I have never seen so much love and care in explaining a concept that can be perfectly replicated by someone who is not into ham radio but can start something with this sort of circuits, thank you ! I have just downloaded the video just in case it gets deleted by your nephews one day
I worked for 25 years as an electrical engineering consultant after working for ten years for various companies. I ruined a perfectly good hobby by turning it into a business. I have enjoyed your videos and others and it has reawakened my interest in electronics as a hobby. Thanks. I have some ideas that I'm going to try and will report on in your comments.
Do you understand WHAT the appeal is in using a crystal radio receiver with a crystal earpeice ? SIMPLICITY : radio reception without using using electricity , power supply, batteries or amplifiers .
This video is a terrific explanation and demonstration of how to add a TRF stage to a crystal set. One question, though... At time 22:00, you say to first tune the TRF stage to the station you want to listen to, and _then_ tune the crystal stage. Is that correct? Are both tuned stages equally selective? If they are both quite selective, I can foresee a situation where _no_ signal gets through, because the two tuned circuits are set to very different parts of the band. Perhaps that is what gave those old TRF radios a reputation for being finicky and hard to tune? You would need to have marked dials/scales on each variable capacitor, so that you at least get both tuned circuits _close_ to each other, and then fine-tune while listening to the received station. p.s. At 16:49, you show a copy of "Design of Modern Transistor Circuits", by Maurice Yunick. In the mid 1970's that was the textbook used in the electronics design course at the University of Manitoba, Faculty of Electrical Engineering. That course was taught by Professor Yunick himself, and I still have my copy of that textbook (signed by the author).
A very good presentation. In the past, I've heard so much about large wire, large diameter coils. (Thin wall 1 1/4" and 1 1/2" pvc sink drain material is good for small diameter coils.) I've made many coils of 3,4,6,8 and 12" diameter. Wound with 14 to 24 gauge solid and stranded wire. Fine-stranded speaker wire is nice. I'm not trying to upstage you with these details. Only letting you know what I've tried. Your knowledge is well beyond mine.) Recently I built several variometer and variocoupler coils which were fun. At any rate, your smaller diameter coils and wire seem to perform better than most of the ones I have built. I may have wasted a lot of money on the bigger/better ideas. As you mentioned, keep it simple. Did you ever experiment with large coils? Thanks for any thoughts! John in Bay City, Mi.
I don't understand what the function of the spark coil in radio reception is. I've already built several Galena radios and I also know the spark coil but I didn't know about its use.
These videos are great and so informative, many thanks!! I think your mix of theory and demonstration are perfect for my needs. Backfilling the basics of radio receivers is really helping my amateur radio education. Cheers, 2E0DAV.
Cool, back in 1970, I joined the US Army, and after a whirl wind training session, I found myself in Vietnam. I was assigned to an Engineer outfit, and since we were a major headquarters, we had to have a lot of field phones, thus a rather large switchboard. I became a switchboard operator, of course we were not allowed to have any distractions in the SB room, but at night, when the board was fairly quiet, we found that we could jack into the line that lead across the CamRahn Bay from Dong Ba Thin, where our HQ was located to CamRahn Bay where the major switching central was to get around the country. If nobody was on the line, the board and headset acted as a sort of radio receiver, and we could listen to the only radio station available, the Armed Forces Radio and Televison Network. They played a lot of current rock and roll, so we could spend the 4 hour shift listening to tunes (they found that over 4 hours at a time on the board lead to some really nasty reaction in some soldiers because of the constant pressure of a busy double SB86 SB with extra stacks of receiver towers.) We worked 4 hours on and 8 hours off constant rotation.
I’ve must’ve watch 70+ Crystal radio videos this was the best demonstration with the clearest loudest sound that actually made me interested. I’ve seen very simple ones and very elaborate but the radio signal and sound quality we’re never that good as the one you just demonstrated. I believe I just found my first crystal radio set to build thank you very much keep up the videos I’ve just subscribed to your channel. 👍👍👍
I used to borrow Morgans' book from the library and wanted to build that radio. As a kid of 10 I never had enough money to buy all the parts. 60 years later it's terrific to see it for real instead of just the drawings in a book. Is there a video where you demo it.
