When I was about 6 years old, my dad got me a spy pen radio. They were advertised in comic books all the time. It had a clip to clip onto something to make an antenna and a clip for ground and a metal sliding pin to tune with. I lived in the city and there were several strong stations that I could get. I thought it was the coolest thing ever and to think that spies used it made it even cooler.
I was maybe more like 10 years old and was really into comic and their advertisements for odd items. I ordered one of those crystal radios.. not sure it was a "spy pen" The one I ordered and got was similar in shape and size to a Pez dispenser. For an antenna, I used my bed frame and grounded on.. I'm not sure.. perhaps I was the ground? It was cheap but it DID bring in a couple of the strongest AM radio stations at the time. As I remember.. the only time I could hear it work was in the dead of night because it was quieter at that time.
I felt in the same way. I wondered why these two coils, one small and amother big. No explanation was offered. Still I am in the dark whether the small cool is connected to the antenna, and what about the other point? Is it also connected to the phone?
Back in the '70's while stationed on a repair ship in the Electronics repair division, I was tasked with getting the radio in the chief's lounge to pick up the station they wanted. After going over the whole antenna system and finding it was good, I made a simple antenna coupler on the back of the radio. The improvement was stunning, where we only had about half a dozen stations, it now was picking up so many stations that there was not a quiet spot on the band.
❤POLISMANS INSTÄLLNING TILL OSMO VALLO SOM OMKOM I KARLSTAD EFTER😢 POLISMAN CHRISTIAN SAAX TILLTAG. MODERN TILL OSMO VALLO,SIGNE MODÉN,FÖRSÖKTE RESTEN AV SITT LIFV,FÅ KLARHET I VAD SOM HÄNDE. OBDUCENTERNA VART JÄVIGA TILL POLISENS FÖRDEL.😢
I built a crystal radio in 1959 . I listened to the general mills theater from Chicago . The shadow knows . Green hornet . There were other programs . I don't exactly remember . It was quite awhile ago.
I've been into amateur radio for nearly a half-century, and cut my teeth as a kid building crystal radios. Periodically throughout my adulthood, the crystal "bug" bit again and I fooled around with crystal set construction. My personal bane has been the selectivity v. sensitivity issue. I can build a set that is very loud, but not selective. Or, I can build a very selective rig that just doesn't have much volume. But, I can never build a passive radio that has both volume and selectivity.
I've been using a trick I learned from Elmer Osterhoudt. Put a 365pf variable condenser between the radio and the ground. Increases selectivity and it still has decent sound.
Getting a set with high enough Q to accept the load of antenna and ground, this means EXPENSIVE and challenging construction. This takeds two movable coils of extremely low loss ( Q over 1500) bifilar high count thin Litz (1040x48) wound bifilar on 1:1.6 ratio (length to diameter). low loss former (polystyrene with stripes of styrofoam to lessen mass near the coil increase the Q) Good variable capacitors ( ceramic insulated clean and preferably silvered copper) as well as the impedance matching network together with. RCA big can balanced armature headphones. Impedance matched diodes with low loss and distortion... It becomes a science challenge. I have gotten DX from across the ocean so it is possible. Sadly not easy or cheap.
Best to do that. teach him how to salvage parts and roll his own. This world might turn around. In a heart beat (EMP) and a little thing as a radio made from salvage parts( razor blade detectors ect) in a camp" folks" would pay for a bit of info. A radio man could be a asset. Worth having. Imagine a little man with a chalk board. Putting out the world news on a chalk board ever morning. (Kinda like the post man) bringing "hope" to the camp.
Back in the mid-60's I got a Science Project book out of our school library and it had plans on how to build a crystal radio set, so I built one. It worked well enough to pick up the more powerful AM station. I listened to baseball games on it. It played all the time and never needed any batteries. I listened to talk radio at night on that thing.
I used to fiddle with crystal sets. As I recall, good standard earphones had more volume than crystal ear buds. I also built a number of sub-min tube and transistor AM and RC plane receivers. Great fun squeezing parts and A and B batteries into small cases.
Back in the mid-fifties I built my first radio from a Cub Scout kit. It had a piece of Galena potted in solder and had a cat's whisker to tune for the best signal. It worked great! In the early 90s I was talking to some guys on ham radio and I said that I wished I could get a chunk of Galena so I could replicate that same crystal radio. Nobody offered any suggestions but a week later I got a package in the mail and I swear that hunk of Galena must have weighed pound!
When I was a mere "Lad", way back nearly 60 years ago, someone gave me a book called: "The Boys Big Book of Electronic Projects", or some such. It had plans and instructions for about five different types of "Crystal Radios"! And I build all of them! Was great fun! And I never had to spend my one dollar a week Allowance on batteries! Back then, even if you could obtain a small pocket sized "Transistor" radio, those rectangle 9 volt, "Zink-carbon" batteries didn't last long! You did better if you NEVER played the music through the tiny built in speaker, but instead always listened via that tiny 👂 piece!
About 50 years ago, I made my own crystal radio and it worked great. A rock collection that I had that was stuck to a sheet of cardboard, also included one quartz rock, and so that one particular rock became my crystal detector. Either sliding the coil bar, or changing the position of the "cat whisker" wire that was probing the quartz crystal, could be used to select channels. The layout I used is the same as what is shown at "Crystal radio - Wikipedia" in the Basic Principles section. See the Pictorial diagram from 1922 showing the circuit of a crystal radio.
Seguiré tu idea, acoplador de bobina, me encantan las radios galena, manos a la obra, a empezar a armar mi propia radio, tengo unos antiguos antiguos auriculares de cristal de ,1950.
John, I have two sets of Brandes phones one set works and the other needs a new Y cable, I have no idea where to get such a thing. They are also 1200 ohm sets, maybe all I have will work, I just thought the SX 100 may have to much power for them.I don't know much about radio, but I have always loved the short waves. GOOD TIMES!!!
A blast from the past !! I built a crystal set here in the UK with just a coil and a variable tuning capacitor, 500mf if i remember correctly, a geranium diode, as i called it then ! and a pair of wartime headfones. We are talking way back in the 1960's, when a lot of ex war stuff was still available. It worked very well, Radio Luxembourg was on every night, I used to pretend to be asleep, with my headfones on, listening to the Shadows, it never ran out of power, wonderbar !!! What puzzzles me now is that I see all these american designs use a wiper across the coil for tuning, that idea didnt exist back in my teenage days, or even the use of the coupling coil... I wonder how much better it could have been with either, or both ?? Circuits were poached from Practical Wireless magazines, a monthly UK electronics magazine, when OC71 transistors were the latest high tech device available 😐 Perhaps you would care to comment on this point, many thanks from Blighy.
