that internet pun was so painful, it hertz

@alecmiranda9837

5 жыл бұрын

Lowen You won the internet. Congrats.

@bulbman2564

5 жыл бұрын

*inhales* "BOI!"

@miguelsojo3376

5 жыл бұрын

Please, don't hurt me more, take my money.

@Jake_2903

5 жыл бұрын

I trust you will find the door on your own.

@MichaelFlatman

5 жыл бұрын

maybe it's a hert

I didn't know that Capacitors were called Condensers in the past. They're still called "Kondensator" in German.

@tofikk

5 жыл бұрын

Anton1699 same in polish :)

@polaroidleftist

5 жыл бұрын

And in finnish

@catsspat

5 жыл бұрын

"Condenser (コンデンサー)" also stuck in Japanese. It's like "capacitor" is the odd one out.

@davidfrischknecht8261

5 жыл бұрын

There's still the condenser microphone.

@JesseLH88

5 жыл бұрын

And my axe!

It's amazing how complicated "simple" things like a radio really are.

@ChaosLemonVIII

2 жыл бұрын

Understatement of the century, especially when you actually work on them

@buckrodgers1162

2 жыл бұрын

The wonderful world without, or before, the silicon microchip. The most mundane things become incredibly complex.

@hansjanssen3364

Жыл бұрын

@@buckrodgers1162 You're joking right? 4 active components in this radio.

@buckrodgers1162

Жыл бұрын

@@hansjanssen3364, Your trolling right? Or maybe you just didn't watch the vid at all.

@hansjanssen3364

Жыл бұрын

@@buckrodgers1162 I replied your comment where you indicate things were more complex before the microchip. They weren't.

Listening to the interference between waveforms is something I was trained to do as a musician. If you’re playing in a band or orchestra, it’s really important to be able to hear that “wobble” of interfering wave forms because it means that someone is playing out of tune. The explanation given in your video is MUCH better than the explanation I was given when I was first learning how to tune my instrument. Great video!

@rpbajb

2 жыл бұрын

That's interesting! Is orchestral music written to eliminate interference between the frequencies of instruments?

@barcodenosebleed5485

Жыл бұрын

@@rpbajb Yes! Basically any Western/commercial music you hear (outside of experimental/esoteric genres) is written this way. Math is essentially the foundation of music theory. The notes in a scale are based on 'pleasant' sounding frequency ratios that basically repeat each time you hit the same note above/below what you start with. This is a bit reductive, but to our ears, good music sounds like a well-reduced fraction. With composition, it's about managing these frequencies and multiples and understanding how any 'interference' might potentially color the harmony/overall song. When you're composing you aren't actually thinking about frequencies or math though. That was all worked out back in a 16/1700s. Rather you rely on a language of abstraction and consider things like scales, keys, intervals, modes and all the techniques that have been developed over the centuries working with those tools. But there's well-defined math at the core of all of those.

@rpbajb

Жыл бұрын

@@barcodenosebleed5485 That's very interesting, thanks for your time in explaining it so well. I love music but I know nothing about it technically. I fooled around with guitar in my youth, but never got serious about it. I'm fairly good at math (up to derivatives and integrals) but musical notation remains a foreign language to me. I was shocked once while attending "Music 101" at Heinz Concert Hall, when the guest violinist showed the audience that her instrument had no frets! The level of dedication and the amount of practice to play professionally must truly be astounding.

In 1980 when I was in high school, transistor radios were all the thing. One day at lunch when we were all outside, I was playing my transistor radio on an Atlanta rock station 96.1FM someone else standing near by was playing a country radio station at 106.7FM on their handheld FM radio. We wanted to compare radios to see which handheld FM Radio was better. We first wanted to see which radio would play the loudest. So my friend turned up the volume all the way playing a country song and I did the same with a rock song. We brought the two radios together to see if one could be heard over the other. To our amazement, my friends radio quit playing the country station and started playing the rock station. Other kids standing around started laughing. I was wondering what was going on. He moved his transistor radio away from mine and it started playing the country station again. We were all dumbfounded...??? There was another kid playing a pop station at the time at 92.9FM and the country station and pop station played together. We put the rock station 96.1FM together with the pop station 92.9 and got the same results as each radio continued to play the perspective stations. We put the Rock station 96.1 together again with the country station 106.7 and the radio playing the country station started playing the rock station. We never really did compare the radios, but we did know that Rock music would beat out country music every time. I later in life learned that the effect was known as Super heterodyning. I repeated the experiments years later with two totally different radios and got the same effect. I thought it the strangest thing.

@Alexagrigorieff

5 жыл бұрын

Looks like one radio was leaking an awful lot of EMI on the intermediate frequency, and the second radio was picking it up.

@Bill_Woo

5 жыл бұрын

I spent time listening to something similar, including listening to WKLS, but also spent a lot of time on 88.1 WRAS and once in a while that weird Tech station. And man, that Clark College WCLK 91.9 jazz, man oh man. I hated Atlanta for its snobs, but musically, it was one of the finest, I'm convinced. BTW I started with AM 79 WQXI "Quixie" on the handlebars of my bicycle, back in Beatles time. One of the DJs there inspired the creation of "WKRP in Cincinnati".

@nathanwoodruff9422

5 жыл бұрын

@@Bill_Woo I started in 1976 with WSB AM750 listening to {Something} theater on Saturday nights starting at 8pm and ran commercial free till 10 pm. I wish I could remember the name of the program. It was the only AM station that broadcast after dark. My mom also would say that I had to go to bed when the station signed off the airwaves at 10pm. When I made it to high school I changed to WKLS when all the cool kids in the school was listing to Z93.

@Bill_Woo

5 жыл бұрын

@@nathanwoodruff9422 WSB and some other powerful stations were called "clear channel stations" (not just a current cute marketing name as it's used now) and they didn't power down after sunset, so you could have an adventure at night picking up stations like WWL in New Orleans or WLS in Chicago (who was top 40, which was fine since music was totally excellent back then). When Atlanta traded away my absolute hero Joe Torre to Saint Louis, I listened to their clear channel KMOX in the dark in my bedroom. Yes, I too remember other stations rather dropping out after sunset, and pretty much everybody switched to WSB every night as that happened.

