What is the metallic circular component in this voltage sensor?

[Wrichik Basu]

While searching for something else, I stumbled upon this https://robu.in/product/voltage-sensor-module/. It is idiotic to buy something like this, because a voltage divider doesn't cost more than a few cents. But what is the metallic circular component in the middle of the sensor? Some kind of heat shield?

 

[Jody]

I don't know the answer, but my guess would be it's a mounting hole.

 

[Tom.G]

I would vote it is a "Feature Item, " a useless doodad added to make the purchaser believe they have an exotic item. (Think chrome trim on a car, or the pattern on your dinner plate.)

 

[DaveE]

It looks like a waste of gold plating to me. But I wasn't ever much inclined to think like the sales and marketing types. For a product like this, that sort of "feature" could double sales.

 

[trurle]

It looks like a waste of gold plating to me. But I wasn't ever much inclined to think like the sales and marketing types. For a product like this, that sort of "feature" could double sales.

This is Chinese product. The Chinese PCB with gold plating and panelizing costs for maker $0.17, terminal block $0.04, other components - $0.03. Plus $0.5 for Chinese goventment subsidized shipping. Total material&shipping cost is $0.74, and catalog price linked here is $1.3, which looks reasonable. Without over-engineered gold-plated mounting hole the material&shipping cost for maker will be down to $0.65 though. My guess is what "voltage sensor" was fabricated on same breakable board as another small production volume PCB which actually do need gold plating, therefore gold plating of "voltage sensor" become essentially "free" for maker. Or maker decided what 15% lower price margin will pay off due higher selling volume of expensive-looking part.

 

[Borek]

Gold plating can be made very thin - it looks good but doesn't survive mounting/plugging - any mechanical action will destroy it.

 

[Klystron]

The circular device design reminds me of pin straighteners ubiquitous on common vacuum tube testers and devices in my childhood. One would insert the tube in the device to straighten bent pins but also to remove oxidation from the connectors before running tests or replacing tubes. Many/most television and radio chassis would include a pin straightener for convenience, matched to the vacuum tubes in the unit.

Brass was not uncommon but I never saw gold plating used on what was essentially a mechanical device. Bit of memorial day nostalgia.

 

[hutchphd]

Looks like a "flux capacitor" to me...is that board rated for gigawatts?

There used to be tube testers at the drug store if my memory serves...