[HN Gopher] What happens when you touch a pickle to an AM radio ...
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What happens when you touch a pickle to an AM radio tower
Author : _Microft
Score : 332 points
Date : 2024-09-06 03:16 UTC (19 hours ago)
(HTM) web link (www.jeffgeerling.com)
(TXT) w3m dump (www.jeffgeerling.com)
| pjerem wrote:
| OK that was pretty unexpected :)
| kylehotchkiss wrote:
| Being curious is a virtue. Now I know how to avoid having to deal
| with a copper flavored pickle if I get too close to my nearest AM
| transmitter.
| greesil wrote:
| Not to state the obvious, but isn't there a damned good reason
| the tower is fenced off? You can see the fence in several of the
| pictures.
| stavros wrote:
| You can also see the reason in several of the pictures.
| unkeen wrote:
| How is it possible that these towers have not been made more
| difficult to access? Is it usual for them to be secured only by a
| low fence?!
| mcpherrinm wrote:
| The AM radio tower that I know is near me has a short wooden
| fence close to the tower, and then a larger area surrounded by
| a high fence with barbed wire tops and warning signs.
| qwertox wrote:
| As soon as some kids jump over the fence and at least one of
| them ends up in a hospital with a severe condition, those
| fences will get replaced.
| hinkley wrote:
| Technically the morgue is in the hospital...
| ablation wrote:
| Death is a pretty severe condition, too.
| xattt wrote:
| Highly incompatible with life.
| pantulis wrote:
| Sounds bad, is it reversible?
| lesuorac wrote:
| Yes but it takes 3 days.
| function_seven wrote:
| They tried to confirm this anecdote with a proper blind
| study, but the study kept proclaiming, "I can see now!"
| hinkley wrote:
| And several doctors have to interact with you even if
| you're dead.
| TeMPOraL wrote:
| The tech is so old-school that it predates the fear culture.
| pewu wrote:
| There's a broader area protected by a high fence with barbed
| wire. They had access there, cause the father is a radio
| engineer and have friends on various sites.
| geerlingguy wrote:
| It's also in bordered by two farms, with a flood plain across
| the street, in a rural part of St. Charles County, in MO.
| Granted, home builders keep building subdivisions closer and
| closer, but just 10-15 years ago the closest residence was a
| mile or so away (outside the couple farm houses).
|
| There's also danger/warning signage around the entire
| property, on all fences (including those around the towers).
| linuxguy2 wrote:
| Is that the KH0J transmitter? I've driven past that
| countless times and it seems so run-down I've often
| wondered if it was still transmitting. So many times I've
| wanted to park in the lot and take a gander... Probably for
| the better that I haven't!
| geerlingguy wrote:
| Yep! Honestly this site is about average in terms of
| local tower site upkeep. Many station owners let their
| sites run a bit wild, unfortunately.
| tpoindex wrote:
| Seeing the frequency on the sign with the FCC station ID
| brought back fond memories of the former licensee, KIRL.
| I listened to 1460 in the late 60's and early 70's when
| it played top 40 rock and roll. A nice alternative to the
| top 40 powerhouse at the time, KXOK 630.
| razakel wrote:
| There'll be a higher external fence for access by vehicles and
| people who need to go near the tower (someone is mowing that
| grass), the short fence is just a reminder to go no further
| unless authorised.
| _joel wrote:
| Jeff's dad works there :)
| lupusreal wrote:
| Most train tracks don't even have a fence.
| ljf wrote:
| I mentioned over dinner at my parents house (about 20 years ago)
| that I'd read that running 240v through a gherkin would cause it
| to glow - and pretty much as soon as dinner was over, my father
| and I had the experiment set up.
|
| Gherkins and even pickled onions glowed brilliantly. I set up a
| basic site to share the video we'd taken and details of the
| experiment, and shared it to B3ta. Sadly all lost to time.
| hinkley wrote:
| Pretty sure my high school physics teacher did this one.
| bsder wrote:
| "WRL Technical Note TN-13 Characterization of Organic
| Illumination Systems" https://simh.trailing-
| edge.com/semi/docs/WRL-TN-13.pdf
| vatys wrote:
| _Further testing indicated that the taste was neither
| enhanced nor diminished, but remained ''very much like a
| pickle.'' Our conclusion is that the culinary potential of
| electrical stimulation is limited._
| voidUpdate wrote:
| I think bigclive would disagree about that, he is known for
| electrocuting his sausage and sometimes enjoying the taste
| after
| smolder wrote:
| This is gold and I will be keeping this .PDF in my rather
| limited data hoard.
