Recent Posts

1

General Technical Chat / Re: US 50% China Semiconductor Tariff

« Last post by S. Petrukhin on Today at 07:51:16 pm »

I remember the US D-Ram tariffs for Japanese memory in the late 80s/early 90s.  Here in Canada, it was finally cheaper to ship in memory direct instead of getting it from US distributors.  It was a mess if you wanted to ship PCs from Canada to the USA.

That was a period when the US was accusing all sorts of people of dumping all sorts of things, many of them Japanese. Those accusations were based on US companies claiming how much various parts of the value chain cost them, with the implicit accusation that nobody could actually be cheaper than "the American way". This was really bogus in many cases, based on highly bloated US figures, especially for things like admin overheads.

Not so long ago, one senator asked why a package of simple bushings costs $90 000 (!) for the US army, although there is a maximum of $100.

2

Other Equipment & Products / Re: What are the chances these are real?

« Last post by Kim Christensen on Today at 07:48:11 pm »

True, but if I needed 44V specs, I'd simply buy a different OpAmp rather than the LM741J...

I need a DIP-8 package.  I guess I could get some other 44V OpAMp and use a carrier/breakout board.  But none of them are cheap either and then you have the expense of the chip carrier and the additional work (not so bad tho..).

If you can find a carrier/breakout board for cheap (Could also design/order a custom one from JLCPCB), then something like the TJM4558CDT could work unless you need the offset null pins from the 741...

3

Metrology / Re: More voltage references - die pictures

« Last post by Noopy on Today at 07:47:17 pm »

For everybody just reading here: I have uploaded some pictures of a LTZ1000A:

https://www.eevblog.com/forum/metrology/ultra-precision-reference-ltz1000/msg5502697/#msg5502697

https://www.richis-lab.de/REF44.htm

 

4

Metrology / Re: Ultra Precision Reference LTZ1000

« Last post by Noopy on Today at 07:46:27 pm »

Now here we have the TLZ1000A. The LTZ1000 has a thermal resistance of 80K/W. The LTZ1000A has a thermal resistance of 400K/W.




The LTZ1000A has the same basic design as the LTZ1000. Only the die attach material has changed. Here you can already see that the material is surprisingly unevenly distributed.








The LTZ1000A shows the datecode 4322, but the design is still the same as it was in 1983. Apart from the fact that the colors are slightly different in this illustration, it is the same design as in the LTZ1000. This was to be expected, as the only difference between the two variants is the heat transfer resistance.






Also in detail there are no differences to the LTZ1000.




The material used as die attach contains glass beads. The glass beads ensure a certain distance between the housing and the silicon, which increases the thermal resistance. The very similar ADR1000 (https://www.richis-lab.de/REF19.htm) also has a special die attach, but this is finely granular. It obviously insulates somewhat less well, as a heat resistance of 216K/W is specified for the ADR1000 (LTZ1000A: 400K/W). The ADR1001 (https://www.richis-lab.de/REF29.htm) uses a similar material to the LTZ1000A. In the LT1088 RMS converter (https://www.richis-lab.de/LT1088.htm), which is based on the design of the LTZ1000, air bubbles ensure good thermal insulation.


LT1088



I have stabbed the die attach of the LT1088. You can destroy it really easy. These are air bubbles!

/LT1088




The PCN 23_0011 shows which glass beads are used in the LTZ1000A. It describes that the glass beads will be changed from “Z-LIGHT Glass Sphere” to “COSPHERIC Glass Sphere” on 14.7.2023. It also states that the new glass beads will have a diameter of 90 - 106 µm. The glass beads in this LTZ1000A appear to be much less well sorted. In addition to the large beads, there are also many small particles in the mass.




If you scratch over the die attach of the LTZ1000A you get just some scratches. It´s hard, it´s glass.






The uneven distribution of the die attach is surprising. This LTZ1000A was purchased from Mouser, so it is almost certainly not a rejected part.




There are even holes under the die. Since a high thermal resistance is desired, one might think that cavities are not a disadvantage. However, it is important to remember that the LTZ1000A is a precision component. An inhomogeneous connection to the housing could lead to an inhomogeneous temperature distribution in the die. It is also conceivable that thermomechanical stresses could arise. The influence of a cavity is certainly small, but can be relevant for a precision component.


https://www.richis-lab.de/REF44.htm

 

5

Buy/Sell/Wanted / Re: Looking for HP Plotter Pens (old and no good also fine)

« Last post by Tony_G on Today at 07:46:17 pm »

Reading the latest posts, I was wondering if there is a 3D Model that might be useful and I stumbled over this:

https://www.thingiverse.com/thing:4911557

The author doesn't say anything about cutting down the pens but seeing that they say that this works in their 7475A I would assume that they have to be. Maybe they also printed a cap to reseal the end after they were cut down.

TonyG

6

Buy/Sell/Wanted / Re: WTB: HP/Agilent 34970A/34972A [EU]

« Last post by Zucca on Today at 07:40:03 pm »

If you find a 34972A for 250€ get two please, I give you the money.
Try to contact/PM Teichhermelin, he should have a 34970A for sale located in Germany.

I have one as well to sell but I am in USA.

7

General Technical Chat / Re: US 50% China Semiconductor Tariff

« Last post by coppice on Today at 07:39:49 pm »

I remember the US D-Ram tariffs for Japanese memory in the late 80s/early 90s.  Here in Canada, it was finally cheaper to ship in memory direct instead of getting it from US distributors.  It was a mess if you wanted to ship PCs from Canada to the USA.

That was a period when the US was accusing all sorts of people of dumping all sorts of things, many of them Japanese. Those accusations were based on US companies claiming how much various parts of the value chain cost them, with the implicit accusation that nobody could actually be cheaper than "the American way". This was really bogus in many cases, based on highly bloated US figures, especially for things like admin overheads.

8

Test Equipment / Re: Test Equipment Anonymous (TEA) group therapy thread

« Last post by factory on Today at 07:35:31 pm »

Think I've got it fixed, multiple shorted tantalums across power rails again. 

The board seems to be for a 0 to 3000.00mV function, of the mystery device, I'm wondering if it's used in something else, as there are parts that were removed for use in this device.





I didn't have a 1.5uF tant beads in stock, a 0.47 & 1uF went in, the yellow STC 1uF promptly went tits up. 
It got cut out of circuit, +/- 15V rails were now working, but not for long, another blue tant expired quickly (without smoke), I'm thinking 35V tants across the unregulated 25V rails are maybe too low.



At this point I got fed up with the tants and fitted some 4.7uF 50V electrolytics in place of the lot, much better. 



While I was in there I checked the rest of the capacitors and replaced a few tired ones on the other board, this board is part of the remote control for the 300V output.





David

9

Repair / Re: Problem with air compressor pump motor

« Last post by Gyro on Today at 07:35:22 pm »

Note that most of those Chinese clones of the Hyundai low noise compressors use CCA (copper clad aluminium), rather than copper wire, for their windings. As a result, they run hotter and are prone to failure. Pay particular attention to any joints you find in the motor and be careful not to accidentally strip the [copper] cladding off the wire, otherwise it will be impossible to achieve reliable connections.

10

General Technical Chat / Re: US 50% China Semiconductor Tariff

« Last post by S. Petrukhin on Today at 07:34:27 pm »

Once again, I'm sorry for the many naive questions.
If you answer, there will be more understanding in the world, which is necessary for all of us.

If anybody is inclined to answer, may I suggest that this be done via PM. This thread is deep into the territory which, in his opening post, Dave had explicitly asked us to avoid.

Of course! Welcome! My participation in the forum implies that you are free to write to me without any permissions.