@nathanwoodruff9422

5 жыл бұрын

@@Bill_Woo I would spend summers in Pensacola Florida at my grand parents house and would still listen to WSB in Atlanta after dark there in Pensacola. My grandfather was a radio operator for a NAVY ship and was big into HAM radio after he retired. He had this huge 5/8th wave antenna running the span of the roof and if I connected the AM radio antenna to it, some nights I could listen to an AM station in New York. I believe my grand father said that I could only pick it up if the moon was in the right position. I never knew if that was correct or not, but it was only one or two nights a month I could tune it in out of the two months that I was there during the summer.

7:09 I love how those old engineers put ball bearings in there, they wanted the radio to last forever. Not like now they don't even put bearings in the wheels of some kids' bikes.

@EddSjo

3 жыл бұрын

I think it has more to do with alignment and smoothness of operation, than longevity.

@vulekv93

2 жыл бұрын

@@EddSjo You are being a contrarian for no reason at all. Gabriel is right. Smooth operation leads to longevity.

@liammarten5468

2 жыл бұрын

@@vulekv93 you’re so cool and smart

@ShaunieDale

2 жыл бұрын

The dial drive cords on some of these radios were a work of art in their own right. As a pre-teenager I was fixing broken cords for faintly and friends.

@JonatasAdoM

2 жыл бұрын

Why do I bother with comments replies? It's always the same pattern.

The hair, the jacket, the voice, the wit... The more I watch this chsnnel, the more i love this guy. It doesn't hurt that his content is interesting, extremely well-researched and always clearly and rigorously explained.

As a dude with no background in engineering, your videos are a really good insight on how tech evolved over time. This is seriously good content.

@schleepysings

Ай бұрын

To be honest, it is also the same for engineers

You are seriously my favorite account on KZread. Not afraid to dive into the real technology left behind by our shiny gadgets of today. And you are really true to yourself and what motivates you! Thank you so much for your videos, even on Christmas! Happy Holidays.

@Ayavaron

5 жыл бұрын

Technology Connections is one of the best channels on KZread.

@alenasGame

5 жыл бұрын

Gadgets of today are also real technology

@OnIcePerspectives

5 жыл бұрын

Hey now, I never said today’s tech wasn’t real either. I just said this was left behind.

@justjoeblow420

5 жыл бұрын

Actually the Super Hetrodyne design is still in extremely wide spread use for radio based technologies. There is a good chance that both your cell phone and PC (if it has WiFi) are probably using them right now whether you realize it or not.

@commodoresixfour7478

5 жыл бұрын

Good point. Crusty old tube amplifiers make the best sound, don't advertise that too much. Then we will have a hard time finding these old (underrated) amps. Most people have no idea how much base an old low wattage tube amp can make. BTW I love all technology and without the knowledge of the old stuff we would be lost.

Heterodyne RF oscillators are also how a theremin works, too - one is at a fixed frequency and the other is varied by the position of the player's hand, and the resulting beat frequency is a tone in audio range. I built a theremin from a kit in high school, and was floored when I realized half-way through that the darn thing was pretty much just a messed-up AM radio.

@mrb692

5 жыл бұрын

There are theremin kits?! Time to pay Google a visit!

@rjhelms

5 жыл бұрын

@@mrb692 The one I made was the Paia Theremax - that was 20 years ago but it looks like it's still available!

@Stoney3K

5 жыл бұрын

Ironically, the machine was actually designed as a research into capacitive proximity sensors, not radio. And guess what our smart phone touch screens are today? Essentially they're tiny Theremins pointing along both of the screen's axes.

@erkinalp

5 жыл бұрын

"Theremins that don't play music"

@glennso47

5 жыл бұрын

rjhelms Do keyboards work the same way?

The outtakes at the end are a real education in how difficult it is to speak clearly and accurately into a microphone. Makes me feel better whenever I stumble over my words.

I am a Polytechnic student and watched this video WAY before I got this topic on book. When I finally got it on book, I faintly remembered this video and rewatched it. This video is so much more comprehensive than the book! I have found more comprehensive explanation from yours two channal than I got from my books. Things like Heat pumps, Radio stuff, TV Things , CRT, Imaging technique, EV and so much more. Please keep making these videos. For your casual viewers (like me) and also for engineering students(also like me). Thanks!

Safety precaution: This is an AA5 radio without a power transformer, therefore No isolation from the AC line. Also, originally it would have been fit with an unpolarized power cord meaning that depending on which way the plug is inserted into the wall outlet there is a 50/50 chance of having the chassis at or close to HOT power line potential. For safety power cord SB replaced with polarized line cord making sure to wire it correctly if not already done. Any capacitor from line cord to chassis SB replaced with XYZ safety cap of same value. Getting a knob for the on-off volume control is a must, even if it doesn't match, touching that bare shaft is an extreme shock hazzard. That is a nice radio and worth a good cleanup and restoration. Just my two cents hoping to keep you safe.

@thegardenofeatin5965

4 жыл бұрын

Wow, I'm amazed it's legal to plug into the grid at this point.

@yahnsolo

4 жыл бұрын

Hehe the bare aluminium shaft issue, of the ON-OFF/Volume pot... Some old knobs have metal and also the holding screw (in-)visible and keep shock-joking around ;) 50’s standards lol

@arthurr8670

4 жыл бұрын

Hopefully he plugs everything into a gfic outlet

@nickv1008

4 жыл бұрын

Daniel, even with a polarized plug, you pay still get a hot chassis if lester put the wires on the wrong terminals in the outlet. White to silver ( big slot), black to gold ( small slot) , but black is ground in the radio go figure..

@utah133

4 жыл бұрын

It's a result of designing receivers as inexpensively as possible. They eliminated the power transformer and used a half-wave rectifier tube with a sufficient filter capacitor (Or two usually in combined in one unit.) You get 160 volts DC that way, sufficient for vacuum tubes. Going to a permanent magnet speaker also eliminated some copper windings. The "Five tube American" became a standard design for nearly all small units. But the chassis was directly connected to one lead the 120 volt power cord!