| dekhn wrote:
| One of the authors, Alan Eustace, was an exec at Google (in
| the days when execs at Google had a clue) and also holds the
| record for highest jump (135K feet).
| edm0nd wrote:
| Bill Gates can actually jump over a chair. og Tech execs
| are awesome at jumping it seems!
| xattt wrote:
| I see a similar comment at the end of the original article that
| mentions that pickles incandesce. Is it true incandescence or
| is it just internal arcing?
| ljf wrote:
| I wish I had the video still - maybe I need to run the
| experiment again, this time with my kids?
|
| Tangent: I look back sometimes and realise how stupidly lucky
| I was to have a father who not only humoured my crazy ideas,
| but actively encouraged them - I only hope I am doing the
| same for my kids.
| kallistisoft wrote:
| Many many moons ago I connected a pickle to a 10kv
| transformer - in that case at least it was definitely the
| result of arcing :)
| kazinator wrote:
| If it's forty below, your pickle freezes to the tower and you
| have to call 911.
| saagarjha wrote:
| Bonk
| tabtab wrote:
| End result of horny people watching "A Christmas Story".
| surfingdino wrote:
| That tower is TikToker magnet.
| chilling wrote:
| Sometimes I feel sorry for myself when I read articles like this.
| At the end of the page, I usually start asking myself, "Why was I
| even curious about this?" Anyway, I will probably use this
| knowledge in 10 years. Hopefully (so far, that's how things have
| been going for me).
| thepuppet33r wrote:
| I mean, sometimes it's edifying to just find out cool stuff
| about the world and the ways it feels a little magical. We have
| a local power company here that has a trailer with a set of
| power wires and a transformer on it, and at their events, a
| TRAINED linesman will do tricks with it. They spend the first
| half of the presentation doing safety instructions ("don't
| touch the wire because you'll get fried", "here's how squirrels
| can cause shorts") and the other half doing magic tricks like
| making pinwheels spin, metal film levitate, etc. Fun stuff to
| see.
| bjornsing wrote:
| A grounded pickle. The word grounded is very important here, and
| missing from the question in the title.
| geerlingguy wrote:
| We also tested a floating hot dog (we detached the leads from
| the ground wire, so it was basically the hot dog and about 3'
| of unattached copper wire), and it still made little sounds as
| it was touched to the tower. We didn't have a way to safely
| touch the hot dog with no extra wire attached, unfortunately.
| eternauta3k wrote:
| I wonder if a floating human would still get zapped, due to its
| non-trivial capacitance to ground.
| geerlingguy wrote:
| Many tower climbers historically jumped onto AM towers
| (usually at lower power levels), and they still felt little
| shocks climbing the tower.
|
| Even if the tower is off, if it's near any other sites, they
| can draw a significant amount of RF (as a good AM tower is a
| good AM antenna) and if it's not grounded, that RF will go
| through a person too!
|
| This specific tower site doesn't require lights on the
| shorter towers, so it's not an issue here, but for sites with
| lights needing replacement, most nowadays turn off power to
| the tower and ground it before anyone climbs the tower.
| bityard wrote:
| Not to do with RF, but there are old YT videos of HV linemen
| who literally hop out a helicopter onto an HV transmission
| line to manually inspect it. As the helicopter approaches,
| they hold out a long pole which is bonded to the aircraft's
| frame to bring it to the same potential as the line. It
| starts arcing quite a few feet out until the potential is
| neutralized and the lineman can "safely" step out onto the
| line and start working.
|
| I imagine this inspection work is done with camera-equipped
| quadcopters nowadays.
| mike_hearn wrote:
| https://www.youtube.com/watch?v=oBJyyEAw-6g
| Supernaut wrote:
| What I didn't see explained in these videos, and which I'm now
| curious about, is the mechanism by which the hot dogs convert the
| radio signal into sound? I understand how a loudspeaker works,
| but since food products typically don't contain coils and
| magnets, how was the AM signal being demodulated and converted
| into sound waves?
| winrid wrote:
| Just the sparks themselves can produce audio! [0].
|
| [0] https://youtu.be/lbubH1FovFc?si=T7Q7CqDNz3NtbLFl
| eternauta3k wrote:
| Putting an AM signal through any non linear process will give
| you (shitty) demodulation.
