Category Archives: Science fair ideas

1965 Light Beam Communicator

Screenshot 2025-02-13 11.35.20 AMThe young man in this drawing is now a senior citizen, but in 1965, he was taking part in the school science fair, using a project shown in the Winter 1965 issue of Elementary Electronics. He was communicating with a light beam, with a rudimentary setup consisting of two audio amplifiers. The output of one of them was hooked directly to a light bulb (in series with a 3 volt battery), and the input of the other one was hooked to a photocell.

According to the article, this unit was good for demonstration purposes only, and was only capable of a couple of feet. I’m surprised that they are so conservative in their estimate, since I made virtually the same setup when I was a kid, and it traversed the length of the house without much difficulty.

The only difference in my version was the addition of a transformer to the output of the first amplifier. The primary was hooked to the amp, and the secondary was wired in series with the battery. I used a flashlight, and just sandwiched two pieces of foil, insulated by cardboard, between the lamp and the battery terminal. I suspect my use of a flashlight, complete with its parabolic reflector, was probably an important factor in my success.

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Science Fair Ideas: Refining Gasoline at Home

1940FebPSIf Junior is looking for the perfect science fair project to secure the coveted blue ribbon, then the February 1940 issue of Popular Science is where to find it. Following the simple instructions there, you can replicate the processes of a modern oil refinery and cook up some gasoline in the lab.

And for an added bonus, you can make the latest in food material science, namely, hydrogenated vegetable oil, also affectionately known as trans fats.



1925 Emergency Foot Bridge

1925FebSciInvBridgeA hundred years ago this month, the February 1925 issue of Science and Invention gave these self-explanatory plans for constructing an emergency foot bridge. It had the advantage of being able to use it as you constructed it, since you pushed each new section into place.

Each support was a pair of jumping poles. You would form them into an “X” shape, and then push them out ahead. Perhaps some student will be inspired to turn this into a science fair project. Or perhaps a scout looking for a good pioneering project might be inspired. (If the water below is deeper than ankle-deep, then the current Guide to Safe Scouting calls for participants to wear a life jacket.)



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Laser Safety: 1970

1970FebPEThe December 1969 issue of Popular Electronics carried the plans for a 0.5 milliwatt laser. The magazine noted that there was a lot of interest in making such a device, and there were finally parts on the market to make one that met two important criteria: It had to be inexpensive enough for experimenter hobbyists, and it had to be safe. They deemed the 0.5 milliwatt device to be safe, given some precautions, and the whole project could be built for under $50.

The illustration above appeared in the February 1970 issue, and it depicted how the magazine viewed a few of its readers. In summary, they wanted to burn holes in things, and they wrote in to the magazine asking for plans to do that. In response, the editors made clear that they had no plans to do such a thing. To cause destruction to something, the laser would require a few watts. But eye damage could easily take place at just a few milliwatts. The 0.5 milliwatt laser was safe, but more powerful units were not, so the magazine didn’t want to be involved. “Out of responsibility and concern for our readers, POPULAR ELECTRONICS cannot suggest or recommend a laser of any higher strength than the one described in the article.”

For the young mad scientists, it’s probably possible to find dangerous lasers on eBay, but we don’t plan to help, either.  On the other hand, you can get safe low-powered laser pointers on Amazon.



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How to Make a Pressman’s Cap

Screenshot 2025-01-30 11.16.41 AMWe know our readers pretty well, and we’re almost certain that when they watch an old movie showing a newspaper printing plant, they notice that the pressmen are wearing hats made out of folded newspaper. They also wonder how to make one.

If you fit in that category, you are now in luck, because you have access to the February 1940 issue of Popular Mechanics, which reveals on page 283 exactly how it’s done. It was sent in to the magazine by one W.R. Greer of St. Paul, MN, whom we hope didn’t get in trouble for revealing this trade secret.

For the sake of categories, we decided to place this one in “science fair ideas.”  For a last-minute project, this one answers the scientific question of, “can durable head wear be constructed from newspaper.”  For similar ideas, we’ve previously shown how paper can be used to construct boxes, and even expedient winter footwear.



1940 Homemade Batteries

Eighty-five years ago, Britain was at war, and that meant shortages of many things, including flashlight batteries. Undaunted, many Britons took to making their own, and the February 1940 issue of Practical Mechanics showed them how to do it.

Screenshot 2025-01-23 9.14.31 AMThere was a learning curve involved, but the magazine assured readers that the task was well within the capabilities of amateurs. The costs of materials were low, and once you were set up, you could laugh at the Nazis trying to deprive you of batteries.

The article pointed out that filling the cells, at least initially, was a messy process. But once you got into a routine, it was relatively easy. The article suggested getting together a quantity of zinc containers and carbon rods, and then commencing the filling process. Surrounding the carbon rod was a “depolarizing paste” consisting of a mixture of approximately equal quantities of carbon or plumbago powder and manganese dioxide (pyrolusite) made into a paste with a 1 per cent. solution of gum tragacanth. The electrolyte consisted of about 85 per cent. of plaster of Paris and 15 per cent. of ordinary flour mixed to a just-wet paste with a strong solution of sal ammoniac,

For the student looking for a science fair project, making a battery is always a worthwhile option.  In addition to this set of instructions, we have many other  similar ideas on this site.



