AM receiver

This should help
Crystal Radio Circuits

Why don't you make a DC (Direct Conversion) receiver. Beside it having double sideband reception, they are very good performers and not too complicated. Also, you will need head phones to receive the signal because you cannot over amplify the 1st and only IF (intermediate frequency) or with all that amplification to drive a speaker you will surely encounter feedback. Never-the-less it is an excellent learning step in how receivers today are made and they can achieve quite superior sensitivity. I have made some that could pick up a 5 watt station in California from Florida.