| ryukoposting wrote:
| I'm not an RF engineer, but I'll take a stab at it:
|
| With any modulation scheme, you have the "carrier signal" and
| the "message signal." The carrier is the frequency you dial
| into your radio. The message is the thing you listen to -
| voice, music, whatever. Those two get "modulated" together and
| blasted out over an antenna, and ta-daa, radio!
|
| Amplitude Modulation is really, really simple. It's literally
| just the product of the carrier signal by the message signal.
| The carrier signal is a really high frequency relative to the
| message, which is where I'm guessing the "resolution" of the
| signal comes from.
|
| Now, hot dogs.
|
| Hot dogs probably don't resonate very well. Or, maybe they do,
| but just a little bit at low-ish frequencies - up to a couple
| thousand Hertz, but no higher. If that's the case, then a hot
| dog would act like a low pass filter! Since AM is just the
| product of a high-frequency carrier and a low-frequency
| message, a low-pass filter could ostensibly leave behind
| something that resembles the message signal.
|
| Proper AM demodulation involves diodes and whatnot, but I can't
| imagine a hot dog has semiconductive properties.
|
| Now, if it's an electrical signal, why can we hear it through
| the hot dog? A hot dog is not a good antenna. It's bad at
| inducing an electromagnetic field around itself. Instead, it
| converts the energy from the radio tower into mechanical force
| - motion, like the way a speaker moves.
|
| All of this could be wrong. Maybe the hot dog isn't serving as
| a filter, and it is indeed reproducing the AM carrier signal -
| it's just too high of a frequency for us to hear it. I don't
| remember my signal processing classes well enough to say for
| sure. Maybe my whole "hot dog is a speaker" explanation is
| bunk. Maybe hot dogs really are semiconductors. Not sure.
| fuzzfactor wrote:
| The closer you are to the source of the radio waves, the less
| sensitivity will be needed in the receiver, and less audio gain
| you will need in your reproduction device.
|
| And the less efficiency you will need in your speaker, aka
| transducer.
|
| At these conditions there is also no more need for user-
| supplied power for the audio output to become audible, so no
| electronic amplification is needed.
|
| As you get closer to the source the need for a carefully
| crafted, somewhat complex, receiver circuit will diminish, and
| when there is only one audio program being broadcast on a
| single radio frequency, no need to discriminate between
| different frequencies.
|
| In an electronic radio, after the single radio frequency
| channel has been selected, then the radio frequencies are
| filtered out before electronic gain is applied to the audio
| alone. Otherwise audio power would be wasted amplifying radio
| frequencies that are not audible.
|
| The hot dog emulates all of these requirements, except for the
| receiver sensitivity that would be needed to respond very
| strongly from a distance. No noticeable demodulation until it
| touches the source directly.
|
| Then as a single-component device, a low-efficiency transducer,
| it conducts the full undemodulated RF power.
|
| Its frequency response as a transducer is probably not even as
| high as human hearing can go, and people can not hear any RF
| being reproduced anyway, so all you hear is the audio.
|
| Plus when it comes to hot dog conductivity, who could forget
| this futuristic home appliance from the 1960's:
|
| Amy demonstrates the Presto Hot Dogger
|
| https://www.youtube.com/watch?v=LMbQmp7yC-Y
| boneitis wrote:
| I haven't watched it yet, but they state in the beginning of
| Geerling's vid that Plasma Channel (run by the third guy in the
| video) should be covering this in their own simul-published
| video.
|
| https://www.youtube.com/watch?v=NowhPAMDOTo
| tokai wrote:
| Reminded me of this old classic video of some intrepid guys
| getting tufts of grass to play music with the help of a radio
| tower.
|
| https://www.youtube.com/watch?v=b9UO9tn4MpI
| _joel wrote:
| Don't tell Rick Sanchez
| BoxOfRain wrote:
| A soapbox of mine here in the UK is that since BBC and commercial
| AM radio is more or less dead with the remaining stations set to
| close over the next few years, Ofcom should open up the band to
| low-power broadcasting hobbyists. These already exist
| illegitimately and have done for decades, you can pick up plenty
| from the Netherlands and a few domestic ones as well on a
| sporadic schedule.
