Category Archives: Emergency Preparedness

1937 Field Day


This weekend was Field Day, an activity in which Amateur Radio Operators set up portable equipment and make as many contacts as possible during a 24 hour period.

My own effort this year was very minimalist. I operated as I did for most of my National Parks On The Air (NPOTA) activations, with my 5 watt Yaesu FT-817  with a Hamstick antenna mounted on the car. I only operated for about an hour, but made 13 CW (Morse Code) contacts to places such as Quebec, Florida, Kentucky, and North Dakota. My power supply consisted of my 12 volt fish finder battery,

Back in the day, both the equipment and the power supplies were much more intimidating, and a successful Field Day operation almost required a team effort. This video shows Field Day eighty years ago in 1937. The film shows W8NCD/8, the Charleston (WV) Amateur Radio Club. It is narrated by W8NCD, who is now a Silent Key.

Field Day has always been primarily a fun social activity, but it also has a serious side. It shows that amateurs are ready for emergency situations. In 1937, hams were able to set up at a remote location, without external electric power or any other infrastructure, and be in contact with the rest of the world. In 1937, there weren’t any cell phone towers, but hams managed to communicate around the world. Today, there are cell phones available, but in the location I was at today, at the bottom of the St. Croix River Valley at William O’Brien State Park, cell service is not available. But with five minutes of setup, I was on the air and communicating, just like they were in 1937

1937 Ohio River Flood


Eighty years ago this week, the United States was in the midst of one of its greatest natural disasters, the Ohio River flood of 1937.

Damage was widespread, starting at Pittsburgh, which had experienced severe flooding the year before, to Cairo, Illinois. Damage was light in the Pittsburgh area, but there was extensive damage in Ohio, West Virginia, Kentucky, Indiana, and Illinois. The pictures at the top of the page are from Evansville, Indiana, and appear in the February 13, 1937, issue of Stand By, the program guide magazine of WLS Chicago, whose mobile unit is shown. The boats shown in the picture, docked at the back door of a hotel, are actually on the street, as shown by the mostly submerged street sign in the picture.

The WLS magazine reported that “radio became the principal means of communication, especially during the early days of the flood, and thousands of lives were saved because of the radio directions sent to rescue workers. Commercial, amateur and military stations all provided communication.”

Hazelton, Indiana, January 23, 1937. National Weather Service photo.

Hazelton, Indiana, January 23, 1937. National Weather Service photo.

In Evansville, the local station, WGBF, had an emergency radio set up at the relief headquarters. The station went to 24 hour service, and the programs were interrupted frequently to broadcast relief messages.

Downtown Huntington, WV, during the flood. Wikipedia photo.

The flood caused 385 deaths, with a million left homeless. Property damage reached $500 million, and relief and recovery was strained, with the disaster coming in the depth of the depression and only a few years after the Dust Bowl.  The head of the Red Cross called the disaster the greatest since the war.  For many impacted areas, it was the most severe flood yet experienced.

The water levels began to rise on January 5, and rains throughout the

Ohio basin continued.  By January 23, it was clear that the flood would be severe.  Martial law was declared in Evansville on January 23.  On today’s date, the water crested in Cincinnati at 80 feet, the highest level in the city’s history.  By the next day, 70% of Louisville was under water.  It wasn’t until February 5 when the water levels dropped below flood stage in most areas.

As might be expected, amateur radio operators played a key role in communications, and many of these stories were recorded in the April, 1937, issue of QST.  Since many of the active hams were also involved in the Army Amateur Radio Service or the Naval Reserve, Army and Navy call signs were often used in addition to amateur calls.

In an action unprecedented since the war, on January 26, the FCC entirely closed the 160 and 80 meter bands nationwide to all but those hams directly involved in flood relief. The FCC order stated:

To all amateur licensees: The Federal Communications Commission has been advised that the only contact with many flooded areas is by amateur radio, and since it is of vital importance that communications with flooded areas be handled expeditionsly, IT IS ORDERED that no transmissions except those relating to relief work or other emergencies be made within any of the authorized amateur bands below 4000 kilocycles until the Commission determines that the present emergency no longer exists.

This order was rescinded on February 5.  The FCC did allow the ARRL to select 60 “vigilantes” to monitor the bands and inform any offenders of the order.  According to QST, this order had a very positive impact in reducing interference.  160 and 80 meters were still packed with signals relaying emergency traffic, but the nets were able to work very effectively when they had the bands to themselves.

Hundreds of call signs in all of the affected states are included in the QST report, but it also acknowledges that it would be impossible to list all of the hams who participated.

The 30,000 residents of Parkersburg, West Virginia, were cut off from the outside world, and about a fourth of them were homeless. Herbert Romine, W8GDF, of nearby West Milford hurried to the town. Lacking sufficient equipment, he hurredly assembled several transmitters from the serviceman’s parts stock, and established stations on fire boats in the city. These hastily constructed transmitters consisted of type 45 tube oscillators, along with another 45 serving as modulator. QST noted that this work undoubtedly saved a number of lives.

Romine then put station WPAR in Parkersburg back on the air, having to dismantle and move it a number of times as the waters rose. Another ham, W8BRE, helped put together a 160 meter radio to link the station with the Naval Reserve station.

At Leon, WV, inactive ham Clarence Casto, W8JJA, had been off the air for three years. But with the emergency, he hastily assembled an emergency version of his station to keep the town in contact.