The superhet today has been partly replaced by direct conversion, iroinically what we used to have before the superhet. The advances in digital technology means modern radios used for mobile phones/wifi etc.. convert directly to baseband without any intermediate frequency and use DSP techniques to provide the selectivity. Direct conversion has shortcomings but in the digital domain they can be tolerated as data can always be re-sent and forward error correction exists too. Some manufacturers such as Ubiquiti in the states have overcome the problems with direct conversion radio chips by adding a superhet stage that acts as a tracking filter. This converts to an I.F. then filters there then converts it back to the original frequency albeit now with just the channel needed present. Easy enough to do as you only need the one injection oscillator to convert down and back up again. They call it AirPrism which is a nod to the early Intersil prism radio chipsets that used superhet techniques as standard. Back in the AM radio days a 455khz I.F. was fine as the image was always out of band, however later they added double conversion. a common frequency for this was 10.7 MHz . this placed the image 21.4 MHz away and meant the entire shortwave band could be tuned from a single radio. they used double conversion so they could do most of their gain and selectivity at 455khz and have less stringent filtering at 10.7MHz. Even when broadcast FM radios came out the first I.F. was 10.7MHz , hence the band was usually 88 to 108 MHz, a 20MHz span , meaning the 21.4MHz image was again out of band at either end (depending if they mixed high or low). Later of course as the spectrum got more crowded and higher frequencies were used they had to increase this I.F. further and 21.4 MHz became popular then 45 MHz and even 90MHz as the technology, mainly in Crystal/ceramic filters improved and so did the high frequency performance of active components. Later still the early WiFi chipsets used SAW (surface acoustic wave) filters that were smaller and cheaper to make than crystal ones and operated in the hundreds of MHZ range. Now we are back at square one, using direct conversion because the technology we have allows it .. Full circle :)

@Altoclarinets

5 жыл бұрын

live one day as an even moderately attractive woman and I think you'll find superhets are alive and well (I kid, I kid)

@jimsteele9261

5 жыл бұрын

Just to add in a bit... some of the early superhets used other IF frequencies before 455kc became standard. I've seen sets with an IF as low as 155kc.

@nickwallette6201

5 жыл бұрын

I do not get the joke. Someone explain to the slow kid?

@Altoclarinets

5 жыл бұрын

@@nickwallette6201 if this is about my comment, superhet - extremely heterosexual (and not shy about it)

@allmycircuits8850

5 жыл бұрын

I'd say what we used before superhet was not direct conversion but DIRECT AMPLIFICATION. The only application for direct conversion was morse code receiving, where frequency difference between local oscillator and signal itself defined the pitch of 'beeps'. To receive sound using direct amplification, phased-locked loop is needed badly. Not a thing you'd meet in tube designs :)

When I was young and had all ratty furniture, I had an amplifier/receiver missing the lid. For fun I wrapped part of the loop FM antenna around the antenna coil core. My friend who knows even more about electronics than I was visiting and scoffed, "What do you call that?" I replied, "That's Super-DUPER-heterodyne!"

6:38 fun fact, capacitors are called "kondensator" in Polish. I often mix those terms and get "condensator" in English and "kapacytor" in Polish

@huseyinuguralacatli5064

Жыл бұрын

We use both "kondansatör" and "kapasitör" in Turkish too

@Commander_Chopper

Жыл бұрын

In german it's called "Kondensator" as well.

So my grandfather, who was a NASA engineer in the 1960s during the Apollo program, sent me a book back in 1988, when I was about to graduate high school and go to college, where I planned to major in electrical engineering. This book had been written in the late 1940s, before the advent of transistors, and it explained many different radio and amplifier circuits, beginning with the simplest "crystal" radio sets and ending with the superheterodyne FM receiver -- all done with vacuum tubes, of course. And no stereo, of course - that hadn't been invented yet. It was a fantastic book that taught me a great deal -- but it was *so complicated.* It had clearly been written by an engineer, for engineering students (which I wasn't quite yet at the time.) I wish there'd been videos like this one back then to help with my understanding... Kids these days have it so easy. ;-)

@therm0tt0

5 жыл бұрын

Was it the Radio Designer's Handbook by F. Langford-Smith? I'm sure there are several books like that, but this one came to mind. It's absolutely filled to the brim with technical discussions and formulas. I bought it for the chapters on audio circuits, and even though it only covers vacuum tubes, most of the concepts also apply to solid state.

@LMacNeill

5 жыл бұрын

@@therm0tt0 Yes, I believe that is it! I could not remember the name or the author, and, although I still have the book, it's in an off-site storage unit, so I didn't have the ability to simply go to my bookshelves and look.

1:51 "ok, how does that help?" My response to everything I've looked at while trying to learn the dark arts of RF wizardry.

@Gmoyer11Tech

5 жыл бұрын

Radios, how do they radio? us -> wizardry and bullshit -> them

@GoldSrc_

5 жыл бұрын

Indeed, anything RF is some voodoo magic shit, I have no idea how it works but it works.

@TeslaLegend

5 жыл бұрын

@@GoldSrc_ Not really, all AM stuff (modulation, demodulation, etc) can be done through simple trigonometric identities

@matthewpalmer9820

5 жыл бұрын

I am a superheterodyne.

@Appletank8

5 жыл бұрын

@@matthewpalmer9820 As long as you are not a Heterodyne descendant, we will have no problems.

As a youngster, I explored ( took apart ) many old radios obtained from various sources. I never had a clue how all that worked. Yours is the first real explanation I ever heard. Thanks for sharing.

I'm really blown away by what a brilliant idea the whole superheterodyne thing is. You did an excellent job presenting it, not to mention figuring it out and how to demonstrate it. Also, your attention to details like mouth noises and such helps make yours an easy channel to watch.

I love your old "cringetastic" videos, though! They're what got me subscribed to you in the first place.

@raychang8648

5 жыл бұрын

I came here to say the same thing!

@andeen

5 жыл бұрын

Same same.

@dcurry7287

5 жыл бұрын

I love em too, but they also nicely demonstrate how much Alex's skills as a host have grown.

@raychang8648

5 жыл бұрын

@@dcurry7287 Don't want to mess with you, but his name is "Alec", not "Alex". Yes, he is greater now than the early ones.

@siliconinsect

5 жыл бұрын

Great video as usual! If you wanna get REALLY nestolgic there were promotional radios usually distributed by contest or lottery that lacked a superhet as they were tuned fixed to the station. They were usually powered with two batteries and considered fairly disposable.

