Author Topic: how does RF feel/taste? how about rf injury?  (Read 4645 times)

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Offline CopperCone

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how does RF feel/taste? how about rf injury?
« on: July 08, 2017, 02:38:26 PM »
Has anyone had the experience of feeling or tasting RF?

I generally don't like touching or licking things connected to the outlet, and I don't have a battery powered lower-voltage RF source available, but if someone does, how does it feel on the hands and taste on the tongue? Typically I worry that something connected to mains can short out and kill me, so I avoid touching anything but ground, even at low voltages/isolated.

How about RF injuries (i.e. higher energy)?

I kind of felt a high frequency before, being zapped by a 10kv boiler transformer at 10khz (i think?), which nearly floored me, but I wondered how the body responds to things.. from low to high frequencies.

Can you still taste something in the GHZ if it does not have enough energy to cause thermal burns, like licking a 9V battery? does anyone care to lick a sweep generator?

« Last Edit: July 08, 2017, 02:41:11 PM by CopperCone »
 

Offline WastelandTek

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Re: how does RF feel/taste? how about rf injury?
« Reply #1 on: July 08, 2017, 02:41:55 PM »
headache, sore eyes, feels like you been kicked in the balls the next day...happened to me twice
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Offline blueskull

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Re: how does RF feel/taste? how about rf injury?
« Reply #2 on: July 08, 2017, 02:52:51 PM »
I was zapped by a royer oscillator (CCFL backlight inverter) a few times. Besides burning and smell of burning skin, there's nothing else. It doesn't feel anything at all.

I would say if you want to play with high voltage, certainly consider high frequency -- they don't cause your heart or any muscles to twitch and hence cab't kill you unless it's too powerful that it can physically burn you to death.

From my own test (tasting 10V pp AC), I think I can't sense anything above 100kHz. It hurts the most at 50Hz~100Hz, and then at 20kHz, it's much less detectable. At 50kHz, it's almost gone and I can't feel a thing at all at 100kHz.
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Offline Muxr

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Re: how does RF feel/taste? how about rf injury?
« Reply #3 on: July 08, 2017, 03:01:31 PM »
Not sure if it counts, but I got burned by my RF induction soldering iron last week. Usually when you get burned by an iron it leaves a blister.. this actually hardened my skin where it touched and it hurt pretty bad for a day.

I was working on a microscope and was handling the iron with my offhand and accidentally touched the hot part.  :palm:
 

Offline blueskull

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Re: how does RF feel/taste? how about rf injury?
« Reply #4 on: July 08, 2017, 03:30:11 PM »
BTW, here are a few videos showing that you can't be electrocuted by playing with high power RF.



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Offline KJDS

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Re: how does RF feel/taste? how about rf injury?
« Reply #5 on: July 08, 2017, 11:10:21 PM »
https://cirugiafacialbenidorm.com/en/the-radio-scalpel-or-radiofrequency-scalpel/

up at 2GHz, then 50W will put a hole in your finger if it has nowhere else to go

Offline CopperCone

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Re: how does RF feel/taste? how about rf injury?
« Reply #6 on: July 08, 2017, 11:41:02 PM »
Thats interesting. I guess your neurons have a 3db point somewhere that prevents you from feeling the 'electrical'?

 

Offline KJDS

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Re: how does RF feel/taste? how about rf injury?
« Reply #7 on: July 09, 2017, 02:01:55 AM »
As I understand it, your muscles can only be twitched up to about 1kHz. Above that they don't respond. Perhaps a frogs leg and an audio gen would be a good way to experiment.

Offline alm

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Re: how does RF feel/taste? how about rf injury?
« Reply #8 on: July 09, 2017, 02:29:50 AM »
It is not so much the muscles I would be worried about. More internal organs. RF can take some interesting paths through the human body.
 

Offline FlyingHacker

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Re: how does RF feel/taste? how about rf injury?
« Reply #9 on: July 09, 2017, 02:40:55 AM »
As I understand it, your muscles can only be twitched up to about 1kHz. Above that they don't respond. Perhaps a frogs leg and an audio gen would be a good way to experiment.

