- #1
CGandC
- 326
- 34
Hello,
I have assembled the following AM radio reciever circuit:
Purpose of the circuit: To receive AM radio signals and provide the output audio of these signals ( demodulated ).
Circuit elements: L ~ 1.5mH , C ~ 300pF , Amplifier IC: LM324N , Diode: 1N4004 ,
The speaker is small and it's resistance is ~ 5 ohm
There are 2 variable resistors, to adjust the amplification.
The antenna is a long wire
The voltage provided to the amplifier is 9V DC from battery ( not drawn )
My expectations from this circuit:
- the antenna would receive a signal
- the bandpass filter would filter the signal so the output signal's ( to the amplifier ) frequency spectrum is centered at ' Fc '
- the filtered signal would get amplified by the amplifier which is connected in negative feedback configuration
- the signal's negative voltage would get truncated by the diode
- the signal would pass through the speaker to the ground and thus I would hear AM radio station broadcast.
Experimental results
- There is no voltage drop on the speaker at all and no current flows through it, thus it is mute.
- Most voltage drops on resistor R2
Notes:
- the central frequency of the bandpass filter is Fc=1/sqrt(LC) ~ 1.49MHz
- the ground in the circuit is the cathode of the 9V battery
My question is:
Is this circuit wrong? , if not, then what do you propose as being the fault to the failure of the system?
If it is wrong, then why?
Thanks in advance for help.
I have assembled the following AM radio reciever circuit:
Purpose of the circuit: To receive AM radio signals and provide the output audio of these signals ( demodulated ).
Circuit elements: L ~ 1.5mH , C ~ 300pF , Amplifier IC: LM324N , Diode: 1N4004 ,
The speaker is small and it's resistance is ~ 5 ohm
There are 2 variable resistors, to adjust the amplification.
The antenna is a long wire
The voltage provided to the amplifier is 9V DC from battery ( not drawn )
My expectations from this circuit:
- the antenna would receive a signal
- the bandpass filter would filter the signal so the output signal's ( to the amplifier ) frequency spectrum is centered at ' Fc '
- the filtered signal would get amplified by the amplifier which is connected in negative feedback configuration
- the signal's negative voltage would get truncated by the diode
- the signal would pass through the speaker to the ground and thus I would hear AM radio station broadcast.
Experimental results
- There is no voltage drop on the speaker at all and no current flows through it, thus it is mute.
- Most voltage drops on resistor R2
Notes:
- the central frequency of the bandpass filter is Fc=1/sqrt(LC) ~ 1.49MHz
- the ground in the circuit is the cathode of the 9V battery
My question is:
Is this circuit wrong? , if not, then what do you propose as being the fault to the failure of the system?
If it is wrong, then why?
Thanks in advance for help.
Attachments
Last edited: