Three months ago I was travelling to my annual vacation across the south of England between 1am and 6am (heading to the Scilly Islands if anybody is interested). It involved travelling through very rural areas and I basically lost all of my digital radio reception in the car and very little on FM. Out of complete boredom and also trying to stay awake I started fiddling with AM, and the only station I could hear that didn't drift in and out was a Spanish radio station operating out of Madrid, about 1200 miles away (can't recall the exact station). My Spanish isn't very good, but I could follow the conversation and it just about kept me awake during the dark hours on the road.
At age 14 or 15 I built a broadcast band crystal radio with galena/ cats whisker detector, I later substituted a germanium diode, and a Quaker oats box for the coil. Great memories here.🎙73's kd9oam
I built a number of crystal sets as a child in the 1970s. They were usually from Radio Shack and started as low as $2.95. They seemed magic because they did not need batteries. But with experimentation, I noticed that only glass diodes worked. Black rectifier diodes did not work. Also, the earphone had to be of the super-sensitive piezo variety. Oh, the mysteries! Later I studied electronics and began to understand some of them. 73 de AB2ES.
Amazing move. I thank for reminder. I learnt radio - engineers 60 years ago. I constructed to sciences such just radio receiver sets on crystal. I greet all HAM's, de SP2EEF and 73 from Poland.
Amazing results from a basic effort technically. But you covered lessons useful across radio. I used to teach, as part of a radio systems engineering course, a quick history of receivers starting with crystal sets. Moved to TRF and regens and then full suprhets and FM. Showed how each built on former. And that there are still bits of old time "DNA" in all but modern SD radios. And why we have desense, spurs, image, mixing QRM and so on. EE students had usually little to no training along this line. There is a place, and an important one, in your experiments and lessons today as well. Especially when EMP hangs over our heads like the Sword of Damocles! Best 73 Karl WA2KBZ
Thanks for making this Mike. The challenge of making a crystal set for the amateur bands is really attractive. I accept the limitations but has to be worth a try!
Mike Oh Mike where shall i start. I find my self going back to watch your videos at random and i would never have thought in a million years i would ever be interested in building a Crystal Set in-spite of its fascinating phenomenon, yet here I am commenting right before hitting it at my bench and digging in "THE Junk Box" to build this beautiful Gem you showed. Again as usual a wonderful visual article. Plz accept my belated interest in Crystal Sets. 73s from Amman JY
Interesting stuff... I should try making one just for kicks. I remember in the late 70s my dad took some little clock radio and added a bunch of coiled wire to the antenna and then we were getting stations from Germany, BBC, etc. That was pretty cool, will never forget that.
Wow! Great video and brings back good memories from the early '60s. I was 12 years old and making crystal sets to swap for anything a kid would want, stamp albums, marbles, etc. Then I made a short wave set, no amplifier just a crystal ear piece. I had a long wire antenna (didn't learn about di-pole or fan for many years) and late at night I could pick up several VOA and BBC stations (I was in Australia so I'm guessing the stations were close) as well as HCJB in Ecuador, FEBC in the Philippines and Radio Peking as it was known back in those days. I do know I had two coils on the breadboard, a salvaged variable capacitor for tuning and a glass crystal diode, other than that I don't recall much detail. I never traded the short wave set because it was so good.
My crystal set I made picked up broadcast band and short wave band. It was my penny radio. A dark penny works better than shiney pennies. my long wire antenna was connected but still picked up short wave. My coil had lots of turns about 4 inches on a 4 inch PVC pipe.. I had no tuning capacitor . You tuned by moving the wire across the penny. Like the fox hole radio. I made the fox hole radio when I was in the seventh grade and used a fat capacitor across the razor blade. I picked up weak station KQV and of course KDKA in Pittsburgh, back to the penny radio . There are exceptions to the rule. A long wire antenna will pick up SW if I remember right I had two stations at once. Frequencies apart . Of course the short wave band is dead now all the foreign stations are gone. I may still build the penny radio again I may be able to pick up a local or two. Probably Cuban radio that's all that's on now in Florida. I remember picking them up when I still lived in Pennsylvania on my Atwater Kent radio. I sure miss that radio I could pick up both WWV and WWVH at the same time on short wave. Usually on 15 Mhz. 73
Crystal radio, a receiver that works without batteries! I prefer to use marked dials that can be tuned easily, epecially National Velvet Venier dials that are so very accurate. Other Knightkit dials are almost as accurate, but elimintion of dial "backlash" is so very important. Thanks for your videos!
