Low Thermal E.M.F. Binding Post TBP3

[mendip_discovery]

Here are some pictures of the lugs and ring terminals.

Nice pure copper.

Note: Due to the limitations of using a vernier calliper to measure small holes please give some leeway to the measurements. They are all approx.

[opa627bm]

IS the group order still open  ?

[branadic]

No it's not, but I have a few gold plated gray and pure copper as well as gold plated black posts left, just in case.

-branadic-

[cat87]

Hi everyone,

    I got  my binding posts a while back, but thought I'd use them for a while before putting into words what I think about these.
So, short story long, I got a Solartron 7081 from a benevolent friend and of course, it came with the  front Fischer connector ( the dmm, not the friend)
And because Reps had done a similar conversion to this, I thought the posts I got might be ideal for this situation.

    The materials are really nice on the posts and the finish on the metal is OK.  The plastic is much nicer than the Pomona posts, so that'a a real nice win.
The screws are all nicely done and nothing wobbles or feels loose.
The plastic spacers are basicallt press fir into the holes in the front panel, and though I applied quite some force to them, they did not warp or distort. Only thing to watch out for is that any mechanical work on these should be done with a  a file, hacksaw, dremel,  but NOT with side cutters like I did, because then the plastic just cracks. Lesson learned

Hope this will be of help to people

[aronake]

Is it likely these posts will eventually make there way onto taobao or aliexpress? Seeing how there is already the TBP2 on taobao

https://item.taobao.com/item.htm?spm=a1z10.5-c-s.w4002-23305896302.13.9d232402qEFccl&id=706702482964

[aronake]

What is the expert panels verdict? With or without plating for this kind of binding posts?

It seems to me plating have the benefit of not oxidizing, but slightly worse EMF.

No plating somewhat better EMF, but if oxidized turn into an EMF disaster.

How quick do enough oxidation to be a problem build up? How frequent to clean and with what?

[Kleinstein]

Neither plating nor oxidation are that bad when it comes to thermal EMF: the layer is very thin and thus very little temperature drop across the surface layer. One usually still needs to keep thermal gradients low, as even just a plain copper wire can show thermal EMF, as mechanical deformation can also effect ther thermopower. I would more worry about thermal gradients at bend wires than the surface layers.

The oxide may be the larger problem: not because of thermal EMF, but because of contact resistance and a possible not that well defined contact position (it is no clear how even the oxide layer is).

[Kosmic]

So I decided to try my luck with the seller on Taobao.

I used Taobao before to get some spade lugs so I had some experience. But, I don't speak nor can read Chinese so it's always a challenge and I rely heavily on translators.

For those of you that never used Taobao, in a nutshell the way it's working is when you buy something from a seller it's consolidated by Taobao and when you are ready you pay the shipping for everything you accumulated and they send you everything in 1 package.

Normally you can pay everything with your credit card but this time things changed a bit. So I had no problem paying for the items but when it's time to pay for the final consolidated shipping, now alipay don't take foreign credit card anymore 

Fortunately there's a workaround. You need to pay with the Taobao app which is entirely in Chinese  So I had to find a second cellphone to translate the app on my main cellphone to pay for the final shipping (normally I simply use the web site with a auto translator)

Anyway, in the end all went well, I was able to pay for everything and I received my package 



They even included the leds and some copper ring lugs.


And some spare parts

[laichh]

Apparently they also make a Pomona 3770 clone and name it TBP2.

https://item.taobao.com/item.htm?spm=a312a.7700824.w4002-23305896296.11.28516517cq9BMj&id=595625345633

[DavidKo]

They are available quite a long time, but the pricing is similar to Pomona's original. At least last time whey I had checked.

[Ismsanmar]

The problem with Taobao is that they don't send to Europe since 2021, when the IOSS system was implemented. You have to go through an agent, and yet, in the end you end up with the same price as if you bought the LowThermal directly.

