Simple FM Transmitter
The following is a design for a very simple fm transmitter. It
also can be used as a bug or wireless microphone.
Construction Info
Using the following values this transmitter can be used on
frequncies between 30 and 110 MHz.
The mic is a magnetic mic for all three version. Although Electric mics
may be more useful as a bug.
To build for the 30-40 MHz range:
L1 - .445uH Inductor with ferrite core. 8.5 turn, MC120 case TOKO coil.
C1 - 15-20 pF trimmer capacitor
C2 - 10-15 pF trimmer capacitor
ant.- 38" wire
To build for the 40-50MHz range:
L1 - .358uH Inductor with ferrite core. 7.5 turn, MC120 case TOKO coil.
C1 - 15-20 pF trimmer capacitor
C2 - 10-15 pF trimmer capacitor
ant.- 37" wire
To build for the 90-100 MHz range:
L1 - .317uH Inductor with ferrite core. 6.5 turn, MC120 case TOKO coil.
C1 - 5.6 pF capacitor
C2 - 3.3 pF capacitor
ant.- 20" wire
Make sure that C1 and C2 are NPO type capacitors so the device will
have some frequency stability.