A few miles downstream in Point Pleasant, WV, William Stone, W8MAO, was able to use a portable 20 meter rig to notify authorities in Charleston that medical supplies were needed by air.  This station was set up in the court house on the judge’s bench.

w8yxgeneratorIn Ohio, much of the relief traffic passed through W8YX, the club station of the University of Cincinnati.  Since commercial power had become unavailable, the station operated with the generator setup shown here.  Two 15 kva alternators were run by the power takeoff of a McCormick-Deering tractor.

In Kentucky, since Frankfort was cut off and flooded, the Governor of the state relied upon an amateur for emergency communications. W9AZY, who was also affiliated with a broadcast station, was able to set up a shortwave link between the Governor and his staff and broadcast station WLAP.

w9mwcThe man identified as “one of the flood’s ham heroes” was W.O. Bryant, W9NKD. On January 22, WHAS in Louisville broadcast the information that Carrollton, KY, population 2500, had been cut off from the outside world. The broadcast included a plea for an amateur to go there with emergency equipment. Bryant answered the call and brought his equipment by boat, where he was the only source of communications for 10 days.  Another such amateur is shown to the left, W9MWC, taking emergency equipment by boat to Shawneetown, KY, in temperatures of 12 degrees and sleet.

What To Do If Lost In The Woods At Night, 1946


Seventy years ago, this day’s issue of Life Magazine, August 26, 1946, showed you exactly what to do if you were lost in the woods at night, courtesy of this advertisement by Eveready.

According to the ad, as long as you had common sense and an Eveready flashlight loaded with Eveready batteries, you would come through. The first piece of advice was that you’re never really lost until you lose your head. Therefore, the best course of action was not to travel at night. Instead, you should use your flashlight to gather boughs and leaves for a bed, and build a fire.

Once you made your primitive camp, the next course of action was to signal SOS with your flashlight–three short, three long, three short. This would guide searchers, especially if you had Eveready batteries, which would send hundreds of such brilliant penetrating light signals.

When morning came, the best bet was to stay put and wait for help to come. But if travel was necessary, you should douse your fire and follow any running water downstream.

In addition to the Eveready flashlight and batteries, the ad reminded that other survival necessities included matches in a waterproof case and a compass. These needs should be with you on every outing.

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Direction Finding With An AM Radio

Portable radio mounted on base for direction finding.

Portable radio mounted on base for direction finding.

Sixty years ago this month, the July 1956 issue of Popular Electronics carried an excellent tutorial on how to use a portable AM radio for direction finding.

Most AM radios, both then and now, are very directional in that there is a “null,” or spot where the signal fades out, on each side of the built-in antenna.  You can demonstrate this by tuning to a relatively weak AM station and then slowly rotating the radio.  You will find that there are two spots, 180 degrees apart, where the station disappears or becomes very weak.  If the radio, like most portables, has an internal loopstick antenna, these are the points where the long narrow antenna is pointing directly at (or away from) the station.

You can use this principle to determine your location.  Even with a very cheap radio, you can usually establish your location with astonishing accuracy.

Detail of direction finding mount for portable radio.

Detail of direction finding mount for portable radio.

The Popular Electronics article shows how to construct a rotating mount for your radio.  You strap the radio in place, turn it for the minimum signal, and the pointer on the mount shows the bearing to or from the station in degrees.  For example, if the station’s null is at 45 degrees, then you can draw a line on a map over the station with that same angle from north.  In other words, in this example, running NE-SW.  Your current location is somewhere along that line.

By repeating this process with a second radio station, you will have two lines drawn on the map.  The point at which the two lines intersect is your current location, sometimes to astounding accuracy.

The mount shown in Popular Electronics is for a more or less permanent installation in a boat.  But this is not necessary.  In most portable radios, the antenna is mounted parallel with the outside case, usually with the longest side.  Therefore, it is possible simply to use the radio itself as a straightedge:  Align the map with the Earth, in other words, place the top of the map toward the north.  Then, rotate the radio so that the signal disappears.  With the radio at the same angle, place one edge over the station’s location and draw a straight line on the map.  Your location is somewhere along this line.

Then, repeat the process with a second station.  The point where the two lines come together is your location.  To confirm your location, you can repeat the process with a third station.  If the three lines come together very close to the same point, then you can be quite certain that the location was accurate.  If one of the lines doesn’t seem to agree, then you can repeat the process with a fourth station, and ignore the reading that doesn’t seem to match the others.

With a bit of practice, you can find your location very accurately.  In an urban area, by using 3 or 4 local stations, I have identified my location within a hundred yards or so.  In a rural area, where the stations might be further away, the accuracy will not be quite as great, but you should be able to locate yourself within a fraction of a mile.

The Popular Electronics article contains instructions on disabling the receiver’s automatic volume control (AVC), because in the case of a strong station, the radio might keep playing at full volume even with the station nulled out.  However, it is not necessary to modify the radio.  Most stations, unless they are very strong, will show a null even with the AVC functioning.  And for those stronger stations, you can compensate by tuning the radio slightly off frequency.  For example, if the station you are trying to locate is at 800 and you can’t get a null, you can reduce the signal strength simply by tuning to 810.  You’ll still hear the station with the radio properly oriented, but the signal will be weak enough that you will be able to detect the null.

Of course, for this method to work, you need to know the exact transmitter location of the radio stations you plan to use.  These often differ from the location of the station’s studio and office.  In some cases, they are many miles from the station’s city of license.

Fortunately, in the United States, this information is easy to obtain from the FCC website.  You can search for a particular station, for all stations within a state, or all stations within a certain radius of a given location.  When you click on the station’s call letters, you will be given the exact latitude and longitude of the transmitter.  (Transmitter locations of most AM stations are also shown on aeronautical charts, since pilots still use this method of direction finding.)

