crystal4.mpg
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- Опубликовано: 8 сен 2024
- The addition of a triode valve (vacuum tube) to our simple radio makes it work much better. As a crystal set, we had got good selectivity on the medium wave; but the price of this was a very low signal level - so low in fact, that the 3 stations we could receive were very faint in our headhpones. Adding a valve did the trick! We used a Cossor 210-DET valve, a type which was around from about 1930. It could both 'detect' our incoming AM (Amplitude Modulated) radio signal, and also amplify it. We attempt to explain how these things occur. We hope we have got the explanations right! We also mention how expensive valves were to buy in the 1920s & early 30s. Valves were 'high tech.' in those days; and besides, you had to get a 2 Volt lead-acid accumulator to feed the filament of the valve, and a high-tension battery to feed the anode - they weren't cheap either.
this series is wonderful. I've been learning quite a lot. besides being a mad scientist, our host is also a Great Professor.
Thank you so much for these videos,ive been interested in radio for 40 years or more ,only just getting back into it ,i spent many hours as a 10yr old listening my grandad explain to me all these things and bits of it are coming back to me ,also my dad who was a Ham he was my last source of help with radio matters he died last year,so now i turn to google and your amazing clear but detailed help ,for the past 2 months i have been building crystal sets but i wanted to finally after 40 years understand how these things work ,many people are very clever and know their stuff but they are unable to get it over to the person who wants to understand ,your videos have unlocked many things as i am typing tears are coming to my eyes , all the thigs grandad and dad told me i know understand .THANK YOU
Mike
I have just discovered this series in late 2018 and just wanted thank you for the best explanation of radio I have ever seen. Thanks so much Norman.
this old series of yours is amazing. thank you sir, for all the great efforts ! :)
Hi there, & thanks for writing. Sorry about the video quality - it's got better recently, but glad you liked it. Cheers, Norman.
It sure would be sweet to see that short wave in part 5,,, nudge nudge hint hint....
Thank you for this series.
Your crystal set series are the best crystal radio videos I've found on You-Tube. You're a real radio-man!
Thank you very much for these videos Norman, I have really enjoyed them.
Wonderful how the addition of a single valve enables the precise reception of Mott the Hoople music from the 1970s. :)
I'm really enjoying your video series. You have a gift of being able to keep it simple and clear. I appreciate your effort you put into these vids and will be telling some others to check it out.
weird coincidence - back in the seventies I built a crystal set and what was on it when I tested it - Mott the Hoople's All the young dudes ----- great video!
Hi there - that was my audio processing program, DC7. It occured to me one morning, relaxing & drinking coffee in bed (I find that a good time to just *think*...) that if I created a sine wave, then *paste-mixed* another sine wave of a nearby frequency, they should 'beat' and give the required wave-form. It worked! The frequencies I used were very close together. Also, the freq. mixed in was attenuated by a few dB, othrwise there would have been 100% modulation, which was never used.
Thanks, Norman. Love these videos. I've had lots of fun with my simple crystal set and a long wire antenna. I've been able to tune in to Memphis, Atlanta , Cuba and even a station called china radio international but only for a few minutes then it faded all from North Carolina. Great fun! Cheers to you too.
Hi Chris.Glad it's working OK for you. Of course, you've noticed that when it's dark, the range gradually increases. I knew an old-timer here in the UK, who, back in the 1930s, would stay up until maybe three or four o'clock in the morning, listening on about 160 metres (~1.75 MHz) because under favourable conditions, you could pick up the transmissions from Police Patrol cars in New York, who then used that wavelength, for purely local communication to HQ of course. But sometimes those signals could be heard 2000 miles away! He sent a reception report to the NYPD, and got a postal 'QSL' card back from them. In any case, you've done 1000 miles between NC & Cuba! Keep up the good work. Cheers, Norman.
Again, another great class!😊
Found your videos very helpful as I
am building a crystal set also.
I think I need the decoupler and load coil. Very good.
Talk about home-brew... when I was a kid, about 1965-66, I made a crude RF amplifier, to improve the signal for my little pirate radio station. (Which was based on the tuned oscillator of an old Co-op mains superhet.) 6 valves, fitted o two Oxo tins. They were type DET-20, which had metal "ears" on top. The anode and grid. The heaters were supplied by a Hornby-Dublo train controller. 6v to the heaters. "Max speed" was 12v. The tuning coil was wound on a toilet roll... GPO were horrified
Easy to follow presentation.
i know this is old but still a very a nice video...hope you still alive and well.
Thanks, Norman. I wish I could get that China station again. I remember the announcer saying it was a beautiful Sunday morning there and it was Saturday night here. The show was in perfect English too. Oh well, probably never get it again. I wonder if I built a coil for the long wave if I could pick up something over where you are. Worth a try I guess. Thanks again. Have a great day.
I really enjoyed this series so far. Thanks to your teaching skills I now have a much clearer understanding of the way a crystal radio works. I'm really looking out for video number 5 (6,7,...) and I guess I'm not the only one... Could you also give us some details on the components you have used so far (values of the variable capicators for instance, a parts list so to say)? Thanks again for doing these videos.
Hi - many thanks for writing, and only sorry I'm so bad at replying!
Hi, you can buy at Conrad Electronics (also in the UK) a 1 tube (or valve) radio kit! It is called the 'FRANZIS MAKE YOURSELF DIODE RADIO', all complete for £ 46,95. They have also a 'Retro Shortwave Radio' and I am building that thing, just for the fun. There is a 'RADIO EXTENSION SET DRM' for that SW radio for listening to DRM or digital radio on Shortwave. You need a pc or laptop to connect the radio and to run the special software to listen to the DRM radio.
Thanks for sharing, on to part 5!
I love you videos, if you could do the kindness of explaining how your modified coil couples that's the one part I don't understand
Sorry, Jan - I haven't got round to making it yet - even after all this time. But I will try harder... 8^) But glad you liked parts 1 - 4...
I wish I had wytłumaczyłeś how the transistor. It is also history.
so essentially now, you are using the gain as a volume control, which would mean that to turn into a weaker station you would actually have to turn your gain / volume control back up
Waiting for crystal 5.mpg
😆
Fun video. I understand digital logic using transistors, but vacuum tubes seem like sorcery to me.
Excellent series. I've been reading the crystal radio blogs and all the information I can find, but a lot of it is way over my head. Your series has cleared up a lot of questions. Are you perchance a teacher?
One thing I am still having trouble with is that two-gang variable capacitor you're using. I have a one gang and a two gang variable but don't understand when or why I would use one or the other?
Thanks again. I too am looking forward to crystal5.
If a wonderful Idea ,make it into a kit
In a metaphorical sense, you are my favorite teacher. I'm afraid to mention, that I cann't find crystl5.mpg. Would you be so kind to let me know what the name is of the fifth video? With regards,
Jan
Fantastic and english :-) what was that software you used to show the electronics please ?
I still don't understand the connection as to how the signal comes off of the valve
Hi my name is Rob and I did like your video (Crystal radio1/4)
have no sequel videos found more of Crystal4.
Not necessary because it was very clear to me.
still a question!
This was for MW (Medium Wave)
Can you make a part 5…6 and maybe 7 now for SW (ShortWave)???
Wood be very nice!
sorry for bad English!
Greetings from the Netherlands
Rob.
What kind of capacitor should be used for the grid leak? Would a ceramic do?
Hi Chris. Yes, a ceramic would be fine - quite a small value: say around 250 pF. The grid leak resistor is always very large: 1 Megohm or even several Megohms. Hope your set works OK! Cheers, Norman.
Where is part 5?
Dang! 90 volts hanging on your head.