The issue with filtering variable frequencies is that the bandwidth of an L-C filter (the simplest kind, and what old radio sets used) is proportional to its resonant frequency. The AM broadcast band traditionally ran from 540 to 1600 kHz - that's about a factor of three. So the selectivity of a pre-superhet set varied by a factor of three: at the low end of the band, audio quality suffered because the high frequencies (which in AM are further from the center of the signal) got cut out. At the high end, selectivity suffered and the set would tend to pick up multiple stations at once. That was the main problem the superhet solved: the selectivity of the set no longer depends on the frequency being tuned. The fact that every superhet receiver is also a weak transmitter was (and probably still is) used by the British to detect unlicensed TV sets. (Yes,*receivers* are licensed in the UK; the license fees are how the BBC is funded.)

@video99couk

5 жыл бұрын

Yes, that's the word that was missing. It's not just about improving how sensitive a radio is, it's about improving how selective it is. TRF (Tuned Radio Frequency) radios had a wide passband so would pick up the intended transmission along with lots of noise and potentially other nearby transmissions too.

@EwanMarshall

5 жыл бұрын

Actually, the BBC licence service probably never did. However the Nazi's did during WW2, giving rise to the use of "trench radios" which were basic crystal (and therefore not heterodyne) radio set. As he stated he stated SDR does not need to use heterodyne techniques as we can do it all in digital using a FFT after sampling (for receive) allowing very broad bandwidth SDRs. It should also be noted, that changing to the local oscillator to the right frequency to mix that would give the intermediate frequency is based on one of those old L-C filters itself. The tuning part didn't change much, we just started adjusting to other component out of those that work together to set the frequency.

@davidbarts6144

5 жыл бұрын

@@EwanMarshall TV detection is a real thing: en.wikipedia.org/wiki/TV_detector_van Yes, the IF is an L-C filter, but it's fixed frequency, so the bandwidth stays the same regardless of where in the band the set is tuned.

@atmel9077

5 жыл бұрын

With a normal FM radio, I can detect the LO signal of another FM radio one or two meters away. With my $10 RTLSDR I can detect the signal 10-15m away through several walls. By recording signals for several minutes, it may be possible to detect LO signals from hundred meters away, buried well below the noise floor. Now the "problem" is that modern receivers are heavily shielded thus the LO leakage is insanely low (a few nanowatts)

@jakebrake5776

4 жыл бұрын

Oi m8! U go' a loicense fer tha' TV set?

I just found your video. Very well done! I'm into collecting and restoring antique radios as a hobby, and I never understood what a "local oscillator" meant. It didn't make any sense to me why a radio needed its own oscillator. I just assumed that the tuning capacitor simply put the circuit into resonance with whatever frequency you wanted to tune to, and so it would selectively pick up only that particular frequency. I had no idea that it was kind of a 2 step process like this. Very interesting!

@dougbrowning82

Жыл бұрын

The type of radio you describe did actually exist before superhets came into existence. They're called tuned radio frequency (TRF) radios. They were highly sensitive and could really pull in weak, distant stations, but they were poor at rejecting adjacent stations close in frequency, which is where the superhet excels. Some superhets had an extra, radio frequency (RF) amplifier ahead of the converter to improve sensitivity, especially car radios and nice, expensive consoles.

I was thought tube theory in Vocational school in the late 70's and we built a "5-tube AC/DC Superheterodyne Radio" in class. This approach was excellent to understanding the fundamentals of electronics.

I would like to add a correction, or rather an improvement to your explanation. Around 5:10, you said former filters were not very precise. Precision in filters is given by the Q factor (blablabla you can search for it). Now, Q = (Frequency / Bandwidth). As the frequency the filter is tuned to increases, so does que the bandwidth it lets pass through. The real problem with this tuning filter is that you cannot have the same bandwidth throughout the whole spectrum, so you would have higher frequency stations having their signals mixed up under the bigger bandwidth of the filter. So yes, you are partially correct, they were not very precise, but it might would be better to say that their precision varied with the frequency. I love your channel, you seem to be so passionate about older technology! People were really clever back in the analog days. None of that microcontroller gibberish!

@allmycircuits8850

5 жыл бұрын

It's a little more complicated than that. For perfect sound reproduction we'd like to have rectangular filter, that is, it passes without any loss at nominal frequency, plus-minus 20 kHz let's say, and rejects everything else. To achieve this kind of response with resistors, capacitors and inductors, several L-C filters are needed with slightly different resonant frequency. And yes, this thing is extremely difficult to tune to arbitrary frequency!

@flatfingertuning727

5 жыл бұрын

I think a bigger issue is that selective filters require a multi-pole topology with different parts that would all need to be tuned to the desired frequency. One could produce a brilliantly selective radio for the 0.5-1.6MHz band using a four-pole passive LC filter if one didn't mind having to set four separate tuning knobs, and not getting any good indications of what one was doing unless or until all of them were set near the right position. Using a superheterodyne receiver makes it possible to have a multi-pole filter which is calibrated at the factory and won't need to be changed after that.

@markc2643

4 жыл бұрын

Precision is not the correct word to use. The RF filter combined with the antenna is precise when you consider the center of the band that it is passing, you want that to be maximized since you haven't amplified it yet. Therefore you can't make it too narrow a bandpass, cause that would reduce the signal strength. The IF filter can be very narrow since it's already been amplified, so the bandpass is the important character, and not a maximized signal strength.

@mrb692

4 жыл бұрын

Is that why the tuning dial on radios like this tend to be nonlinear? If you look at this one, 500-600 is about the same dial distance as 1200-1600. I’ve seen linear tuners in things like hi-fi components, but having the higher frequencies crammed together seems more common.

@jonathanberry9502

4 жыл бұрын

@@flatfingertuning727 You didn't see William W. Campbell-Shepherd IX's message to you, maybe you can reply and he can miss your reply too :)

Love your videos. I've been into electronics since I was 10 (I'm 56 now), I have been into computers for over 25 years and have been an Amateur Radio Operator for almost 30 years. I'm not afraid to admit that your videos teach me things I didn't know or even thought about. I think the very first video of yours that I watched was the one of the original PlayStation copy protection. I have a feeling that if we were to have a face to face conversation, we could talk all day, or at least I could, but I'm sure I might do more listening than talking. LOL Merry Christmas.

@theencube5379

5 жыл бұрын

Another ham!

@yellowcrash10

5 жыл бұрын

Nice, another ham!