Playing with an MK484 radio chip a few years ago, I got strong reception in the 7 MHz range, which is quite above it's range. Figuring that the MK484 was acting as a regenerative receiver, I tuned another receiver to 7 MHz and got a signal from my MK484. When I tapped on the tuning capacitor, I heard the sound on the other SW receiver. It crossed my mind that two MK484 circuits near each other might be able to transmit and receive at the same time. I plan to play with this idea in the near future.
When I was a kid I built my own crystal sets. Once I tapped on the piezoelectric earphone of one of my crystal radios and heard the tapping on a nearby AM superhet receiver! The crystal set was connected to an external antenna. I want to try to recreate this experiment. Another event, in more recent years, was that I was playing with a toy with an electronic sound generating chip inside. With its preprogrammed sounds playing, I placed this toy near an AM radio. The sound could be clearly heard on the AM radio! The toy was somehow generating an AM signal. The whole idea of low power RF experimentation is intriguing me. Crystal sets are the epitome of that.
As a little kid I was fascinated with my dad's old Grunau Teledial that picked up a lot of SW in the 40's, must have had a decent "aerial" and ground. I fiddled with crystal sets, mini tube and transistor AM and radio control circuits as an adolescent into adulthood. Never absorbed much theory but learned soldering and electronic assembly, eventually got a starting job in electronics assembly, and later became an aerospace electronics assembly/soldering instructor later moving into contracts/administrative work.
Soldering correctly for aerospace is a serious situation and those who do it have to be constantly checked and trained on the latest methods and standards.
Came back again to get more pointers. I am working on a crystal radio series and your info has really helped once again. I will reference your channel in my video and hope to send some viewers your way. Thanks as always.
I had forgotten that I wired up a SW crystal with open air spacing many years ago and it worked great. Thanks for this vid as I will now go and rebuild what I had.
Thanks for being our Elmer,you have tought me so much.you sparked my interest in Ham radio.I studied and now am a General class Ham on my way to Extra class,also practicing cw in Hope's of going on straight key night as you showed us what fun it is.Radio is no doubt your passion in life and I see you really enjoy it.
Dear Gentleman, surfing the web I discovered your channel, I saw your video and I found very interesting, you are very didactic, very professional working, thank you very much for giving us your time and knowledge, greetings from Henry of USA.
Great video! I learned more in this video about the components of a crystal radio and how they work than any other video, hands down. Thank you for sharing. Thumbs up.
My dad, W5EWF ( sk but i have his call), retired Signal Corps, made am incredible crystal set. Pancake coils matching taps, pre and main tuning andan s meter. It had a volume xtrl on the meter! In Chicago suburbs it was needed. As i fine tuned it kept pinning. On my Baldwins room filling volume ( small room though) and very selective. These are amazing sets. Thanks for your neat vids. 73 Karl WA2KBZ & W5EWF ( Hondo Johnny, RI
Ein besonderes Dankeschön für diesen Filmbeitrag. Dieser Film gehört ebenfalls zu den empfehelenswerten Beiträgen in den Physikunterricht von Bildungseinrichtungen. Mit wenig finanziellen Mitteln ist ein Kurz-Mittel-Langwellenempfänger betriebsbereit aufgebaut.
I like the tilting antenna coil coupler and the tuned dipole idea on your crystal set. Your setup looks very similar to my CB radio crystal set video I made years ago. I did use my regular Homemade ground plane CB antenna I normally use for my Galaxy DX 959 when shooting skip. put a PL259 connector on my xtal set plugged the CB antenna in and worked real well. I may try making a bigger dipole for my other (nicknamed ) HAARP Detector SW set very similar in design to the CB crystal set.
Wow, this is really cool. That seems totally usable. In this era of SDR, I find the simplicity and elegance of minimalist radio to be magical, especially when you consider It works without the amp and external power. In grade school my friend had a RadioShack 101 kit and hooked up the crystal radio project to a wire out the window to a tree and to a radiator for ground - "there's no batteries???" - amazing, and it still works. At least hams will keep broadcasting.
Stainless tig welding wire makes great coils. Never had much luck using tube detectors at these frequencies. Found a nice diode from a science fair electronic kit...
