(this is the last of my unknown components).

It is less than 1 cm (half inch) diameter, has one wire on each end.

It has description:

CNR C8G 75L RU G12

The RU is written reversed.

enter image description here

  • 4
    \$\begingroup\$ Looks like a spark gap to me. \$\endgroup\$ – Wouter van Ooijen Aug 27 '17 at 14:47
  • \$\begingroup\$ Thanks ... I think this components comes from an old Philips CRT \$\endgroup\$ – Michel Keijzers Aug 27 '17 at 14:50
  • 1
    \$\begingroup\$ might be a varistor. Check where it came from – if it's from a degaussing coil circuit, almost certainly a varistor. \$\endgroup\$ – Marcus Müller Aug 27 '17 at 15:03
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    \$\begingroup\$ Looks like a 75 volt gas discharge tube. \$\endgroup\$ – Mike Waters Aug 27 '17 at 15:36

It's a GDT

What you're looking at is almost certainly a Gas Discharge Tube, or GDT for short. They are basically a spark gap inside a sealed chamber filled with a specific inert gas mixture -- this allows them to provide more precise protection than an air spark gap. They're used for the same things as spark gaps, though -- mostly, overvoltage protection as when they break over and start conducting, they will "crowbar" the overvoltage.

  • 1
    \$\begingroup\$ It is, definitely. CNR makes GDTs, and the PDF I just found (but couldn't copy the link on this tablet) shows TV applications. If it's 75 volts, it may be slightly radioactive. \$\endgroup\$ – Mike Waters Aug 27 '17 at 15:48
  • 1
    \$\begingroup\$ Here is the link. \$\endgroup\$ – Mike Waters Aug 27 '17 at 16:02

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