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Clearing Snow by Burning It: 1925

1925JanSciInvWhen I was a kid, my family received a mail order catalog from an outfit called Sunset House. You can see an example at this eBay listing.  The catalog was full of useful products you couldn’t find anywhere else, and one of them was a little blowtorch. The blowtorch had many uses, but the most practical, it seemed to me, was shown in the accompanying illustration, and that was for melting snow off the sidewalk. It seemed a lot simpler than shoveling, and I begged my parents to buy a blowtorch. They didn’t, and they pointed out one objection that I couldn’t counter–the water would just flow elsewhere and freeze. But still, it seems like a good idea, if you could just work this bug out.

And the idea has been around for at least a century, as shown by the cover of the January 1925 issue of Science and Invention. This one didn’t involve a flame, and the magazine didn’t think that my parents’ objection would be an issue, since it matter of factly stated that the snow would melt, “which runs off in the form of water.”

The magazine didn’t use a blowtorch. Instead, it used a method that might be of interest to young scientists in search of a science fair project. You simply sprinkle calcium carbide on the snow. It sinks in (you start the process by poking a few pieces into the snow) where it mixes with water, creating acetylene gas, which is highly flammable. You strike a match and set the snow on fire. You go forward sprinkling more calcium carbide ahead of the flames, and as the flames catch up, it sets fire to the snow you have sprinkled.

For the science fair, Junior simply finds a patch of snow outside the school, seeds it with calcium carbide, and sets it ablaze. It’s sure to take home the blue ribbon.

Junior does need to be reminded to be careful. The magazine article contained these warnings:

Great care must be exercised in sprinkling calcium carbide upon snow, so that when the gas is evolved and ignited, it will not set fire to shrubbery, trees or the house itself. Under no conditions should such a snow remover be used when a gale is blowing, and the individual drawing the mechanism over the road should always see to it that he heads into any slight breeze which may be blowing, so that his own clothes will not be ignited.

If Junior sets the school, or himself, on fire, then he’s unlikely to get the blue ribbon.

As with everything, Junior can get the calcium carbide on Amazon. If he wants to augment his project, he can explain how this chemical was used in miners’ lamps.



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1954 “Little Shocker”

1954DecRadioConstr1954DecRadioConstr2Seventy years ago this month, the December 1954 issue of the British Radio Constructor noted that with “the festive season is drawing near, the reader may be interested in a simple little gadget which is guaranteed to liven up the party in more ways than one.” We’re sure that many of our readers might be similarly inclined.

This device is self-explanatory. It’s similar to a homemade Ford spark coil. An autotransformer steps up the voltage of a battery, and the coil also serves to operate a crude relay to convert the voltage to DC. The two handles are formed from the foil from a candy bar glued over wood. When it’s switched on, it make an inviting buzzing sound, and you ask your friends to grab the handles.

This might make an interesting science fair project, although we suggest that you determine first whether the science teacher has a sense of humor. If not, another project might be better suited.

Also, even though the resulting current is very low, since some of that current will pass directly through the heart of your subject, we wonder if it might be dangerous in some cases. Therefore, if you’re going to make this project, we wonder if it might be better to make sure that both electrodes go to the same side of the body.

We should note that as a youngster, we independently invented a similar device, making use of an old filament transformer and a buzzer. No harm was caused to anyone.



Science Fair Ideas: Smoke Rings

1924NovSciInvIf Junior is looking for a fun science experiment involving some dangerous hazardous substances (both of which are readily available on Amazon or at almost any hardware store), then he or she can’t go wrong with this 1924 demonstration of how to make “smoke rings” from the November 1924 issue of Science and Invention.

You start by getting some ammonia (called “ammonia water” in this diagram) and some good ol’ Hydrochloric Acid (also known as muriatic acid). Arrange them in bottles and tubes as shown here. To avoid spillage, you need to make sure the ends of the tubes are level with the level of the liquid in the bottles. The fumes combine in the box to form ammonium chloride, and the tiny crystals form a thick white “smoke”. When you tap on the back of the box, a smoke ring emerges.

Note: These chemicals really are dangerous, so use great caution in carrying out the experiment. In particular, we recommend doing it outside, or in a room with lots of ventilation.



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1944 Instructional Model Telephone

1944NovPracMechEighty years ago, Britain was at war, but that didn’t stop students from building instructional instruments, as shown by these plans for a telephone appearing in the November 1944 issue of Practical Mechanics.

The set was based upon the original telephone of Alexander Graham Bell, and could be built by senior schoolboys in the science room using readily available material. The magazine provided all of the construction details. Two instruments could be used to communicate from one room to another, strictly with sound power. For longer distances, the magazine recommended a carbon microphone with a battery running to the phone.

It could also be used as an extension for a Morse buzzer. All construction could be done with a few simple hand tools. The most delicate part of the operation was spacing the diaphragm just the right distance from the permanent magnet.