I remember when the Bell Labs people were flooding the schools with little kits of early transistors and diodes, seeding the next generation of engineers. I was given an early solar cell in Physics class.
A few points from my days of doing this: 1) The ends of the coils that face each other should be the ground ends. 2) It can be simpler to slide the antenna side coil away along a track than to rotate it away. 3) A small capacitance across the input side of the audio transformer can help. F=1/(2*PI*sqrt(L*C)) = 10KHz The windings of transformer tend to be a lossy capacitor. 4) A capacitor in the feed to the RF transformer primary can help but you need to keep it well away from your circuit ground. 5) Don't forget the "drip loop" on the coax. Before it enters the house take the coax lower than the actual entry so rain water runs off instead of through the wall. 6) In some houses a dipole inside the roof works fine.
Good tips! 1. Ground to ground or cold to cold is even more important in regenerative receivers where the hot side can pull the set off frequency as the coupling is changed.
@@MIKROWAVE1 Yes, if your topology is one where the inductive feedback is from a point with a large amplitude the capacitance can be a big issue. That is a long way out from crystal stuff.
Oh, there was an early times detector before germanium overshadowed it, called the zinc oxide crytal. It had odd features and seemed to self oscillate giving a slight gain. Finicky but i suspect that it was acting like a tunnel diode or even a transistor. It was dropped as impractical. We could have had transistors long before had this been fully understood and pursued. A good topic for a video/ experiment perhaps. 73
I’ve never built a crystal set before and I’m now wondering why I never did it earlier. They’re great fun and quite a good learning tool. As I’m doing my full licence at the moment I feel that the importance of doing crystal radio earlier wasn’t stressed but probably should have been! Excellent video BTW, I learned loads!!
Great Video here :) I sometimes build regens ! My last was a NA5N PIPSQUEAK It is a real shame there is not more on shortwave When I was a young kid I accidentally built a crystal set that would pick up shortwave ! I was truly experimenting :) You can only truly experiment When you really have no understanding of how to get where you want to be :) I just got lucky with the LC and likely had really good conditions ! I do not experiment anymore ! I have learned enough to understand what I would really need to do if I were capable :) Knowledge does at times take the fun out of things ! Nothing compares to ignorant Bliss when things work 73
Wow, what a great video! You went into a lot of detail and your diagrams were fantastic. One thing though, I was hoping you would have talked more about your Faraday shield and how it reacts with it in the circuit - and without it. Perhaps you can go into more depth in your next video. Keep up the great work, I always look forward to your videos.
excellent work, crystal radio receiving short waves. I'm from Brazil, I have a radio from galena to band of 520 khs to 1700 khz made by me sorry that we do not have more broadcasts in om operating here in my region Thanks for the video
Very informative and inspiring work, thank you for posting it. To expand on the text overlay seen at 6:54, performance can be improved by making the bypass capacitor C2 no greater than 1000 picofarads (pF) and connecting it as directly as possible between the anode of D1 and the rotor terminal of C1. This maximizes radio frequency current through the diode, D1, and increases the audio frequency load impedance. A ceramic or mica dielectric capacitor (as shown in the assembly) is preferable because these types usually have less inductance. The reactance of C2 at .01 microfarads (uF) as shown in the schematic diagram will be only around 7961 ohms at 2 kilohertz (kHz) and 3981 ohms at 4 kHz, attenuating the audio signal and defeating the purpose of using high impedance headphones, transformer, or a high input impedance amplifier. The .006 uF used on the breadboard gives reactance of 6635 ohms at 4 kHz, still quite low. Making C2 1000 pF would give a reactance of just under 40000 ohms at 4 kHz. Since this set doesn't tune to less than around 5 megahertz, it is arguable that a bypass capacitance of 50 pF would be sufficient. Additionally, the input resistance of the LM386 is 50 k ohms, not particularly high. It combines with the reactance of C2 and the 10 k ohm attenuator shown. The net audio load impedance at 4 kHz with the .006 for C2 and the 10 k on the LM386 input set for no attenuation is 3694 ohms (ignoring j).
Nice job. i remember long time ago when 16 i built an short wave cristal set with audio bc 187 transistor for af power. i heard Radio Netherlands in the transmissions directed to Mexico. TKS 73 XE2EJ
Very good Performance,best Whish Matthias.The Last Years I finished my Job in Selfmade AMCoil Windung with Hands.🇩🇪ist Aline in AM,Not ready Stations,Radio ist Death in AM.
