How to Make a Foxhole Radio
Вставка
- Опубліковано 9 лют 2025
- During World War II, GIs in the field built really amazing simple radios to listen too. These were made with materials that they could get their hands on and were small enough to carry around in a big pocket. You can modify this design if you want to set it up so that it's tuneable too! To see all the plans, go to makezine dot com slash podcast!
Find more at the Maker Shed: makershed.com
Make: Electronics, 3rd Edition: www.makershed....
Learn more here:
cdn.makezine.c...
i have been an electronics tech for nearly 50 years and didn't know about the razor blade thing wow! You learn something new every day!
jesus i watched this video in 2007 once..... remembered it.... and found it again 14 years later
What does JESUS have to do with this?
@@sallycarroll6329a lot of
@@sallycarroll6329wow you're truly a very intelligent individual
@@sallycarroll6329 Alright Sally, time for arts and crafts...
12 years and the quality of the video is amazing
Heating the razor blade creates a dioxide layer on the blade (2 materials) which turns the razor to a detector (diode). I think kind of that layer is also being used at the gate of mosfet transistors.
u simply create a layer of "something", that is coincidentally already attached to something already conductive (the rest, un-oxidized portion of the razorblade´s iron)... earlier, u´d have used a crystal, but then, u´d also have to build a "holder" for it, but here, u don´t have to, cause the iron-dioxide is already firmly attached to the iron underneath it. I think, that´s the N, of a PN-junction (which is a diode). so it´s half of a diode. the other half of the diode, it´s the pencil-graphite.
I made one just like this over 50 years ago. Fun to see it resurrected! The reason the 'blued' blades work better is because they have a selenium coating. You can put the point of the safety pin directly on the blade with those... no pencil required. Thanks for this vid!
This was the very first UA-cam video I ever watched, oh the memory's
Hahahahaha
I watched Me at the zoo. Gives me the willys to know what you watched. Its so interesting. Im going to like this comment and have my followers all like it too so you get money from UA-cam.
@@UpcomingJedi what lol
I actually had to check the upload date. The production value is so high!
Did you watch it while you had the movie “Hart’s War” on pause…. Like I do now? 😂😂
This video is over 9 years old, becoming a great classic crystal set project video.
13 now 😂
@@dixiegracebrown SIXTEEN NOW 💯🔥
@@agostinodublino138722 now! 😅😳
This is exactly the kind of plan I was looking for. Years ago I found plans in a real old boy scout manual that used the cardboard tube and cats whisker, but it used a galena crystal. I think it also used varnish coated wire and the varnish was removed from an arc that the tuning arm traveled.
Great Brie, Another project to do with my great grandson. Thanks so much.
pierre from New Mexico
I like how clear and easy to understand your vid was with a bit of history thrown in.
They did this in Masters of the Air! Awesome video.
The problem you had with the Razor blade was the rust resistant coating that comes on modern metal to make it last longer. you can burn it off or scratch off the coating with sand paper
I tried to make one of these a while back with a kit and couldn't get it to work. Really tough for some reason.
Bre I'm glad that you actually showed some "failures" along the way on this one. Keeping it real and showing that electronics aren't always a perfect science :)
HERE HERE, WELL SAID.
That sound quality's pretty impressive! It's a shame you weren't able to get a music station. People don't know AM can sound GREAT because radio manufacturers use really cheap components and roll off the lows & highs. Great job!
Learned to make them in the scouts back in the 70's.
Props for showing the entire learning curve, failures and all. It helps us understand the diagnosis process better. Thanks.
My father made this radio in WW2 in the Netherlands. The Germans forbade people to have radio's. This one did not need power and he could use the line that his smother used to dry clothes with as a antenna. There were broadcasts from England especially for people in Holland to help them keep up the spirits and remember that help was on the way.
the razor blade and the cat-whisker or in this case the pencil "rectifies" the signal that is received. You can use an old Diode that just about anything electronic has a number of. The part usually has a symbol on like this →⊢
I have been looking for a video like this for a WHILE thank you. I can’t wait to make this with my 1st grader.
