Electronics > Metrology

4-wire connections to reference resistors

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leonerd:
I'm planning to make myself a reference resistor; basically just putting a Vishay Z201 in a box with some banana sockets. E.g. this 10k

  http://www.mouser.co.uk/Search/ProductDetail.aspx?R=Y145310K0000V9L

I'm going to make two - a 100R and a 10k (because those are the values mouser has easily - I don't see a 10R or 1k). Less so for the 10k, but the 100R at least likely benefits from having 4-wire connections on it, so do two onto each leg in the case.

I wonder - if I mount the resistor on stripboard, I can attach two sets of wires to it, one on each side. For minimising the error, should I "cross over" the force vs. sense flows? I.e. should I put the force on two diagonal corners and the sense out of the other two, or doesn't that matter?

Relatedly, if I'm using a larger scale SMT resistor on a PCB (such as a 2010wide) and adding 4-wire sense support, should I pass the two flows in parallel, or cross them over?

TiN:
Just twist sense+/- together into one pair and current+/- into second pair, and you likely be okay to go for hobby needs. I'd recommend 4 wire connection for both values.
Make sure you use fresh cleaned copper wires and copper terminals if you after good accuracy.

leonerd:
Ah, just free mount it in air? That might be better actually, because looking at the data sheet, the pin spacing is 0.15" - who thinks that's a good idea? :( Won't fit in 0.1" stripboard. Well, *maybe* I could angle it diagonally; 0.15 is very nearly 0.141... but I don't like the idea of the stress.

Speaking of - what would be best for physically mounting it within the case, if it's not mounted on stripboard which is then glued to the case? I don't know what I can sensibly do to the resistor without risking ruining its high precision.

TiN:
Have the suitable box, which allow air-tight seal (could be metal to provide more shielding).
Mount good copper banana plugs on case securely, and then use copper wires (e.g. strands from CAT5 LAN cable work great) to do the wiring.
There should be no tension to resistor legs or body. Good idea to drop in some humidity desiccant bags to dampen humidity effects (resistors in plastic package are not hermetic and subjected to humidity/resistance changes).

Here is worklog on one of my resistance boxes I've build, but it's more specific to my needs with triaxial ports instead of banana. But idea is the same. I'd recommend also having separate box per resistor, so you can manage it easier.

kripton2035:

--- Quote from: TiN on July 11, 2016, 04:18:28 pm ---Have the suitable box, which allow air-tight seal (could be metal to provide more shielding).
Mount good copper banana plugs on case securely, and then use copper wires (e.g. strands from CAT5 LAN cable work great) to do the wiring.
There should be no tension to resistor legs or body. Good idea to drop in some humidity desiccant bags to dampen humidity effects (resistors in plastic package are not hermetic and subjected to humidity/resistance changes).

Here is worklog on one of my resistance boxes I've build, but it's more specific to my needs with triaxial ports instead of banana. But idea is the same. I'd recommend also having separate box per resistor, so you can manage it easier.

--- End quote ---
are the gloves necessary to handle these components ?? =)

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