Herzlichen Glückwunsch zum Gewinn einiger schöner AM-Band-Induktoren. Ja, die AM-Stationen überleben, sind aber in einigen Gebieten der Welt weniger zahlreich.
A crystal out of an old microwave works fine for an ear piece. I did glue a piece of 5/8 pvc pipe on to the crystal, so I can hear the soundwaves better. I also taped a small piece of ferrite on a bamboo stick, and slide it up and down in the pvc pipe with the magnet wire coils around it, when I find a station. It does emplify the sound.
Regenerative Receiver construction and improvements become quite addictive! Parts 1 to 3 are done. Now that it is working, I want to try some alternate tubes and even pull the tubes and stick in FETs and see what happens.
Very well made, most of RF Enhancements, limitations, building techniques allmost fully and nicely covered in this video, Shortwave reception technique is beyond doubt fantastic i feel. Would like in future if the SW broadcast bands are individually spreadout technique is shown, 13M to 12M.
594:8 Like ratio.. Fantastic! Go out and look at a TenTec Rig going for $5000 and up - then we see what is really happening on the bands and how easily it CAN be extracted from the ether - using the most basic of materials and methods. You're giving everyone a chance to expand their minds w/o drugs to feel what Guglielmo Marconi and Tesla and Hiram Percy experienced for pennies on the dollar.. making learning FUN again! - 73 OM! More power to ya! -
Ist time I have ever subscribed to a youtube channel. In lock down due to corona virus scare. Wicked good source for time killing projects and it never hurts to learn a thing or two by watching and then doing. Live Free or Die!
That's pretty impressive! I've built a few crystal sets, when I was a teen in the '60s, but never thought that shortwave was possible. Probably wasn't, with the crude techniques I was using then. But it gave me a start. I became a ham and have been licensed over 50 years now, and retired as an electrical engineer.
I started out in the early 60’s also. I built a few crystal sets and then amplified them with early transistors. I didn’t get real serious with them, but by experimenting with coils, I was able the get the shortwave bands. I was licensed at age 14 in about 1964. I’m 71 now and still hold a license, but I’m not very active now. Plan to get back to it. One item of interest, I used a crystal radio, actually an untuned RF detector with tiny speaker (self powered) as my CW monitor. WB0ETN
@@kensmith5694 I have built such a difference discriminator with two resonance circuits. It is very difficult to tune it well and to avoid the 50/60 Hz from environment. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-QDlCOB80kVE.html
@@JohnSmith-eo5sp Yes, "toning" was a typo. The "ratio detector" circuit works somewhat as a crystal radio but as typically designed, the focus is on making it very linear not making it loud. Basically, it is the classic double tuned crystal radio design as a starting point. A tap on the primary side drives the center tap on the secondary. When you are exactly on the station, the primary voltage is exactly at 90 degrees to the secondary voltage. From the point of view of the two ends of the secondary, the phase is leading on one and lagging on the other. This makes the two diodes make the same output so they cancel. As you go either side the phase changes from 90 making one side bigger than the other. Effectively this is the two tuned circuit idea with fewer parts.
Sir, Thank you for the educative video. I enjoyed it very much. I will be assembling one, similar to yours using OA71, OA79 Germanium Diodes. I live in a rural area, therefore I can have better Dipole antennas for better reception on 25, 31,41 and 49 Meter Bands. Instead of wood, I will go for Phenolic Fibre board and 500pF variable capacitor. I am fascinated at the Faraday's Shield, which you made. I'll be making the similar shield with tuned coil setup. The idea of LM386 1Watt amp was a good thinking. I may use ECC81 or ECC82 or ECC83 double triodes instead along with high impedence Head phones. Thanks for inspiring me as much as it may have inspired many dX enthusiasts. I have Grundig 6000 Satellite receiver with external BFO unit. FYI I received a Radio Taxi Xmission from Philippnes. That's all for now thanks much, once again. Cheers.
Very nice! But in my naivete, I have used my 120' long wire antenna and my crystal receiver, which work great for AM radio, and simply put in a much smaller coil to try to hear 3 to 20 MHz. It has worked great! The AM signals have not come in at all. I also don't have a Faraday screen, but it seems to work just like the AM radio with the larger coil. I do, however, use a guitar amp as my audio output, since the stations tend to be an average of a couple of thousands miles away... I did make a center-fed dipole antenna in my attic, sized for about 9 MHz, and it is good but surprisingly not hugely better than the long wire!
