I built my 1st crystal radio at 10 and have recently gotten interested again. I've read a LOT about them on the net, but it wasn't until I saw this video that it finally clicked how the coil/capacitor resonate circuit works! What a great teacher! Thank you so much!!!
I never comment on videos....until now. I have been a licensed ham radio operator for 10 years, and have never truly understood the inductance/capacitance relationship until now. I can't thank you enough for your wonderful explanation Norman!
Norman, I am a 72 y/o retired family doctor and extra class ham since 1960. You remind me so much of my 9th grade physics teacher, Mr. Polman. He made science come alive. I have watched all your crystal set series and have a better understanding of coils and capacitors than I have ever had in all these years. Thank you. This old dog still can learn new tricks or understand how the tricks work. Dave K8WPE
Hi David. Thanks for writing; your comments were received with 'humble delight' - if there is such a thing. Alas, I'm a terrible correspondent, but I hope this reply can also (if you don't mind) be addressed to others who may read it, and to whom I have not replied individually. I'm 73 years old, and radio, along with all basic sciences, is still fascinating to me. 'I Can't Put It Down', one might say. There are so many fascinating things in this world; to keep looking at them, even of only the basics, is - *invigorating*!" That's why we all keep going, isn't it? There's more, so much more, to find out about. From your icon, I think you've got a grand-child sitting on your shoulders? My first grand-child arrived last September, and am looking forward to doing the same! Thanks again and best 73, Norman G4LQF.
I think I understand how the antenna, ground and diode work, but I have long wondered what the coil did and why it was necessary. A lot of information is available on the web that mentions resonant circuits, but I couldn't for the life of me figure out what it was or why it was necessary to make a radio work. Your video has made this concept crystal clear to me for the first time! Thank you. Thank you.
Absolutely brilliant. The best explanation anywhere of the principle workings of a radio. I wished, all teachers would be at least half as good as you. Thank you Norman
Fabulous clear and simple explanation. I watched this set of videos about a year ago and the interest has stuck with me. Revisiting them now Iv'e noticed little nuggets of info I missed first time. Thank you so much. Best explanation I've seen on basic electronics and radio.
Watched this video again,and a bell wrung in my head when you talked about not tuning in,but rather tuning out the desired frequncy.Outstanding ,so the light goes on for me as to resonance.
Thanks for writing. Yes - its a 'rejector' circuit. And, as so often, the opposite is a coil and a capacitor in *series* - which, reassuringly, is an 'acceptor' circuit! 8^) Cheers, Norman.
Hi Christopher, & thanks for writing. When you subscribed, looked you up on QRZ.com to email you, but there was no address - still, I can see you like retro radio, & if you haven't seen it, this link ruclips.net/video/kO9R4AeRgWA/видео.html shows a guy who has made a very simple coherer detector which works fine. Of course, I had to make one straight away, using a short piece of polythene tubing & a couple of bits of quarter-inch dia. brass rod. It works a treat - one of the simplest & best videos I've seen for ages. (You do have to use a long-stemmed gas lighter, though.) Old-time gear is great fun, isn't it? Best 73, Norman G4LQF.
I was so fascinated by radio when I was a kid. I read everything about the technology. But I could never get a kit to work, and I didn't really understand electronics. Even though I have taught very basic electrical theory to computer technology students, this is the first time anyone's ever properly explained a detector to me so that I could understand it. I am grateful.
Thanks a lot, Benard! Glad you enyed the stuff. OK about getting a kit to work; sometimes, it isn't you. I've known duff components, and my first one-valve receiver (I was about 12 years old, and was taught soldering by an ex-army service engineer) never worked. I stripped it down & rebuilt it twice. Not a peep out of it! My father was very disappointed. Years later, I needed a 3 pole 3 way rotary switch, so stripped it out of my failed one-valver. It didn't work! The kit had included a FOUR pole 3 way switch, from which ONE pole and THREE ways had the tags snipped off. Whoever did it, snipped off THE WRONG WAYS! It wasn't my fault after all - yeehaah! Persistence wins, they say! Best wishes to you & yours, Norman.