Direction finding, even with a very cheap AM radio, can give amazingly accurate results.  It is certainly not as convenient as other methods, such as GPS.  But in an emergency, it should not be overlooked as a backup method to determine your location.  It requires very little equipment (just a radio, map, and pencil).  It also requires a bit of practice beforehand, since you need to learn the characteristics of the radio you will use.  And it requires knowledge of the location of some local transmitters.  But if you can locate those transmitters on your map, you can also locate yourself.

As I mentioned, I’ve been able to determine my own location within a hundred yards by knowing the exact locations of local radio stations.  But even without an exact knowledge of their location, I was able to locate myself, at night, within about 30 miles, simply by using the approximate location of strong distant stations.  For example, I know that WBBM’s transmitter is in or near Chicago.  I know that WSM’s transmitter is in or near Nashville.  I know that CFZM’s transmitter is in or near Toronto.  Even though I did not know the exact locations of these transmitters, when I used this method at night, I was able to locate myself within about 30 miles.  There’s probably little practical application for doing it this way, since it’s unlikely that someone would find themselves not knowing what state they are in.  (However, it should be noted that before the invention of accurate chronometers, most mariners wouldn’t know their location that accurately.)  But it is still rewarding to know that you can determine your location on Earth with such primitive equipment.

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Product Review: Wise Food Storage “Savory Stroganoff”

One of this site’s advertisers is Wise Food Storage, who recently sent me a free sample to review.  The company supplies dehydrated food for emergency food storage, camping, and backpacking.  On their website, they sell mostly packages consisting of assortments of food, such as the package shown below, which is billed as providing enough food for two people for 72 hours:

72 Hour Kit for 2 PeopleTHe sample I was sent was a single meal, namely their “Savory Stoganoff.”

I was initially a bit skeptical, since my experience has been that most suppliers of “survival” food seem to charge a considerably higher price than one would pay for comparable items at the supermarket.  In many cases, they hide the higher price by making inflated claims as to how long the product will last.  For example, some companies offer a “30 day supply” of food, but if you look carefully, you realize that you would be eating starvation rations for those thirty days.

It was refreshing to see that Wise doesn’t follow this same practice, and the claims on their website are reasonable.  A normal diet consists of about 2000 calories per day.  You can certainly survive on less, but if you want to replicate a normal diet as much as possible during an emergency, you should plan on having about that many calories per day per person.  And Wise seems to use honest figures on their website.   For example, the 72 Hour Kit for 2 People shown above supplies over 13,000 calories, which is indeed enough to feed two people for three days, with their normal caloric intake.  In fact, with a bit of scrimping, it would probably last even longer than advertised.  It is refreshing to see a company that didn’t fall into the trap of making exaggerated claims.  As you shop around, you might see lower prices.  But before you buy, make sure you’re really getting the number of days’ supply that the company is claiming.  In Wise’s case, you are.  In the case of some other suppliers, you are not.

I’m not normally a fan of “kits” for food storage.  From a price point of view, you’re probably better off buying normal food from the supermarket.  You’ll know that they are items you like to eat, the cost will be lower, and the supermarket has many items that can be stored for a long period of time, especially if you rotate them into your family’s normal diet.  On my food storage basics page, I have ideas for emergency food storage using items available at any supermarket.

On the other hand, there is something to be said for buying a well thought out “kit.”  You know that everything is optimized for long-term storage and minimal preparation.  And there’s something reassuring about looking at a single container and knowing that it will give you enough food to eat for X days.  I wouldn’t recommend a kit as your family’s sole source of emergency food, but they do have their place.  In addition to Wise’s 72 Hour Kit, they have a variety of other similar assortments. such as a 1 Month Emergency Food Supply for 1 Person – 56 Servings and a 2 Week supply geared for backpackers.  Again, you can probably put similar kits together yourself at a somewhat lower price, but for some people, the convenience is worth it.

Package of Savory Stroganoff being reviewed.

Package of Savory Stroganoff being reviewed.

Wise’s website doesn’t seem to sell individual meals, but they are available from WalMart.  For example, you can purchase a single package of the “Savory Stroganoff” reviewed here.  The price is quite reasonable, and you can order online and have it delivered to a local WalMart, so there is no shipping cost.

The Savory Stroganoff I reviewed exceeded my expectations.  I wouldn’t describe it as a gourmet meal, but it was reasonably good tasting, easy to prepare, and would be quite adequate during an emergency or while camping.  The nine-ounce package was billed as having a storage life of 25 years.  It was packaged in a heavy plastic pouch with an oxygen absorber inside (and I’ll say more about the oxygen absorber in a moment).  According to the nutrition facts, the package supplies four servings of 250 calories each.  In other words, the one package contains a thousand calories, or about half of one person’s caloric needs for the day.  We did feed four people lunch using the one pouch, and the meal was filling.  Each serving contains 45 grams of carbohydrates, 4.5 grams of fat, and 7 grams of protein, so it’s a reasonably well balanced meal by itself.  The vitamin content is relatively low, supplying 0% of the daily requirement of vitamin A, 2% of the daily requirement of vitamin C, 8% of the calcium, and 8% of the iron.  During a short-term emergency, vitamin deficiency isn’t an issue, but those planning for a longer-term emergency would be well advised to include some multivitamin tablets if relying on this kind of storage food.

The main ingredient is the pasta, along with nondairy creamer and textured vegetable protein.  You can view the full list of ingredients and nutrition facts at the WalMart website.

