgot to attach the picture. ;D
_mike

[Ir afhamz]

Hi,
i am am working on a remote control project. can u help me with the remote control circuit. i am using PIC16F84a microcontroller.
i need both the transmitter and receiver citcuits.plzzz

[Theatronics]

What do you need to know?

-Mike

[steev]

well that pic u posted look like FM transmitter?
but u said u want RF transmittr right...aim i confused :-\

[audioguru]

well that pic u posted look like FM transmitter?
but u said u want RF transmittr right...aim i confused :-\

It transmits AM on the AM broadcast band. Look at the size of its capacitors and its inductor that determine its frequency. A similar FM transmitter uses much smaller capacitors and inductor and produces combined AM and FM on the FM broadcast band. Replace the microphone with a circuit that makes data if you want.