Parts List
R1 = 27k TR1 = BC547 R2 = 330k TR2 = 2N2219 fitted with heat sink R3 = 5k6 MIC = piezoelectric microphone R4, 5 = 10k R6 = 100R
C1, 2, 3 = 330 pF C4 = 2–10 pF trimmer C5 = 4p7 C6 = 1 nF
C7,C8 = 40uF/25V Electrolytic
L = 6 turns 22 gauge enameled wire wound on 3⁄16″ former