Preparation was very straightforward, and we followed the instructions on the package exactly.  You start by boiling four cups of water, turning off the heat, and then adding the contents of the package to the boiling water.  We used the stove, but the water could be boiled by any emergency heat source.  Since the only actual cooking is the boiling of the water, there’s really nothing that can go wrong.  You simply cover the pot and wait 12-15 minutes.

The glitch in the instructions was that it didn’t mention the oxygen absorber inside, so we wound up pouring it into the boiling water, where we had to fish it out.  But other than this oversight, the instructions were self-explanatory.

After 15 minutes, you remove the cover, and let it stand for another 2-3 minutes.  We used a normal kitchen pan, but any container with a lid could be used.  In an emergency, to minimize the amount of cleanup, I would boil the water in one container, and then “cook” the food in some kind of disposable container.

The completed Stroganoff.

The completed Stroganoff.

The finished product didn’t look particularly appealing.  Perhaps it would have looked better if we had let it sit a while longer, but it was rather watery.  It looked more like a thick soup than Stroganoff.  It was best served in a cup or bowl and eaten with a spoon.

However, it tasted quite good, and neither my wife and I nor our kids had any complaints.  It did not have the “dehydrated” taste that I feared it would have.  It tasted like noodles and sauce.  There was a bit of seasoning–I noticed that the ingredients included dried onions.  However, it was rather bland, and adding a little bit of salt and pepper improved it considerably.  My daughter added a little bit of Knorr chicken bouillon, and she reported that this made it taste quite good.  So my main advice if you’re going to rely on prepackaged items like this, it would be a good idea to also include familiar seasonings.

In summary, the stroganoff tasted better than I expected without a “freeze dried” taste, and was more reasonably priced than I expected.  It’s more expensive than comparable supermarket items, but much less expensive than comparable items billed as “survival” or “backpacking” food.  I probably won’t order one of Wise’s food “kits,” but I’ll probably purchase a few packages of the stroganoff and other meals to keep in the camper, or just to keep in the house for times when a relatively quick meal is needed.

Full Disclosure:  The product reviewed was supplied to me free of charge by Wise Compnay, one of this website’s advertisers, in exchange for an honest review.  All product links on this page are affiliate links, meaning that if you click on the links and purchase the product, I will receive an advertising fee.

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Piezoelectrics For Your Time Travel and Post-Apocalyptic Needs

Completed piezoelectric speaker from 1968 article.

Completed piezoelectric speaker from 1968 article.

A few weeks ago, I wrote about some plans for homemade microphones from 1945. One was very crude but easy to duplicate. But one was quite sophisticated, and could be made at home by growing a piezoelectric crystal from a saturated solution of Rochelle Salt.

The piezoelectric microphone is particularly intriguing because it should function equally well as a piezoelectric speaker.  For this reason, it has an interesting application, albeit perhaps not one that is immediately practical.

Being Prepared for Inadvertent Time Travel

The knowledge of how to build such a speaker could come in handy in a couple of situations, at least one of which is probably unlikely.  The first situation would be that of inadvertent time travel.  If you get caught in a time warp and sent to the past, it would be wise if you could make the best of a bad situation and be able to “invent” some technological devices.  (And as I’ve previously written, having a WikiReader in your pocket would make the situation much more bearable.)  And as a loyal reader of this blog, it stands to reason that one of the technologies that you could “invent” would be radio.

While there are no documented cases of this ever happening, the science fiction literature is full of examples.  Probably the oldest example is Mark Twain‘s A Connecticut Yankee in King Arthur’s Court.  Other examples include 1632 by Eric Flint and the Island in the Sea of Time series by S.M. Stirling.

Cobbling together a transmitter would be relatively easy, as long as the time period into which you were deposited had some rudimentary industries.  You’ll need some wire for winding coils and putting up an antenna, some metal for building capacitors and a spark gap, some acid for making batteries, and a few other bits and pieces that should be readily available in the Middle Ages.  With a bit of ingenuity, you should be able to come up with a transmitter with a range of hundreds of miles.

And with the exception of one component, a suitable receiver would be relatively easy to make.  Once again, you’ll need some wire for the coil and antenna, a few pieces of metal for fabricating other parts, and something to serve as a detector.  The detector would be quite simple.  The most common material, which would give good results, would be a chunk of Galena (lead ore).  If you find yourself in an area where this mineral is unavailable, there are many substitutes, as discussed in my earlier posts (this one and this one) about “foxhole radios” or my earlier post about emergency wartime crystal sets.

The one part, however, that will be difficult to procure is a suitable earphone.  If you’re lucky enough to be transported back in time after the invention of the telephone, then your problem is partially solved.  A telephone receiver will have an impedance that is too low for your receiver, but by rewinding the coil, you should be able to come up with a suitable headphone.  If the telephone hasn’t been invented yet, you can of course take the honors and invent it.  But if you want to jump ahead to radio technology, you’ll need to fabricate a suitable headphone to hook up to your radio.

This brings us back to the piezoelectric microphone we discussed earlier.   This type of microphone works equally well in either direction:  It can change electrical impulses to sound, as well as working the other way around and changing sound into electrical impulses.  Therefore, if you build a piezoelectric microphone, you can hook it up to your crystal set and listen to that transmitter you put on the air.

As discussed in my earlier post, the piezoelectric microphone/headphone should be relatively straightforward.  All you need, in addition to the scraps of metal you already procured, is a piezoelectric crystal.  And the article linked there gives you the basics of growing one.  In addition to water, all you will need is Rochelle Salt, also known as potassium sodium tartrate tetrahydrate.  This compound was first prepared in 1675 by Pierre Seignette. So if your time travel lands you after that date, you should be able to procure it. Of if it’s about 1675 and you’re anywhere near La Rochelle, France, you would be advised to look up Monsieur Seignette and collaborate with him on the project.

