Gold plated banana plugs - question

[beanflying]

Interesting thread. A few of the earlier replies stated to test with a magnet. Brass and in fact some copper alloys are mildly magnetic to strong magnets. So to state they are non magnetic is not a good guide or method.

I have just tested some of my older Gold Bullet connectors from some earlier electric R/C (circa 20 years old) and they are weakly magnetic and they were at the time definitely Gold Plated 'brass' ex Germany and very expensive. We incidentally were pulling 90-100A plus at 25V+ through these at the time. The trend is toward 6mm and 200A+

The couple shown below are some cheap sub $1 each ebay ones and some very cheap ebay ones. The Red and Black ones appear to be brass back end and either the shield or pin at the front is iron based. The colourful ones exhibit the same sort of magnetic properties as my old ones in that the Neo magnet stack will attract them but is not sufficient to pick one up. https://www.ebay.com.au/itm/10set-5color-Gold-Plated-Brass-Stackable-4mm-Banana-Plug-Speaker-Cable-Connector/253102319127?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

edit: just removed the shield of the red and black and it is the spring that is iron based, the entire underlying pin and back end appear very mildly magnetic like the others.

If the plating is in fact gold on either is a completely different matter

[beanflying]

Just for a little more info I have dismantled for 4mm evilbay binding posts I had in stock. Nuts and washers on both are Iron based Posts and post nuts are not.

Seems that if you solder to the back end of these and use the couloured plugs above then you are running without any iron in the loop.

[001]

Why You call it "gold plated"?

It is only shine like a gold but it is not gold anyway
It can be coated with titanium oxide or something else IMHO
What is we reason to use this oxide-coated contacts in metrology?

[beanflying]

And part of the reason NOT to buy Chinese origin evilbay Titanium Oxide cutting tools, chances are they are 'gold plated' too 


https://www.finishing.com/375/26.shtml 

[001]

Is it china bananas have identical "goldlike" TiO covering to china drill bits? 

It is OXIDATION covering. Is it good conductor for measurings?

[cdev]

I wonder if the "gold plated" SMA (RF) connectors Ive been buying recently are in reality titanium oxide coated?

They take solder quite well so i've been assuming that its real gold plating..

If it was titanium, I doubt if it would conduct very well, silver would likely be far better.

[001]

It is very interesting to know what this "gold" in fact
But extra cheap "gold" rca connectors is easy soldered too

[Muttley Snickers]

Slightly off topic as I wasn't sure where to ask, has anyone recently purchased or reviewed a set of these cheaper kelvin leads pictured and linked below, they appear similar to the quality Pomona set also pictured but obviously I expect they would not be in the same league, I need a couple of sets but nothing fancy and they don't look too bad considering the price.

Random Ebay listing.
https://www.ebay.com.au/itm/LCR-Meter-Test-Leads-Lead-Terminal-Kelvin-Clip-Wires-for-UT612-UT611/332008183641?

[martinr33]

They surely look nice, and that looks like gold plating. The problem is, the clips might be brass (most likely) or steel underneath. My experience is that these are pretty much never copper. I have a box of nice-looking inexpensive connectors from multiple suppliers that are gold plated and claim to be copper, but have only found two suppliers of plated copper connectors. You have to grind off a bit of the plating to see the color of the metal underneath.

Some of them are pot metal - a cheap zinc alloy.

[001]

I have some cheap "gold plated" bananas and jacks for about 8 years
And few tips became muddy or pale (probably from fat of the hand skin)

[Mickle T.]

Some of my old thermal EMF measurements (relative to copper, dT=100 C. deg.):

[zhtoor]

hello Mickle T.,

what is the gadget on the left of the picture, constant pressure against copper bus-bar?

also can you measure contact thermal emf of a 1cm^2 piece of copper-clad pcb against another copper-clad pcb?
would that be a viable poor-man's low thermal emf connection?

regards and keep up the good work.

-zia

[Mickle T.]

The gadget on the left of the picturea is a lab. device for measuring the Seebeck coefficient: heaters, thermocouples, ovenized uV amplifiers, PIDs, ADCs e.t.c.

[Awesome14]

It shows the current coming out of an LED from ambient light shining on it.

Glass diodes and LEDs are also passive photovoltaic devices. 

[Gyro]

Well... Active semiconductor devices actually.

[beanflying]

Evilbay at work again. I got these in for a non metorology use but interesting lack of consistency. All the bits on the right of photo 1 are magnetic and with a little closer inspection all the positive banana posts are made with an IRON based washer (2 piece pressed together)  at the base and not brass like the others (single piece cast brass) in the same bag 

The rest of the Positive post appears to be plated brass after a little grinding and sparks from the washer