I build on a them there in 1957 It used a Ferrite Coil for Freq. Tuning. It came as a Rocket Ship Radio but I took it apart and kinda hot rodded it, A 'Wave Magnet" thing from 1935 Dake's Cyclopedia of Electronics was a Devive where two Coils Were Able to Tume Down inbetween eatch other-s Coils as Senictivy emmiitteerrs. Or something. Hell, I cannot think any more too good. Youre More Older then me...I am a 1949 Model. Perhaps I need a Oil Change?
About 1954/55 I made a matchbox crystal set from a plan that I bought somewhere, on which the 'variable capacitor' was actually the matchbox drawer (wound with x turns of z gauge wire) gently sliding in and out of the matchbox case itself (wound with a greater number of turns of y gauge wire, or maybe it was it z again?) A friend of mine was so impressed, I made one for him, too, telling him that he would need to buy his own arial and earth wires - which he did. The crystal set had a germanium diode and it picked up several Melbourne radio stations quite well. I'm no radio expert, but I have grandchildren who might be interested making it for a science project. May I ask whether you, Squarewave2, or your subscribers may have seen this tiny model, and might know the necessary number of turns and wire gauges for the 2 coils? I've seen 'matchbox models' referred to online, but they're larger and I've not been able to find this particular model with the two movable coils. I do remember the two wires coming in, and the earpiece coming out, of such a small matchbox did make it look a bit weird, but it did grab the admiring attention of adults! :) Unfortunately, I remember that it didn't survive as long as a couple of larger and sturdier crystal sets that I'd made earlier.
love this guys videos......easy to understand.....explains a lot......a few videos ago, he had one with the different taps (how to wind them....) and a switch I think....can't remember what type of radio it was....loved it....the cat is ok too....I gotta get back at the tinkering thing again....been a long time.....junk box is waaaay low....got a QRP HF rig (a Elecraft K1) and a limping HW-101 here in SW Montana.....need to pick up a decent SWL receiver....maybe build a simple radio and see what's up.....nearest AM transmitter from my place is 30 miles +/-.....I dunno....I got 66' of wire up, and two dipoles at 20 Ft.....limited at the rent house....mancrib has 12 wire antennas from/to NE/SW, and NW/SE, and N/S for 80-10....30 miles away....going there today for the NAQP SSB that's going on right now till 11PM MST....again....love your videos.
Swan 350 at the mancrib.....weak tubes, only 70-100W out, but the SSB audio is excellent.....was told a few months ago that whatever I was doing, don't touch it.....damn good SSB boat anchor.....I love it.....need some fresh finals though.....I checked them.....they are weak allright.....
I had planned on doing a crystal radio demo at the field day site this year......tower is about 1 1/2 miles away, and that would have been perfect for an easy/quickie demo......but an angry person burned down the studio, so no more local radio station....the 550 kHz station is about 25-30 miles E-SE of here.....hell it might work.....if I did it right.....I still might try it....5000 watts daytime, 1000 nighttime....my ham radio elmer has been there 36+ years....my CW elmer....ran big contests w/him in the early 80's as a novice.....back when the big boys would go to the novice bands....US and DX.....run us slower guys......did a LOT of logging for him as well.....and as long as I stayed in the novice bands, he would let me use his amp to get up to the 250 watts input at the time for a novice I think it was....now it's 200...??? Any hoo....nice to have his beam and big wires while he was at work....loved it....keep up the damned fine work, sir.
There are crystal radios that are more simple, basic and fundamental than this one. Not sure why you'd say that. Otherwise, I like this video alot. And not to nit-pick further... it's the Cub Scout radio. I'm glad you upgraded it. It's elegant and cleverly designed.
Have 40 mtr dipole. Full wave. I use it on my pixie tranciver. It works verry well for xtal set. Because it's 40 mtr. I get a lot of welcome over seas broadcast. Tks kv4li
Why is the 90 to 25 turn ratio specified for the tuning vs. antenna coil? Could you explain the math for why this ratio has been recommended? Also, does the wire for the antenna coil have to be enamel wire, or can it be standard insulated hookup wire, since the sheathing doesn't need to be scraped away? Lastly, why does it matter if the antenna coil is 24 AWG? Couldn't it just be 22 AWG wire like the tuning coil? Thank you in advance for your responses and suggestions, and for your excellent video.
i made it when i was in 6th class in primarey school its very wonderful Radio reciver i like it specialy it work without any battry or electric . it work with the wave comes from Radio stations enter to inttena and the germanium diod and coil and earth . The electric wave go out by earth and the sound wave stay and go to the cristal earphone
Very well done. Don’t forget to use high impedance headphones or high impedance ear phone. I see you have other interesting subjects. I am now subscribed.
Hey I built a radio exactly like thes except I used #36 magnet wire. The broadcasts are so squeezed together but tuning is super selective so I plan to continue using this wire and on an narrower diameter coil then I will buy some germanium detector radio diodes
Though mine only gets one measly station and a cb operator , i am totally not disappointed at getting Something using bits of garbage i had laying around
Hey I absolutely love this concept of no battery connection and I want to include it in my final project. I greatly enjoyed your video and explanation and I was hoping you could show me the schematic with the values and connections so I can make a radio just like that one. Also is the tuning capacitor 365pF? Thank you so much for you time will recommend to my friends.
Hi Anthony, Thank you for your nice comment! If you want to build crystal radios you really should look for the book "Radios That Work For Free" by K.E. Edwards. It has this diagram and others. Yes, the tuning capacitor is 365pf.
Maybe I missed it but I didn't hear you mention the ground connection. It is just as important as the long antenna wire. either a water pipe or an AC socket ground prong.
The schematics may have made sense to someone a bit more savvy with electronics. I like the updated version but could not see the wiring. You are clearly knowledgeable with these type things. Was looking to build a version. But simple got complicated. May have to go back to a rusty razor blade and a stinky scranton pencil.
John, I see by the diagram that there is a capacitor between the head phones, and also between the black and red nobs? what are nobs for? and please tell me about the caps. Also I love the videos. GOOD TIMES!!!
Hi Dragos 4! The black and red "knobs" are not knobs at all but binding posts to connect headphones that don't have a plug. Not counting the tuning capacitor, there is only one capacitor; it is connected across the head phone terminals. I should really have put another one across the headphone jack! There are two ways to connect phones. The value is .003 microfarads. The capacitor function is to "smooth out" the RF carrier so as to make the audio envelope more intelligible to the ear phones. Thank you for your comment!
