3
\$\begingroup\$

I've found a handful of these strange things in a stock of new old stock components, in the middle of capacitors, resistors, old potentiometer knobs and such lovely surplus cheap stuff.

They measure 1" x 0.5" each and they seems to be mainly made of white ceramic. I've found only these variants (green with two pads and blue with three). The surface of the pads is conductive.

Strange things

The other side is white ceramic with no visible features. It seems that the entire content is 'printed' on this side only. No ID or other information are printed, or engraved, or whatever.

The visible snakey "path" between the pads (protected by the colored paint) suggests that some sort of current should flow between them, but the DC resistance between the pads seems to infinite (or at least > 2MOhm), even between the closest pads in the blue one. I've even tried to apply 12V DC tension with both polarity, but no current flows.

The shape of the 'circuit' in it suggests some form of inductance (HF antenna?), and the blue one seems to be a variant with a tap closer to the top pad (like a transformer). But shouldn't inductors be still conductive at DC level? The same if they should be fuses or other current/voltage protection device.

I haven't tested capacitance but I don't expect them to be capacitors... or not?

Random googling hadn't helped much. I've never seen something like this before and I'm really puzzled now!

\$\endgroup\$
  • \$\begingroup\$ Antenna would be my guess also. The blue one would have the extra pad to allow it to be used at 2 close but different frequencies. Green one lower frequency - longer trace. \$\endgroup\$ – scorpdaddy Jan 4 at 16:37
  • 3
    \$\begingroup\$ Poor conductor for an antenna. But maybe a good high voltage resistor \$\endgroup\$ – Sunnyskyguy EE75 Jan 4 at 17:09
  • \$\begingroup\$ Have you tried finger pressure in the blue/green area, while measuring resistance/capacitance between pads? \$\endgroup\$ – glen_geek Jan 4 at 17:59
4
\$\begingroup\$

These are high voltage flat resistors.

But, the colour on top of it i think it may be epoxy coating for protection from environment.

The below image is leaded ones with out epoxy coating on top.

follow this link for more details and applications of this component: link

Sample data sheet of leaded type:DATASHEET

enter image description here

\$\endgroup\$
  • \$\begingroup\$ Correct, I've just tried with a higher DC voltage and eventually able to read 1 microampere: the shortest path of the blue sample measures something like 35MOhm. So probably these things are in the range of Gigaohm. Thanks! \$\endgroup\$ – MadLux Jan 4 at 20:56

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.