Very simple, sensitive AM radio circuit can be made with MK484 monolithic integrated circuit and few external components.
Main features of the circuit MK484 AM radio circuit include low supply voltage operation and low drain current.
This MK484 AM radio circuit provides a complete solution including : RF amplifier, Detection and AGC circuit (automatic gain control ), which requires only a few external components to give a high quality AM Tuner.
The MK484 device is particularly suited to small hand-held radios.
No setting up or alignment is required and the circuit is completely stable in use.
The circuit has an input impedance of 4Mohms and operates over a frequency range of 150KHz to 3MHz. The IC will run with DC supply between 1.1V and 1.8V typical 1.4V and a current drain of 0.3mA makes it suitable for battery operation.
The output signal is to low to drive a speaker ( typical from 40 to 60 mV ) and is necessary a audio power amplifier .
The coil needs approximately 55 turns of 0.315mm diameter enamelled copper wire on a 100mm long ferrite rod.