|
| It would be a nice thing to do from several angles I think and
| would help drive interest in radio as a technology in general; as
| well as building transmitters and aerial systems, there's things
| like setting up an audio processing chain to get the best
| possible modulation and being a disc jockey which will always
| have a bit of a buzz from being on the 'real' radio. If valves
| and vintage equipment are involved it would be an interesting
| form of technology history preservation and 'living history', and
| there's also an environmental angle where old analogue radio
| receivers could be prevented from becoming e-waste.
|
| There could be a minimal licencing regime to demonstrate the
| individual is not a complete numpty and a fee to PRS for music
| rights along the lines of how streaming works. Maximum power
| could be kept low especially at night to avoid interfering with
| countries in Europe where AM radio is still an active platform,
| and I don't think there'd need to be a lot of enforcement with
| respect to content since you'd only realistically be broadcasting
| to other anoraks. Additionally there's already precedent for non-
| profit stations where the medium of AM itself plays a role, for
| example former pirate Radio Caroline which uses it to keep its
| historic radio ship in operation.
| bArray wrote:
| I think lots of communities running localised AM stations could
| be super cool.
|
| > There could be a minimal licencing regime to demonstrate the
| individual is not a complete numpty [..]
|
| I wouldn't bother and it just adds more resistance.
|
| > [..] and a fee to PRS for music rights along the lines of how
| streaming works.
|
| I think the quality is so low and the audience so few that it
| wouldn't matter.
|
| > Maximum power could be kept low especially at night to avoid
| interfering with countries in Europe where AM radio is still an
| active platform, [..]
|
| Yeah, not sure where the sweet zone would be though.
|
| > [..] and I don't think there'd need to be a lot of
| enforcement with respect to content since you'd only
| realistically be broadcasting to other anoraks.
|
| That would be the point, just low-power decentralised
| communities. Only real reason to get involved is if the power
| goes too high or band use is not respectful to other users.
| BoxOfRain wrote:
| That's a good point about the regulation given the low
| quality, I suppose if it was a problem they'd already have
| gone after public SDRs capturing the broadcast bands.
|
| It doesn't sound like the sort of thing Ofcom would go for as
| I suspect it'd be seen as making unnecessary work for them,
| but you never know. Someone there clearly likes Radio
| Caroline (despite Ofcom's predecessors having fought to close
| it for decades in its pirate days) because they got awarded a
| 1 kW and later 4 kW power limit when AM community stations
| are usually much lower, so there might be sympathy towards
| the idea of more community AM generally. It would be a
| difficult thing to lobby for politically I think because it's
| such a niche interest, but it'd be an easy thing for them to
| do and there's not much else that part of the spectrum can be
| used for easily.
| dgacmu wrote:
| The reason for licensing is similar to the reason for
| licensing ham radio: you get a slightly higher level of clue
| about not creating huge amounts of accidental interference,
| and a point of contact to yell at if they do. and a little
| safety education....
|
| The ham radio licensing process is not onerous.
| bArray wrote:
| I went through it (admittedly many years ago), but ham
| licensing wouldn't really do anything for safe radio
| operation. I learned the real stuff from two very
| experienced operators.
|
| It would probably be easiest to regulate the transmitters
| than the people using them.
| dgacmu wrote:
| Me too, but at least there's some stuff in there (for
| extra) about RF safety. Not a lot, but enough that
| someone with an extra class license should know that they
| need to go do some calculations about the safe distance
| from their antenna based upon radiated power, etc., and
| hopefully that's enough to get them to actually do it.
| IIRC there was a question or two in the pool about RF
| burns.
|
| Not much in there that would stop you from electrocuting
| yourself, though, I agree.
|
| Licensing the transmitters is the FCC's other standard
| approach and would probably work except for radiated
| power safety and antenna issues -- which can be pretty
| big. You could easily create significant interference or
| hazard from a botched antenna or connection. (But also
| which you don't learn enough from just passing the exam.)
| WarOnPrivacy wrote:
| > I think lots of communities running localised AM stations
| could be super cool.
|
| I agree. My US thoughts on the likelihood of (and potential
| outcome of) opening AM to the public - they all focus on
| content.
|
| US AM content is mostly religious, conservative, sportsball
| and ethnic-usually-Latino. Those are the opposing interests
| to opening AM. To counter opposition, I'd open the upper half
| of the AM band to the public. To ease friction, I'd lift any
| regulatory fees and offer subsidies to offset costs.