If you arrive before 1675, all hope is not lost. According to this site, you can whip up a batch using the ingredients cream of tartar and washing soda.  Cream of tartar is a byproduct of the wine making process, so it should be available at any time after the invention of wine, which dates back to antiquity.  So as long as those ingredients are available, you should be able to recreate radio.

An alternative method of building the headphone is described in the book The Voice of the Crystal by H. Peter Friedrichs.  This is a magnetic headphone which would require a very fine gauge of insulated wire, but a good jeweler of almost any era should be able to help you procure the components.

Rebuilding Civilization After a Collapse

The other time one would need to recreate radio technology would be after a collapse of society.  There are billions of radios in existence, any many more component parts, so it is very unlikely that you would need to start from scratch.  Even after hundreds of years of dark ages, many relics of our current technological society would still be available to provide usable parts.  This scenario is discussed in detail in the book The Knowledge: How to Rebuild Civilization in the Aftermath of a Cataclysm by Lewis Dartnell, which I previously reviewed.

The most abundant source of headphones for your post-apocalyptic crystal set would probably be the microphones from the billions of cell phones currently in existence.  In most cases, these are probably piezoelectric, and would work well for a crystal set headphone.  (The billions of stereo headphones and earbuds probably wouldn’t be of much use, since they are too low an impedance to work properly with a crystal set.)

Science Fair Project

Even if you don’t anticipate time travel or TEOTWAWKI (The End Of the World As We Know It), a homemade speaker or microphone could be part of a most impressive science fair project.  Even very young students could fabricate the simple three-nail microphone shown in my earlier post.  And more advanced students will be capable of making speakers or microphones that rival commercially available ones.

A More Refined Version of the Piezoelectric Speaker

Near perfect crystals from 1968 article.

Near perfect crystals from 1968 article.

The 1945 piezoelectric microphone linked in my original post is probably suitable for all of your time travel or post-apocalyptic needs.  However, a more refined version, shown at the top of this page, is from the May-June 1968 issue of Elementary Electronics.  While the 1945 article probably gives enough detail for the experimenter to grow a crystal and put it to work, the 1968 article goes into much greater detail.  It gives detailed instructions on growing the crystal, and the completed crystals, shown here, turn out nearly perfect.  In particular, the 1968 article gives detailed instructions on starting with a seed crystal and maintaining the temperature of the saturated solution as the crystals form.  While the 1945 article would probably result in a usable crystal looking like a piece of rock candy, the details in the later article result in a crystal that can be further ground to dimensions that would make it quite sensitive.

Construction details of 1968 piezoelectric speaker.

Construction details of 1968 piezoelectric speaker.

The construction details of the final speaker are shown above.  The crystal is ground and polished to about 1/16 inch in thickness, and then sandwiched between two pieces of aluminum foil.  (If your time travels take you to a time when aluminum was still considered a precious metal, substitution of other metal shouldn’t present a problem.)  A current applied to the two pieces of foil causes the crystal to vibrate.  The author of the 1968 article used the cone of a defunct 12 inch radio speaker, which could be replaced by some other type of cone.  For use with a crystal set, the large cone might prove a detriment, since the crystal set might not be putting out enough audio to set it into vibration.  Constructing some sort of headphone would probably be more suitable for a crystal set.

The photo above shows a matching transformer, but this would not be necessary for use with a crystal set.  The example shown in the 1968 article was designed to replace a standard low-impedance permanent magnet speaker.  The high impedance of the piezoelectric speaker would be perfectly suited to the output of a crystal set.

For even more details on growing crystals, the author of the 1968 article recommends the book Crystals and Crystal Growing by by Alan Holden and Phylis Morrison, which is still available and in print.  And if you’re just looking to make a crystal set and want to buy a piezoelectric earphone (or other needed parts), you can find them on my crystal set parts page.



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How To Get Yourself Down From a Cliff

1915SheepshankIf you ever find yourself stranded on a high spot with a rope, you’ll appreciate this trick. Of course, you know that you can tie the rope to something sturdy and then climb down. You probably assumed that you would need to abandon the rope.

But thanks to this trick which appeared in Popular Mechanics a century ago, November 1915, you can now retrieve most of the rope.  The trick is to tie a sheepshank knot, which is normally used to temporarily shorten a rope.  First, you secure the rope.  You then tie the sheepshank close to the top.  You will notice that at point C, the rope is not supporting any part of your weight, so you cut the rope at this point.  Then, being careful to maintain tension on the rope, you descend.  After you’re safely on terra firma, you simply give the rope a shake, and most of it falls down beside you.  You’re on your way, and you have all but a small piece of your rope.

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Science Fair Ideas: Homemade Batteries from 1965


When the aspiring young mad scientist is looking for ideas for the science fair, someone invariably suggests making a homemade battery. Making a battery is a fairly simple proposition. All you need are two dissimilar metals and an electrolyte. A common choice for electrolyte is a mild acid such as lemon juice, and copper and zinc make good dissimilar metals. No matter how badly you construct the thing, a little bit of electrical current is bound to flow, and you can probably coax a little bit of light out of a light-emitting diode (LED) or even power a small electronic device such as a digital clock.

A good choice for the kids who aren’t as smart as you are.