Thanks, Norman. I’ve been licensed since the 1970's, but that's the clearest explanation of the operation of a resonant circuit that I've ever heard. My simplest crystal set is a 1980's telephone magnetic earpiece with a 1960's germanium junction diode connected across it. It receives the local 10kW MW transmitter's signal loud enough to be heard throughout most of the house, when about 50-60ft of wire and an earth are connected to it. The only capacitance is parasitic. The transmitter is less than two miles away from here.
Awesome !. I've never tried to make a primitive crystal set like that. Grand explanation of the principles involved thanks. And great to see that old crystal tin. Best wishes from New Zealand.
Thanks: glad you liked it! Yes, it does have a diode detector; in fact, it wouldn't work without one. The detector is the bit of crystal lying of the top plate of the capacitor, which has one strand of wire pressing on it. The contact point between the wire and a facet of the crystal acts as a diode. Hopefully I'll make more videos in this series, which will improve on this completely basic 'first attempt'.
I remember my "pappy" telling me about "cat's whisker" and crystal radios and often wondered how it works. Nice to see that you have some laying around and putting it to use in this video. The detailed explanation of how it works is well done! I suppose I may be able to make something similar with the use of a modern day diode in place of the crystal? The audio from the amp sounded much better than I thought, very strong signal and so on. Thanks for sharing this video and taking the time to explain it in terms we can understand.
Hi Samson. Thanks for your kind comments! Yes, it's still just as easy to make a crystal set, BUT, the diode must be a Germanium diode. Other common types are Silicon diodes, but they won't work at very low signal levels. Just search ebay for 'Germanium diode' & you will see plenty of 'NOS' (new old stock). The Mullard 0A80 & 0A81 are still available - you''ll see ex-military packets date-stamped 1958 - they're about £2 each, but they're just the job for a crystal set. Good luck! Norman.
Hi Alex, and thanks for writing. Yes, it's fun working with 'minimalist' home-made things - to be honest, I was also surprised that it worked well - of course, a half-a-Megawatt transmitter a few miles away was a big help! 8^) People who lived *very* near to that station would sometimes get reception from a frying pan on the gas stove, because the old-time coal gas would leave a little soot on the the underside of the pan, and that would act as a detector. Imagine your frying pan suddenly saying 'Here is the 8 o'clock News...' 8^) It actually did happen sometimes. Cheers, Norman.
It really helped me understand the concepts much better than I ever had .. And I hate to admit it, but I started a London University degree course in Electronics when I was a kid ! My brain was not up to it then I suppose. Most of it was such bizarre maths I gave it up.
Very good. It is absolutely fascinating to me how such a simple circuit works, and works well. I bodged together a similar one years ago trying to get WWV, and it worked as well. This is the kind of teaching we need in our schools. The real surprise to me was a station at about 200 khz broadcasting audio. Any stations around here on that band (Oklahoma, USA) are mostly beacons transmitting morse code as beacons.
Hi there & thanks for writing. As you know, the Long Waves were used more in Europe because the countries in Europe are small compared with the U.S.A., so there could be just one Long Wave station that would cover the whole country. So it's really great to know that Long Waves are also used in the U.S.A. for special purposes. Within the range, those waves are very stable & reliable. I even think that ultra-long waves - say 20 or 30 kHz were/are used for very long range communications, say from submarines far from their home bases. 'Traditional Radio' is certainly still a very useful mode! Cheers, Norman.
Very interesting. I always wondered how a Crystal radio would work as I have seen several advertisements on old (Korean) newspapers - Thanks for posting this!
It is very nice of you to write and say this, thank you. I enjoyed making the videos, though of course it took some work. But if it explained something new to you that had been a problem to you before, then that is the best result of all!