|
| As for content on the newly open bands, I could see at least
| 2 of the current AM interests firehosing cash to saturate the
| newly open bands and markets (which might unwind over the
| long term).
| the_arun wrote:
| Where is the energy coming from? The power source towers
| are connected? Already our electric bills are super
| expensive. How can we run localized AM Stations with high
| cost of maintenance?
| bArray wrote:
| It depends how powerful, but running a 1kW station could
| be feasible for a home owner. Also I imagine they would
| generally have operating times which would greatly reduce
| operational overheads.
| WarOnPrivacy wrote:
| True and a community station might have community content
| and funding. Buying airtime is as old as broadcasting.
|
| It could also power down for a bit. I'm old enough to
| remember commercial TV going off-air overnight.
| discretion22 wrote:
| I think you are looking for a Restricted Service License :
| https://www.ofcom.org.uk/tv-radio-and-on-demand/restricted-r...
| neilv wrote:
| Just yesterday, I was talking with a colleague in the UK, who's
| selling a serious-sounding amateur radio tower.
|
| Whilst waiting for regulatory change, besides amateur radio
| station, are there other fun RF things one could do with such a
| tower's height?
| geerlingguy wrote:
| Stick a meshtastic node at the top of the tower and be the
| envy of every meshtastic user!
| thelastparadise wrote:
| I'll be keeping my pickle far away from any radio towers.
| tabtab wrote:
| If you simply had my personality, your pickle would never be at
| risk of getting used.
| JohnMakin wrote:
| I always wonder if there would be any pain in the death that
| results from touching one of these. I'd assume it'd be instant
| from the electricity traveling through your heart - or would you
| just burn up more slowly?
| tigerlily wrote:
| Might end up in hospital for three days, and then die.
| alnwlsn wrote:
| I've been gently bit by a small Tesla coil before (100s of kHz
| but lower frequency than AM). There is absolutely no
| 'electrical' pain to speak of - it is nothing like getting a
| static shock or touching line voltage. However, it still hurts
| because it burns you, like touching a tiny flame, which is the
| only way I could tell anything was happening. It also vaporizes
| your skin, which smells terrible.
| gosub100 wrote:
| it may not kill you. the ways that electricity harms the body
| is unpredictable. Depends on things like bare skin vs gloves,
| humidity, sweat, what phase your heart is in at that exact
| moment, and probably many more factors. since the voltage is
| oscillating very quickly, it _may_ not cause your muscles to
| lock up, so you _may_ just get the zap of your life and bounce
| off. Whereas other types (non-RF) electrocution cause the
| muscles to lockup and for them to remain in contact with the
| voltage, which increases the chances of death.
| JohnMakin wrote:
| All I'm reading from this is "electric shock - nature's
| russian roulette."
|
| What you wrote makes sense from my layman's understanding.
| thanks!
| justanother wrote:
| I understand he got permission and everything was checked out by
| actual RF eggheads, but damn. I won't even change a HV run
| capacitor unless i'm wearing crocs, standing on cement, and
| wearing the rubber oven mitts. And even then, I keep one hand
| behind my back. Because there have been accidents, and they hurt
| (the pool pump run cap fails approximately annually in this
| climate and if I paid someone to change it every time, I'd be a
| lot poorer).
|
| That said, the food demodulating the signal into audible noise is
| badass.
| shepherdjerred wrote:
| Why standing on cement? Wouldn't cement be considered a ground?
| alexjplant wrote:
| Indeed it is. Anybody who's spent time jamming in old
| basements with bad ground or two-prong plugs has learned this
| the hard way via a microphone or guitar (myself included).
| Shoes are essential - not even flip-flops are good enough
| because even something as simple as walking across a wet lawn
| will leave enough residual moisture to zap you.
| SoftTalker wrote:
| Just short the terminals with a screwdriver before you touch
| anything else? (Look away in case there's an brief arc flash)
| justanother wrote:
| Yeah, I try to bleed it with a long-handle screwdriver for 30
| seconds. In fact, the couple times I've managed to zap myself
| was with residual current even after that, so I can't imagine
| what the full potential is. It's just a no-fun job.
| FiatLuxDave wrote:
| Oh man, that reminds me of a mistake I made a few years back.
