FM Receiver

You could use a small FM receiver for convenience taking the output signal from the headphone connector connected to an external volume control ( about 10K ohms ) then to the decoder.

If you have something smaller in mind then the following FM receiver can be constructed with the TDA7000 IC which is still available from some distributors . No special skill is required except care must be taken that all the capacitors all wired as close as possible to the pins. The recommended supply voltage is 4.5 volts but up to 9 volts can be used .

The coil (L1) is made of 6 turns of # 20 insulated wire on a 1/4 " form . Tuning is simple enough once you have your transmitter operating simply tune the variable capacitor with a non-metallic screw driver very slowly until the signal is detected anywhere on the FM band .

The signal output is very small , only suitable for crystal headphone and must be amplified if you want to hear it . The LM386 amplifier is well suited for that purpose . See LM386

Parts list C1 = .15 uF C2 = .002 uF C3 = .022 uF C4 , C5 = .01 uF C6 = 180 pF C7 , C9 = .003 uF C8 , C14 = 330 pF C10 = 150 pF C11 = 100 pF C12 , C15 = 220 pF C13 = .1 uF C16 = 47 uF /15v C17 = 10 -20 pF Var. R1 = 10K R2 = 22K L1 = see text