[Posted on behalf of student]
Hello! My name is Gracie i am in 8th grade, I'm doing my science fair project on a crystal radio. I've built my radio, got it to work, and tried different things to make it sound better. But my manipulated variable is either the antenna length or the amount of coils, and I'm not sure how to measure the output variable thingy, the thing that changes. Basically, my project would be, for example, "How does the length of the antenna of a crystal radio affect the sound quality of the radio", so the output variable would be how good the radio sounds. However, Since this is sort of a matter of opinion, I'm not sure how to measure how "good" the radio sounds. I've tried, like, counting how many word i can clearly understand in a certain amount of time, and there were too many to count properly. I've had some other lame ideas, like rating the sound quality 1-10 or something, but at my school, science fair is a HUGE deal, so basically this project has to be as perfect as possible. I've seen "measuring the output impedance of a crystal radio" or something like that but it was WAY to complicated for me. Anyway, enough of my blabbering, any ideas on how i can measure this? Thanks so much for your time!
-- Hello! Sorry i already e-mailed you but I'm gonna have to bother you again. So when you coil the wire around the "oatmeal box", you make "taps" or like strip off the insulation and twist the wire, every I don't know five or so coils? Well anyway, when the entire radio is completed and set up and you put the alligator clip on one of the taps/loops, I don't quite know how to word this, but whats the difference between putting it on each tap? Like what changes when you put the clip on the 1st tap vs the 5th? Is it just using different amounts of the coil? And also how do you change stations/frequencies? Just the height of the antenna, right? Anyway thanks for your time! (Again!)