Yes, that would work. Take the aerial in through the 125 pF variable to a tap on the coil, probably fairly low down it. Then take a tap higher up it to your 365 pF variable, & the other side of it to the bottom of the coil. Then take the signal from the 'hot' (upper) end of the 365 pF to your diode & from there to your headphones or amplifier. In this usage, the coil is called an 'auto-transformer' and the method was widely used in the early days.
You're absolutely right: it would work as you say. In fact, very early on, that was probably the most common way of getting medium and long wave on one set without having the bother of unplugging one coil and plugging in another. In the earliest times, you just had a coil with many taps, selected by a rotary switch (or a slider) and relied on the capacitance of the aerial & other 'stray capacitance' to tune the circuit. Short wave reception is possible, but too difficult for me! Cheers.
A 365 pF variable capacitor is ideal for tuning a Medium & Long wave crystal set. If 'Radio 5 Alive' is very powerful and 'swamps' other signals, you must first reduce the coupling of the aerial (antenna) into your foxhole crystal set. The simplest way to so this is by putting a small capacitor in series with the aerial. Say 100 pF, 200 pF. That will increase the selectivity, albeit at the expense of volume. I think this is illustrated in part 2 of my videos. Good luck!
Thanks for writing. Well, it's great fun to go through things like this. I always like 'proving' that things taught by science teachers actually work. Of course, most of it was worked out 100 years ago - but it's great to prove it over again, 'in front of your very eyes'. Good luck with your own projects! 73, Norman. G4LQF.
Hello, I very much enjoyed your explanation of how a crystalradio works and I thank you for that. I almost cann't wait to watch your other video's. Until now I learned a lot from it. Regards.
your videos helped explain in more detail then over a hundred vidoes and websites i have looked at have been able to thank you. i had an idea if i made a coil with lets say 1000 turns and every 10 turns i make a loop. would i be able to get short, meduim and long wave by just moving to a different loop and have a variable capaciter to closer tune the stations
@bixanorak funny you should say that i have a varible 125pf cap to the other idea i thoght about 2 sliders on the coil one for the diode and the other the antenna then place a 365pf varibale cap between the diode terminal and the ground terminal of the coil i think this way i should get a very large varation of coil winds to tunabailty what you think
so if i make a coil and use a slider think that be best more tuning ability couls i also use a 365pf varible cap in parallel with the coil for finer tuning is so how would i wire this i looked at loads of circuits and they all do it diferent ways so im very confused at present moment radio five live kills any channel selection on my fox hole radio
Hi, I'm Andreas! Really like your videos, are you going to receive a stereo signal later on? Have a nice evening, thanks for interesting and funny entertainment!
![Electronic Circuitry Diagnosis And Fault Finding! [Repair]](http://i.ytimg.com/vi/LC7OjuYAOQE/mqdefault.jpg)
Norman, I am 74 years old and must say you have presented the best explanation of how radios work I have ever heard or seen. Thank you ever so much.
I built my 1st crystal radio at 10 and have recently gotten interested again. I've read a LOT about them on the net, but it wasn't until I saw this video that it finally clicked how the coil/capacitor resonate circuit works! What a great teacher! Thank you so much!!!
I never comment on videos....until now. I have been a licensed ham radio operator for 10 years, and have never truly understood the inductance/capacitance relationship until now. I can't thank you enough for your wonderful explanation Norman!
Norman,
I am a 72 y/o retired family doctor and extra class ham since 1960. You remind me so much of my 9th grade physics teacher, Mr. Polman. He made science come alive. I have watched all your crystal set series and have a better understanding of coils and capacitors than I have ever had in all these years. Thank you. This old dog still can learn new tricks or understand how the tricks work.