I love the emergency siren in the back ground wile your heating the rasor
You MUST have a CRYSTAL earpiece/ headphones! This is crucial to the functioning of the foxhole radio!!!!
No, the high impedance headphones for other stuff works OK on this.
All you need are these.... Later in the video.. and these and these and these and these and these and these.
Cubejam And in your case... You'll need a brain.
Cubejam LMFAO
Dude was really feeling himself upon the completion of his first sideburns.
2:33 they found you, bree...
I made one of these once when I was in grade school. I bought a kit and put it all together. I was super proud of myself!
Like a MacGyver! AWESOME!!!
This was one of the best videos on a diy radio to date!
XD trying calling in and say "I'M USING A RADIO DONE BY GI'S IN WWII!" "Who is this guy?" "I CAN'T HEAR YOU,THIS RADIO IS SOFT!"
"...-,-"
Great Job. Your dad, McGyver,would be proud. I really like the fact that you actually go through some mistakes and show people it's not a one shot deal. Thanks for sharing. Great Post.
Just wonderful
This is extremely well made for 2007.
Haha sound like mike francesa when he played the radio station!
Him lighting the torch with sirens in the background is absolute comedy gold
better product than the makerbots
My brother did this when I was a little kid ,and it worked! 5-yr old learned electronics! Gotta love big brothers (even when they hit you for touching their stuff).
Heard the toilet paper companies are getting rid of the tubes. Then what?
buy a radio
Easy, measure up an existing tube while you can, and make a replica tube out of printer/copier paper. Or, there is nothing to say you can't use plastic waste pipe, or even a small medicine or drink bottle. The tube doesn't even have to be of any specific material. You could even get more adventurous and dispense with the paper tube altogether and build a simple frame antenna, but I digress.
Nice! Glad to see you had a fire extinguisher on hand.
Page not listed or has been moved?!?!?!
Learn nothing there!
late,but:cdn.makezine.com/make/wp_foxholeradio.pdf
cool video,my uncle who passed away a few years ago like making this kind of stuff
Warning: This may turn out to be a Fox Talk Radio :)
That's still a FOX Hole radio... Not to be confused with an Ass Hole radio...
i like how, as you were getting ready to fire up the torch to heat up the razor blade, the sirens got closer.
The pencil lead / razor blade combo is a basic diode, allowing the current to flow in only one direction.
I and my father did it when I was young, in the sixties. Very nice to see it again.
"Blue" razor blades had a silicon coating so they wouldn't rust. This was in the days before stainless steel was cheap enough for blades. You can still find a few in antique shops and on-line.
I made this 14 years ago when i was a child. It really works.
I used slightly different things but the principle is the same. Its fun and sometimes usefull in certain situations
You can use pipe for tap water, you can use a gas pipe, you can dig a whole in your garden and dig in a big metal plate to which you connect the ground lead wire.
Rofl the Cat6 wire
On a serious note, bluing is a process by which carbon steel (non-stainless steel) is coated with a specific iron oxide that inhibits rust slightly, but even more importantly, allows the metal to hold oil better to further prevent rust. The result is an item with the strength/etc. of carbon steel and the ability to not rust easily like stainless steel. Another widely used option in guns, but less so in blades, is Parkerization, which is similar but grayish and phosphate-based.
Yes the number of coils will affect the tuning frequency.
Using a ground maximizes the potential difference between the radio wave and ground. In other words it makes the signal bigger.
Yes u were correct about the type of Metal Treatment. I think its called "negative resistance". The coil is the antenna. The razor blade is the oscillator.
One safe way to heat the blade is on an electric stove. Lay the blade on one of the elements, turn in on high, wait until everything is glowing nice and amber / orange, then turn the element off.
This might not get the blade quite hot enough to temper / oxidise - but its worth a shot.
bluing is a process of heating and cooling that not only strengthens the metal but also does something to the internal electron configuration.
This is really, really nicely done. I've not seen a razor blade used as a detector before.
