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What is thing blue thing (pointed by red arrow) below the resistor? It comes in blue, red, silver, green, and red. Is it part of the resistor? What does the color signify?

enter image description here

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    \$\begingroup\$ Some context is always useful in questions like this. What does the circuit do? In what section are the resistors? Add the info into the question and someone should be able to confirm their type and explain why they are there. \$\endgroup\$
    – Transistor
    Commented Oct 1, 2022 at 23:15
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    \$\begingroup\$ Probably a plastic spacer for stress relief. \$\endgroup\$
    – Mattman944
    Commented Oct 1, 2022 at 23:25
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    \$\begingroup\$ It's input resistor to an op amp. I thought it was some form of enhanced tolerance or temperature coefficent or additional feature. \$\endgroup\$
    – Samzun
    Commented Oct 1, 2022 at 23:34
  • \$\begingroup\$ It comes with blue, red, silver, green, red? ... are you asking if it is available in different colors? \$\endgroup\$
    – jsotola
    Commented Oct 1, 2022 at 23:40
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    \$\begingroup\$ It looks like the board was laid out for a physically smaller resistor - perhaps one with a lower power rating. If so, the substitution could have forced the need for vertical mounting, which created the need for what could be a spacer. FWIW, where resistors are vertically mounted, it's usually to save space on the board; the pads would be closer together. This seems a bit wasteful of space, so seems to me like there may have been some sort of design error here. \$\endgroup\$
    – Anthony X
    Commented Oct 2, 2022 at 13:50

1 Answer 1

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Looks like a simple spacer. It's bad (for reliability and stability through soldering) to have the part too close to the solder blob.

Those are precision resistors (and it looks like some kind of industrial or similar higher-than-average cost/specification product).

The beads look a lot like test point spacers:

enter image description here

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    \$\begingroup\$ I agree, a spacer. High-reliability construction. For space between the body and the solder joint. This ensures the solder joint forms a good fillet & doesn't extend up to the body. Mechanical shock & vibration will be evenly spread out, to minimize cracks forming in the joint. The color may be a code to indicate what diameter of wire its designed for. But this in particular product, vertical mounting is not a reliable choice. Vertical mount has higher center of mass than if horizontal, and, if dissipating any significant power, will lead to temperature hot spot at the top. \$\endgroup\$
    – Rich S
    Commented Oct 2, 2022 at 0:08
  • \$\begingroup\$ Big chance it’s a ferrite bead \$\endgroup\$
    – RemyHx
    Commented Oct 2, 2022 at 3:07
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    \$\begingroup\$ @RemyHx Not sure what possible use a ferrite bead would be on a 10MΩ 1% resistor lead, but if they are magnetic then would believe it. Not everything has to make sense. \$\endgroup\$
    – Spehro 'speff' Pefhany
    Commented Oct 2, 2022 at 4:14
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    \$\begingroup\$ @SpehroPefhany that’s a good point. It’s a pity we don’t have more info about the board. \$\endgroup\$
    – RemyHx
    Commented Oct 2, 2022 at 5:48
  • \$\begingroup\$ Normally you'd just use lead forming to hold the resistor off the board. I wonder why they used a physical spacer. \$\endgroup\$
    – Hearth
    Commented Oct 2, 2022 at 21:49

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