Please Help with This Circuit

Discussion in 'General Electronics Chat' started by mrkabukiman, Dec 3, 2008.

  1. mrkabukiman

    Thread Starter New Member

    Dec 3, 2008
    Hi, I am rather interested in this whole circuity business, and would love to make this fm transmitter :

    The only issue is, and this makes me feel a little retarded, that I cant find where to hook up the negative power terminal. The bit in the upper right hand corner clearly labels the positive power input, but for the life of me I cant find where the negative input goes. I am rather new to this, and would appreciate any help.

  2. leftyretro

    Active Member

    Nov 25, 2008
    The negative power terminal wires to the terminal just below the the one labeled positive power, labled GDN. The little arrow pointing down from that terminal means it connects to all the other down arrows throughout the diagram. That is known as circuit common, or sometime ground, and they show it that way to eliminate all those points having to be drawn together and making the drawing harder to read.

    Make sense?
  3. PRS

    Well-Known Member

    Aug 24, 2008
    See that + in the upper left corner? Right below that is a hole. Hook your ground to that.
  4. Audioguru


    Dec 20, 2007
    The BA1404 FM transmitter IC has not been made for many years and had poor performance. It was replaced by Rohm with much better ones. An Australian magazine made The Micromitter project that uses one of the newer ICs. The IC uses a frequency synthesizer with a quartz crystal and a phase-locked-loop.
  5. Farlander

    Active Member

    Oct 14, 2008
    Could this newer fm transmitter IC switch a fet carrying about 100 amps? Over what frequency range?
  6. Audioguru


    Dec 20, 2007
    The FM transmitter has a sine-wave output from 88MHz to 108MHz.
    A FET can switch and make a square-waves but not at such a high frequency.

    What are you driving with 100A?