Dave K8WPE
Hi David. Thanks for writing; your comments were received with 'humble delight' - if there is such a thing. Alas, I'm a terrible correspondent, but I hope this reply can also (if you don't mind) be addressed to others who may read it, and to whom I have not replied individually. I'm 73 years old, and radio, along with all basic sciences, is still fascinating to me. 'I Can't Put It Down', one might say. There are so many fascinating things in this world; to keep looking at them, even of only the basics, is - *invigorating*!" That's why we all keep going, isn't it? There's more, so much more, to find out about. From your icon, I think you've got a grand-child sitting on your shoulders? My first grand-child arrived last September, and am looking forward to doing the same! Thanks again and best 73, Norman G4LQF.
I think I understand how the antenna, ground and diode work, but I have long wondered what the coil did and why it was necessary. A lot of information is available on the web that mentions resonant circuits, but I couldn't for the life of me figure out what it was or why it was necessary to make a radio work. Your video has made this concept crystal clear to me for the first time! Thank you. Thank you.
Absolutely brilliant. The best explanation anywhere of the principle workings of a radio. I wished, all teachers would be at least half as good as you. Thank you Norman
Fabulous clear and simple explanation. I watched this set of videos about a year ago and the interest has stuck with me. Revisiting them now Iv'e noticed little nuggets of info I missed first time. Thank you so much. Best explanation I've seen on basic electronics and radio.
Watched this video again,and a bell wrung in my head when you talked about not tuning in,but rather tuning out the desired frequncy.Outstanding ,so the light goes on for me as to resonance.
Thanks for writing. Yes - its a 'rejector' circuit. And, as so often, the opposite is a coil and a capacitor in *series* - which, reassuringly, is an 'acceptor' circuit! 8^) Cheers, Norman.
A great fun and meaningful use of time - watching the series of six videos. Informative and entertaining … thank you.
Hi Christopher, & thanks for writing. When you subscribed, looked you up on QRZ.com to email you, but there was no address - still, I can see you like retro radio, & if you haven't seen it, this link ruclips.net/video/kO9R4AeRgWA/видео.html shows a guy who has made a very simple coherer detector which works fine. Of course, I had to make one straight away, using a short piece of polythene tubing & a couple of bits of quarter-inch dia. brass rod. It works a treat - one of the simplest & best videos I've seen for ages. (You do have to use a long-stemmed gas lighter, though.) Old-time gear is great fun, isn't it? Best 73, Norman G4LQF.
I was so fascinated by radio when I was a kid. I read everything about the technology. But I could never get a kit to work, and I didn't really understand electronics. Even though I have taught very basic electrical theory to computer technology students, this is the first time anyone's ever properly explained a detector to me so that I could understand it. I am grateful.
Thanks a lot, Benard! Glad you enyed the stuff. OK about getting a kit to work; sometimes, it isn't you. I've known duff components, and my first one-valve receiver (I was about 12 years old, and was taught soldering by an ex-army service engineer) never worked. I stripped it down & rebuilt it twice. Not a peep out of it! My father was very disappointed. Years later, I needed a 3 pole 3 way rotary switch, so stripped it out of my failed one-valver. It didn't work! The kit had included a FOUR pole 3 way switch, from which ONE pole and THREE ways had the tags snipped off. Whoever did it, snipped off THE WRONG WAYS! It wasn't my fault after all - yeehaah! Persistence wins, they say! Best wishes to you & yours, Norman.
@@bixanorak Thank you for your kind response, sir. I am seriously thinking about finding a project. Maybe a crystal set.
Thanks, Norman. I’ve been licensed since the 1970's, but that's the clearest explanation of the operation of a resonant circuit that I've ever heard. My simplest crystal set is a 1980's telephone magnetic earpiece with a 1960's germanium junction diode connected across it. It receives the local 10kW MW transmitter's signal loud enough to be heard throughout most of the house, when about 50-60ft of wire and an earth are connected to it. The only capacitance is parasitic. The transmitter is less than two miles away from here.
Awesome !. I've never tried to make a primitive crystal set like that. Grand explanation of the principles involved thanks. And great to see that old crystal tin. Best wishes from New Zealand.
Bravo for your wonderful multi-part exposition of radio technology!Delightful, sir!
