RF Transmitter

Discussion in 'Wireless & RF Design' started by raveel, Apr 17, 2007.

  1. raveel

    Thread Starter New Member

    Apr 17, 2007
    3
    0
    Hi All,

    Planning to build my own short distance transmitter for car and home… any ideas where I should start from. I'm familiar with circuit theory - may need to refresh few things, but that's the point of this project.

    Also like to simulate my circuit in Pspice, if I’m lucky, I would get some kind of ac/dc repsonse before buying any component that I may not use.

    Transmitter initial specs:
    9v battery or less (1.5v is ideal) -- low power consumption as it’s meant to be for a very short distance
    Variable frequency (may need POT)
    FM: 86-108MHz will be used..


    Please help and point me in the right direction as there are many circuits already available on the internet. Selection is overwhelming. PLL or no PLL.. just a tank or oscillator?


    Regards,

    Raveel
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    Putting the freq on the FM broadcast band may cause problems. The FCC wants this part of the spectrum reserved for paying customers.

    Might something like a baby monitor work for your purpose? the transmission is one-way, but they are quite inexpensive. There are also walkie-talkies available that don't wreck the budget. It's usually best to stay in frequency bands where the activity is permissible.
     
  3. PDubya

    Member

    Mar 16, 2006
    28
    0
    Do companies that produce FM transmitters have to get some sort of license for their products?
     
  4. John Luciani

    Active Member

    Apr 3, 2007
    477
    0
  5. Tube Tech

    Active Member

    Jan 11, 2007
    46
    0
  6. raveel

    Thread Starter New Member

    Apr 17, 2007
    3
    0
    Hence, the short range - there are products/transmitters like this in the market for you to use. They sale them at radio shack.. and you can use your radio frequencies.. but you'd have to find freq that's not already in-use.

    I am looking for circuit ideas to start my design.

    Cheers,

    Raveel
     
  7. Gadget

    Distinguished Member

    Jan 10, 2006
    613
    0
    Google the BH1417H PLL stereo transmitter IC or its sisters.
     
  8. raveel

    Thread Starter New Member

    Apr 17, 2007
    3
    0
    Thanks Gadget.
     
  9. windy

    Member

    Apr 19, 2007
    26
    0
    And yes do stick with PLL you will not have a problem staying on freq.
     
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