# What’s Happening at the Ann Arbor Hands-On Museum

When I last blogged about this, I simply reported that we’d applied for a grant from the IEEE Foundation. While we don’t expect an answer to our proposal for a while, Jack, WT8N, and I have been brainstorming about how we might use the money. Part of the money we requested were to go towards, “two to four tabletop displays,” and given that we are working with the “hands on” museum, we’ve been trying to come up with exhibits that kids could actually get their hands on.

Accordingly, we’ve come up with several ideas that will attempt to demonstrate some aspect of wireless technology, but in a “hands on” kind of way. What we’ve come up with so far includes:

• Morse Code. Being ham radio operators this is a natural. The question is how to do it. Kids do seem to love to “pound brass,” so getting them to use the key to produce a sound is a no-brainer, but how to get them to learn something is another matter. One idea is to have them type in their name, send that in code, then have them try it. Another is to have two stations and have kids send code to one another.
• Ohm’s Law. The idea for this exhibit would be to have users switch resistors in and out of a circuit, and possibly set the level of a voltage source and have a big ammeter so that they see how changing the voltage and resistance in a simple circuit affects the current in a circuit.
• See your voice on an oscilloscope. Kids would speak into a microphone and see their voice on an oscilloscope display.
• Transformer. Similar to the Ohm’s Law display, kids would somehow be able to switch in more or fewer windings and see how that affects the output/input voltage ratio. We’re kind of sketchy on how to actually do this, though.
• Tuned Circuit. Kids would tune a capacitor and see how that affects the output frequency of an oscillator. This might be a visual display (oscilloscope) or audio output.
• Directional Antennas. In this display, kids rotate directional antennas and note that when the antennas are pointing at one another, they are able to hear a signal or talk to other kids at second station. We were thinking of doing this with 440 MHz antennas and radios, as the antennas would be of a reasonable size. This might not, however, be legal for unattended operation, even with very low power. Anyone know of a frequency we could use for this kind of thing?

All of these displays would be accompanied by some text that explains the phenomenon.

In addition, to the tabletop displays, we were thinking of conducting regular fox hunts. Kids seem to love fox hunts. One thing we’re wondering about, though, is how well we could conduct a fox hunt inside the museum. That is will the fox’s signal reflect off all the metal inside making  finding it nearly impossible.

Another concern is how safe it will be to have kids running around with 440 MHz Yagi antennas. I’ve done a little surfing on fox hunting, and thought I’d found a way around this by using a loop antenna. One website, though, says that while they are great for direction finding at HF frequencies, they’re not really that good for VHF. Anyone have any experience to share with us on this point?

1. Nathan Neulinger says:

You should take a look at the physics/chemistry section of the Oregon Museum of Science and Industry in Portland… They have several stations set up like you mention above, including a pair of code stations, and several “hook stuff together” kid friendly electronics stations.

2. Dan KB6NU says:

Cool. Thanks for the pointer.

3. Yes, indoor RDF at UHF frequencies would be pretty confusing for kids. Why not go to the other end of the spectrum? Use the unlicensed LowFer band (160 to 190 KHz) and the RDF antennas could be multi-turn loops on ferrite rods, very easy for kids to handle.

4. Dan KB6NU says:

The more I look into this, the more I think that’s the way to go. Would you have any references and/or links to websites where I can find out more?

5. I wrote a section on RDF for recent ARRL Handbooks that discusses loop and rod antennas. You should find it in Chapter 13.

Also check your local library for my book “Transmitter Hunting — Radio Direction Finding Simplfied,” which has a chapter on loop and rod antennas.

Loops and rods are also included in the page on 80-meter foxhunting in my Web site (www.homingin.com). The page URL is http://www.homingin.com/joemoell/80intro.html.

73, Joe

6. I see that the link doesn’t work because a period was added at the end. Delete that period and it should work OK.

7. Dan KB6NU says:

Thanks, Joe! I’ll check out your website and the Handbook. I think the latest I have is the 2005 edition.

Amazon is selling your book for \$18. I might just pop for that. I checked the online catalog of our library here, and they don’t have it.