Marvellous. Never heard an exposition like this. Absence of fast talking is so enjoyable. Thanks, Norm.
Thanks for the great videos, I used to make germanium diode radios as a child and you've sparked my fascination again.
Thanks: glad you liked it! Yes, it does have a diode detector; in fact, it wouldn't work without one. The detector is the bit of crystal lying of the top plate of the capacitor, which has one strand of wire pressing on it. The contact point between the wire and a facet of the crystal acts as a diode. Hopefully I'll make more videos in this series, which will improve on this completely basic 'first attempt'.
I think that this is just about the best RUclips Video that I have ever scene. It is very simple and easy to understand.
Fantastic! Thanks Norman for reminding me of basic 'electronics' learned at school and long forgotten.
Thankyou ,dear friend, would like to see more.I had fun,as you are a delightful person to listen to.
What a great class, Dear Mad Professor!!!!!!!😊
Absolutely Brilliant. Impressive indeed! I truly understand inductance/capacitance relationship in terms of radio signals!
I remember my "pappy" telling me about "cat's whisker" and crystal radios and often wondered how it works. Nice to see that you have some laying around and putting it to use in this video. The detailed explanation of how it works is well done! I suppose I may be able to make something similar with the use of a modern day diode in place of the crystal? The audio from the amp sounded much better than I thought, very strong signal and so on. Thanks for sharing this video and taking the time to explain it in terms we can understand.
Hi Samson. Thanks for your kind comments! Yes, it's still just as easy to make a crystal set, BUT, the diode must be a Germanium diode. Other common types are Silicon diodes, but they won't work at very low signal levels. Just search ebay for 'Germanium diode' & you will see plenty of 'NOS' (new old stock). The Mullard 0A80 & 0A81 are still available - you''ll see ex-military packets date-stamped 1958 - they're about £2 each, but they're just the job for a crystal set. Good luck! Norman.
Brilliant! I've heard radio explained so well before - many thanks Professor! I was amazed that the set worked so well.
Hi Alex, and thanks for writing. Yes, it's fun working with 'minimalist' home-made things - to be honest, I was also surprised that it worked well - of course, a half-a-Megawatt transmitter a few miles away was a big help! 8^) People who lived *very* near to that station would sometimes get reception from a frying pan on the gas stove, because the old-time coal gas would leave a little soot on the the underside of the pan, and that would act as a detector. Imagine your frying pan suddenly saying 'Here is the 8 o'clock News...' 8^) It actually did happen sometimes. Cheers, Norman.
It really helped me understand the concepts much better than I ever had .. And I hate to admit it, but I started a London University degree course in Electronics when I was a kid ! My brain was not up to it then I suppose. Most of it was such bizarre maths I gave it up.
Very good. It is absolutely fascinating to me how such a simple circuit works, and works well. I bodged together a similar one years ago trying to get WWV, and it worked as well. This is the kind of teaching we need in our schools. The real surprise to me was a station at about 200 khz broadcasting audio. Any stations around here on that band (Oklahoma, USA) are mostly beacons transmitting morse code as beacons.
Hi there & thanks for writing. As you know, the Long Waves were used more in Europe because the countries in Europe are small compared with the U.S.A., so there could be just one Long Wave station that would cover the whole country. So it's really great to know that Long Waves are also used in the U.S.A. for special purposes. Within the range, those waves are very stable & reliable. I even think that ultra-long waves - say 20 or 30 kHz were/are used for very long range communications, say from submarines far from their home bases. 'Traditional Radio' is certainly still a very useful mode! Cheers, Norman.
The big archive on crystal I should say... Enjoyed listening...Thanks...!
Very interesting. I always wondered how a Crystal radio would work as I have seen several advertisements on old (Korean) newspapers - Thanks for posting this!
It is very nice of you to write and say this, thank you. I enjoyed making the videos, though of course it took some work. But if it explained something new to you that had been a problem to you before, then that is the best result of all!