In fact, for students with limited scientific abilities, you can just go out and buy yourself a Potato Clock kit. You simply open the box and jab the electrodes into a potato, and the potato juice serves as the electrolyte. It’s completely safe, since I can hardly think of any chemical more benign than potato juice. If you drop the potato on the floor, you don’t need to bother calling the haz mat team. And unless you screw up horribly, the clock will instantly come to life. There’s nothing wrong with the humble potato clock, but if you’re reading this looking for ideas, you probably want to come up with something a bit more spectacular. And while you’re at it, you probably want to use chemicals slightly more dangerous than potato juice.

So you might want to go back in history a bit when adults weren’t quite so concerned with hazardous chemicals, and use something slightly more powerful in making your battery. You can go back in time fifty years, when adults let their responsible children play around with slightly more dangerous chemicals such as household bleach, often referred to by its most popular brand name, Clorox. Not only will you have more fun, but you’ll wind up with a much more powerful battery, suitable for powering much bigger electronic devices.

For details on how to put the battery together, you can go to page 98 the Fall 1965 issue of Elementary Electronics.  That article describes two batteries that you can make at home, both of which are hundreds of times more powerful than the one running that other kid’s potato clock.

Warning:  Bleach really is a dangerous chemical.  You need to be careful with it, and keep it out of the reach of children who are not as smart as you are.  If you get any on your clothes, your mom will be mad.  If you get any in your eyes, you’re facing a major medical emergency.  Your mom is probably right when she tells you, “you can put an eye out with that.”  Ask your parents and/or teacher for permission.  If they balk at the idea, ask them to read the article about how to make the battery.  To show how responsible you are, show them that you read the Material Safety Data Sheet (MSDS).

Homemade battery using drops of bleach.

Battery using drops of bleach.

The article shows how to make two batteries.  The first one, while much more powerful than the potato, is “more of a novelty than a practical device.”  It is shown here, and consists of fifteen sets of aluminum strips and copper wires. The metallic pieces are arranged in a circle around a piece of Plexiglas. The copper and aluminum are close together, but not touching.  When ready for use, a drop of bleach is placed on each one.  When the last drop of bleach is added, the connected radio or other device springs to life.  If measured with a voltmeter, the complete battery will put out about 15 volts.  However, this drops when there’s an actual load, and 15 cells is about right to power a radio that normally calls for 9 volts.

Unlike the potato battery, this one will run a radio for several minutes.  But the article concedes that it’s more of a novelty.  Therefore, the article goes on to describe another more powerful battery.  The bigger one is even suitable for use around the house in case of a power outage.  If the power is out and you’ve used up the last battery, there’s probably still a bottle of bleach down in the laundry room, good for hundreds of homemade batteries.


Homemade battery using ice cube tray.

The larger battery is constructed in a plastic ice cube tray.  You use six of the individual compartments, so you can cut the ice cube tray in half and make two batteries.  Each compartment of the tray contains one piece of aluminum and one piece of copper.  You simply fill each compartment with bleach, and you have enough power to run a radio for several hours.  When the battery finally goes dead, you pour out the old bleach and replace it.  You can re-use the battery hundreds of times before the aluminum finally gets worn away completely.

Voltaic pile similar to the 1799 version. Wikipedia photo.

With either battery, you have essentially recreated the work of Allesandro Volta, who invented the Voltaic pile in 1799.  He was eventually able to build a battery large enough to administer an uncomfortable electric shock.  Until the electric generator came along in the 1870’s, anything that required electricity (such as the telegraph or telephone) was powered by batteries similar to those created by Volta.

Armed with this fifty year old article, a bottle of bleach, and a few pieces of scrap metal, you can now make your own Voltaic pile.  You’ll get to use dangerous chemicals.  You can generate significant amounts of electrical power.  Perhaps you can even administer uncomfortable electric shocks to your friends, teachers, and parents.

You’ll have the most interesting project at the science fair.  And the kid who goes home with a participation ribbon for his potato clock is going to be pissed.

Check out my other science fair ideas, some of which are slightly dangerous.

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Emergency Water Storage in Your Bathtub

Recently, I’ve had a number of visitors to my website who have purchased emergency drinking water storage systems that use the home’s bathtub. If there’s a risk of being without water, then the simple expedient of filling the bathtub before the water is out could be a lifesaving measure. It’s designed to store water, so there are no worries about it leaking, or the floor underneath not being able to support the weight.

Even if you take no steps to sanitize the tub, simply filling it is a good idea, since you can use the water for many purposes, such as cleaning. However, unless you clean the tub thoroughly before filling it, you probably don’t want to actually drink the water from the bathtub. Also, the tub is uncovered, so the water can be contaminated. Finally, there’s the possibility that some of the water will leak down the drain. The plug is designed to hold the water long enough to take a bath. If it leaks even a tiny amount, the water could be gone in a few days when you need it.

The products shown here are designed to solve those problems, and they do. So for some people, having one of these on hand could be cheap insurance. If you live in hurricane country, you should consider the problem, and having one of these might be part of the solution.

Essentially, each of these products is the same: A large plastic bag, made of food-grade plastic, that fits inside your bathtub. The bag itself would burst under the weight of the water, but cradled by the bathtub (which was designed to hold water in the first place), the bag serves simply to keep the water sealed up safely. It also prevents the water from leaking in case the tub’s drain doesn’t have a perfect seal.

Each of these comes with a spout to fill the bag from the tub’s normal faucet. To get the water out, each of them comes with a hand pump to transfer the water to more convenient containers. So overall, each of these products is a good idea, since it gives you a convenient way to store between 65 and 100 gallons of drinking water. For some people, having one of these could be a good solution.

