Electronics > Beginners

My purchase list for my new lab -- budget $1000+, thoughts?

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rstofer:
When it comes to stackable banana plugs, I would prefer to buy them pre-molded rather than side wire them where the wire leaves at 90 degrees to the axis of the plug.  Standard spacing on banana jacks is 3/4" center-to-center and it seems to me that the horizontal wire exit is going to get cumbersome.  It would be out of the question for my application and less than desirable in even a PS lead (in my view).  Or maybe having the power supply on a shelf with the wire running straight down from the plug is a neat feature.  I guess it depends...

I would rather buy the cables pre-built and, if necessary, buy them long enough to cut in half to make up two cables with dupont ends (or whatever).

https://www.digikey.com/product-detail/en/pomona-electronics/B-4-2/501-1322-ND/737950

This Pomona B series is what I have been buying (among other leads).

Page 41 here:
https://www.pomonaelectronics.com/sites/default/files/Pomona_Electronics_Catalog_2016.pdf

The 1325 series stackable plug doesn't have that horizontal shield where the wire comes out.  Page 32.  This would be somewhat easier to use but the safety of the shield is gone.  For my voltage levels, that's not an issue.  But I'm not going to build my patch cables anyway.  In any event, Pomona limits their recommended use in either case to 30V when handling.


rstofer:
Test lead holders:

https://www.digikey.com/products/en?keywords=holder%20test%20lead

Different sizes but I suspect the 1508 Pomona will do just about everything.  It holds 0.210" dia cables.

Mount it high enough to allow scope probes to dangle.

AnyNameWillDo:
Minigrabber 3925 vs. Minigrabber 4555
Termination: Solder, 0.090" (2.29mm) Wire Opening, vs. Solder, 0.144" (3.66mm) Wire Opening

Any advice on picking one or the other? Picking the larger opening seems safer but also possibly riskier if it implies more wear and tear. On the other hand I don't know if the other would be too narrow. Most AWG charts seem to ignore insulation.

tooki:

--- Quote from: AnyNameWillDo on July 31, 2018, 01:37:08 am ---Minigrabber 3925 vs. Minigrabber 4555
Termination: Solder, 0.090" (2.29mm) Wire Opening, vs. Solder, 0.144" (3.66mm) Wire Opening

Any advice on picking one or the other? Picking the larger opening seems safer but also possibly riskier if it implies more wear and tear.

--- End quote ---
Wear and tear? Huh? It simply needs to match the wire. Choose the model that matches the wire you intend to use.

I wouldn't bother making minigrabber cables, since they're readily available. Make the ones you can't easily buy. ;)


--- Quote from: AnyNameWillDo on July 31, 2018, 01:37:08 am ---On the other hand I don't know if the other would be too narrow. Most AWG charts seem to ignore insulation.

--- End quote ---
[crash course in wire]They "ignore" it because they can't know: there isn't ONE size insulation for a given gauge!! (It's like asking "how fat is a bicycle tire?" — well, it depends…)

Test lead wire has much thicker insulation than ordinary wire of the same gauge, and high-voltage wire (e.g. the stuff used to power neon signs at 10KV) uses far thicker insulation still. And the differences in stranding means stranded wire of a given gauge isn't necessarily the same diameter (excluding insulation!) as a differently-stranded wire of the same gauge, never mind of solid wire, which will be thinner. The only thing that's the same at a given gauge is the total cross-section.[/crash course]

Insulation thickness (that is, the outer diameter of the wire) absolutely is on the spec sheet of any wire you look at. So go to digi-key and look for test lead wire and you'll see what I mean.

AnyNameWillDo:
Figured as much -- I just didn't see any insulation data on the wire I had bought, so I was a little unsure. I could probably go measure a cross-section myself but my ruler isn't here yet. :P

At any rate, considering:

3 of these: https://www.digikey.com/product-detail/en/1825-2/501-1077-ND/603384/
3 of these: https://www.digikey.com/product-detail/en/1825-0/501-1076-ND/603383/
1 of these: https://www.digikey.com/product-detail/en/1825-5/501-1247-ND/736243/
3 of these: https://www.digikey.com/product-detail/en/3782-36-02/501-1324-ND/736657/

Which I presume would cover all test-lead issues :P

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