Thanks!
Great! The world desperately needs people like you.
BTW, Bre, The station you received was WFAN on 660 kHz. Happy Listening
500 degrees is the temperature steel turns blue.
If you heat steel to red (called super heat) and let it slowly cool, the metal will be softened.
if you heat steel to red and quickly quench in water, the steel becomes very hard but brittle.
(crystalizes).
So, to get optimal strength, steel is first crystalized then shined up with abrasive and then reheated till blue. Blue is the strongest.
The quickest way is to quench in oil, which cools down to 500 and turns the object blue.
you don't need too much heat to blue the steel. A simple pocket lighter will ussually do the trick.
I used to build these as a kid. They are an excellent way to learn about how radio signals can power devices.
Hey, we love your video! My son and I enjoyed it very much and the best part, it worked! Keep up the fun stuff. Many thanks!
I built that today and it worked ! Thanks for posting
AWESOME! It works good! It's neat how the heated blade makes it work as a diode.
The magnet wire has a coating on it that will prevent it from making the connection. If you still want to use the wire to connect the paper clips, take a lighter and hold the end of the wire over the flame until you see the coating burn away. It only takes a few seconds.
nice yesterday i started making this, my dad had some old world war 2 german razor blades so i took one. I made my coil with 300 turns, and used my washing line as an antenna and it works GREAT!
i remember over 10 years ago when I watched this, there was a lot i didn't understand from this video
@yasowhatup it is the air capacitance of the air coil. it is very low, however, the inductance of the open air coil is also very very low. thanks for you question
I live in Africa so I didn't really expect to hear anything as there were few radio stations: what I heard was electric sparks in the earphones though. Thanks to you, I will redo the experiment.
@lukasm14 this device shown is an AM radio. 102.6 MHZ is in the comercial FM band, where transmissions are in a different format. That Format is Frequency Modulation. Amplitude Modulation is "detected" by the diode action of the "cat's whisker" or, razor blade/pencil tip combination. Frequency Modulation, is deteted by a more complex method, and requires more complex equipment.
Cool project. Easy to make tunable. Just move the paper clip on the right to the center of the coil and stretch out the paper clip so that it rests on the coil with spring like tension. Make the coil almost twice as long. Use the edge of a metal file and remove about an 1/8" strip of enamel coating from the magnet wire. Tune by moving the paper clip across the coil to tap the coil in different places. :)
This is so high quality for 2007 damn
I Googled this a lot and discovered this radio lacks a bar across the wound wire to tune in different stations.
To make a speaker for this google this exact term with quotes :
"Making High Impedance Headphones With less than 5 bucks"
Also check this out for making radios, google this exact term with quotes :
"Building a simple crystal radio." That shoudl bring you to Sci-Toys website, many pages about building different radios.
Nicely done! By the way, the talk radio is Mike Francesa of WFAN in NYC. One of the smartest sports reporters ever. He's syndicated, so not sure what station it was.
If you can't get hold of a high impedance ear piece like the guy uses in the project you can also use an old cord phone as a speaker. Just take the cord out of the phone where you would dial, leaving you with the hand held part and cord coming out of the other end. Strip the wires and match them up. (There'll be four wires, so you can either use trial and error to find the right two or google it (: )
@fifthStitch The ground wire is for preventing you from getting shocked from static electricity. You COULD run it without one but it you could get electrocuted or at the very least zapped when the electric components built up enough electricity.
You could just attach the ground wire to anything metal that will absorb the electricity.
Heat treatment to blue changes the metal from hard and brittle to springy. The color is a product of oxides.
btw also if you use an audio jack and connect to + and - terminals you can use your computer speakers. Which is way more convenient as you can adjust the volume and you dont have to use the earphone
I'm a radio collector, thanks! I'll try this. Cool stuff.
10 years later, we may be needing to make these ourselves
I did some research and found out you can change the length of the antenna or coil, or install a tuning capacitor.
