The cry usually goes out on a Sunday
night "I have to have my science project done by tomorrow; what can I do?"
If this happens to you, about all you can do is shrug your shoulders and
set to work making yet another paper mache volcano to be filled with baking
powder, into which your own little genetic experiment pours some vinegar
at the appropriate moment. However, we will not concern ourselves here
with the last minute one-off science demonstration, but rather a research
project to be documented, written up, and mounted on a cardboard display
board for judging in a science fair. With luck, the cry will be timely
enough to give you a running start, say, two weeks or a month (I understand
this actually happened once in 1983).
Crystal radios make for very good
science fair projects. The designs can go from the quite simple to
the complex, there are a whole bunch of variables which can be examined,
they involve technology (and solid state at that), they have residual value
after the fair, and you can actually learn something useful.
There are some other features about crystal sets for science fair projects
that make them winners:
a. A lot of the judges, particularly
in the physical science areas, are guys like me, and we got our start with
these little sets, so you get some added appreciation along with the nostalgia
bonus.
b. Most science teachers and
other teachers of science got the bulk of their training in life sciences
and/or chemistry. They are duly impressed when they see a project that
doesn't have as a title "Do plants grow better with fertilizer" , "Is Pepsi
The One?" and the like. (they will also probably not try to dissect
the project in its infancy either)
c. Little or no competition,
particularly at the earlier grade levels - electronics projects are rare.
d. Once the project
is underway, which may require some assistance getting parts together and
an antenna up, not much parental help is needed. Once the set is up
and working, the kid can pretty much take care of the rest.
e. The same equipment can
be used as the basis for future science fairs.
Before you go any further here,
jump over to the Xtal Set Society site and get their science fair information,
then come back.
Science Fair Projects and Parents & Teachers Page
Here is another "must read" site on doing a science
fair project, not just for crystal sets:
EXPERIMENTAL SCIENCE PROJECTS: An Introductory Level Guide
Now let's look at some nuances of good research projects and how they apply to one using crystal sets.
1. Change only one thing to examine the effect. This is generally called the experimental variable. Everything else should remain the same. If what you are doing involves the reception of local stations only, you might get away with collecting your data at any convenient time of the day or night except for those stations that change power level at sunrise/sunset, as many do. For distant stations (dx), propagation conditions have a lot to do with reception, so data involving them should be gathered during specified times of the day (early evening, usually). Once a particular set design has been determined, it shouldn't be changed, unless the experiment has to do with changing one aspect of the set's design.
2. "No" can be a valid answer. Your child's teacher will usually insist on a hypothesis, or educated guess, on what will be the outcome of the experiment. That does not mean the guess has to be correct. Much in the way of scientific research results in "failure", which is perfectly okay as long as something is learned. The important thing is to try something out and take good notes.
3. If you change the experiment in the middle of it, that's okay, but you have to go back and rewrite your hypothesis and the procedure for the experiment to accommodate the change; this happens in the real world all the time. With crystal set experiments, as with other investigations, it isn't uncommon for a line of inquiry to dead end or be harder to evaluate than originally thought. If something better comes along, go for it, but go back and do the paperwork. I have seen a number of projects at science fairs which had obviously gotten off track. That's not to say what got done wasn't interesting, but the connection of the project to the original theme was tenuous at best. Your project might start out to investigate antenna length vs stations heard, and end up being a comparison of stations heard two hours before and two hours after sunset.
4. Keep it simple. We're not trying to
invent the warp drive here. The objective is to do a nice clean research
project that has a testable hypothesis, conduct a straightforward experiment,
and report the results. The description of the experiment and
the results should be clear enough that someone else doing what was described
would get the same results.
Doing the Fair: Some shoulds and shouldn'ts.
Chances are you child might never
see the actual judging take place; this is often the case for elementary
and middle school fairs. This means that the display should speak for
itself. This also means that anything left out can disappear.
Don't risk the loss of a vintage Baldwin headset for the sake of a more favorable
consideration from the judges.
Do not plan on giving a demonstration,
no matter what anyone says (and if they insist, refer them to me), and don't
even offer to consider it. When your child's teacher blithely chirps
how wonderful it would be for people to be able to listen to the set, it
is merely a display of enthusiastic ignorance. Don't fall for it.
I won't go into the whys and wherefores here, but will be happy to discuss
it if you contact me. And no, don't even bother to ask me how to do
it; even if I told you, your chances of success are slim. Some projects
lend themselves well to working models at the fair. Even these usually
require an attendant. Crystal sets fall into the "static display"
category at best.
A picture and an electronic schematic
of the set are always appreciated on the display board, along with a Polaroid
of you clinging to the top of an extension ladder rigging the antenna.
A good display has an eye catching
title across the top, a clear statement of the purpose of the project, a
one or two sentence description of the experiment, some experimental data
that makes sense, either tabular of graphed, a quick summary and a statement
as to whether or not the hypothesis was supported.
Back to the original problem. Just what can you do with a crystal set project? For some ideas and thoughts, go HERE.
When all else fails - ask Elmer:
There is a bunch of research information
on the web to back up a crystal radio science fair project. You can
access most of it from my links
page.
To get response to specific questions, you can post them on Rap 'n Tap the Xtal Set Society forum, and expect to get quick responses. This is an open forum, and anybody can join in - nothing to join, and no secret passwords or handshakes.
For more personal assistance, be it moral support, specifics of how-to, or even material support, send an email to either me or Larry Pizzella. We've been involved in this before and can probably help you out.
Good luck.