@organiccold

4 жыл бұрын

@@theencube5379 74 from CT9ABQ -M0IVC

@zaphodb777

4 жыл бұрын

73 de AE7EC

@danielpenaofficial4186

4 жыл бұрын

Terry C. What’s your call? W7ZAR 73’s from WA I’m good on QRZ

I only wish I had the resources to support you, the History Guy, Dr. Mark Felton, and Drachinfel! You all do outstanding work!

5 minutes into one of my 4th year classes the prof said superheterodyne as if we knew what that meant. Thank you for teaching me lmao

i can’t tell you how much i appreciate the care, attention and humour that goes into your subtitles. thank you!

I'm ashamed to admit it took me about ten seconds for the penny to drop on the 404 joke... ;)

@ChrisGozzardThatPhysicsGuy

5 жыл бұрын

I only just got it from your comment.. :(

@janosnagyj.9540

5 жыл бұрын

@@ChrisGozzardThatPhysicsGuy Me too... Seems like I'm not geek enough :)

Superb, old boy. I learned about Superhetrodyne radios while fixing up a 1929 DeForrest Crosley (2x 245 tube push-pull audio output, 3 227s, 2 226s and an 80 rectifier, if I recall). I picked up off the side of the road. What a machine, I miss her dearly!

It constantly blows me away what engineers in the past were able to accomplish with their circuit designs. Like who just comes up with a way to do things like this? Truly geniuses.

For those of you who had never heard of "beat" in that sense before, here's a fun fact: Deliberately causing beats similar to the first demonstration is what produces the "wub wub wub" sounds in dubstep.

@TheBBQify

2 жыл бұрын

Thats not what that is 🤦‍♂️

Your puns could be considered a crime against humanity. I love you so much

Thanks for this, I'm an extra class ham. My club teaches all of the courses needed for us to pass all of our tests but I never really understood how a heterodyne radio really worked. I did learn about the components in a heterodyne radio and the function of each, but until you did that demonstration with the speakers, I didn't understand it. Now I'm beginning to get a real grasp of it. Thanks for making this.

That was a great video, thanks. I've tried reading about heterodyne receivers (via radar detectors on Wikipedia) before but it never quite clicked for me. Now it all (mostly) makes sense!

SAT TV is almost impossible without this method. There are basically three very high frequencies that can enter and pass through the atmosphere without being dampened. Those frequencies are far too high for copper wiring to be passed to your living room without serious losses. First generation dishes had to be 30ft in diameter or more to get enough signal to the receiver or the receiver had to be real close to the dish. The LNB in the focal point of the dish mixes down the incoming frequency so a common coaxial cable can handle the signal.

@Powertampa

4 жыл бұрын

Though one has to say that coaxial cable is still stressed quite a bit to push that signal. It can get warm and bundled even melt the insulation together. Not fun to deal with in large buildings with lots of those running through the ducts. Most modern installs now transmit the last hundred feet via ethernet which also adds the benefit of wifi tv and recording straight to disk on a nas. Those boxes are expensive though so you only really find them in hotels and multiunit buildings.

@markcondrey2297

4 жыл бұрын

In those early days of satellite t.v. the frequency was ...in the KU band, and the broadcast power was limited by the FCC to 5 watts. This was to limit interference with Ma Bell telecomucations on the ground. Since the orbital satellite was limited to 5 watts, a large surface area receiving dish on the ground was a must! In later years the frecuency was changed on the satellites as we entered the digital age. They were allowed to broadcast more power, requiring a much smaller ground receiving dish.

@numbr6

4 жыл бұрын

No, it is impossible without down mixing. C-Band (2.4GHz) and Ku band (11.7GHz) can only be routed through "waveguides" which are not wires, they are hollow metal cavities that allow the raw GHz signal from the dish to reach the LNB, which is only inches away from the dish focal point. At that point, mix 1 occurs, leading to an IF frequency of 950MHz-1450MHz, at least in North America. That is routable over RG-6 cable from the dish LNB to the satellite receiver inside a home. That cable run can be 40 feet or longer. The satellite receiver does another down mix in frequency to an intermediate frequency that is manageable for IF filter selectivity, and amplification. Given the extremely weak satellite transponders, at least in the early days of C band, some were only 10W, it is amazing this works at all. Even with a 10 ft C/Ku dish, observing a 10W radio source 22000 miles away and getting a viewable signal is quite remarkable. About dampening: Ku band frequencies are affected by rain, so called "rain fade". This is why image quality is lower/lost during heavy rain storms, even for Dish Network. C band is immune to this phenomena. As you can imagine, I'm a serious Satellite TV hobbyist. I've got 2 C-Band 10ft , one 3ft Ku and one 18 inch Ku dishes, all in operating condition. I got into the hobby in 1994, which was well before the "digital transition". There was lots of very interesting things to watch then. There still are, but it is much harder to even find satellites, as nearly everything is digital. I think ARTS and C-SPAN are the only two remaining analog NTSC signals up on C band to this day.

@shana_dmr

4 жыл бұрын

You could get coax fancy enough for Ku band, but the price is quite unfunny;) Using 950-MHz-1450MHz IF allows to use typical dirt-cheap 75 ohm TV/cable grade coax and F connectors, also one could in some cases avoid getting any new cable in existing installation (using diplexer to combine signal from OTA antenna & dish LNB and then splitter at the other end).

@numbr6

4 жыл бұрын

@@shana_dmr Possibly so. However, the consumer satellite market is competing with cable, today. 80s-90s C-Band hobbyists were mostly considered Pirates, except for the 2-3 million satellite subscribers to premium channels. Remember Videocipher / Videocipher II / II+ RS? Back to your topic. As the existing consumer satellite market is exclusively Ku band today, competing with cable, Internet streaming services, anything they can do to keep costs down, they will. Using an IF signal over 5 cents, or less, per foot RG-6 cable is part of that calculation. It has been ever since the C band market was barely a C band market, and before LNAs were replaced with LNBs.

I first heard the term "superheterodyne" in radar detector design. They made it sound like the latest thing and not a holdover from the early days of radio!

What a fantastic explanation. I restore Philco radios, nice to see one on display!

I followed your dissertation as best I could but did not understand a dam thing while being fully engaged, focused, interested, mesmerized, fascinated, and filled with wonder about how people can think in ways to bring sound from frequencies into and out of a speaker ... Thanks. 😃

Thanks for giving me the term "beat frequency". I tune my bass by that, listening for the "waver" in the harmonic tones (octave), and adjusting 'til it goes away, leaving a clean unwavering octave. Now i know what to call what I'm listening for.