John, Thank you for your fast reply, I would have seen it sooner, but was watching some of your other videos. Should all crystal sets have this cap. across the head phones? Again thank you very much... GOOD TIMES!!!
sir, long time model airplane builder and just getting into these xtal sets and have a question>>>>>>>>> I see on the left you have a phone jack, then on the far right thiers a bracket with red/black knobs and assuming thier for an optional 2 wire crystal ear phone, is that correct??
Yea, Stan, you are correct. I can connect two different types of earphone leads. Be sure to get the book I recommend: " Radios That Work For Free" by K.E. Ewards .Good luck!
John, I hope I don't bother you with my ???s but I have a hallicrafters SX - 100, and would like to know What a good set of headphones for it would be. I have a navy wwII NOS for my crystal sets, but don't want to try them as they are 2000 OHM. Please help... GOOD TIMES!!!
No bother at all! Go to Ebay and search for "antique headphones". Look for the "Brandes" phones. That's what I have. They will run you about $50. Just make sure the seller says "working". "73".
Being a retired aerospace radio-frequency design engineer I like your videos. Have you thought about including the formula's for calculating resonance so that tuning is not so difficult for specific frequencies?
@@2nostromo You can calculate the coil and cap values based on the frequency with a standard formula. I can't find it, but it's everywhere. They have lots of free stuff at the library.
@squarewave2 Hello. Not sure if you see comments and questions from past videos, but after watching this and a few other videos you have posted about crystal radios, I was wondering if you have any knowledge of the "METRO Jr." set from the 1920's. It is inscribed on the aluminum base to be from the "METRO ELECTRICAL CO. INC., NEWARK, N.J. U.S.A." It looks somewhat similar to the design of the Boy Scout Radio you depict here, but from what I can tell it has a slightly different circuit, most notably the aerial is connected directly to both the headphone and one end of the coil. I inherited the basic unit (i.e., without the box, instructions, and original headphones) from my late father, and for kicks I want to see if I can get it to work. I vaguely recall it working in the 1970's when my father demonstrated it to me, but that could be a false memory. About all I can get now is static. Hoping you might be open to an exchange about trying to get this to operate again, perhaps making it the subject of some future vide. ~Ed from Baltimore
Hi Edward, Sorry, I don't know anything about a Metro Junior radio. If you are getting any sound at all, even static, it's a good sign; radio is probably working ok. Are there any broadcast stations in your area? Perhaps they are just too far away. Remember, you need a good, long wire antenna. Good luck.
One more question...every other crystal radio design I've seen requires the use of an approx. 47K resister in parallel with the earpiece. Instead, in this design, you recommend a small capacitor. Could you explain the reason for that?
I've never found the need for either using a crystal earphone or magnetic headphones. But in theory (some say practice) the AC capacitor shunts any remaining AC signal to ground. The only thing you want reaching your ear is pure, rectified DC signal. Of course an AC capacitor is invisible to DC, so there is no risk of the capacitor bleeding off your audio signal. On the resistor, it is said that a resistance is necessary to "load the detector", although this hasn't been my experience. What many builders do is include BOTH the capacitor and the resistor.... both issues solved. Probably better, experiment with different values of both. One of the best items on your workbench should be a pair of capacitance and resistance substitution boxes. You just clip them into your circuit and spin the knob through the different values to find the ones that work best.
I built a crystal radio that used a crystal piezo earpiece and got a very loud distorted signal. The 47k resistor made it sound clear. However, in most cases you don't need a resistor
CAN I MAKE A CRYSTAL EARPHONE? Yes. I saw a UA-cam where a guy did that. He used a piezo buzzer from a microwave oven. For the earpiece, he hot-glued on a piece of a Bic pen barrel. You can buy piezo elements from All Electronics or Electronics Goldmine. If you can’t solder, buy a piezo element with leads.
Many designs like this appear to call for a .001 cap across the phones for filtering. I noticed you used a 332K /.0033 cap, any special benefit of this. Wonderful video, Thanks Denny
Hi Denny, I've used different values across the phones with no difference I can hear. In fact, I usually omit this part completely. Thanks for your comment!
Please excuse my ignorance as I am new to this as a retirement hobby. I have built the simple Boy scout radio that you have demonstrated it works! I then moved on to the improved version. I wound my own coil quite nicely and think that I have put it all together correctly by looking at your video and stopping it to get a better look. I cant get it to work so I have screwed up somewhere. However, I cant quite see where both tags go from the larger coil, one goes to diode phones and ground but I cant see where the other fits. I would be grateful for some advice please. I have tried enlarging the picture but still cant see it.
Hi mvv650mvv, The primary coil, the big one, is connected to the circuit between the slider and the diode. The wire from the left end of the primary coil is not connected to anything which my diagram shows. Hope this helps.
WHY USE A 47K “LOAD RESISTOR” ACROSS THE CRYSTAL EARPHONE? To provide a DC return path for the signal, allowing current flow. (The crystal phone acts like a capacitor, which blocks DC current.)
Question re wire wrapped tube. There has been some question about using toilet paper cardboard center rolls as the platform to wrap the wire however I have questions regarding its durability and the fact that it could crinkle in a moisture environment. I have opted for PVC piping so my question is schedule 20 is not as strong as schedule 40 but it's definitely strong enough to support the wire and endure climate challenges. So my question is should I use the schedule 20 instead of the 40 because it's thinner and therefore will pick up more signal or does it not matter? Is the signal is coming from the outside or the inside of the tube where the wire is wrapped? I appreciate your help on this. I was even going to use the plumbing 'P' trap replacement pipe which is even slightly thinner than the schedule 20 if the tube thickness matters.
The best tube is a 1 1/2 inch diameter MAILING TUBE. It's easier to dill hols in than PVC pipe. The "signal" is coming from the antenna to the antenna coupler coil and then to the tuning coil by induction. Don't even think of toilet paper tubes!!
Thanks for the quick reply. I am waiting on the crystal earphones (ordered online) to see if my setup is functioning. If so I plan to rebuild one that merits respect. The goal is to have some form of long term form of news in the event of a disaster. Thanks for the help. TP tubes get recycled.
Approximately, on 20 mm diameter PVC tube 0.2 mm wire ( 32 AWG ) That project at least on 40 mm ( 1.56 inch ) diameter paper tube winding 0.4 mm wire ( 26 AWG ) at most 0.8 mm wire on 50 mm diameter PVC tube 0.5 mm wire ( 24 AWG )
foil capacitor, yes that has been done and works. Using card stock paper and foil. The antenna coupler connects one end to ground and the other to the antenna. Then it will magnetically couple to the main tuning coil through the air.
