How to Make a Foxhole Radio

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!
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[@Themaxleydog]

jesus i watched this video in 2007 once..... remembered it.... and found it again 14 years later

[@sallycarroll6329]

What does JESUS have to do with this?

[@greg2818]

@@sallycarroll6329a lot of

[@transcendbeing]

​@@sallycarroll6329wow you're truly a very intelligent individual

[@duaneritter3932]

@@sallycarroll6329 Alright Sally, time for arts and crafts...

[@berkozkaya8365]

We did it with my friend when I was 12 years old. Although we cannot get sound from the radio, I am an Electronic engineer candidate right now :)

[@AliasUndercover]

I bet you could get one to work now.

[@25_26]

i made one when i was 8. It is not a big deal.

[@berkozkaya8365]

@@25_26 congrats mate im happy for you

[@dudewithout_a_face5573]

How did it go? Your uni I mean

[@ethancobb4002]

Just a candidate? Not even an engineer?

[@yoramstein]

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.

[@GGWalace]

12 years and the quality of the video is amazing

[@DarkenedCrux]

This was the very first KZbin video I ever watched, oh the memory's

[@texaselite1355]

Hahahahaha

[@UpcomingJedi]

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 KZbin.

[@arthurmead5341]

@@UpcomingJedi what lol

[@bubbythebear6891]

I actually had to check the upload date. The production value is so high!

[@AninoffsMagister]

Did you watch it while you had the movie “Hart’s War” on pause…. Like I do now? 😂😂

[@StuPadazzo]

Props for showing the entire learning curve, failures and all. It helps us understand the diagnosis process better. Thanks.

[@OurInfiniteFuture]

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

[@AdamEbelgccengineering]

This video is over 9 years old, becoming a great classic crystal set project video.

[@dixiegracebrown]

13 now 😂

[@agostinodublino1387]

@@dixiegracebrown SIXTEEN NOW 💯🔥

[@johnblackmore2067]

@@agostinodublino138722 now! 😅😳

[@pierre5325]

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.

[@Reubenhubert]

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.

[@merrittorius]

They did this in Masters of the Air! Awesome video.

[@JohnBerthoty]

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!

[@GeneSavage]

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!

[@kyCap222]

I love the emergency siren in the back ground wile your heating the rasor

[@CubejamF1]

All you need are these.... Later in the video.. and these and these and these and these and these and these.

[@rogerdodger8415]

Cubejam And in your case... You'll need a brain.

[@texaselite1355]

Cubejam LMFAO

[@clyde5057]

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 →⊢

[@nbarrager]

2:33 they found you, bree...

[@MikeGervasi]

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 :)

[@dogboymalone11]

HERE HERE, WELL SAID.

[@sheriefelghandour2760]

Just wonderful

[@lunhil12]

Learned to make them in the scouts back in the 70's.

[@kyleburns3925]

Haha sound like mike francesa when he played the radio station!

[@johnnywad7728]

You MUST have a CRYSTAL earpiece/ headphones! This is crucial to the functioning of the foxhole radio!!!!

[@kensmith5694]

No, the high impedance headphones for other stuff works OK on this.

[@ksarnaszek4436]

Like a MacGyver! AWESOME!!!

[@numberoneappgames]

This was one of the best videos on a diy radio to date!

[@harmlesshawk1794]

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!" "...-,-"

[@malgray2]

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.

[@natemcgraw3690]

better product than the makerbots

[@2passnthru2]

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.

[@ufoengines]

Heard the toilet paper companies are getting rid of the tubes. Then what?

[@3dgamerman]

buy a radio

[@28YorkshireRose12]

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.

[@shahzad612]

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.

[@archangel20031]

Page not listed or has been moved?!?!?! Learn nothing there!

[@nb4032]

late,but:cdn.makezine.com/make/wp_foxholeradio.pdf

[@joycepalm9190]

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).

[@kevoice]

Warning: This may turn out to be a Fox Talk Radio :)

[@Xposse]

That's still a FOX Hole radio... Not to be confused with an Ass Hole radio...