Why is there a Nut Glued to the speaker paper? If I may ask

@TechnologyConnections

5 жыл бұрын

What a fine question! The speaker cone was torn in a transit accident, and while I was able to repair it with a special adhesive, it has buzzed really badly ever since. When the chassis is in the case, the front of the case presses against that nut which eliminates the buzz. It actually ended up improving the sound markedly!

@boxman139

5 жыл бұрын

@@TechnologyConnections My grandfather used that old trick! He had a cheap set of speakers with paper cones, and if they ruptured then he would just hot glue them back together. He used the same nut trick to reduce the buzzing, however the sound probably didn't come out as good since the hot glue created an unevenness in the cone.

@marselle6926

5 жыл бұрын

@@boxman139 plus, the pressure will impact the drivers' ability to move freely, which, from my experience, makes it sound worse. But thats entirely subjective

@cheesetipsandtricks8783

5 жыл бұрын

I didn't originally notice this, and went back to look for a hazelnut

@PileOfEmptyTapes

5 жыл бұрын

@@TechnologyConnections Sounds like the surround may have come unglued, it's not an uncommon sight even when the speaker has not been involved in any accidents. Something worth checking in any case.

The beats remind me of choir warm ups in high school. The choir director would have part of us drop a half pitch and listen to the beat so we knew we did it right

@InflatablePlane

3 жыл бұрын

It reminds me of acoustically tuning guitars, drums, and piano strings by ear. Works the same way. The slower the beats, the closer to pitch you were.

Okay the amount of joy that I just experienced from hitting play on this video I've never seen before from KZread because I've never been actively thinking and mulling over in my head a title and then finished the mulling just when I hit play and then you seamlessly pick up the conversation that was going on in my head and steered in a new direction. It was perfect. OMG

It's obvious from what we see and the tone of your voice, you are on a very personal journey, thank you for allowing us to look over your shoulder and enjoy the experience!

You did a better job with this subject than most of the HAM Radio training books and videos I've ever seen. Well done! -W8SDF

I used to look at these circuit diagrams in the 60s and wonder what the hell was going on. Finally when I got to university I found that everything was starting to appear in little balck boxes and all these lovely old fashioned diagrams withs valves (I'm in the UK), capacitors, etc.. had gone. I never really got to look at them and see what was happening. Finally, 50 years later I begin to see what all the fuss was about. Thanks for your videos - they have taught me a lot.

Learned this stuff and how to build a 5-tube superhet bare-chassis in high school in the 60s. Who remembers the 60s, when kids actually learned useful stuff in school? I was an electrical geek from the time I could hook a light bulb to a dry cell. Put myself through electronics trade school and eventually became an electronics tech, trainer, and inventor. It's great to refresh my memory of the days of tubes and condensers. My highest tech work consisted of combining TTL logic chips (gates, inverters, flip-flops, timers, and buffers) to make cool and profitable stuff. Then I went on to teach myself PLC programming. Now I'm retired and I fool around with Arduino. I wish that had been around when I was working.

That is probably the best explanation of a superhet radio that I have ever heard! I built a 10 tube superhet when I was a teen in the mid sixties. I used parts that I had, built it on a Philco tv rf chassis. It sounded great, but I never worked out the tracking so I kept it tuned mainly on one station. :)

You're really good at this. I'm so glad you've decided to keep it up.

7:15 the tuning knob rotates on a ball bearing. wow.

I took an electronics class in the underfunded school in my town in 1976 that still used vacuum tube teaching consoles. I'm sure they trained students in the 1950's interested in becoming TV repair technicians. I transferred to the school that had digital electronics classes. I did enjoy learning the old technology and repaired an old black and white TV while in that class. Swapping vacuum tubes was something you had to be more careful with because of the heating elements, and some of the typically higher charges they could be carrying. I learned not to pick up a TV picture tube by the neck because of watching someone else do it - the neck cracking - and the rest of the tube dropping 10 cm to the desk it was just picked off of. We were lucky the rest of the tube didn't implode. XO

This is the best channel on KZread! It's detailed, but with fun things as well. Thank you so much, Alec!

Thank you, you explained something about how radios work that has always mystified me. Also I lol'd at your 404 joke. When 4:04 rolls around I often think "time not found"

@coopergates9680

5 жыл бұрын

Scheduling ability not found (April 4th)

@RyanTosh

4 жыл бұрын

One interesting fact I think a lot of people don't know is that there is a whole system for these numbers; anything starting with 4 (404=not found, 403=forbidden, etc.) is a user-error, anything starting with 5 is a website error, anything starting with 3 is a redirect, anything starting with 2 is success, etc.

Great job making the complexity of radio reception more accessible.

I love that this channel is usually in the results of whatever weird thing I'm trying to google to find information about.

By the way I love that you're covering radio topics. Please stick with that! I would love to see your explanation of single sideband or FM vs AM etc

That high pitch sound from the headphones hertz my ears

@mac11380

5 жыл бұрын

Watt did you say?

@johnx6670

4 жыл бұрын

As one of our college students said "after a few KHz your ears start to drop off".

So, honestly, I find all of your videos to be great and top-notch, but this one was absolutely amazing. I'd admittedly never really considered how a radio could receive a specific frequency through all the noise out there, but this was a jaw-dropping realization. Kudos, buddy!

6:35 Side-note: In Germany those little drums are still referred to as "Kondensatoren" (Condensers), but it's usually shortened to "Elkos" instead of "Elektrokondensatoren" ("Electric condensers")

beat frequency, thats how we tune our instruments e.g guitar, bass, piano, violin etc great work! Its also music, not just math/science

Now go take an advanced HAM exam and you'll be licensed this is basically as harsh as the material gets

@kevinmencer3782

2 жыл бұрын

You do have to study for it though. If your knowledge of electronics can fit inside a matchbox, there's some stuff you have to pick up on.

The hi frequency tones set off my tinnitus! ❤ your videos!