Mount that frog leg to a Ukulele and you have and YouTube sensation.
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Offline G0HZU

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Re: how does RF feel/taste? how about rf injury?
« Reply #10 on: July 09, 2017, 03:39:48 AM »
I've worked in RF labs all my working life and I've had quite a few minor RF burns over the years across HF/VHF/UHF. In my case, I usually get a burn from being lazy and letting the lower edge of my palm (i.e. the sensitive skin near the base of my little finger) brush against the artwork of something like a 10W power amplifier when it is producing full power.

The sensation isn't the same as being burned by brushing against a hot sharp object. A hot sharp object will dish out instant 'hot' pain and cause instant reflex action against the pain. The best way to describe a mild RF burn is that it initially feels like someone squeezing the skin in sharp tweezers but it fairly rapidly builds up to something far more intense and 'burny' causing rapid withdrawal. It's a bit like getting a regular burn but spread/ramped up over maybe a second and without the 'hot' feeling and in my case it's very focussed into a fine point on the skin where the contact with the circuit is made. Sometimes it leaves a little pale dot on the skin where the contact was made.

I've never had a bad RF burn up at high power from a big RF amplifier because I'm a lot more careful at high power. I'd imagine that it hurts a lot...
« Last Edit: July 09, 2017, 03:48:47 AM by G0HZU »
 

Online dmills

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Re: how does RF feel/taste? how about rf injury?
« Reply #11 on: July 09, 2017, 04:57:08 AM »
I had a 250W @ 100MHz accident years ago, working on an output filter, got distracted by the phone and forget the PA was on line, reached in and squeezed one of the coils.

Damage goes deep and takes a bloody age to heal, but you don't really feel it at the time, half an hour later however.....

Regards, Dan.
 

Offline DaJMasta

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Re: how does RF feel/taste? how about rf injury?
« Reply #12 on: July 09, 2017, 07:16:29 AM »
Thats interesting. I guess your neurons have a 3db point somewhere that prevents you from feeling the 'electrical'?

I think it's probably more like your flesh acts as a low pass filter.... so instead of a sharp sensation or sudden muscle contractions, you just sort of get cooked.  I haven't experienced any myself, but my dad's told me stories of working on jammer pods for aircraft where their ground tests required everyone to be outside of a shielded test chamber building or inside the shielded cockpit, because it would literally only take a little bit to cook you if you were close when it was on.  Energy is energy, after all.

Offline T3sl4co1l

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Re: how does RF feel/taste? how about rf injury?
« Reply #13 on: July 09, 2017, 08:48:09 AM »
Relevant to thread,



I think it's probably more like your flesh acts as a low pass filter.... so instead of a sharp sensation or sudden muscle contractions, you just sort of get cooked.  I haven't experienced any myself, but my dad's told me stories of working on jammer pods for aircraft where their ground tests required everyone to be outside of a shielded test chamber building or inside the shielded cockpit, because it would literally only take a little bit to cook you if you were close when it was on.  Energy is energy, after all.

Nerve potentials roll off around 700Hz, IIRC.  Below that, you feel about the same amount of shock, and above that, you feel less and less.

Skin effect doesn't have much to do with it; the skin depth of flesh is still several cm at 2.45GHz.  Think of this next time you're microwaving something big, like a bowl of soup, or a roast.

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Offline CopperCone

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Re: how does RF feel/taste? how about rf injury?
« Reply #14 on: July 10, 2017, 04:48:05 AM »
I've worked in RF labs all my working life and I've had quite a few minor RF burns over the years across HF/VHF/UHF. In my case, I usually get a burn from being lazy and letting the lower edge of my palm (i.e. the sensitive skin near the base of my little finger) brush against the artwork of something like a 10W power amplifier when it is producing full power.

The sensation isn't the same as being burned by brushing against a hot sharp object. A hot sharp object will dish out instant 'hot' pain and cause instant reflex action against the pain. The best way to describe a mild RF burn is that it initially feels like someone squeezing the skin in sharp tweezers but it fairly rapidly builds up to something far more intense and 'burny' causing rapid withdrawal. It's a bit like getting a regular burn but spread/ramped up over maybe a second and without the 'hot' feeling and in my case it's very focussed into a fine point on the skin where the contact with the circuit is made. Sometimes it leaves a little pale dot on the skin where the contact was made.