I’m trying to build this version but can’t tell where all the wires coming off the coils go to can u please describe where the tuning coil wires and the antenna coil wires go thanks
Hi Corey, One end of the smaller coil (the antenna coupler) is connected to ground and the other end to the antenna. One end of the larger tuning coil is connected to the rotor plates of the tuning capacitor and the other end is not connected to anything. The sliding tap is connected to the stator plates of the tuning capacitor and to ground. I hope this helps. Good luck!
squarewave2 sorry to bother you again but one more question.. the germanium diode goes from the variable capacitor and antenna wire to the tie point and then straight to the ear phone hook up ? Sorry I can’t see well and I’m having a hard time identifying the wiring
antenna 300 mmps / 1 mhz = 300 meters for a full wave 75 meters for a quarter wave the stations use 75 meter towers for their antenna on a counter poise so your antenna should be vertical 75 meters so you raise your coil off the board with metal standoffs
Thanks. from n5qdm. A long wire, 100-200 feet of wire at least thirty feet high and a good ground rod connection. Your bench is very "neet". I think it is time to clean mine up and chunk the junk.
Best AM crystal radio: 25 turn primary (antenna coil) on a section of aprox 3 inch diameter pvc pipe....120 turn secondary (start winding right behind first coil)....another 25 turns in center of secondary. Wrap a strip of paper over secondary before winding third coil. Use 24 AWG magnet wire. Connect 365pf air variable capacitor across 120 turn coil. Connect germanium diode and high impedance crystal earphone/headphones to 25 turn coil wrapped over the 120 turn coil. Telephone speakers work well too. Connect antenna/ground to first 25 turn coil. Antenna can be any type of small insulated wire at least 100 feet long as high off the ground as you can get it. 250 feet long is even better. A fishing rod can be used to get antenna wire up in a tree. Tie a lead weight to fishing line and throw it over the tree top. Tie fishing line to antenna wire and pull it up then tie fishing line to base of tree. Or you can string out the antenna wire between trees....just get it high enough that nobody will walk into it and rip it down. You can use a counter poise antenna as a ground....just attach another length of insulated wire to primary coil instead of a ground wire and string it out through the bushes or trees in the opposite direction. Get it up high enough that nobody gets tangled in it. This is a very sensitive and selective crystal set. PS: PVC pipe diameter isn`t critical. You can use 2 3/4 inch pipe or 3 1/2 inch pipe with almost same results and tuning range....520khz to about 1600khz. You can buy 500 ft spools of cheap insulated wire off Amazon. TIP: Use super glue to hold windings in place as you wind coils. This way you can rest some and not have to do it all at once. Hot glue works well too. Be creative.
I want to know from the viewers. In my childhood days (that is 70 years hence when i was a lad of 10 or so!), my elder brother made a crystal radio. I remember that has a receiver of the phone (bought from some shop, called second hand market), and had a crystal (galena material), of course there was a coil, which I cannot rememeber at such age, I am now 80). Can anybody enlighten me about it? How was it made? I want to make it in his memory (he passed away few years back, had he been alive I would have known the mechanism of it). Few words more: we could losten to the local Calcutta station so distinctly which I cannot believe. He was a miracle man to me. It had an antenna, may be 20 to 30 yards, which was hung on the rooftop. My mother beiieved that it was some illegal activity and police can arrest us, so he had to give it up.
Long wire, random length antennae are not tuned to a specific radio band like a dipole antenna. You can pretty much receive any radio signals with the long wire.
Hi! Thanks for sharing this! -How thick wire sould i use when making this? -How thick should the coils "paper" be? (you show us the coil's "paper" 3:20 - 4:20) -Which diode can i use? -any germanium? -How long antenna should i have? -The variable capacitor -how many pF? -The other capacitor -kind of? (cheramic / polyester, etc.) -how many pF / nF? Which one is the best? -this one or ua-cam.com/video/AaNpFYe5dSo/v-deo.html ? Thanks!
When I was about 6 years old, my dad got me a spy pen radio. They were advertised in comic books all the time.
It had a clip to clip onto something to make an antenna and a clip for ground and a metal sliding pin to tune with.
I lived in the city and there were several strong stations that I could get.
I thought it was the coolest thing ever and to think that spies used it made it even cooler.
I was maybe more like 10 years old and was really into comic and their advertisements for odd items. I ordered one of those crystal radios.. not sure it was a "spy pen" The one I ordered and got was similar in shape and size to a Pez dispenser. For an antenna, I used my bed frame and grounded on.. I'm not sure.. perhaps I was the ground? It was cheap but it DID bring in a couple of the strongest AM radio stations at the time. As I remember.. the only time I could hear it work was in the dead of night because it was quieter at that time.
So fun! I built this for my survival merit badge back in the 80s. This is so great! Thanks for the pleasant memory
@@foobarmaximus3506 I know right! The professor and his coconut radio lol
It was nice to hear you mention the wire info for the coil. MOST people DON'T. It must be frustrating for beginners!!
I felt in the same way. I wondered why these two coils, one small and amother big. No explanation was offered. Still I am in the dark whether the small cool is connected to the antenna, and what about the other point? Is it also connected to the phone?
@@drmrinalkantinath4336 - The 2 coils are inductively coupled together.
Back in the '70's while stationed on a repair ship in the Electronics repair division, I was tasked with getting the radio in the chief's lounge to pick up the station they wanted. After going over the whole antenna system and finding it was good, I made a simple antenna coupler on the back of the radio. The improvement was stunning, where we only had about half a dozen stations, it now was picking up so many stations that there was not a quiet spot on the band.
❤ESCARGENCY ❤😂❤
❤POLISMANS INSTÄLLNING TILL OSMO VALLO SOM OMKOM I KARLSTAD EFTER😢 POLISMAN CHRISTIAN SAAX TILLTAG. MODERN TILL OSMO VALLO,SIGNE MODÉN,FÖRSÖKTE RESTEN AV SITT LIFV,FÅ KLARHET I VAD SOM HÄNDE. OBDUCENTERNA VART JÄVIGA TILL POLISENS FÖRDEL.😢
I built a crystal radio in 1959 . I listened to the general mills theater from Chicago . The shadow knows . Green hornet . There were other programs . I don't exactly remember . It was quite awhile ago.
Really enjoyed your video, I just built a scrap box crystal radio following mostly your schematic with a bit from a few others. Thank you so much.
I've been into amateur radio for nearly a half-century, and cut my teeth as a kid building crystal radios. Periodically throughout my adulthood, the crystal "bug" bit again and I fooled around with crystal set construction. My personal bane has been the selectivity v. sensitivity issue. I can build a set that is very loud, but not selective. Or, I can build a very selective rig that just doesn't have much volume. But, I can never build a passive radio that has both volume and selectivity.
I've been using a trick I learned from Elmer Osterhoudt. Put a 365pf variable condenser between the radio and the ground.
