Q1 amplifies the input signal via C4 from the electret microphone.
Q2 acts as an oscillator and the signal coming off C2 is fed onto the base of Q2.
L1/C1 is a so called ‘tank’ circuit and operates in the 88-105MHz band on your regular AM/FM radio dial.
L1 is a 1uH variable inductor coil to be able to tune it a little bit, and the range of 1uH is approximate.
The antenna can be as simple as a 8″ (21cm) piece of wire of any kind.
List:
R1 = 10K (brown-black-orange)
R2,R3 = 100K (brown-black-yellow)
R4 = 470 ohm (yellow-violet-brown)
C1,C3 = 4.7pF (4p7), ceramic
C2,C4 = 4.7uF-16V, electrolytic
C5 = 0.001uF (1nF), ceramic
C6 = 470pF, ceramic
Q1,Q2 = 2N2222, NPN transistor
L1 = 1uH, variable inductor
Mic = Electret mike, 2 wires
August 4th, 2009 at 5:03 pm
for how long distance you can hear from radio?
thanks
August 4th, 2009 at 6:07 pm
Almost max 100 meter , if there is no elevation difference or barrier.
August 16th, 2009 at 11:46 am
Which reciever, used for here sound . after i compleated this circuit. how can tested and how can i hear sound .?
September 18th, 2009 at 9:16 pm
You may use you radio to recieve mic sounds.But you have to find the right frequency first.