@ps5hasnogames55

2 жыл бұрын

deserved

+TechConnectify *I got a cursory overview of heterodyne transceivers years ago.* Superheterodyne technology is used in radio systems from Longwave AM receivers to J-band Pulse-Doppler radars; vacuum-tube radios use pentagrid mixer-amplifiers for frequency up/down-conversion in addition to dual triodes, pentodes, and (in the case of transceivers) beam power tubes. Today's digital technology uses a specific type of solid-state diode as a voltage-controlled capacitor for miniature LC tanks in addition to direct conversion for data detection from the receiver IF.

Absolutely love your videos! I'm really excited about teletext and the vinyl video discs in particular. Merry Christmas and happy holidays, keep it up!

"Its Science, Its Math, Its Fantastic." ❤️

I watch these overwhelmingly informative and fascinating videos in a state with legal lettuce, and it's a wonderful treat.

I’m studying for the amateur radio extra exam, and the whole thing is stuff like this in great detail. IDK how my brain has been taking the punishment. But your way of explaining it is very easy to understand. Also, superheterodyne is preferred over software or SoC receivers, because they’re better at filtering out high intensity RF that’s nowhere near the desired frequency. They’re also better with squelch. Cheap radios will go in to receive mode if placed next to a computer monitor, PC, or LED light, even if it isn’t making any sound. Superheterodyne radios don’t have that problem.

You need mixing, NOT just interference. If you measure the beat frequency from two good speakers with a good microphone and then look at the spectrum, you will find no actual spectral line at the desired frequency, because the signals were added in a linear way. You need a nonlinear element to create mixing products.

@TeslaLegend

5 жыл бұрын

Yup, it is the multiplication of LO and the RF (not addition) that is performed by the mixer to produce IF

@TechnologyConnections

5 жыл бұрын

Good points.

@TeslaLegend

5 жыл бұрын

@@TechnologyConnections Excellent video

@russbellew6378

5 жыл бұрын

@@TeslaLegend Actually, the mixer produces the sum and the difference of the desired signal and the local oscillator signal - not their product.

@TeslaLegend

5 жыл бұрын

@@russbellew6378 The mixer multiplies LO and RF waveform, the product of the waveforms will result in difference and sum of the frequencies as in: cos(a)*cos(b)=0.5(cos(a+b)+cos(a-b))

I only just realised that the word radio is related to the word radiation.

@TechnologyConnections

5 жыл бұрын

Radiated audio, pretty much,.

@AceSkates

5 жыл бұрын

@@TechnologyConnections the worst part is I studied physics at university and never made the connection between the two words.

@davidnotonstinnett

5 жыл бұрын

AceRidesBikes that’s the funny thing about words. It’s why phrases like how you could or couldn’t care less change. It’s just sounds that convey meaning, and as long as the meaning is there then it’s good enough

@BertGrink

5 жыл бұрын

I _may_ be wrong, but I believe that it comes from Latin, where it would mean "I radiate", in a similar way as 'Video' means I see, 'Audio' means I listen, 'Ludo' means I gamble, 'Volvo' means I roll.

@EssenceofPureFlavor

5 жыл бұрын

Yup!

When I was young I the early sixties I used to have fun tuning one radio to interfere with a nearby one and now thanks to you I know why this happened.

I just love geeking out by watching you! So good and you are so unapologetic about how you enjoy your work. Bravo! Love your channel, man!

We must credit the genius inventor of superheterodyne Edwin Armstrong who also invented FM radio.

@ralphburns6659

3 жыл бұрын

The greatest genius of the 20th century!!!!!!!!!!

@vaclavcepelak4276

3 жыл бұрын

@@ralphburns6659 And RCA killed this man.

@vinquinn

3 жыл бұрын

@@vaclavcepelak4276 They certainly did. And that is why there was no channel one on analog TV in the USA. It was supposed to be the FM band. The whole Dolby system is just a ripoff of Armstrong's FM noise reduction system of high frequency pre-emphasis and de-emphasis.

@gyrgrls

3 жыл бұрын

@@vinquinn Oh, a discriminator, are you?

@kiowablue2862

3 жыл бұрын

@@vaclavcepelak4276 But his widow got revenge. She took them to court and won ALL of his patent infringement suits.

Damn!! I am again impressed at the level of detail you describe the way radio works! I should note this technique is in fact still used even in digital wireless communications. Look into QAM and DSB-SC demodulation. Other than that you pretty much covered 2 weeks of material I learned in a university graduate class in wireless comm this past fall semester!

@donaldviszneki8251

2 жыл бұрын

Replying to 2yo comment... but demodulation isn't mixing or filtering

@power-max

2 жыл бұрын

@@donaldviszneki8251 mixing down is often a part of demodulation. I guess if you want to be very precise then fine technically it is an intermediate step. whatever haha

@donaldviszneki8251

2 жыл бұрын

@@power-max I guess as an amateur I feel like it's important to get this distinction right, or else I'll be forever confused

@power-max

2 жыл бұрын

@@donaldviszneki8251 My knowledge in the field is only a single 4 credit hour elective from a few years ago haha. That and Wikipedia/google.

I have a General class amateur radio license, and this is the first time somebody explained this concept to where I feel like I truly understand it.

This is the very best explanation of how a receiver works that I have ever run across. Thanks for your hard work and research. I remember having problems with harmonic signals or signals that would ride in with the one that you are tuned to. Back in the days of yor, some people would use single side band modulation and most of us could not understand the garble but we learned that adding a AM carrier to the SSB carrier would make it readable without owning a special SSB reciever.

Great vid...very interesting! I only wish you had mentioned Howard Armstrong, who not only invented the superhet, but also invented regeneration (which allowed the vacuum tube to not only detect, but also transmit radio signals) and frequency modulation. He was a true genius and is the man most responsible for making radio what it is. I consider him--not Marconi or DeForest--to be the true "father of radio."

I read somewhere that superheterodynes were the real reason why soldiers behind enemy lines during WW2 had to avoid using radio except under specifically defined conditions. The local oscillators in their portable units tended to be noisy, which allowed the enemy to triangulate their location whenever the units were powered on, even when they were only receiving. Noisy oscillators also gave away the presence of speed radar detectors, at least the models that were around when I was younger. Many states outlawed radar detectors, so police could detect your radar detector and ticket you, even if they weren't actually using their radar at the moment.

EXCELLENT ANALOGY with the speakers.. demonstrating resonant frequencies

I have to have my Audiologist watch this video. While you had the two speakers simultaineously on my Tinitus disipated. I'm listening to this over and over again

This is how sound cancelling technology works, if I'm not mistaken. Edit: I love the flubs at the end. Sometimes it hertz to talk.