[@kcmazdaguy]

@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.

[@w1wcn]

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.

[@Parlay007]

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!

[@Zecastronomo]

I and my father did it when I was young, in the sixties. Very nice to see it again.

[@timberwolves100]

@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.

[@CassetteMaster]

AWESOME! It works good! It's neat how the heated blade makes it work as a diode.

[@855h0le]

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.

[@doccpu7]

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.

[@lhmcfield]

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.

[@vancouverizer]

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).

[@canuma100]

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

[@mysss29]

The advent of stainless razor blades was actually a big deal, made possible by metal technology that allowed the stainless steel to actually hold a decent edge. Usually (afaik) bluing is actually done with chemical aid, but apparently heating it like crazy can oxidize it too? So where did the GIs get earpieces? And what did they usually wrap the wire around? Just curious. Thanks for the video!

[@mysss29]

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.

[@field16]

The pencil lead / razor blade combo is a basic diode, allowing the current to flow in only one direction.

[@rjy8960]

This is really, really nicely done. I've not seen a razor blade used as a detector before. Thanks!

[@kcmazdaguy]

@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

[@DaveTadlock]

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. :)

[@thatguy.mp7950]

would wire straight from an electric motor work?

[@irishdevil]

bluing is a process of heating and cooling that not only strengthens the metal but also does something to the internal electron configuration.

[@purplemutantas]

Nice! Glad to see you had a fire extinguisher on hand.

[@Scott-kc5fg]

I am a WWII history buff, however I never knew how the GI'S and resistance built the field radios

[@LUVITALL9]

Dude! This is really cool! But I gotta ask, what is it in your opinion, that makes the heated up , blue razor blade better than a normal, almost stainless razor blade? i'm not disputing, just curious what YOU think the difference is! I am gonna tinker with this over the next few days, although I live out in the boondocks of central Arkansas, there are of course AM station everywhere. One other question-how long, roughly, should this long wire antennae be? 3 feet? 8 feet? Good tutorial!

[@wilwad]

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.

[@fastmoni]

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!

[@政廷-e2q]

Thank you really, I finally understand the simple radio structure.

[@RJSoftware2000]

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.

[@thinkingjohn2099]

I built that today and it worked ! Thanks for posting

[@sarahmichaels8610]

The wire that is connected between the paper clips and the razor blade--is that also the magnet wire or a different kind of wire?

[@nicholasgonzalez]

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

[@MrUnidyne]

"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.

[@kcmazdaguy]

@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.

[@spystyle]

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.

[@RockGodZeppelin]

wow thats pretty neat, simple design with most household items. One question tho what kind of metal are those razors made from? it must be a resistive metal very nice though well done

[@missyrawien]

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 (: )

[@gccengineering1996]

BTW, Bre, The station you received was WFAN on 660 kHz. Happy Listening

[@substance1]

Not sure how you got the sound to the camera mic since there isn't enough power coming out of the radio to drive the mic. That's why you have to use that special ear-phone to hear the audio.

[@0rip0]

Are you saying that with just the parts shown here, and no amplifier you can get sound through a speaker? Please let me know when you post that video. I'd be very interested to see that.

[@redheadmaddy]

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.

[@frunomaol5069]

Thank you. A question re the schematic: Where is the PDF mentioned at min 1:34?

[@Holyscotsman]

you can hear the fire trucks and police on standby at 2:33 waiting for you to blow the place up. But you have certainly inspired a new weekend project!

[@rwstewart45]

I had forgotten about these radios. In the early 50's we called them "Crystal Radios." Does the number of turns determine the Radio Frequency received, or is it the "cat whisker?"

[@eh42]

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.

[@kcmazdaguy]

@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!

[@onijujitsu]

Good information! You could probably set up simple hand crank device to wind the wire around the tube, using the free hand as a guide - similar to a device used by smiths to coil steel wire for chainmail.