Congratulations! Not everyone has a clean and well balanced radio environment. It only takes a couple of strong stations to desense or bleed in and dominate reception for many.
I used to build crystal sets with just a coil and a 1n914 germanium. Then i expoxed these in a bottle cap and used transistor jacks for my 3 wires which lead to the transistor amp box. Thought i was going sell these or something. No tuner. Just a 50k watt kmpc station.
You make the best technical/detailed/relaxing videos. Thankyou for your efforts! I am curious as to the effects of the faraday shield, operation with and without the shield?
I still have a KB ....Kolster and Brandt 2000 ohm speaker I aquired in the 50's and a set of high impedance headphones (cans), both still going strong...difficult to source a 300 or 500 pf variable cap though nowadays...happy listening............
i THINK THE PERFORMANCE WAS GREAT. FOR THIS SIMPLE RADIO. SW GETS BETTER LATE AT NIGHT AND SOME NIGHTS ARE BETTER THAN OTHERS. SURE THE SOLAR MINIMUM IS AGAINST US BUT SW IS STILL THERE. VERY NICE VIDEO. GOT ANY SCHEMATICS FOR AN EASY BFO WE CAN USE ON OUR CRYSTAL SET AND TELL US WHERE TO GET EXOTIC PARTS IF POSSIBLE FOR BFO. .THANK YOU!
When I was a kid, I built a crystal radio using a loopstick antenna rather than a huge coil and wiper. I lived 5 miles from the hill where most of the AM and TV broadcast towers were. Instead of a crystal earphone, I installed a 2K to 8 ohm audio transformer and speaker out of a pocket radio. I had to install a volume control to cut distortion and keep the volume to a comfortable level. It didn't really need a wire antenna but it did require a ground though. I used to play mostly with CB and the outbands, (frown if you must). I've worked in a shop repairing them and I used to repair them for our local crime watch when I lived in Florida. I have 100 CB's in my collection that I have chopped and channeled from crystal to pll although they're collecting dust now as age and disability has taken me over. I told you that to ask this. Have you ever tried a ground reflection antenna? Personally, I'd never heard of it nor have I seen anything mentioned about it in the ARRL antenna handbook or other publications so I call it this because this basically what it is. In my days of experimentation, I had an old Radio Shack 5 watt 40 channel walkie talkie that I bought in some yard sale for $5.00. I peaked it up to a true 5 watts and eliminated the two AA dummy cells in the battery case. It had an RCA jack in the side for an external antenna. I used it mainly for long wire antenna experiments because it was convenient, light, self contained, cheap and no big loss if I burned it up. One day, I was out in the yard with my SWR / WATT meter, some coax, some wire and a long screwdriver as a ground stake. I know that vertical dipoles have a mirror image in the ground so I began to wonder what if I connected my coax shield to a quarter wave piece of wire and strung it horizontal along my wooden basket weave fence and connected the coax center conductor to the screwdriver staked into the ground. I tried it and got a 1.4:1 match. The receive was very quiet as horizontal antennas tend to be on a band of mostly verticals. I got a contact from a guy 10 miles away talking skip on a horizontal beam. I was literally in the middle of a mobile home park full of aluminum clad homes. (This was 1976) I couldn't convince him that I was talking to him on a 5 watt walkie talkie using 103 inches of wire as my ground spaced 8 inches off the ground and using the earth on my hot lead. I credit the gain of his beam more than my "antenna" setup for the connection though. I offered to meet him somewhere and take him to my back yard and show him my setup but he thought that I was going to lead him on a wild bunny hunt so he wouldn't come. Anyway, it's something to think about.
Yes some wild hookups. I had a setup on my Columbia 3 Speed with a tire generator power supply. I would go riding away and my buddy would monitor my transmissions to estimate range. CBs are fun and my most annoying trick was to learn CW on Channel 14. Yes imagine two kids sending morse code endlessly. The local CBers just loved that. Ha. In college I converted a CB to 10 meters. That was too easy. Instead I did one up for 15 Meters SSB. That was at the peak of the solar cycle in the early 80's. I also played with the tube type units which sometimes had 3 channels and a buzzing vibrator power supply on 12V. Antenna like you describe are Magic - who knows what you were lighting up?