Increases selectivity and it still has decent sound.
Study up on transistors and bandpass filters. That will help.
Getting a set with high enough Q to accept the load of antenna and ground, this means EXPENSIVE and challenging construction.
This takeds two movable coils of extremely low loss ( Q over 1500) bifilar high count thin Litz (1040x48) wound bifilar on 1:1.6 ratio (length to diameter).
low loss former (polystyrene with stripes of styrofoam to lessen mass near the coil increase the Q)
Good variable capacitors ( ceramic insulated clean and preferably silvered copper)
as well as the impedance matching network together with. RCA big can balanced armature headphones.
Impedance matched diodes with low loss and distortion...
It becomes a science challenge.
I have gotten DX from across the ocean so it is possible. Sadly not easy or cheap.
Looks like a great project for my grandson as he gets old enough when I first start introducing him to electronics in radio equipment
Best to do that. teach him how to salvage parts and roll his own. This world might turn around. In a heart beat (EMP) and a little thing as a radio made from salvage parts( razor blade detectors ect) in a camp" folks" would pay for a bit of info. A radio man could be a asset. Worth having. Imagine a little man with a chalk board. Putting out the world news on a chalk board ever morning. (Kinda like the post man) bringing "hope" to the camp.
Back in the mid-60's I got a Science Project book out of our school library and it had plans on how to build a crystal radio set, so I built one. It worked well enough to pick up the more powerful AM station. I listened to baseball games on it. It played all the time and never needed any batteries. I listened to talk radio at night on that thing.
I used to fiddle with crystal sets. As I recall, good standard earphones had more volume than crystal ear buds. I also built a number of sub-min tube and transistor AM and RC plane receivers. Great fun squeezing parts and A and B batteries into small cases.
Back in the mid-fifties I built my first radio from a Cub Scout kit. It had a piece of Galena potted in solder and had a cat's whisker to tune for the best signal. It worked great! In the early 90s I was talking to some guys on ham radio and I said that I wished I could get a chunk of Galena so I could replicate that same crystal radio. Nobody offered any suggestions but a week later I got a package in the mail and I swear that hunk of Galena must have weighed pound!
Have you ever tried a safety pin point as a cat whisker on a penny? I think a wheat penny would be better (old). It uses corrosion as a diode.
No, but I have used the safety pin trick on Old Gillette blue blades with moderate success.
Calvin, yes the copper oxide on an old penny works well. I got about three stations on a 150 year old penny
Thanks a lot ! the antenna coupler explanation helped a lot !
When I was a mere "Lad", way back nearly 60 years ago, someone gave me a book called: "The Boys Big Book of Electronic Projects", or some such.
It had plans and instructions for about five different types of "Crystal Radios"!
And I build all of them! Was great fun! And I never had to spend my one dollar a week Allowance on batteries! Back then, even if you could obtain a small pocket sized "Transistor" radio, those rectangle 9 volt, "Zink-carbon" batteries didn't last long! You did better if you NEVER played the music through the tiny built in speaker, but instead always listened via that tiny 👂 piece!
Very nice of you to make this video and thank you for your useful tips. Going to make a crystal radio set soon.
Very informative, Thanks. This video was well made ***** video and audio
Parabéns top gostei muito chiqui amigo belíssimo
About 50 years ago, I made my own crystal radio and it worked great.
A rock collection that I had that was stuck to a sheet of cardboard, also included one quartz rock, and so that one particular rock became my crystal detector. Either sliding the coil bar, or changing the position of the "cat whisker" wire that was probing the quartz crystal, could be used to select channels. The layout I used is the same as what is shown at "Crystal radio - Wikipedia" in the Basic Principles section. See the Pictorial diagram from 1922 showing the circuit of a crystal radio.
Quartz can't be used as a detector!
You need a piece of crystalline metallic mineral ore for use in a "Cat's Whisker radio detector"
There was probably a piece of iron pyrites in among the quartz
they don't teach this stuff in schools anymore.
@@JohnSmith-eo5sp All I know is that it worked perfectly. I had the rest of the quartz rock wrapped in tin foil.
Thanks for the very useful information! Great video.
Good explanation! Thanks for sharing!
Seguiré tu idea, acoplador de bobina, me encantan las radios galena, manos a la obra, a empezar a armar mi propia radio, tengo unos antiguos antiguos auriculares de cristal de ,1950.
Respect and recognition ...
John,
I have two sets of Brandes phones one set works and the other needs a new Y cable, I have no idea where to get
such a thing. They are also 1200 ohm sets, maybe all I have will work, I just thought the SX 100 may have to much
power for them.I don't know much about radio, but I have always loved the short waves.
GOOD TIMES!!!
Rule number ONE in radio 101: Antenna is _EVERYTHING!_
Awesome video. Thanks
I will start making it. I have this tuning caps. I made a crystal radio back in 1989 in school days, using a diode in a telephone ear piece.
A blast from the past !! I built a crystal set here in the UK with just a coil and a variable tuning capacitor, 500mf if i remember correctly, a geranium diode, as i called it then ! and a pair of wartime headfones.
We are talking way back in the 1960's, when a lot of ex war stuff was still available.
It worked very well, Radio Luxembourg was on every night, I used to pretend to be asleep, with my headfones on, listening to the Shadows, it never ran out of power,
wonderbar !!!
What puzzzles me now is that I see all these american designs use a wiper across the coil for tuning, that idea didnt exist back in my teenage days, or even the use of the coupling coil...
I wonder how much better it could have been with either, or both ??
Circuits were poached from Practical Wireless magazines, a monthly UK electronics magazine, when OC71 transistors were the latest high tech device available 😐
Perhaps you would care to comment on this point, many thanks from Blighy.
wow oc71 sounds stone age never heard of it...thanks for sharing your.experiences
"A Geranium diode"? Didn't know you had a flower detector😉
I build on a them there in 1957 It used a Ferrite Coil for Freq. Tuning. It came as a Rocket Ship Radio but I took it apart and kinda hot rodded it, A 'Wave Magnet" thing from 1935 Dake's Cyclopedia of Electronics was a Devive where two Coils Were Able to Tume Down inbetween eatch other-s Coils as Senictivy emmiitteerrs. Or something. Hell, I cannot think any more too good. Youre More Older then me...I am a 1949 Model. Perhaps I need a Oil Change?