Yes, that would work. Take the aerial in through the 125 pF variable to a tap on the coil, probably fairly low down it. Then take a tap higher up it to your 365 pF variable, & the other side of it to the bottom of the coil. Then take the signal from the 'hot' (upper) end of the 365 pF to your diode & from there to your headphones or amplifier. In this usage, the coil is called an 'auto-transformer' and the method was widely used in the early days.
well done and enjoyable explanation of the basic theory.
You're absolutely right: it would work as you say. In fact, very early on, that was probably the most common way of getting medium and long wave on one set without having the bother of unplugging one coil and plugging in another. In the earliest times, you just had a coil with many taps, selected by a rotary switch (or a slider) and relied on the capacitance of the aerial & other 'stray capacitance' to tune the circuit. Short wave reception is possible, but too difficult for me! Cheers.
Very Interesting Video,,,Nice Job Norman!!!!!!
Thank you for this excellent video and explanation. Best regards.
Thanks for writing, and glad you enjoyed it. Sorry about the fuzzy video; it's a bit better in recent videos! Cheers, Norman.
hello Norman thanks for posting this .
be well all the best .
A 365 pF variable capacitor is ideal for tuning a Medium & Long wave crystal set. If 'Radio 5 Alive' is very powerful and 'swamps' other signals, you must first reduce the coupling of the aerial (antenna) into your foxhole crystal set. The simplest way to so this is by putting a small capacitor in series with the aerial. Say 100 pF, 200 pF. That will increase the selectivity, albeit at the expense of volume. I think this is illustrated in part 2 of my videos. Good luck!
This is truly brilliant. Very well done sir. Thank you.
I really enjoyed your video and learned from it, thank you.
Marvelous !!!
40°56'50"N 72°53'53"W
Brilliant mate! ... I shall do something similar myself soon... DE M0XXX 73
Thanks for writing. Well, it's great fun to go through things like this. I always like 'proving' that things taught by science teachers actually work. Of course, most of it was worked out 100 years ago - but it's great to prove it over again, 'in front of your very eyes'. Good luck with your own projects! 73, Norman. G4LQF.
Hello, I very much enjoyed your explanation of how a crystalradio works and I thank you for that. I almost cann't wait to watch your other video's. Until now I learned a lot from it. Regards.
i love this stuff.. radio is king,.,.
Nice work norm
HI there, & thahks for writing! Cheeers, Norman.
Another wonderful lesson.
Excellent video!!
your videos helped explain in more detail then over a hundred vidoes and websites i have looked at have been able to thank you.
i had an idea if i made a coil with lets say 1000 turns and every 10 turns i make a loop.
would i be able to get short, meduim and long wave by just moving to a different loop and have a variable capaciter to closer tune the stations
@bixanorak funny you should say that i have a varible 125pf cap to the other idea i thoght about 2 sliders on the coil one for the diode and the other the antenna then place a 365pf varibale cap between the diode terminal and the ground terminal of the coil i think this way i should get a very large varation of coil winds to tunabailty what you think
I really enjoyed it Norman!
You know what? You're an excellent teacher. I wonder what you did for a living before you (I'm assuming) retired.
I have heard that the BBC intends shutting off the LW service from Droitwich. Is this the case?
You're catching the right frequency, but you're tuning out the carrier frequency in order to be left with the original radio frequency.
great video
so if i make a coil and use a slider think that be best more tuning ability couls i also use a 365pf varible cap in parallel with the coil for finer tuning is so how would i wire this i looked at loads of circuits and they all do it diferent ways so im very confused at present moment radio five live kills any channel selection on my fox hole radio
Nice, no diode for detection?
Hi, I'm Andreas! Really like your videos, are you going to receive a stereo signal later on? Have a nice evening, thanks for interesting and funny entertainment!
very nice- thanks
Never-mind... found it in part 2! :)
ty think i gor that pictured in my mind
I don't think you explain why or how the crystal is required :(
after this was made the long wave section was closed. what a loss. so is medium wave .