A Little Sunshine, Miss

How to use solar power to power a hand-held radio telescope or a simple solar voltage meter

Summer means sunshine and here are a couple of neat projects that you can quickly build for exploring two different properties of the sun: radio spectrum analysis and solar radiation measurement. While both of these projects are very simple in their construction, you can still perform crude data collection with each one. Throw in some exciting solar experiments and now you're talking daytime science fun for entertaining youngsters during the dog days of summer.

Handheld Radio Telescope

No, this isn't a large radio telescope array like Jodie Foster used in the movie Contact, rather this is a little device that converts light waves into sonic waves. In other words, you can now listen to the sun.

Parts List

* 6V solar panel (Electronic Goldmine #G15555; $8.95; or, salvaged from an old calculator or outdoor lighting unit)
* 3.5mm stereo cable (The Electronic Goldmine #G15449; 99¢)
* Audio amplifier with microphone or line input jack

How To

Step 1. Snip off one plug of the 3.5mm stereo cable. Prep the snipped end exposing the red, white, and black wires. Twist the red and white wires together.

Step 2. Determine the positive and negative terminals on the solar panel. Connect the red and white twisted wires from the stereo cable to the positive terminal of the solar panel and attach the black wire to the negative terminal.

Step 3. Insert the stereo cable's remaining plug into the audio amplifier's microphone or line input jack. Place the solar panel in direct sunlight and turn up the volume on the audio amplifier.

Depending upon your model of audio amplifier the resulting sound could range from a quiet "hiss" to a loud droning "buzz." Use your handheld radio telescope to sample various light sources. Record these samples. What conclusions can you draw from these various light source sounds? Based on your conclusions, draw a "waveform" for each sound sample. Do your sound sample waveforms match the visual appearance of each light source?

Solar Power Meter

A really simple way to measure solar power is to connect a solar panel directly to an inexpensive multimeter. Most of these cheap meters can read both current and voltage. Once you've made a couple of wiring connections, you can use either scale for monitoring the sun's power.

Parts List

* 6V solar panel (Electronic Goldmine #G15555; $8.95; or, salvaged from an old calculator or outdoor lighting unit)
* Pocket analog multimeter (All Electronics #AMM-241; $5.95 or any other inexpensive electricity test meter)

How To

Step 1. Connect the positive and negative terminals on the solar panel to the red (positive) and black (negative) test probes, respectively, of the multimeter.

Step 2. Set the meter to read DC current and place the solar panel in direct sunlight.

Step 2a. Alternatively, if your meter does not have a scale for measuring current, use the voltage setting, instead.

Use your solar power meter to measure the amperage or current (or, voltage, if your meter can't measure electrical current) from the sun. This measurement should vary throughout the day. Does it? Make a solar power sample every hour and record the meter's current setting. Plot the results for these hourly readings on a graph with the current or amperage reading on the vertical y-axis and the day's hour on the horizontal x-axis. Record a week or month's worth of daily solar power readings. Compare your readings against known atmospheric events in your neighborhood (e.g., rainy days, smoggy days, etc.). How do these atmospheric events affect the solar power readings? How do solar power readings change throughout a season? Or, throughout a year?

Either of these projects can go a long way towards forming a viable science project. You know, a science project for the science fair at school…which should be starting pretty soon, now. Enjoy your summer, what's left of it, anyways.