The capacitor in the (breaker points) ignition system of an internal combustion engine is still called a condenser, at least it is in the US.

I love your videos! So informative, you mix tech, history and humour and it’s just awesome!

Harmonic tuning is when you tune the strings of an instrument from the harmonics. Basically you lightly tough a string at certain distances along the length and play harmonic overtones of what the string is tuned to. Because of regular tuning systems there are two harmonics, exactly alike, on two string directly adjacent to eachother, and playing them together is a super simple finger position. By listening for that same beating demonstrated earlier in the video (sorry, I'm too invested to discard this comment to find the time code) you can tune all your strings. Always love it when technology connections overlaps with my own niche interests.

I’d love a video of you discussing AM Stereo!

BTW Destructive interference is how noise cancelling works.

Brilliant design and brilliant explanation! Nice you used WBBM as an example. "Traffic and weather together on the 8's."

Great, simple explanation for this concept. Anyone can give a difficult to understand explanation of a complex problem, to simplify it and making it more easily understood is a true talent.

Mr Carlson's Lab (channel) has a ton of videos on these old radios, how they work and how to restore them. Worth checking out. :)

Great videos, keep 'em coming. Merry Christmas! If you multiply 2 frequencies you get sum and difference of the 2 frequencies, i learned that when I tried to write a software modem... and used it again when I wrote a software RDS decoder. The Goldwave audio editor has an expression evaluator which makes testing and seeing these effects quite easy too.

I'm an electronics technician by trade and we "only" learned intensively about FM. Our radio at school was a Sailor RT2048 VHF maritime radio. A fully synthesized double super (with two intermediate frequencies). We did, however, build an AM receiver for the DCF77 clock signal.

I just found this video because I found that radio at an estate sale and picked it up. I've been searching for videos/tutorials on how to convert it to a internet streamer with a raspberry pi. I was already subscribed to your channel previously and I loved being able to see how my radio would have worked ~80 years ago! Thanks for your work!

I'm surprised you didn't get into the history and development of the Super-Het circuit. Edwin Armstrong was a brilliant inventor who not only invented AM but also FM. Unfortunately he ended up in a massive law suit with RCA over patent rights and came to a tragic end.

@jimsteele9261

5 жыл бұрын

It's almost criminal to talk about the superhet and not mention Armstrong. :-)

@4nradio782

5 жыл бұрын

Exactly! I'm surprised Armstrong wasn't mentioned. It also brings to mind the excellent book--and NPR video--"Empire of the Air". Armstrong is one of the three key players in this fascinating look at the development of radio (from a USA perspective). Ken Burns, of "The Civil War" documentary fame, directed Empire of the Air. There's a full version of it right here on KZread.

@rayceeya8659

5 жыл бұрын

@@4nradio782 I've seen that one. I think it was directed by Ken Burns.

@RandallJennings

5 жыл бұрын

I have the DVD of "Empire of the Air" at my house. I watched it at home one day when I was home from school sick. I even had a license plate, "W2XMN." Didn't Lee DeForrest take credit for the SuperHet?

@RandallJennings

5 жыл бұрын

@@rayceeya8659 I thoght that might've been before Burns' time, but that may have been one of the first uses of the, "Ken Burns Effect." 1992. en.wikipedia.org/wiki/Empire_of_the_Air:_The_Men_Who_Made_Radio

10:22 That was sometimes solved by stuffing that oscillator into a metal cage. Or coating the inside of the radio with a metal. I had seen such stuff pretty often.

As a teenager back in the 1960's I got interested in radio. All circuits except the superheterodyne had trouble separating stations. I remember the old five tube radio well. With the superheterodyne it was possible to pick weak or distant stations. No other radio could detect them.

I LOVE tubes and I love watching your videos on them even though I already know most of this stuff. Great presentation, I have used your videos to explain radio concepts several times now

Great video, I'm a huge fan of your content!! Thanks for sharing your knowledge with us!

Minor detail regarding the mathematics, but your explanation on 'mixing' isn't entirely correct. Mixing two HF signals together means the two signals are in fact mutiplied together, not added: The mixer tube has an amplification circuit that can amplify (multiply) one signal with the input of another, it is a VCA. By multiplying two signals which have a sine waveform, you will produce a pair of signals which are either the sum or the difference of the 'carrier' (local oscillator) and the modulator (the radio front-end). There's some math involved which is fairly easy to look up, but that's the principle on which both AM modulators ánd superhet receivers work -- which also meant making a *trans*ceiver out of a superhet radio was very straight-forward. Heterodyning works best when the signals are perfectly in phase, which renders the highest signal strength, so the invention of the phase-locked loop catapulted the technology into the 21st century, paving the way for television and digital telecommunications, with the basic principle still being used on modern tech like WiFi and 5G today.

@wernerfritsch6436

3 жыл бұрын

Yes, mixing means multiplication. In analog receivers such as the vacuum tube type shown, multiplication of the two signals is performed by adding the signals on a nonlinear transfer curve. That nonlinearity is the key feature of the mixing stage. Any nonlinear curve means that a portion of the input signals are multiplied. Later and better analog receivers have a multiplier circuit as a mixing stage such as a sp-called Gilbert cell. Now multiplying is easy in software.

@MichaelWillems

3 жыл бұрын

Hang on. The frequencies are added/subtracted, right? Not the signal levels. Are we confusing the two here?

@Stoney3K

3 жыл бұрын

@@MichaelWillems Correct, multiplying two signals in the time domain means adding or subtracting their frequencies. Adding the signals together and passing it through a nonlinear fillter (like a diode or NPN transistor) has the same effect.

@MichaelWillems

3 жыл бұрын

@@wernerfritsch6436 Of course. I should have remembered that. Thanks, now it's clear.

@LightningHelix101

2 жыл бұрын

@@wernerfritsch6436 didn’t these circuits basically turn on and off the input at the oscillator frequency by having the local oscillator change the bias of the pass stage? So it’s performing mixing like the Gilbert Cell, but with no input balancing

Thanks for that explanation, I really enjoy the amount of detail you include in all of your videos.

My dad was an electrical engineer and ham radio operator, he built all his gear form scratch and always had hand drawn schematics he was working on. Oh and collecting old TV's and radios for parts when we went to the dump. =)