Help Pls

Discussion in 'General Electronics Chat' started by fpj09, Jun 6, 2013.

  1. fpj09

    Thread Starter New Member

    Jun 5, 2013
    1
    0
    Hey, i did this "3 Stages FM Transmitter" on project board & got result. It tuned at 91.3 MHz (frequency vary all the time).
    But the problem is to calculate the oscillating frequency at the 2nd stage(Q2, oscillator circuit).
    If i use
    L = (d²n²) / (18d+40l)
    (Where L is the inductance of the coil in uH, d is the coil diameter in inches, l is the coil length in inches and n is the number of turns.)
    and f=1/(2π√LC)
    then the frequency i got is not in the range of FM, its almost around 200 MHz.

    (Coil L1 comprises four turns of 20SWG enameled copper wire wound to 1.5cm length of a 4mm diameter air core &
    Coil L2 comprises six turns of 20SWG enameled copper wire wound to 2.1cm length of a 4mm diameter air core.)

    I attached the circuit diagram. Someone help me pls, i know you guys are really helpful.
    Thanks
     
Loading...