[@millenkatz5894]

I’ve been trying to get my ‘fox hole’ radio to work and I haven’t had much success. I was wondering if you could answer a few questions that I have: • I am using magnet wire with the proper gauge. When trying to tightly and evenly wrap the wire around the toilet paper role, the cardboard collapses. As a result, the wire is not as tightly wound, as I would like it to be. Could I use a metal cylinder instead? Would that affect the electromagnetic field surrounding the coil? Otherwise, would a wooden dowel work? • The magnet wire that I am using has a lacquer finish, which I believe acts as insulation. When connecting the magnet wire to the antennae, the diode, the headphone and the ground, should I be sanding off the insulation on the magnet wire? • Is it necessary for the wire used for the coil to be insulated? Could non-insulated wire be used? This would eliminate the need for the sanding mentioned above. • Before experimenting with the razor/graphite diode, I purchased a diode from Amazon. Does the direction of the diode make a difference? I would think not. If anyone can answer these questions, that would be fantastic. Thanks.

[@JdsWolf]

You could use a PVC pipe

[@millenkatz5894]

Thanks Jds Wolf for your answer. I'll try to grab one at Home Depot.....and do you know about the magnet wire? I saw in another video that I would have to strip off the lacquer coating when making connections. That makes sense. But what about the wire in the coil. Does it matter if it is insulated or partly insulated?

[@JdsWolf]

It has to be insulated, if the cable is connected all over the coil it won't do anything, so all insulated in the coil and the tips can either be sanded or scratched with a knife for the connections.

[@millenkatz5894]

Cool. Thanks.

[@nicholasgonzalez]

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!

[@candr]

@gomenaros One; safety, built up static electricy, two, its part of the antenna that uses ground radio frequencies (RF) to improve your signal.

[@KAFKUBA]

how did you tune the coil? did you remove varnish or add taps?? I don't understand

[@elusive.firstname.lastname]

Whoa bluing is a process that you put gun metal through to get that black metal look. I think you’re describing tempering.

[@willyb7353]

Sounds suprisingly good.

[@spacepirateivynova]

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.

[@AninoffsMagister]

Where did you get the earpiece? What could you do for an improvised speaker?

[@franzyland]

I did some research and found out you can change the length of the antenna or coil, or install a tuning capacitor.

[@Mindraker1]

Totally awesome and simple. Beginner hams would totally dig this. Perhaps a safer substitute for the burned razorblade, but otherwise, I totally dig it.

[@Eighteen87]

Could you just use uninsulated copper wire instead? And is the razor a must or is any peace of thin metal bit okay?

[@BigCroca]

This is so high quality for 2007 damn

[@GratefulCraig]

Real cool! I watched it twice and that looks like a real cool weekend project.

[@IvanSRBfilip]

You made my weekend.Can u tell me where I can get a "blued" razor blade because I dont have a blow torch?

[@anjwicks]

I meant, how much power (voltage or amps?) is a radio signal itself? Probably a dumb question but I'm fascinated there's "juice" floating around in the air.

[@chrismofer]

@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.

[@kcmazdaguy]

@SolgerLemp acutally....moving the pencil has little effect of changing the channel....changing the length of the wound coil/wire changes the channel...However, this primitive radio does not have an ability to focus its ability to listen to a single channel very well, it is said to have "poor selectivity". It basically listens to whatever channel happens to be nearby, that has the most energy signal.

[@drew6017]

Great video. One of the best I've seen about the foxhole radio.

[@PeteyPeteee]

im sure iv seen something like that in a book years ago, try connecting a wire at the ariel side and taking some of the varnish off the wires on the coile, then you can adjust the inductance and find a better tuning point, i think...

[@TomMcRand]

i like how, as you were getting ready to fire up the torch to heat up the razor blade, the sirens got closer.

[@paskperfect]

graphite of the pencil lead is an electrical conductor. I don't know if it is necessary for anything but a wide contact with the razor surface. The razor, on the other hand, *must* be rusty for this to work; iron, and iron-oxide (rust) crystals for the semiconductor that changes the alternating AM signal into a Direct Current to operate the head-phone piece.

[@0rip0]

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.

[@franzyland]

I am going to try this one for sure, but one question. How do you change channels?