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Other Vintage Household Electrical or Electromechanical Items For discussions about other vintage (over 25 years old) electrical and electromechanical household items. See the sticky thread for details.

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Old 17th Jul 2020, 2:09 pm   #61
rontech
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Default Re: DIY X-Ray & Auto Jigger transmitter

A further thought has occurred to me. If you operate these ultra high voltage machines in the present day; is there a risk of taking out some of the sensitive solid state devices in the vicinity? E.g. those in iphones laptops and so on.
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Old 17th Jul 2020, 3:40 pm   #62
GrimJosef
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Default Re: DIY X-Ray & Auto Jigger transmitter

You can destroy solid-state gear easily if there's direct contact with an HV source, even a 'static' one, hence the anti-stat packaging, work-stations etc. But I think field-induced damage is rare unless the source is a thermonuclear weapon.

At work we took what care we could, but in the end we had to drive a 400-500kA (yup, kiloamps) 170ns long pulse of electrons into a metal tube (40cm dia, 220cm long) whose ends were sealed only by glass (strictly speaking fused silica) so were pretty much transparent to RF. The pulse risetime was 15ns or so. So dI/dt was roughly 3x10^13A/s. We got away with doing this a few times an hour for days on end and the kit operated this way for several years. We ran modern (1990's technology) high-vacuum gauges and vacuum photodiode power supplies within a few metres of this and the building's fire-alarm and internal phone system seemed perfectly happy too. Tek and HP scopes ran within 10m without coming to any harm.

Of course RF transients can disrupt some items' operation temporarily.

EDIT: I should say all this stopped before the turn of the millennium. So we were only concerned with 1G and 2G phones I think.

Cheers,

GJ
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Old 17th Jul 2020, 5:15 pm   #63
rontech
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Default Re: DIY X-Ray & Auto Jigger transmitter

Thanks GJ Comforting news!
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Old 17th Jul 2020, 6:56 pm   #64
Malcolm G6ANZ
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Default Re: DIY X-Ray & Auto Jigger transmitter

The linacs I worked with produced 6Mv x-rays. All around the head was lead shielding to try and protect the semiconductors .It helped that the majority of the x rays went forward from the target so only back-scatter was present.
The board didn't fail in a spectacular manner but gradually stopped working correctly. One set of boards had to demultiplex and drive 40 motors to millimetric position. When new they worked perfectly but as they got damaged the complete bank of motors would start to drift with no command signal. We put this down to the darlington drivers becoming leaky.
The linac head tries to show the amount of electronics surrounding the head. The target for the x rays is just in front of the brown disc. The disc is a thin 'window' to allow electrons to pass if electron therapy is used.
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Old 12th Aug 2020, 9:13 pm   #65
Records
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Default Re: DIY X-Ray & Auto Jigger transmitter

my aunt worked in an xray department until the late 80's she told some strange tales, she was a smoker quite heavy, she died of cancer in 94, i always wondered what got her, the smoking or the xray machine
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