Similar principle, they would wind wire on nails dipping the nail in wax after each set of turns then they would put the nails in a can and lightly cover the open end of the can with foil they usually got from candy wrappers. There's also a way to make a small speaker with charcoal and a small metal cup they would make on a hot stove.
I am a WWII history buff, however I never knew how the GI'S and resistance built the field radios
Great video. One of the best I've seen about the foxhole radio.
Totally awesome and simple. Beginner hams would totally dig this. Perhaps a safer substitute for the burned razorblade, but otherwise, I totally dig it.
Real cool! I watched it twice and that looks like a real cool weekend project.
My grandfather told me that he used to carry a jar with varnish with him all the time, so he can coat the wires for all the people in his batallion. Also he told me how once he traded a barrel of sauerkraut he stole from a farm for a dozens of earphones with some german soldiers. Strange thing that all they could listen to was in german because the earphones were made by Telefunken. After that they received a shipment of earphones made by Westinghouse so they could listen to radio in english.
Thank you really, I finally understand the simple radio structure.
Blue Wilkinson Sword razors were used, and a small bit of lead.
Putting an acidic drop of acidic fruit juice on the lead on top of the blade caused lead crystals to form, and moving the point to different places on the blade, now a sort of a crystal tuner.
POW's made these in the camps.
it is the rust spots that make the good connections.. different size rust spots get different stations. you can get blue blades from crystal radio parts supply.
@LUVITALL9 Razor blades are excellent in crystalline structure."Bluing" or oxidizing them in extreme heat, interferes with that structure.The interface point of this surface, and the semi-conductor characteristics of carbon, in this case, graphite in the pencil makes for a diode effect, which detects, or demodulates the am signal to an audio signal. make your antenna as long as possible. At least 50 feet for best results!
@gomenaros One; safety, built up static electricy, two, its part of the antenna that uses ground radio frequencies (RF) to improve your signal.
Sounds suprisingly good.
The razor blades had to be rusty or corroded so the contact point ( a bent wire or safety pin) becomes a diode. A very good diode was a green penny or other corroded coin. I finally did it with a galena crystal which is like the tiny crystal in a 1n34 diode. Which works very well.
@k915 actually he can find magnet wire in a speaker. i think the most common places would be a speaker, a motor, or a power transformer.
you are the man! a "macgyver" radio...that it!i finally found my jota-joti project topic!
thanks!
The more turns the lower the frequency range on the beginning of the band. 500 turns will receive the longwave bands like 200 kHz to 600 kHz. if there are more turns you can tune in 150 kHz to 400 kHz. 120 turns will be just fine for the AM (MW) bands.
When WWIII lands home, I'll be glad I learned how to make one of these!
01100110 01110101 01110010 so true
@Tcosp Assuming the AM station is transmiting in stereo, if two of these devices where made, each with its own antenna, razorblade/pencil lead combo..etc, with earpieces....and one was tuned slightly above the frequency chanel in question, and one slightly below, then yes....stereo effect could be achieved! It would have poor stereo seperation specs due to the poor selectivity of this design, however, it would technically work.
It picks up AM frequencies. If you want to build one for SW you would need to wind less turns. FM is very hard to make, but it can be done.
That is soooooo kool!
I built a superheterodyne radio in high school and that took days in class to solder up.
I didn't know that this was possible though!
Oh well back to my 3d printing duties
UA-cam algorithm, you fool! I found this video not in my recommendation, but in the results i searched.
a wire connection with a hot water radiator plumbing or water tap or iron embedded in watery ground, even just a wire lying on wet ground, I think.
PDF is Portable Document File its basically an extension used as .pdf along with the file name for example documen.pdf. Its viewed with Adobe reader. You can find tonnes of books on internet using the same format.
The drill press will work really well, just reduce the speed. You don't show the entire press, but it looks like the type that has an adjustable drive belt. If it is, just move the belt to a lower speed (a speed you would typically use when drilling metal).
I did too, in the 4th or 5th grade, except I used a diode as a detector. I was always trying to improve the thing.
Ironically, I lived on the east coast then but I live near Mesa now.