|
| I had opened up a motor controller to fix it, and I knew to
| discharge the cap before messing around inside. I applied a
| screwdriver across the terminals to short it out, and was
| rewarded with a beautiful long and skinny arc as the
| screwdriver came into contact. I said out loud, "That was
| cool", and my coworker sitting behind me said, "What was
| cool"? I told him that I had just shorted out the cap and the
| arc looked really cool. So he said, "Can you show me?" I said
| sure, and plugged the controller in for a few seconds to
| recharge it, then unplugged it and proceeded to repeat what I
| had just done.
|
| What I had forgotten was that previously the motor controller
| had been unplugged overnight. When I touched the screwdriver
| to the freshly charged capacitor, there was a boom, a three
| inch fireball, and the end of the screwdriver was completely
| gone. As I sat there thunderstruck, my coworker said, "You're
| right. That was pretty cool".
| jdironman wrote:
| Well, your comment was my deep laugh for the day. excellent
| story. When I was younger, I saw my father working on a
| ceiling fan...while it was on. I asked him why he did not
| flip the breaker first and he said "well, as long as you
| don't touch both wires at the same time, you'll be fine "
|
| Fast forward a few days later I am at school, and I see in
| one of the outlets one of the prongs for a power cable had
| broken off in it. I remembered his advice about not
| touching both sides and proceeded to try and pull it out
| using my fingers...you can probably imagine what happened.
| It grabbed hold of me for a few seconds and a lesson was
| learned.
| SoftTalker wrote:
| In theory, if you were wearing rubber shoes and not
| touching any other path to ground, you would have been
| fine.
| quickthrowman wrote:
| Ideally you'd short a run cap with a suitable resistor, but
| you're right, short the cap right after de-energizing the
| motor circuit before touching it with your hands.
| fortran77 wrote:
| Cement is surpisingly conductive. I have a thick rubber mat I
| stand on when doing high voltage (CRT, etc) repair work, and
| even then I have a full set of rated protective gear, and
| precautions (one hand in pocket, etc)
| chadcmulligan wrote:
| you can light up fluorescent tubes as well
|
| https://youtu.be/SDL9O2Fwb64
| geerlingguy wrote:
| We actually tried that experiment; the tubes we had were a
| little older, so not sure how much that affected it vs the
| power at this site (the middle tower is 7 kW, which is a lot
| less than the 50 kW towers at more mid/high power AM sites).
|
| But it didn't light up near the tower. It did near the RF
| circuits above the phasor, though!
| amelius wrote:
| Why isn't there a bigger fence around it?
| JCM9 wrote:
| For folks wondering why these sort of videos (there are lots on
| YouTube) always focus on AM towers:
|
| 1. On AM the radio energy literally pulses (the amplitude
| modulation) and thus the arcs of plasma will pulse too thus
| creating the audio noise. AM has a carrier wave that's constant
| but the two sidebands of signal pulse from zero energy at silence
| to more power the louder the sound being transmitted. FM signals
| broadcast essentially the same power all the time since it's the
| frequency and not the amplitude that's changing.
|
| 2. Because the signal frequency is much lower on the AM broadcast
| bands the wavelength is much larger and thus the antennas are
| much bigger. On AM the tower itself is typically the antenna vs
| FM radio where the antenna is typically only a meter or two long
| at the top of a very tall tower. That's what makes AM towers more
| dangerous as the tower can be carrying many kW of energy and if
| you touch it you'll go zap zap. The towers typically sit on top
| of a ceramic insulator to insulate them from the ground whereas
| FM towers typically just are attached right to the ground
| (although with grounding straps for lightning protection).
|
| Finally (some folks don't always know this) you can operate AM on
| the frequencies typically used for FM... it's just a mode and
| works on any frequency. Aviation radios operate on AM but in the
| VHF band near FM broadcast frequencies.
| timr wrote:
| Another thing to note, since people seem to be focusing on the
| RF aspect of this: there's 20-30 Amps running to the tower in
| this video. If your body is the connection to ground for a 20
| Amp current, from any source, you're going to have a lot more
| to worry about than a burnt pickle (I guess it's cool that
| you'd make radio sounds while you died?)
|
| When they put the pickle/hotdog/whatever an inch away from the
| tower _without actually touching it_ , it doesn't even get
| warm. This isn't RF, it's just standard-issue AC electrocution.
| Maybe the one "radio" thing here is that the ground underneath
| a tower like this is essentially a big metal mesh, but even
| that isn't a factor -- they're literally hooking a jumper cable
| from the pickle to ground.