I asked a seller on aliexpress if he could sell those TBP3 as I bought from him some TBP2, but the same problem arises with the price. aliexpress.com/item/1005005496017446.html

I'm looking to buy 16 units, but the difference between the price offered by branadic and what those sellers offer is too big.

[deepfryed]

I asked a seller on aliexpress if he could sell those TBP3 as I bought from him some TBP2, but the same problem arises with the price. aliexpress.com/item/1005005496017446.html

Wow, that's quite a markup. I've always wondered how much of a difference it'll make, I might get some C11000 from a local supplier and try turning a few binding posts. I've got a couple of LT1021s in the parts bin, thinking of making a 10V, 1V and 100mV reference box for funsies.

[DavidKo]

...
I asked a seller on aliexpress if he could sell those TBP3 as I bought from him some TBP2, but the same problem arises with the price. aliexpress.com/item/1005005496017446.html
...

I'm not sure, but last time I have checked TBP2 the price was same as today (~$30). The price on Digikey or Mouser for original Pomona 3770 is $13 and both are shipping world wide. So I do not see any reason to buy knock off for double the price.

TBP3 are different. The Fluke terminals are not commonly available.

[Ismsanmar]

...
I asked a seller on aliexpress if he could sell those TBP3 as I bought from him some TBP2, but the same problem arises with the price. aliexpress.com/item/1005005496017446.html
...

I'm not sure, but last time I have checked TBP2 the price was same as today (~$30). The price on Digikey or Mouser for original Pomona 3770 is $13 and both are shipping world wide. So I do not see any reason to buy knock off for double the price.

TBP3 are different. The Fluke terminals are not commonly available.

I bought them for $14.71 each, including the discount coupons. At that time, they were $18.37, but when they arrived, the seller raised them to the $30 they cost now. It seems that the sale he made to me was not worth it.

The price of the Pomona is without VAT (and shipping if you don't reach the minimum for it to be free), and then you have to take into account that they have brass and steel parts, and that they don't offer the option of copper without plating. On the TBP2, all the parts are made of copper, washers and nuts included.

[Kosmic]

...
I asked a seller on aliexpress if he could sell those TBP3 as I bought from him some TBP2, but the same problem arises with the price. aliexpress.com/item/1005005496017446.html
...

I'm not sure, but last time I have checked TBP2 the price was same as today (~$30). The price on Digikey or Mouser for original Pomona 3770 is $13 and both are shipping world wide. So I do not see any reason to buy knock off for double the price.

TBP3 are different. The Fluke terminals are not commonly available.

TBP2 are 9.53$ US on taobao https://world.taobao.com/item/595625345633.htm

Pomona 3770 are around 12-13$ US on Digikey.

Not a big difference but still cheaper.

[laichh]

Found another seller on Taobao selling low thermal emf binding post.

https://world.taobao.com/dianpu/70023207.htm

[sahko123]

this is the guy i bulk buy my spade connectors, those 20yuan 3ish euro connectors are SOOO much cheaper than the ones i got during that first bulk buy

[deepfryed]

Nice find, Taobao makes it so hard though. I wish they supported international purchasers like Aliexpress do.

[deepfryed]

I can see why people complain about machining copper 

I started prototyping one and may have to make the binding post slightly oversized because pure copper is sticky as heck and not very strong. Wondering if the added thermal mass is going to be an issue.

[aronake]

I used to use the taobao TBP2, but then found these, which is my standard connector now:

https://item.taobao.com/item.htm?spm=a1z09.2.0.0.36252e8d1EdBBD&id=40823926055&_u=62lgsmeg6d51

Seems to be copper, around half price compared to TBP2 (4 USD each) and slightly smaller, which I see as a benefit.

[deepfryed]

Finally had some free time to nearly finish my DIY pure copper C110 binding posts. I just need to make some plastic (ptfe) knob bits later.

Total cost ~$10 in materials and a couple of hours on the lathe.