About 1954/55 I made a matchbox crystal set from a plan that I bought somewhere, on which the 'variable capacitor' was actually the matchbox drawer (wound with x turns of z gauge wire) gently sliding in and out of the matchbox case itself (wound with a greater number of turns of y gauge wire, or maybe it was it z again?) A friend of mine was so impressed, I made one for him, too, telling him that he would need to buy his own arial and earth wires - which he did. The crystal set had a germanium diode and it picked up several Melbourne radio stations quite well. I'm no radio expert, but I have grandchildren who might be interested making it for a science project. May I ask whether you, Squarewave2, or your subscribers may have seen this tiny model, and might know the necessary number of turns and wire gauges for the 2 coils? I've seen 'matchbox models' referred to online, but they're larger and I've not been able to find this particular model with the two movable coils. I do remember the two wires coming in, and the earpiece coming out, of such a small matchbox did make it look a bit weird, but it did grab the admiring attention of adults! :) Unfortunately, I remember that it didn't survive as long as a couple of larger and sturdier crystal sets that I'd made earlier.
P.S. I subscribed to your channel, and thumbs up all videos. many thanks.
le sigh. love the workshop.
Great job... Thanks
love this guys videos......easy to understand.....explains a lot......a few videos ago, he had one with the different taps (how to wind them....) and a switch I think....can't remember what type of radio it was....loved it....the cat is ok too....I gotta get back at the tinkering thing again....been a long time.....junk box is waaaay low....got a QRP HF rig (a Elecraft K1) and a limping HW-101 here in SW Montana.....need to pick up a decent SWL receiver....maybe build a simple radio and see what's up.....nearest AM transmitter from my place is 30 miles +/-.....I dunno....I got 66' of wire up, and two dipoles at 20 Ft.....limited at the rent house....mancrib has 12 wire antennas from/to NE/SW, and NW/SE, and N/S for 80-10....30 miles away....going there today for the NAQP SSB that's going on right now till 11PM MST....again....love your videos.
Swan 350 at the mancrib.....weak tubes, only 70-100W out, but the SSB audio is excellent.....was told a few months ago that whatever I was doing, don't touch it.....damn good SSB boat anchor.....I love it.....need some fresh finals though.....I checked them.....they are weak allright.....
Thank you, Cooker440. I love to get such nice feedback!
I had planned on doing a crystal radio demo at the field day site this year......tower is about 1 1/2 miles away, and that would have been perfect for an easy/quickie demo......but an angry person burned down the studio, so no more local radio station....the 550 kHz station is about 25-30 miles E-SE of here.....hell it might work.....if I did it right.....I still might try it....5000 watts daytime, 1000 nighttime....my ham radio elmer has been there 36+ years....my CW elmer....ran big contests w/him in the early 80's as a novice.....back when the big boys would go to the novice bands....US and DX.....run us slower guys......did a LOT of logging for him as well.....and as long as I stayed in the novice bands, he would let me use his amp to get up to the 250 watts input at the time for a novice I think it was....now it's 200...??? Any hoo....nice to have his beam and big wires while he was at work....loved it....keep up the damned fine work, sir.
no sweat, fella.
There are crystal radios that are more simple, basic and fundamental than this one. Not sure why you'd say that. Otherwise, I like this video alot. And not to nit-pick further... it's the Cub Scout radio. I'm glad you upgraded it. It's elegant and cleverly designed.
Have 40 mtr dipole. Full wave. I use it on my pixie tranciver. It works verry well for xtal set. Because it's 40 mtr. I get a lot of welcome over seas broadcast. Tks kv4li
Very nice video
Nice video!
Good work.
Why is the 90 to 25 turn ratio specified for the tuning vs. antenna coil? Could you explain the math for why this ratio has been recommended? Also, does the wire for the antenna coil have to be enamel wire, or can it be standard insulated hookup wire, since the sheathing doesn't need to be scraped away? Lastly, why does it matter if the antenna coil is 24 AWG? Couldn't it just be 22 AWG wire like the tuning coil? Thank you in advance for your responses and suggestions, and for your excellent video.
John, Where do you buy the parts for your projects. It can become expensive.
Great!
i made it when i was in 6th class in primarey school its very wonderful Radio reciver i like it specialy it work without any battry or electric . it work with the wave comes from Radio stations enter to inttena and the germanium diod and coil and earth . The electric wave go out by earth and the sound wave stay and go to the cristal earphone
Brilliant detail.
Could you please tell me tube diameter for the coils?
Many thanks.
Thanks!!!
Ottimo
Very well done. Don’t forget to use high impedance headphones or high impedance ear phone. I see you have other interesting subjects. I am now subscribed.
Interesting !!
Hey I built a radio exactly like thes except I used #36 magnet wire. The broadcasts are so squeezed together but tuning is super selective so I plan to continue using this wire and on an narrower diameter coil then I will buy some germanium detector radio diodes
nice video! buddy
What is the gauge of coil's wire and nos.of turns? Can i use old rotary telephone's ear piece as a earphone?
ありがとうございます。arigatōgozaimasu.
とても わかり やすかったです。totemo wakari yasukattadesu.
thank you.
It was very easy to understand.
Though mine only gets one measly station and a cb operator , i am totally not disappointed at getting Something using bits of garbage i had laying around
What us the value of the variable air capacitor?
How to tune 150 - 500c.p.s with crystal radio sir
What is the Diamater of the carbaord tube?
what up with the cap across the headphones?
Hey I absolutely love this concept of no battery connection and I want to include it in my final project. I greatly enjoyed your video and explanation and I was hoping you could show me the schematic with the values and connections so I can make a radio just like that one. Also is the tuning capacitor 365pF? Thank you so much for you time will recommend to my friends.
Hi Anthony,
Thank you for your nice comment! If you want to build crystal radios you really should look for the book "Radios That Work For Free" by K.E. Edwards. It has this diagram and others. Yes, the tuning capacitor is 365pf.
have you got a cat in the workshop with you ? i got a crystal radio kit but i cant get it to work
I have a cristal radio set mounted on a carboard box it works just fine and i can hear radio with no electricity
Maybe I missed it but I didn't hear you mention the ground connection. It is just as important as the long antenna wire. either a water pipe or an AC socket ground prong.
The schematics may have made sense to someone a bit more savvy with electronics. I like the updated version but could not see the wiring. You are clearly knowledgeable with these type things. Was looking to build a version. But simple got complicated. May have to go back to a rusty razor blade and a stinky scranton pencil.
👏👏👍
💯💯💯💯👍👍👍👍👍💎
John,
I see by the diagram that there is a capacitor between the head phones, and also between the black
and red nobs? what are nobs for? and please tell me about the caps. Also I love the videos.
GOOD TIMES!!!
Hi Dragos 4!
The black and red "knobs" are not knobs at all but binding posts to connect headphones that don't have a plug.
Not counting the tuning capacitor, there is only one capacitor; it is connected across the head phone terminals.