There are a couple of downsides, however, that you should consider. First of all, all of these are really only good for a single use. There’s no way to completely empty it. So once you’ve used it, you need to dispose of it. For that same reason, there’s really no way to test it. I’ve never heard of one of these having a leak. They appear to be well made, and it’s very likely that they will serve the intended purpose. But if it proves to be defective, there’s no way for you to know until the hurricane is bearing down, at which time it’s probably too late to get a replacement.

In addition, there is the matter of cost. While the prices are very reasonable, it’s still something that you hope you never need to use. And it’s possible that you’re reading this hours before a hurricane is expected to strike your area. If you don’t have one of these stored away, it’s probably too late to get one. So it’s important to think about alternatives.

Obviously, clean water is one of your most critical needs during an emergency. You should store it in all available containers, whether or not you have one of these. Your kitchen probably contains many pots, pans, and other containers, all of which were designed to hold items for human consumption. Your first order of business should be to fill them with tap water while that water is still safe to drink. Also, if you believe that the water might become unsafe at some point, it’s a good idea to turn off your water heater and turn off the intake valve. Then, you can get safe water from the tap at the bottom. (You’ll probably need to open a hot water tap on a higher floor in order for air to enter the system as you draw out the water.)

In addition, you can probably find additional containers in your recycling bin by making use of soft drink bottles. Simply clean them thoroughly and refill them with water. (Plastic milk bottles probably can’t be cleaned sufficiently to use for drinking water, although they also represent a way to store water for other purposes.)

Even without a special liner, the bathtub can still be used for water storage.  You can clean it thoroughly for use.  Presumably, if you get every last bacteria, then you can simply drink the water.  However, you have no way of knowing whether you cleaned it well enough.  But even if the water is questionable, you could later purify it with bleach.

You’ll also need water for things other than drinking.  So even if you have plenty of drinking water stored elsewhere, filling the tub is cheap insurance.

If you do use the tub without a liner, you’ll want to make sure that the drain is completely closed and makes a good seal.  If you’re not sure, a piece of plastic and caulk can ensure that the tub will remain full.

You can also make your own liner in one of two ways.  The easiest would be to line the tub with a clean plastic sheet.  Then, simply fill it as usual.  It won’t be covered, but you can take care of that with additional plastic sheeting.

If you don’t have any plastic sheeting, you can also use normal garbage bags.  Of course, such a bag will quickly burst if you just started filling it with water, because it was never designed to hold that much weight.  But it will still keep the water contained.  And the tub will provide the required support.

The process of filling them is not particularly difficult.  Take enough bags to completely cover the surface of the tub.  With a normal household garbage bag, you will probably need four or five.  Place them in the empty tub, and open them up the best you can.  If there is any sharp edge in the tub, such as the drain, it’s best to cover it up with something like a washcloth.

When you have them placed, you’ll need to start filling them.  But you can’t immediately fill one of them all the way, because it won’t hold the weight.  The bag will need to be supported by the tub, and by the other bags.

Therefore, you need to take turns filling them partially, while they’re already in their assigned spot.  You won’t be able to get water from the faucet into the bags at the rear; so you’ll need to come up with another method.  If you have some kind of hose that you can attach to the bathtub faucet (or another nearby faucet), that would be easiest.  Lacking that, you’ll need to use another container.

Fill one bag part way, and then fill the one next to it to the same level.  Once you’ve filled all of the bags to the same level, go back and add more to the first one.  Eventually, all of the bags will be full, and snugly fitting in the tub.

When you pick the bags to use, make sure that you’re using ones that don’t have any kind of insecticide.  This is a case where cheaper is better.

When all of the bags are full, you can tie off the tops to keep them sealed.  Getting the water out will be slightly challenging, but not too difficult.  A pump of some kind would be ideal.  But if you don’t have one, you can simply use another container to remove water as needed.

Just as you filled them evenly, you’ll need to take the water out evenly.  You’ll need to take turns taking water out of different bags so that the water level stays about the same.

If one of the bags springs a leak, that’s not a major emergency.  You won’t be able to use that water for drinking, but it will still be safely contained in the tub for other uses.  And because the other bags are separately sealed, you can still drink that water.

waterstorageIf you need more ideas for storing water in an emergency, a good source of ideas is chapter 8 of Nuclear War Survival Skills.  Despite the title of the book, it is also an excellent source of information for practical ideas for other emergencies.  For example, the illustration here is from that book, and shows a man carrying ten gallons of water in burlap bags lined with a plastic trash bag.  You might not have burlap bags around the house, but you probably have pillowcases, and they will work as well.  You can also use a trash can or heavy cardboard box with a garbage bag as a liner.  (All of these will be heavy once filled, so you’ll want to put them where you need them prior to filling.)

For more information on emergency preparedness, please visit some of the following pages on my website:

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Book Review: The Knowledge by Lewis Dartnell


My website contains a review of the WikiReader. This little device set me back about $20. It’s apparently no longer available on Amazon, but there do seem to be examples available on eBay and elsewhere. It’s a small battery-operated device that contains in its internal memory (with some limitations) the full contents of the English language Wikipedia.

In other words, it contains what its manufacturer called “the Internet without the Internet.” If you’re transported back in time, if you get stranded on another planet or on Gilligan’s Island, or if the world suffers TEOTWAWKI (The End Of The World As We Know It), you’ll no longer have access to the Internet, but you’ll have a pretty good summary of just about any subject. The batteries of the WikiReader will eventually go dead, but before that happens, all you need to do is find the Wikipedia article on the history of the battery, take some good notes, and you’ll be able to whip yourself up a new one when the time comes. Once you’re settled in in your new era, you find an interesting article such as the one on the electrical telegraph, put together a prototype, and then make arrangements to demonstrate it to Julius Caesar or Louis XIV.

