The schematic shown below is a simple am receiver circuit uses only one transistor and some other components. The 80 turns coil and 365pF variable capacitor form a tank circuit which receives the signal through the antenna, and then the signal is detected by OA91 diode and amplified
by BC547 transistor. Coil is equal to 80 turns of 26 s.w.g. Enameled copper wire wound on an empty card board toilet roll or an off cut piece of plastic waste pipe. Try different coils you can also experiment with the coil found in AM portable radios.