For Christmas 1983 (age 12) I got this: And one of the projects is a crystal set, using the variable cap, ferrite bar coil, and germanium diode. Had lots of fun with this kit as a teenager, and still have it! Can't wait for my son to get just a little bit older so I can bring it out and play with it with him. I remember I also made a "click click" telegraph key with it, using the relay and included "Morse key," the blue box in the compartment on the right. Only I didn't know Morse back then.