Hola..hello..this radio is SW..??. Homemade radio SW??! ( web, project..!!).si alguien sabe dónde puedo encontrar planos de proyectos de radio SW, me pasarían los Links gracias.
Great video. Thanks for doing all the projects for us. BTW a neat trick for soldering enameled magnet wire is to put an aspirin tablet on a piece of wood under the wire and then push the soldering tip against it. I saw this in an old magazine somewhere and tried it. It works like a champ, but the fumes are horrible.
Very nice, simple project. Thanks for uploading this. I am looking forward to seeing how much difference there will be in the reception of crystal sets that I make now I live out in the country and I can put up a high wire antenna without worrying about complaints from neighbours, - I don't have any now!.
Another great video, with the promise of more to come. I'm sure it won't be long before comments and links start showing up on the Radioboard. Thanks, Karl
Awesome video, do you mind telling me what the outside diameter is of those tubes you used for the inductor coils? I tried making mine this morning with some 1.5 inch PVC that has an OD of 1 and 5/8 in. I didn't count my turns, I was doing it hastily LOL but my antenna is a couple 100ft long but most of it's laying on the ground when I get home I'm going to work on trying to raise it up at least a couple feet. It was hard to tell if I heard something I could have sworn I heard ever so faintly a station I got to mess with it some more.
Hello sir, can you help me with a pocketradio. I want to remove the mute moment between the sweeping through radio channels? I hope you can help me? Thanks
My transistor TRF is working like a champ finally, with one annoying problem yet. I just can't seem to get a set of coils that will really bring in the lower end of the band. I struggle to get anything much below 800-900khz. Some nights slightly better than others but not by much. Any ideas ??
The German military used TRF receivers in WW2 . They were very effective partly because of their robust construction. Take a look at www.nonstopsystems.com/radio/pdf-hell/article-hell-24.pdf for some details
I think the idea of a crystal radio set is not needing a power source. We could be without power for weeks and possibly months, after a hurricane comes through. A crystal radio set would at least pick up stations. As for the video thanks for the enlightenment in the electronics field. I always played with electricity when a was a small child and later into electronics. It's good to know I still learning old technology like it was new. Thanks again big 73!
I have an idea, maybe its possible to pick the best germanium multiband crystal radio design, and add a separate regenerative transistor powered circuit coupled inductively to the coil? One that is powered by an untuned separate antenna or coil that rectifies and provides current to the feedback circuitry transistors? No batteries needed?
Hi Verynice video i like how historical it looks on those wooden boards dont stop. I made better Crystal rx since last time. It Is for LW band ( longwave ) 150-288kHz i would send you a schematic but i know you dont have LW band in US And it Is schematic which i never seen anywhere on internet.
sweet.....can one be done w/out any batteries, or transistors/tubes? just curious...good AM radio antenna cut to freq. would be large, but should be more volume with the longer antenna....excellent video, and looking forward to part deux….
@@Radioman.These days people say "HFE" instead of "Beta" but yes you got it right for the frequencies you are working at. Really there is "Re" and also "re". The little "re" in inherent in the silicon transistor and can be said to have 25mV on it at whatever the emitter current is. There are other effects that make the input impedance smaller in extreme cases. To a tuned circuit, the transistor's capacitances only change the frequency a bit but the fact that those capacitances are not good capacitors adds an extra loss.
