Schematic of single-turn BFO detector:

B1=9 volt DC power source.
C1, C14=22 Micro Farad
C2, C5, C6=0.0015 Micro Farad
C3=10 Micro Farad
C4=0.0036 Micro Farad
C7=47 Micro Farad
C8, C16, C17=0.27 Micro Farad
C9=0.01 Micro Farad
C10=330 Pico Farad
C11=660 Pico Farad
C12, C13, C15=0.1 Micro Farad
All resistors 1/4 watt.
R1, R8, R9, R12, R13=220 Ohms (red, red, brown, gold)
R2, R7, R10=2.2 K Ohms (red, red, red, gold)
R3, R4, R15=1 K Ohms (brown, black, red, gold)
R5= 4.7 K Ohms
R6= 270 Ohms
R11=470 Ohms
R14=100 Kilo Ohms
Headphone Jack:
J1= Headphone jack 1/4 or 1/8 inch
L1, L3= 4.7 mH, choke coil
L2= Broadcast band loopstick (adjustable)
L4= Search coil, a loop made of copper wire(1/4 inch) in 9 inch diameter, 1 inch gap between points A and B.
Q1,Q8= All 2N3638 or equivalent PNP transistors.
S.C.= Shielded Cable

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