| geerlingguy wrote:
| RF burns are a lot different than electrocution-style burns,
| though. But I'm not an expert on either topic, I'd defer to
| some people who know more about it.
| MisterTea wrote:
| > electrocution-style burns
|
| Do you mean burning via resistive heat dissipation from
| current flow through flesh? There are also burns from
| plasma in arc discharge events. An arc discharge to the
| body can produce both.
| timr wrote:
| Definitely, but this video is not that.
| geerlingguy wrote:
| Same disclaimer: I'm not an expert on this... but I have
| been talking a lot about RF burns and arcing with RF
| engineers, and I think there's more nuance to this.
|
| It would be interesting to see the difference grounding a
| hot dog through 7 kW AC (60 Hz) and seeing any difference
| in internal heating and arcing. Maybe a topic to explore
| in another video--especially if I can get access to a
| transmitter manufacturer's testing lab...
| timr wrote:
| Sure. I'm not trying to suggest that it isn't a factor
| _at all_ , just that it's not what's ablating the hot hot
| dog/pickle in this example. I wouldn't want to sit next
| to a working AM tower and have lunch or anything.
| runjake wrote:
| Anecdotal: I was cooked by some pretty powerful ECM
| [electronics countermeasures] gear, because an ECM officer
| was dumb and had his equipment turned on while on the
| tarmac. My abdomen was up against the area where the
| antenna was, about 6 inches away.
|
| No outward signs of injury, I just felt an internal burning
| sensation and severe nausea pretty quickly. I was feeling
| okay after about a day or two. I never did get checked out
| by medical, so no clue of what permanent damage was done.
| hermitcrab wrote:
| I had no idea that radio towers used that sort of ampage.
| timr wrote:
| I might be misremembering the tower (i.e. I might be
| remembering the amperage for a 50kW tower), but they
| definitely do.
|
| Amperage on a 6kW tower will still be more than enough to
| kill you.
| geerlingguy wrote:
| 16A on this full array, as measured by the RF ammeter
| feeding the phasor in the transmitter building.
| pclmulqdq wrote:
| 50 kW is a respectable AM station, while 6 kW is pretty
| short range.
| ck2 wrote:
| The history of AM radio and the invention of the mechanical
| sparkgap transmitters by Reginald Fessenden is absolutely
| fascinating.
|
| Imagine only having telegraphs and morse code and amateurs
| listening every night to the spark noises in morse then
| suddenly in 1906 (first done in 1900 !) you hear voices and
| music!
|
| https://en.m.wikipedia.org/wiki/Reginald_Fessenden
|
| can't seem to direct link the photos but scroll down to see
| what you are talking about with the base of the tower being a
| massive insulator
|
| scroll to: Brant Rock, Massachusetts, facility
|
| https://en.m.wikipedia.org/wiki/Reginald_Fessenden#Rotary-sp...
| jhallenworld wrote:
| You can still see operating Alexanderson Alternators running
| at SAQ (Grimeton Radio Station). Not AM, but the same
| equipment was used for AM by Fessenden.
|
| https://en.wikipedia.org/wiki/Alexanderson_alternator
|
| https://www.youtube.com/watch?v=yYZjz745yGA
| CobrastanJorji wrote:
| Why would we want aviation radios to operate in AM? Is it just
| that we standardized on AM before the 60s, it works well
| enough, and migrating would require a worldwide effort? Or is
| there some interesting advantage to AM for planes? Maybe
| superior range?
| K7PJP wrote:
| AM doesn't exhibit the capture effect, so you can hear
| multiple transmissions at once.
| https://en.m.wikipedia.org/wiki/Capture_effect
| gwbas1c wrote:
| > The ability to receive multiple signals simultaneously is
| in some cases considered beneficial and is one reason that
| the aviation industry, and others, have chosen to use AM
| rather than FM for communications.
| retrac wrote:
| It's also possible to detect the presence of an AM
| transmission (if not necessarily decode) at a much lower
| received power than with FM. With FM there's little in the
| way of graceful degradation. As signal strength falls it
| can go from full fidelity to silence with very little
| transition.
| dumbo-octopus wrote:
| This makes AM radio more fun to listen to, as you get knobs
| for both your radio and your mental "tuner". At night, you
| can pretty consistently hear 3+ broadcasts at once, and
| listen to them all simultaneously a la overhearing many
| conversations at once in a busy room.