I'd say you gave me the secret to making my super passive radio work much better. I've always thought there should be a way to make a passive amplifier. And apparently this is it. I will have to add this circuit to my version of the lyonodyne Crystal Radio by Mike Tuggle. Of course as I'm into having a completely passive radio, I won't be using an amplified speaker. But with this circuit added and the sound powered transducer elements that I have for headphones, this should really be quite something. And I still get to keep my passive criteria on the radio in tact. Maybe this is why as a brand new ham I seem to be enjoying QRP. I really look forward to knowing CW well enough to be able to communicate. With a 1 watt or less radio it will be interesting to see what I can do. to see just how much I can do. Unfortunately, it's looking like it may take me quite a while to get CW down well enough to effectively communicate with it. I never thought it would be easy, but it may be harder than I thought it would be.
You'll never learn any new language without total immersion and/or many hours spent studying and practicing. CW is just the same--and as you've figured out, it's the best way to maximize QRP success. I'm relearning code myself, but not for the tests this time, for the airwaves. I haven't built a crystal set-yet. Catch you out there, 73 de W1ADE
@MIKROWAVE1 Can you show or do you have a video of the antenna? I have HOA restrictions and would like to know if I can run an antenna in a low profile way and achieve similar results as shown in this video.
I used a TRF in my Novice ham days. I found an RME DB-22A. Worked wonders in front of my cheap general coverage solid state receiver (Lafayette HA-600). Love your videos! 73 de WB2SMK
16:00 To maintain the spirit of this hobby, the TRF should be made with only pre-1960's technology and parts. No microchips(IC's), and preferably vacuum tube tech! To use 'modern electronics' is to render the endeavor as unauthentic
Yes as a purist, historian, collector or preservationist, I would agree. But I was learning electronics in a very strange time period of the early 1970's where I still had tube design and slide rule courses, right along side semiconductor design classes. The "Hybrid Era". It all flows together. There is very little new in the actual designs till we get the PLL and processor.
Wonderful tutorials and demonstrations. I love it! However, late model TRFs of the 1930s? Didn't you mean late 20s? I have an American Bosch made in 1928 that has ganged TRF. Also a Majestic floor model, same ganged TRF setup, 1929. By 1932 the superhet patent ran out and everyone made superhet radios, though one could get the small TRF due to the depression, and a 3 tube TRF was cheap.
Awesome video. As for your rf amp stage at 18:20 in your video: In order to find the value of the self biasing resistor do you just use ohms law and look up the 2n2222 base emitter current to get .6 to .7 volt at the base to keep it turned on? I don't understand why the emitter resistor adjusts the gain. Is there extra reading I could do to find out how this works? I have the essentials of radio book u show on your video. Thank you for sharing your knowledge. How is the performance of a typical vacuum tube detector with a grid leak resistor and capacitor compared to a 1n34 diode??
Its pretty loose, and it does not take much to get almost any transistor into the linear region enough to handle the small signals. In other words it does not need to be exactly biased to half VCC, that's for sure (but it would be nice...).
I love crystal radios but was that a SR-150 transceiver in the intro? The SR-150 was my first SSB rig back in the 70's - Thanks for the TRF video de WA4JAT
HOOOWWwww I missed almost these videos !!! (Part 1 and 2) yes this is fun! this is delicious! simple but work like a cannon! friendly greetings from The Netherlands! Rob
A good varactor to play with is the Motorola MV1662, 250 pF. A couple of these should do the trick. Typically tune with a well bypassed pot like a 10K or 50K with a 1M resistor off the center feeding the two diodes which in turn are coupled to the coil with a 0.01 cap. Play with inserting resistors to the bottom and top of the pot to scale it.
Can a loop antenna be used for a crystal radio? I have watched many videos on making a crystal radio but none of them really discuss the antenna and what options are for a portable AM radio. I am trying to watch all your videos so maybe I just haven't got to it yet.
A loop antenna based pure crystal set with no amplification would require a large very low loss loop. It would be tuned. I small table top loop of say 15 inches on each side of a square loop would work only for nearby ground wave stations. So for real performance, imagine winding a loop of say 3 to 5 ft. on a side using low loss Litz wire. Then you would have an inner loop of a couple of turns that you feed the diode with. This gives you an idea of what we are talking about, and this one is small. aa7ee.wordpress.com/2013/11/17/a-tuned-loop-antenna-for-the-am-broadcast-band/
@@MIKROWAVE1 Thanks for the info. I think I might try something like your active antenna with the ferrite core. I want to build a portable AM radio that I can carry. I am also looking at your 2 tube amp design with the battery tubes...pretty cool!