The WikiReader has a number of practical limitations, and I rarely use it. But it’s carefully put away just in case I’m involved in inadvertent time travel. In my pocket, I have the important knowledge of the 21st century. If I accidentally get stuck in a time warp, I’m going to make the best of the situation.

It appears that I’m not the only one who thinks that way. I recently got an e-mail from Amazon stating that customers who bought the WikiReader also bought a book with the intriguing title The Knowledge: How to Rebuild Civilization in the Aftermath of a Cataclysm by Lewis Dartnell. The book is available in the usual places, such as Amazon, in Canada, or your local library.

As the title suggests, the book is written for the benefit of some future inhabitant of Earth who needs to reconstruct (or “reboot” as  author Dartnell calls it) civilization after some sort of cataclysm.  The first chapter suggests some possible sources of the disaster, and the second chapter discusses the “grace period.”  After some types of disasters, such as a pandemic (such as happened in Earth Abides by George Stewart or in my own novel Caretaker), the survivors of the disaster have at their disposal the spoils of the earlier civilization.  It’s a relatively simple matter to eat canned food, set up generators, and take advantage of what was left behind.  In some cases, such as pandemic, that grace period might extend for generations.  In other cases, such as nuclear war, there will be fewer benefits available from the earlier civilization, and survivors will need to get to work right away tending to their immediate needs.

Dartnell doesn’t dwell a great deal on the grace period, since he correctly notes that numerous other survival manuals have been written.  What he spends most of his time talking about is rebuilding a technological civilization after the grace period has ended.  With a few exceptions (such as how to make soap), he doesn’t provide enough detail about any given technology in order to show exactly how they’re done.  But Dartnell does give enough clues in order to point survivors in the right direction.

For example, in the section on radio communication, he describes how to build a crystal radio, and he gives enough detail to allow the future archaeologist to recreate one.  He gives some of the theory, but no unnecessary theory.  In our current timeline, for example, it probably would have been impossible for society to come up with radio without first having an understanding of Maxwell’s Equations.  Instead, Dartnell gives only enough theory to make the thing work.  After building a few radios, the post-apocalyptic society would eventually come up with Maxwell’s Equations on its own.  So future history would follow the same general course, but in the opposite order from ours in some instances.

In addition to the plans for the receiver, Dartnell also gives enough detail so that someone could probably come up with a workable spark-gap transmitter.  I think the stumbling block for the future inventor would be coming up with an earphone sensitive enough to work with the receiver described.  Armed with theory in our own civilization, the telephone was created first, which gave the required prior technology.  Dartnell does qualitatively describe both a magnetic and piezoelectric earphone, but either one would require a great deal of trial and error.  In our own history, a skilled inventor would know enough theory to realize that sound would come out of a telephone receiver if hooked up properly.  If it didn’t work the first time, he would eventually figure out that he needed to make it more sensitive by adding more windings to the coil.  The post-apocalyptic inventor would have more trial and error.  But if he or she had enough faith in the book (perhaps because he knew that the soapmaking description was correct), that might provide the incentive to keep experimenting.  (Dartnell does provide the future inventor with Edison’s admonition that genius is 1% inspiration and 99% perspiration.)

Similarly, Dartnell gives enough clues to invent the triode tube.  There isn’t nearly enough detail to make one, but he tells just enough about the Edison effect so that a gifted future scientist could verify it, and some hints as to how this effect could be harnessed to provide amplification.  Dartnell mentions in passing that oscillation is possible, although I hope the future scientist figures out that feedback is necessary in order to get the thing to produce radio signals.

In order to jump-start science, Dartnell provides a few simple experiments to prove non-intuitive concepts, such as the Earth spinning on its axis (Foucault’s Pendulum) and revolving around the sun (stars rising four minutes earlier each night).   In case the surviving society has lost track of time, he shows how to establish the year, either by the proper motion of Barnard’s Star or changes in the night sky due to the Earth’s axial precession.  The book contains convenient charts showing the reader the year (as well as a map and picture to locate the Svalbard Global Seed Vault).

In short, the future reader will get a lot of useful information from this book.  In most cases, the ideas contained in the book will need additional details, but Dartnell points the future inventor on the right path for either experimentation, or at least a clue as to which ancient texts he or she should try to recover.  (The book contains an extensive bibliography to help the future inventor in that quest.)

Chances are, nobody would read a book entitled, “The History of Science and Technology.”  But when you get to the end, you realize that’s exactly what you read.  In detailing the easiest course for future civilization, he necessarily recreates our own.  There will, of course, be some differences.  For example, most readily accessible deposits of fossil fuels will be gone for the next civilization.  But he offers a number of workarounds.  And since the current nitrate supplies of our early civilization (see The Guano Islands Act for an interesting discussion of a seemingly mundane commodity) are also depleted, he goes into more detail regarding the relatively simple chemistry required to fix nitrogen from the air.  On the other hand, aluminum requires a great deal of industry to refine.  But in the case of a future society, even hundreds of thousands of years in the future, our dumps will provide ample mines of high-grade ore that will need little more than melting down and re-casting.

In short, if you bought a WikiReader after reading my review, then, yes, Amazon was right.  You’ll want a copy of Dardnell’s book as well.

More information, including a discussion forum, is at the book’s website:

   Buy this Book on Amazon:
USA:                              Canada:

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