I should really have put another one across the headphone jack! There are two ways to connect phones. The value is .003 microfarads. The capacitor function is to "smooth out" the RF carrier so as to make the audio envelope more intelligible to the ear phones. Thank you for your comment!
John,
Thank you for your fast reply, I would have seen it sooner, but was watching some of your other videos.
Should all crystal sets have this cap. across the head phones? Again thank you very much...
GOOD TIMES!!!
The capacitor across the earphones is optional. Your set will work without one.
sir, long time model airplane builder and just getting into these xtal sets and have a question>>>>>>>>> I see on the left you have a phone jack, then on the far right thiers a bracket with red/black knobs and assuming thier for an optional 2 wire crystal ear phone, is that correct??
Yea, Stan, you are correct. I can connect two different types of earphone leads. Be sure to get the book I recommend: " Radios That Work For Free" by K.E. Ewards .Good luck!
Tradicional.
hi may i ask for some help please . i need to make 2small coils at 5000ohm what do i need please
John, I hope I don't bother you with my ???s but I have a hallicrafters SX - 100, and would like to know
What a good set of headphones for it would be. I have a navy wwII NOS for my crystal sets,
but don't want to try them as they are 2000 OHM. Please help...
GOOD TIMES!!!
No bother at all! Go to Ebay and search for "antique headphones". Look for the "Brandes" phones. That's what I have. They will run you about $50. Just make sure the seller says "working". "73".
Being a retired aerospace radio-frequency design engineer I like your videos. Have you thought about including the formula's for calculating resonance so that tuning is not so difficult for specific frequencies?
@@2nostromo You can calculate the coil and cap values based on the frequency with a standard formula. I can't find it, but it's everywhere. They have lots of free stuff at the library.
Whoa ... we're just ordinary people out here. We're not rocket scientists.
Hey guys does this one actually work even now because I can see comments like in the 70s and 80s
@squarewave2 Hello. Not sure if you see comments and questions from past videos, but after watching this and a few other videos you have posted about crystal radios, I was wondering if you have any knowledge of the "METRO Jr." set from the 1920's. It is inscribed on the aluminum base to be from the "METRO ELECTRICAL CO. INC., NEWARK, N.J. U.S.A." It looks somewhat similar to the design of the Boy Scout Radio you depict here, but from what I can tell it has a slightly different circuit, most notably the aerial is connected directly to both the headphone and one end of the coil. I inherited the basic unit (i.e., without the box, instructions, and original headphones) from my late father, and for kicks I want to see if I can get it to work. I vaguely recall it working in the 1970's when my father demonstrated it to me, but that could be a false memory. About all I can get now is static. Hoping you might be open to an exchange about trying to get this to operate again, perhaps making it the subject of some future vide. ~Ed from Baltimore
Hi Edward,
Sorry, I don't know anything about a Metro Junior radio. If you are getting any sound at all, even static, it's a good sign; radio is probably working ok. Are there any broadcast stations in your area? Perhaps they are just too far away. Remember, you need a good, long wire antenna. Good luck.
How to build it?
Please tell
Plz make a mini helicopter step by step, I shall be very very thankful to you
One more question...every other crystal radio design I've seen requires the use of an approx. 47K resister in parallel with the earpiece. Instead, in this design, you recommend a small capacitor. Could you explain the reason for that?
I've never found the need for either using a crystal earphone or magnetic headphones. But in theory (some say practice) the AC capacitor shunts any remaining AC signal to ground. The only thing you want reaching your ear is pure, rectified DC signal. Of course an AC capacitor is invisible to DC, so there is no risk of the capacitor bleeding off your audio signal. On the resistor, it is said that a resistance is necessary to "load the detector", although this hasn't been my experience. What many builders do is include BOTH the capacitor and the resistor.... both issues solved. Probably better, experiment with different values of both. One of the best items on your workbench should be a pair of capacitance and resistance substitution boxes. You just clip them into your circuit and spin the knob through the different values to find the ones that work best.
I built a crystal radio that used a crystal piezo earpiece and got a very loud distorted signal. The 47k resistor made it sound clear. However, in most cases you don't need a resistor
CAN I MAKE A CRYSTAL EARPHONE? Yes. I saw a UA-cam where a guy did that. He used a piezo buzzer from a microwave oven. For the earpiece, he hot-glued on a piece of a Bic pen barrel. You can buy piezo elements from All Electronics or Electronics Goldmine. If you can’t solder, buy a piezo element with leads.
Be prepared! three fingers!
You are missed, sur. I hope you make more videos, in the future.
Others have made some videos on the topic. Even I made a couple.
I think I might make another.
eBay has them to.
why diode its inverted ?
Many designs like this appear to call for a .001 cap across the phones for filtering. I noticed you used a 332K /.0033 cap, any special benefit of this. Wonderful video, Thanks Denny
Hi Denny,
I've used different values across the phones with no difference I can hear. In fact, I usually omit this part completely.
Thanks for your comment!
I mostly use magnetic headphones -Alnico, ACME, Cannon, Dictograph, Newcomb, I don't ever use a capacitor across the phones
Aliexpress Cyrstal Radio used 222 (2200 pF= 2.2 nF = 2n2 ), 2.2 nF =0.0022 uF
this project used 332 ( 3300 pF =3.3 nF =3n3 ) 3.3 nF = 0.0033 uF and K means -%10 tolarance ...
Please excuse my ignorance as I am new to this as a retirement hobby. I have built the simple Boy scout radio that you have demonstrated it works! I then moved on to the improved version. I wound my own coil quite nicely and think that I have put it all together correctly by looking at your video and stopping it to get a better look. I cant get it to work so I have screwed up somewhere. However, I cant quite see where both tags go from the larger coil, one goes to diode phones and ground but I cant see where the other fits. I would be grateful for some advice please. I have tried enlarging the picture but still cant see it.
Hi mvv650mvv,
The primary coil, the big one, is connected to the circuit between the slider and the diode. The wire from the left end of the primary coil is not connected to anything which my diagram shows. Hope this helps.
@@squarewave2 super. Thanks for this. I was looking for something that didn't exist. That's life!
If I use 20awg wire for both coils will it make a difference?
It should still work.
WHY USE A 47K “LOAD RESISTOR” ACROSS THE CRYSTAL EARPHONE? To provide a DC return path for the signal, allowing current flow. (The crystal phone acts like a capacitor, which blocks DC current.)
Amazon has a couple of those books for $149, Abe Books has one for almost $300. Collector item. Kindle version is $10.
Upvotes for off-screen Radio Cat!
