This is an easy to build AM radio with very few parts and fairly good reception.I had built a radio prior to this but I did not like the design even though it worked very well. About the only problem with this radio is that it does not drive a speaker. I will continue to work on that part.
After testing the circuit, I put it together on a very small board and stuffed most of it into a 35mm film container. I have the tuning dial and the variable resister on the outside. The dial is on the lid of the container and the variable resistor is on the side. I also have the ground and antenna leads coming through holes in the container. The coil consists of another film can wrapped the full length with enameled 30 gauge wire. If you want to fool around some, you could experiment with different coils. I have picked up Radio Canada International with a much smaller coil. That is not too bad from CT. I have the 2 containerz taped together to make a nice neat package, with the 9 volt battery taped onto the coil container. The battery can be stuffed into the coil container when the radio is not in use, but changes the inductance if you try to use the radio with the battery inside of the coil. This radio does have to be grounded, but I can receive my local station without an antenna. A long wire is sufficient for an antenna.
This was a fun project, rather inexpensive and I felt that it was a good learning experience with a useful radio as a result.
Here is the schmatic or the the radio. The op amp is a 741 that I got at the infamous Radio Shack.
I hope that some of you also build this nice little radio. Perhaps you can teach your children a bit about radio with this simple unit.
Any and all comments sent to me will be read and suggestions will be considered. Here is my email address, but if you click on the link, you will have a pleasant surprise when you go to my very special email page.