I've never had a bad RF burn up at high power from a big RF amplifier because I'm a lot more careful at high power. I'd imagine that it hurts a lot...

I have some PAs. They will really injure you at only 10 watts from a brush? At 50 ohms, this is only 22 volts right?

On dry skin? That would mean its more dangerous then low frequency, in a way. I can't really feel 20V .
 

Offline G0HZU

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Re: how does RF feel/taste? how about rf injury?
« Reply #15 on: July 10, 2017, 07:16:47 AM »
Quote
They will really injure you at only 10 watts from a brush?.

I'm not sure 'injure' is the right word but it can feel a bit like being mildly stung by an insect in that the pain/shock rises like a ramp before I pull my hand away. But a regular burn from a hot object is instant.  I don't think it does any harm and I only seem to get them on the sides of my hand or side of my little finger where the skin is very sensitive. It's also the part of the hand most likely to catch the PCB tracks where RF can be present.


 

Offline CopperCone

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Re: how does RF feel/taste? how about rf injury?
« Reply #16 on: July 10, 2017, 07:25:43 AM »
so skin impedance is lower at rf
 

Offline radar_macgyver

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Re: how does RF feel/taste? how about rf injury?
« Reply #17 on: July 10, 2017, 08:18:04 AM »
"For the first millisecond, it just felt like the skin was warming up. Then it got warmer and warmer and you felt like it was on fire. ... As soon as you're away from that beam your skin returns to normal and there is no pain."

I can confirm you feel heat at 2.7 GHz (pulsed source, ~700kW, 0.1% duty cycle). Feels like a sunlamp. Haven't been exposed to more than a few milliwatts at higher frequencies. We're always advised to never stare into open waveguides or antennas, since your corneas can get cooked due to lower blood flow compared to the rest of the body.
 

Offline JohnG

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Re: how does RF feel/taste? how about rf injury?
« Reply #18 on: July 11, 2017, 02:41:35 AM »
I've worked in RF labs all my working life and I've had quite a few minor RF burns over the years across HF/VHF/UHF. In my case, I usually get a burn from being lazy and letting the lower edge of my palm (i.e. the sensitive skin near the base of my little finger) brush against the artwork of something like a 10W power amplifier when it is producing full power.

The sensation isn't the same as being burned by brushing against a hot sharp object. A hot sharp object will dish out instant 'hot' pain and cause instant reflex action against the pain. The best way to describe a mild RF burn is that it initially feels like someone squeezing the skin in sharp tweezers but it fairly rapidly builds up to something far more intense and 'burny' causing rapid withdrawal. It's a bit like getting a regular burn but spread/ramped up over maybe a second and without the 'hot' feeling and in my case it's very focussed into a fine point on the skin where the contact with the circuit is made. Sometimes it leaves a little pale dot on the skin where the contact was made.

I've never had a bad RF burn up at high power from a big RF amplifier because I'm a lot more careful at high power. I'd imagine that it hurts a lot...

At my first real engineering job doing mobile RF PAs for Motorola, I was troubleshooting and followed already-ingrained habit of touching various circuit points to see what happened. When I touched the stamped-mica cap at the output of the matching network, I burned the S**T out of my finger. For the first half-hour or so, all I could see was a tiny dot on my fingertip, and I didn't think much of it. As the day went on, it hurt more and more, and by the end of the day there was a big, deep, dark blister that covered my entire fingertip and hurt like hell. It took weeks to heal. I think the RF made a little hole in the out layer of skin, hit the live layer, and spread out. I really think hard about circuits now, before I go sticking anything in them.

The amp was an 800 MHz amp rated at 35 W.  All I touched was a DC blocking cap, so I didn't get anywhere near full power.
 

Online dmills

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Re: how does RF feel/taste? how about rf injury?
« Reply #19 on: July 11, 2017, 08:05:09 PM »
For the first half-hour or so, all I could see was a tiny dot on my fingertip, and I didn't think much of it. As the day went on, it hurt more and more, and by the end of the day there was a big, deep, dark blister that covered my entire fingertip and hurt like hell. It took weeks to heal.
Classic RF burn, they do suck do they not.
I suspect everyone working with proper RF power does this once.

