Hi just brought my first osilscope and it has a CRT just wondering if they were in any way dangerous or emit and dangerous radiation
Thanks
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They are not dangerous in the way of emitting xrays or anything like radiation. What is dangerous, possibly lethal, is playing around inside with the CRT and it supporting high voltages without proper instruction and experience. Use it with confidence. Don't poke around inside unless you understand the risks.
My monitor proclaims (on an internal panel) that it produces something like 0.5uSv/hr of x-ray output; somewhere around background radiation. Most CRTs should have similar performance, but I suppose you could always find an unlucky brand:
Tim
Hi just brought my first osilscope and it has a CRT just wondering if they were in any way dangerous or emit and dangerous radiation
Thanks
\
Yes. Look at all these people who have been using CRTs for 30+ years. They are all slowly dying. They say you will be older by a year every year you use a CRT.
[Yes. Look at all these people who have been using CRTs for 30+ years. They are all slowly dying.
Life: The incurable, fatal sexually transmitted disease.
Yeah, all vacuum tubes that use high voltages > several hundred volts occasionally create an high-energy photons in very low levels, soft x rays. Pre-transistor TVs were even worse because they not only had the CRTs, but also around 50 other vacuum tubes to run it. Anyway, nothing to worry about. A few microsieverts are not going to kill you, you will probably get more from natural potassium exposure.
I wouldn't worry too much about the X-rays from an oscilloscope as much as the lead that you're exposed to while soldering / desoldering.
Or how about the toxic chemicals and epoxies that go into PC boards.
If you eat a CRT, you might get sick.
Life: The incurable, fatal sexually transmitted disease.
@BradC: So funny! but so true.
Using an oscilloscope CRT is ok, anyway everything has more or less been proven to give cancer nowadays. However every time I disassemble a device with glass under vacuum stuff in it and see stickers like "Handle with care! Risk of implosion!" it creeps me out.
If you eat a CRT, you might get sick.
I wouldn't be surprised to find this on some safety sticker!
If you got yourself an 80 inch CRT, sat in front of it for months with it showing a bright white image at maximum brightness and minimum contrast, you will get the equivalent of eating a bunch of Bananas in that period.
As somebody who, when growing up, had a garden that was more than half banana plants, and where we regularly had 3 40kg bunches hanging on a steel hook where we had to either eat them, cook them or make banana bread by the freezer full out of them before they went too bad to touch ( was rare, I like bananas) I ate a lot of them. I have normal radiation levels in my body ( confirmed a few times going into a nuclear plant, you could trigger the alarm with a bunch of bananas in your lunch) after all that.
Thanks guys just paranoid.
Thanks guys just paranoid.
Serious question, i do not want to be mean, i am just curious
Might i ask you how old you are?
Until a few years ago CRTs were everywere, multiple ones in each household.
You could not walk 100 meters in a straight line without running into one.
It seems that we reached the point were they have become something the youth only knows from pictures?
Greetings,
Peter
It seems that we reached the point were they have become something the youth only knows from pictures?
Like self control, self censoring and the ability _not_ to share their entire lives on-line?
you need in the teens of kilovolts to start generation of x-rays.
Your 'scope is probably 1 to 5kv.
Make and model?
you need in the teens of kilovolts to start generation of x-rays.
Surely this depends on the method of generating the X-rays?
If you break the glass and eat it yes it could be dangerous, BTW avoid looking at the wrong end that could be Dangerous. high voltage there.
It's the stopping of the electron, that emits a photon, energy /frequency = voltage. The rate of radiation is very low and the energy similarly so. I recall there were some 'tricks' to reduce the radiation but it is very low. Be more worried about the mains voltage and some of the dodgy chemicals.
My understanding is that there was some significant radiation from early shadow-mask color CRTs, from the electron beam hitting the metal surface of the mask, rather like an X-ray tube. But then they started using leaded glass to block most ionizing radiation.
IIRC, The amount of radiation from monochrome CRTs (i.e. virtually all CROs) was only a laboratory curiosity and not considered harmful by any measure.
Of course the high voltage used by any fire-bottle is potentially lethal, and the extra high voltage used by CR tubes even more so.
Note further that many (most?) TV tubes actually have an intrinsic capacitor formed by the aquadag conductive coating on the inside of the tube, the glass envelope of the tube, and an outer coating of aquadag which is grounded. This forms a filter capacitor for the accelerating voltage when it is generated by the 15,750 Hz flyback transformer. Same effect as a Leyden Jar.
Many people have been seriously zapped by tubes which they assumed were "inert".
http://en.wikipedia.org/wiki/Aquadag
stay away from back of the CRT as I said .
CRT necks aren't usually too bad... depends though. Scopes, and maybe some very old TV sets, use -HV on the cathode and ~0V on the anode. (Fancy Tek tubes usually do this, but have a final HV in the 5-15kV range anyway. The voltages are kind of all over the place.
) Almost all magnetic deflection tubes use ~0V around the neck, with up to 100-200V for grid/cathode voltage (which admittedly is still enough to be dangerous to those leaky meat-sacks with fingers
) and one pin in the ~kV range (focus anode).
Of course, TV sets are usually not isolated, so touching anything inside carries line potential with it, with respect to earth ground, as well. Whether you're in the HV area, around the LV signals, or the power supply line area itself.
Tim
Xrays are not an issue with an intact tube/mounting system. But be careful with possible implosion of TV tubes - wear safety glasses, watch out for high voltages stored in the tube, and if the tube breaks open dispose of it with care due to heavy metals in the getter. A CRT is a huge capacitor with a glass dielectric and aluminum and dag conductors. When the unit is turned off the tube will store thousands of volts. There is often a bleeder resistor to take the voltage down, but even after discharging it and disconnecting the anode lead, charge will slowly migrate from within the glass and you can still get a painful poke, even days later. I worked in the CRT industry, standard lab practice was to push an insulated handle screw driver, with a grounded wire clip on the metal shaft, under the anode cap to discharge the tube before disconnecting the anode. This assumes the outside dag coating is grounded - just be sure the anode button is shorted to the dag. The rimband is probably connected to the dag so it's mounting ears can make a good attachment point for the lead clip.
When you push that screwdriver under the anode cap make sure you do not scratch the glass, or
be prepared for a face transplant. Nice if screwdriver had no edges or pointed contact points.
Regards, Dana.
I don't think the OP uses that CRT scope anymore, because it broke (mentioned in another thread). This thread is almost a year old.
When you push that screwdriver under the anode cap make sure you do not scratch the glass, or
be prepared for a face transplant. Nice of screwdriver had no edges or pointed contact points.
Regards, Dana.
Not to worry, they're a lot more sturdy than you might expect and the leaded glass is not easy to scratch, especially deep enough to compromise it's mechanical integrity.
If you do compromise the vacuum it is most likely to occur by breaking the neck which is more fragile but that will not cause an implosion.
Another caution, never remove the implosion protection which is generally a rimband which usually doubles as the mounting bracket. The tension band greatly minimizes the possible damage from an implosion.
