AM receiver circuit
Description.
Here is a low cost AM receiver circuit that can be tuned from around 550 to 1100 KHz. Three transistors are used in this project. The transistors Q1 and Q2 are wired as a compound transistor pair in which Q1 is an emitter follower and Q2 is a common emitter amplifier. The emitter follower prevents the loading of tank circuit, while the common emitter amplifier necessary voltage gain. The L1 and C2 forms the tank circuit.The L1 also does the job of antenna.The series combination of R6 and R7 gives a regenerative feedback between output of the Q2 and tank circuit. The transistor Q3 performs the demodulation of the carrier signal. It also provides amplification the demodulated signal. The audio output is coupled out from the collector of Q3 via the capacitor C3.Capacitor C6 provides some noise filtering.
Circuit diagram.
Notes.
- The circuit can be assembled on a general purpose PCB.
- Use a 9V PP3 battery for powering the circuit.
- R7 can be used to adjust the sensitivity and selectivity of the circuit.
- A high impedance head phone can be used for listening the radio.
- For L1 make 60 turns of 26 SWG enameled copper wire on a 3/8 inch diameter, 3inch long ferrite rod.
- The moving plates of C2 must be connected to the base of Q1 and fixed plates must be connected to the junction of C3 and R6.Reversing the connection may decrease the stability.
Some voltage values at different points on the working circuit.
Q1 (b) 1.31V
Q2 (b) 0.71V
Q2 (c) 1.34V
Q3 (b) 0.62V
Thank you for the circuits. I am a simple hobbyist who does not know about electronics, but can appreciate the gadgets. I live in India. Will you please give me some addresses of your people who live in and around ANDHRA PRADESH in India?
Thank you for your service to the innovative ideas!
All the best!
prasad
hello prasad.i live in kerala,india.my name is rithwik.my mail address is rithwiktom_tcr@yahoo.com.plz mail me ur address.
there is no ‘plz’ in my mail address
Thanks for the circuit!!
I’m a newbie at electronic circits..
Can anyone please tell me how & where to supply input to this AM receiver circuit ??
Hi Neeraj B1 is the 9volt battery through switch S1 gives the power to the circuit.
Thank you Seetharaman.. But i meant how to apply the input signal [the already modulated signal] to the circut..
I would like perform a stimulation of the circuit using a circut stimulator..
I meant if i already have an AM modulated signal how should i give to the circuit? What changes should be made?
hi Neeraj use 2 to 3 turns loop (may be with 7 stranded insulated flexible wire) through which you feed your modulated signal and keep the loop close to L1. L1 will pick up your modulated signal Q1 and Q2 will amplify and Q3 will detect and feed the demodulated audio at the audio out.
Thank you Seetharaman.. I’ll definitely try & tell you my result….