You do get more voltage out if the output impedance is high enough and the signal is strong enough to turn on two diode drops. The penalties are increased output impedance, increased distortion and less SENSITIVITY.
Great video !! ....That 1 Transistor really Woke up the Crystal radio Sensitivity & Selectively !! .....Now that a battery supply is Utilized, maybe Foward Biasing the detector Diode a few Microamps could "Hotrod" even more Weaker DX stations !!
I had one recently. Oh they don't cancel, they usually allow the complaint source to monitize. Any and all of my videos could be scrutinized. Even inadvertently recorded music as tuning across the band can be tagged.
I've tried building this seemingly simple TRF front end onto a Crystal set and absolutely does not work !! Voltages at the collector & base are all over the place and never near what you show in your video schematic. I'm totally lost as to what's going on 🤔🤔
Simple is not always easiest when it comes to bias. Thus we have H bias. All it takes is a variation in the current gain to greatly influence the Q point with simple bias. First attempt to get the first stage collector somewhat centered between VCC and ground.
@@MIKROWAVE1 Fifth try was the charm !! Working like a champ. Even with 40' INDOOR antenna running thru a loading coil !! One thing I'm curious about, why does it seem Crystal Set output seems to be bass heavy ???
@@stevenlitkey9354 That's great about getting it biased! - it could be that the output filter cap on the phones side is too large. Try reducing it to a .005 uF.
That little speaker was built by my high school shop teacher. He was a crackerjack woodworker cabinet maker. He even made Banjo Necks with inlays. The grille is a steel stamping and the speaker is a simple 4 inch PM.
A Vacuum has a relative permeability of 1. Air is 1.00000037. Water is .9999992. Wood is 1.00000043. Pure Iron 1000. So it depends on how wet the wood is and if it has magnetic impurities! Maybe zero effect. Q is another story.
@@MIKROWAVE1 - polystyrene has good permeability and a good Q. I would like to make a printed spider-wound polystyrene coil form with a tubular glass variable cap. You just got me interested in making a super crystal set once again. Thanks so much.
This calls for a bad pun I read many years ago in Pop'tronics........ At one national industry consumer electronics show, sitting in one corner of a display area, was an old horse drawn passenger conveyance. The over a century old wooden vehicle's paint was nearly completely worn off, and the only lettering left on one side were the initials of its long gone operator, 'R.F'. The faint sound of music wafted out of the carriage, and group of engineers gathered around it, scratching their heads and trying to figure out what was the purpose of this exhibit. Finally, one of them face palmed, and spoke up. "Of course", he exclaimed, "it's a 'Tuned RF Stage!" Both of those transistors are often used in RF applications up to 50 mhz. The gain may fall off from the DC value that high, but they work. If you used the dual gang capacitor and placed the two coils at right angles to each other, you could have built a single control radio. The coils would have to be wound exactly the same, but by using the trimmer caps on the variable you could have gotten them to track. Ganged control sets were common in the late 1920's, by the 30's superhets were more common.
Can I make the RF amp ( at 18:09 ) with a gain of 100 by setting a very small emitter resistor and using only 1 meter of an antenna? I live in the city, so I can't have a 40 foot antenna! Really appreciate an answer...
Joanne, the kind of antenna that you are describing is called an Active Voltage Probe. These can be very effective if there is filtering to focus on the band of frequencies you are interested in. For instance, for the broadcast band, you would want one with a sharp low pass filter set for 1.8 MHz. To make the tunable amplifier in this video work as a demo, you may try to increase the gain to a reasonable level of 20 to 30 and attach your very short wire to the very top of the tuned circuit (no primary coil needed).