| nsxwolf wrote:
| One reason is that AM signals blend together whereas with FM
| the stronger signal will tend to "capture" the others and be
| the only one heard. This matters a lot in busy airspace where
| multiple people may be talking simultaneously.
| kmbfjr wrote:
| Audio loudness is correlated to signal strength, so it is
| clear a very strong signal is from a source that is close,
| important to know in aircraft.
|
| Two transmissions will produce a heterodyne (whine) due to
| the offset of carrier frequencies, so you hear both and the
| tone to know there are two transmitters. On FM, you'd hear
| only one, the strongest who captured your receiver.
| mlyle wrote:
| To answer you in a different way:
|
| Today we would build these systems with FM or digital voice.
|
| But there are enough advantages we've gotten used to
| (graceful degradation, better handling of doubling, etc...)
| that it's not really unequivocally a win to switch to FM.
| There would be downsides that anger existing users, _and_ it
| would be expensive, _and_ the net benefit would be relatively
| small.
| upofadown wrote:
| >Is it just that we standardized on AM before the 60s
|
| This one mostly. As otherwise mentioned, there is some
| advantage in the case of multiple transmissions at once for
| AM, but in practice both are often entirely garbled. The loud
| tone caused by any slight difference in transmit frequencies
| is the big indicator that something has gone wrong. If one
| signal is much stronger than the other then that tone will be
| very faint and will likely be missed. So AM has something
| like FM capture effect in that case.
|
| AM has allowed for very narrow channels on the aviation band.
| In Europe mostly, the channels are only 8.33 kHz apart.
| Typical narrow band FM voice communication requires 12.5 kHz.
|
| Since the end points in aviation are usually within line of
| sight of one another, radio communication is very easy. Any
| modulation method would work well. Of course in practice this
| means that the equipment is allowed to degrade that much more
| before anyone gets around to fixing it...
| JosephRedfern wrote:
| I'm curious as to how much paperwork was involved here. Was the
| pickle grounding out the transmitter and (presumably)
| interrupting the broadcast not an issue?
| awful wrote:
| side comment; Cub Scout project books of the 1960s, as I recall,
| had you make a hot dog cooker by connecting line voltage to two
| nails through a board...
| SoftTalker wrote:
| There was actually a kitchen appliance that did this, we had
| one when I was a kid:
|
| https://www.youtube.com/watch?v=029jcmv4tIU
| awful wrote:
| Haha; Thank You for sharing that.
| pacaro wrote:
| The tech trivia related to this that springs to mind is that the
| DEC Alpha processor was known internally by the code name EV,
| which stood for "Electric Vlasic" -- although the suits backfit
| this in to "Extended VAX".
|
| (Vlasic is an American pickle brand.)
| dekhn wrote:
| well, alan eustace who's on the DEC electropickle paper also
| worked on the alpha, I bet he suggestedit.
| jhallenworld wrote:
| A thing that just happened in Boston is that Bloomberg swapped
| their relatively low power transmitters with iHeart's Alternative
| Rock 92.9. This is awesome for Bloomberg's reach, but it means
| that we now have an AM rock station, probably for the first time
| since the 1960s: 1330 AM. We'll see how long this lasts.. Red Hot
| Chili Peppers on AM right now..
| grugagag wrote:
| Is pickle a new term for hot dogs? Probably similar conductors
| are congruent in this case, the heating/buring makes a lot of
| sense but what I wonder though is how it produces sound.
| fortran77 wrote:
| On a related topic, they used to sell to consumers hot-dog
| cookers that just put mains voltage through a hot-dog. Here's Big
| Clive pumping 2x the rated volage through one:
| https://www.youtube.com/watch?v=n2ZZbuOeNmw
| walrus01 wrote:
| As a sort of a side note for everyone who thinks AM radio is dead
| as a useful medium, they've probably never lived and driven a car
| in a city that has:
|
| (a) a 50kW AM radio station with frequent and accurate traffic
| updates, often much better detail than what you can get from
| using google maps or waze or similar, and
|
| (b) massive, frequent traffic problems and congestion at major
| bridge and tunnel locations.
|
| It's still a very useful thing to have when driving and you don't
| need to take your eyes off the road at all.
| topspin wrote:
| In the taxonomy of RF circuits, the pickle is an (extremely
| inefficient) direct-conversion receiver.
|
| I've seen at least on video of this being done with a wrench,
| where the RF current forms a visible arc through the air to the
| wrench.
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