Regards, Dan.
 
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Offline CopperCone

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Re: how does RF feel/taste? how about rf injury?
« Reply #20 on: July 13, 2017, 05:04:24 PM »
if you made "swim goggles" out of mesh (deep mesh, structured like beehive material), using RFI gaskets instead of rubber gaskets for the 'seal' against the skin, that you could wear, would this protect your eyes from cataracts from a strong microwave source (that can plausibly cause the cornea to overheat)?

This would be instead of a full hood., which still does not offer eye protection (but is commercially available!) Now, they might get hot.. but the only un-healable areas of the body for microwave exposure are eyes right?

So if you were blasted with some strong microwave, you would experience burns on the face skin, heavy burns around your eyes (from metal gasket heating)... but presumably the cornea would be heavily protected?

Could the interface between the RFI gasket of the goggle 'outline' and the skin be enough to protect microwave access to the eyeball surface? Or would you need to supplement with something like silver conductive paint (perhaps latex mixed with silver powder)? on your eyelids and area around the eyes? (so you look like you have tin-man makeup on...). 

I'm entirely serious btw..

Does anyone know the mechanics of the eyelid acting as a cooling system too? If your eyes are closed.. how good is that? I;m guessing that tis heating in depth due to skin effect? So you would need an actual shield.
« Last Edit: July 13, 2017, 05:07:06 PM by CopperCone »
 

Offline T3sl4co1l

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Re: how does RF feel/taste? how about rf injury?
« Reply #21 on: July 13, 2017, 05:37:46 PM »
Linemen doing in-situ work have Faraday cage garments, made with something like 10% stainless fiber.

That exact clothing wouldn't be ideal, but something a bit heavier in copper would do a fine job, yes.

but the only un-healable areas of the body for microwave exposure are eyes right?

Well, the testes.

Or, really, any area that has poor blood flow that can be heated dangerously by ambient radiation.  Or given enough radiation, any area at all.

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Offline jpb

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Re: how does RF feel/taste? how about rf injury?
« Reply #22 on: July 15, 2017, 07:05:31 AM »
Microwave ovens give a good demonstration of the effect of RF, especially at frequencies where there is strong absorbtion by H2O.

As a young engineer in the 1980s working on MMICs, there was a guy in his 60s in the lab who worked on microwave/radar systems in the early days just after the war I guess and he had some slightly wild stories. At one time they tested the effect of microwaves on concrete blocks - nothing happened for a long time and then they exploded because of the built up steam pressure.

I think that there was a high incidence of cataracts in radar operators in the war with the early sets that were very leaky - basically they were cooking their eyeballs but this may be just legend.

There have been a few court cases over people claiming that they develop tumours as a result of excessive mobile phone usage - as it is non ionizing radiation I guess it must be down to increased temperature if the claims have any validity.

We used to use an antenna consultant who kept his microwave oven in a shed - he wouldn't have it in the house because he reckoned that there were dangerous levels of leakage that would have a cumulative effect.
« Last Edit: July 15, 2017, 07:07:50 AM by jpb »
 

Offline David Hess

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Re: how does RF feel/taste? how about rf injury?
« Reply #23 on: July 16, 2017, 02:27:06 AM »
Less than 5 watts into a helical resonator can give you a severe burn; even 1/2 watt can burn you in this case because the coupling is so efficient.  After I discovered this and tested it with a neon bulb, I decided that if I ever try to make a gas laser, I am going to use a helical resonator for excitation.

5 watts or more into a dipole can be "felt" as you run your hand along the length of the dipole.
 

Offline Harb

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Re: how does RF feel/taste? how about rf injury?
« Reply #24 on: July 17, 2017, 10:18:13 PM »
I have had some minor RF burns from time to time....sort of feels like its burning from the inside working its way out.......I did see an uplink tech jump about 10 feet in the air and come down breaking his wrist after pushing his leg up against a dummy load port on a Sat uplink TX once.......the scream almost gave me a hearing problem.
 


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