Question re wire wrapped tube. There has been some question about using toilet paper cardboard center rolls as the platform to wrap the wire however I have questions regarding its durability and the fact that it could crinkle in a moisture environment. I have opted for PVC piping so my question is schedule 20 is not as strong as schedule 40 but it's definitely strong enough to support the wire and endure climate challenges. So my question is should I use the schedule 20 instead of the 40 because it's thinner and therefore will pick up more signal or does it not matter? Is the signal is coming from the outside or the inside of the tube where the wire is wrapped? I appreciate your help on this. I was even going to use the plumbing 'P' trap replacement pipe which is even slightly thinner than the schedule 20 if the tube thickness matters.
The best tube is a 1 1/2 inch diameter MAILING TUBE. It's easier to dill hols in than PVC pipe. The "signal"
is coming from the antenna to the antenna coupler coil and then to the tuning coil by induction.
Don't even think of toilet paper tubes!!
Thanks for the quick reply. I am waiting on the crystal earphones (ordered online) to see if my setup is functioning. If so I plan to rebuild one that merits respect. The goal is to have some form of long term form of news in the event of a disaster.
Thanks for the help. TP tubes get recycled.
Approximately,
on 20 mm diameter PVC tube 0.2 mm wire ( 32 AWG )
That project at least on 40 mm ( 1.56 inch ) diameter paper tube winding 0.4 mm wire ( 26 AWG ) at most 0.8 mm wire
on 50 mm diameter PVC tube 0.5 mm wire ( 24 AWG )
Dear Sir can we add variable capacitor made with aluminium foil, thanking you in advance. also please explain how to connect antenna coupllar coil
foil capacitor, yes that has been done and works. Using card stock paper and foil. The antenna coupler connects one end to ground and the other to the antenna. Then it will magnetically couple to the main tuning coil through the air.
I’m trying to build this version but can’t tell where all the wires coming off the coils go to can u please describe where the tuning coil wires and the antenna coil wires go thanks
Hi Corey,
One end of the smaller coil (the antenna coupler) is connected to ground and the other end to the antenna.
One end of the larger tuning coil is connected to the rotor plates of the tuning capacitor and the other end is not connected to anything. The sliding tap is connected to the stator plates of the tuning capacitor and to ground. I hope this helps. Good luck!
Thank u so much I appreciate you sharing your knowledge with others,, have a good day sir
squarewave2 sorry to bother you again but one more question.. the germanium diode goes from the variable capacitor and antenna wire to the tie point and then straight to the ear phone hook up ? Sorry I can’t see well and I’m having a hard time identifying the wiring
Looking down view on this setup.. where does the left end of the main coil go?
The left end of the coil is NOT CONNECTED to anything
@@squarewave2 gotcha.. ty for responding 👍
antenna 300 mmps / 1 mhz = 300 meters for a full wave 75 meters for a quarter wave the stations use 75 meter towers for their antenna on a counter poise so your antenna should be vertical 75 meters so you raise your coil off the board with metal standoffs
Thanks. from n5qdm. A long wire, 100-200 feet of wire at least thirty feet high and a good ground rod connection.
Your bench is very "neet". I think it is time to clean mine up and chunk the junk.
i live in wa state and picked up an AM station in san fran over 1k miles away
Best AM crystal radio: 25 turn primary (antenna coil) on a section of aprox 3 inch diameter pvc pipe....120 turn secondary (start winding right behind first coil)....another 25 turns in center of secondary. Wrap a strip of paper over secondary before winding third coil. Use 24 AWG magnet wire. Connect 365pf air variable capacitor across 120 turn coil. Connect germanium diode and high impedance crystal earphone/headphones to 25 turn coil wrapped over the 120 turn coil. Telephone speakers work well too. Connect antenna/ground to first 25 turn coil.
Antenna can be any type of small insulated wire at least 100 feet long as high off the ground as you can get it. 250 feet long is even better. A fishing rod can be used to get antenna wire up in a tree. Tie a lead weight to fishing line and throw it over the tree top. Tie fishing line to antenna wire and pull it up then tie fishing line to base of tree. Or you can string out the antenna wire between trees....just get it high enough that nobody will walk into it and rip it down.
You can use a counter poise antenna as a ground....just attach another length of insulated wire to primary coil instead of a ground wire and string it out through the bushes or trees in the opposite direction. Get it up high enough that nobody gets tangled in it.
This is a very sensitive and selective crystal set.
PS: PVC pipe diameter isn`t critical. You can use 2 3/4 inch pipe or 3 1/2 inch pipe with almost same results and tuning range....520khz to about 1600khz. You can buy 500 ft spools of cheap insulated wire off Amazon.
TIP: Use super glue to hold windings in place as you wind coils. This way you can rest some and not have to do it all at once. Hot glue works well too. Be creative.
WHY DO SOME PEOPLE FEEL THAT THE CAPACITOR HAS NO EFFECT? These folks are using a crystal headphone, which is itself a capacitor.
if this antenna can be a transceiver, if you can make such an antenna, the transmitter wants to be interested in the detector-locator range
sir, just built a boyscout radio and wondering if a 100 ft of coated speaker wire will work plez reply asap thanx
Yes, Stan, 100 feet of any wire insulated or not will work fine. Good luch with your project and remember to ground the set to a cold water pipe.
if you made a coil with 120 turns of 32 gauge wire, how many turns should the smaller coil be?
I want to know from the viewers. In my childhood days (that is 70 years hence when i was a lad of 10 or so!), my elder brother made a crystal radio. I remember that has a receiver of the phone (bought from some shop, called second hand market), and had a crystal (galena material), of course there was a coil, which I cannot rememeber at such age, I am now 80). Can anybody enlighten me about it? How was it made? I want to make it in his memory (he passed away few years back, had he been alive I would have known the mechanism of it). Few words more: we could losten to the local Calcutta station so distinctly which I cannot believe. He was a miracle man to me. It had an antenna, may be 20 to 30 yards, which was hung on the rooftop. My mother beiieved that it was some illegal activity and police can arrest us, so he had to give it up.
100 ft? so the antenna length formula dosent apply to this like 234 or 468/fq mhz
Long wire, random length antennae are not tuned to a specific radio band like a dipole antenna. You can pretty much receive any radio signals with the long wire.
Is the diameter of the coil of importance to the result?
As long as the coil is between 2 and 3 inches it will still work.
Hi!
Thanks for sharing this!
-How thick wire sould i use when making this?
-How thick should the coils "paper" be?
(you show us the coil's "paper" 3:20 - 4:20)
-Which diode can i use? -any germanium?
-How long antenna should i have?
-The variable capacitor -how many pF?
-The other capacitor -kind of? (cheramic / polyester, etc.) -how many pF / nF?
Which one is the best? -this one or ua-cam.com/video/AaNpFYe5dSo/v-deo.html ?
Thanks!
Can you include parts list