Author Topic: The LTFLU (aka SZA263) reference zener diode circuit (Read 197043 times)

fitzfish · « **Reply #125 on:** April 07, 2016, 07:47:37 am »

Looking more closely, they don't look like transistors. They are probably just degenerating the compensating transistor with a trim-at-test resistor as you suggest.

The two now more visible devices in the center look like they could be a candidate for the compensation transistor...

Gyro · « **Reply #126 on:** April 07, 2016, 10:57:49 am »

I wonder why the fuse between the Base lead and the upper resistor block (assuming that's what it is) is blown on both dies?

Edit: Or is that one the '16' fuse instead?

branadic · « **Reply #127 on:** June 08, 2016, 10:38:20 am »

Quote from: BU508A on March 22, 2016, 10:57:22 pm

Just a quick update:

I received today the 5 "LTFLU-1ACH", here are some pictures of them.

So, how to identify them, if they are fake?
I have here a reference board from a Fluke 3330B which runs with a SZA263 and my first idea was:
- solder out the original SZA263
- solder some wires to the solder points
- solder the new LTFLU-1ACH to the wires
- do some measurements and post the results here

But I do not really dare to solder out the SZA (which maybe would be a mistake) but I think using this board as a reference for comparison would be helpful.

Any suggestions / ideas?

Cheers,

BU508A

I today had the chance to open the part you have sent to me. While the pin 1 marker doesn't fit with the printing the package seems to contain a real LTFLU. If any pictures more are required please let me know. So no fake at all. Here's a first shot.

Sad it's now broken

BU508A · « **Reply #128 on:** June 08, 2016, 12:10:42 pm »

Quote from: branadic on June 08, 2016, 10:38:20 am

I today had the chance to open the part you have sent to me. While the pin 1 marker doesn't fit with the printing the package seems to contain a real LTFLU. If any pictures more are required please let me know. So no fake at all. Here's a first shot.

Sad it's now broken

Thank you very much branadic for your efforts. I've sent a second one to plesa, so let's see what he will find.
I'll do a test circuit for my other three LTFLU ones and will keep you updated here.

Thank you very much for looking into it, much appreciated.

Cheers,

Andreas

fitzfish · « **Reply #129 on:** June 08, 2016, 04:16:12 pm »

Great photo branadic!

Quote from: branadic on June 08, 2016, 10:38:20 am

I today had the chance to open the part you have sent to me. While the pin 1 marker doesn't fit with the printing the package seems to contain a real LTFLU. If any pictures more are required please let me know. So no fake at all. Here's a first shot.

Sad it's now broken

branadic · « **Reply #130 on:** June 09, 2016, 05:02:23 pm »

Updated the picture with a more sharp one, after our microscope was newly adjusted today.

BU508A · « **Reply #131 on:** June 09, 2016, 07:26:59 pm »

Hello,

Quote from: DiligentMinds.com on June 09, 2016, 05:18:35 pm

I am absolutely flabbergasted... I would have thought that for certain it was a fake. Wow! So, you might want to buy quite a few of these if you are interested as long as they are available from that supplier. Personally, I like the LTZ1000 better because I don't have to rely on precision resistor pairs to maintain the 7V-10V boost function, but if that is your plan then the LTFLU is probably the way to go [but it must be ovenized to eliminate hysteresis and make the drift rate constant].

I just placed another order of 5 pieces.
My plan is to build some circuits and do some measuring to bring some light into the specs of this circuit,
since there is no datasheet around (wasn't able to find one).
Perhaps it is possible then to compare the LTZ1000 and the LTFLU-1 which is imho interesting, because Fluke is using
the LTFLU-1 in their high precision gear (e.g. 732B or (probably) 8508A).

Btw, nice finding: http://www.edn.com/electronics-news/4389635/Go-inside-Fluke-s-electrical-metrology-lab

Cheers,

Andreas

fitzfish · « **Reply #132 on:** June 09, 2016, 07:50:20 pm »

Quote from: BU508A on June 09, 2016, 07:26:59 pm

because Fluke is using the LTFLU-1 in their high precision gear (e.g. 732B or (probably) 8508A).

732B, 5700/20/30A, 5500/20/22, and yes, in the latest revision of the 8508A. The original 8508 used an LTZ1000.

lukier · « **Reply #133 on:** June 09, 2016, 07:50:26 pm »

Quote from: BU508A on June 09, 2016, 07:26:59 pm

I just placed another order of 5 pieces.

Wow! For me Aliexpress shows "?6,221.33 / piece".

BU508A · « **Reply #134 on:** June 09, 2016, 08:00:05 pm »

Quote from: lukier on June 09, 2016, 07:50:26 pm

Wow! For me Aliexpress shows "?6,221.33 / piece".

*lol* You should not believe that. :-) I asked for a quotation in my first order and he is selling it for 25 US Dollars per piece plus shipping plus PayPal fee. So, no worries, I didn't won a lottery nor I am Bill Gates. ;-)

Andreas

BU508A · « **Reply #135 on:** June 10, 2016, 07:23:05 pm »

Hello,

branadic sent me some pictures with a higher resolution. Every picture has around 10 MByte,
probably here are some people which can do an analysis of these pictures.

Here is the link:
http://www.mounty.de/LTFLU/index.html

And thanks again to branadic and his efforts.

Regards,

Andreas

branadic · « **Reply #136 on:** June 11, 2016, 08:29:17 pm »

While the puppy is already broken I could do some simple resistor measurements with some probe needles in 4w measurement technics and our K2002. This way we could find out, if the upper and lower bar is a heater and which resistance it has.
We do have a Keithley semiconductor analyzer but it's not worth the effort to dig into this gear.

Any measurement suggestion is welcome. Please briefly describe what, how and where to measure at the die and I will see what I can do.

zlymex · « **Reply #137 on:** June 12, 2016, 01:56:54 am »

I'd like to know the resistance of those binary resistors(If they are resistors). One measurement of a large one(16 or

will do as the rest of them can be deducted.

TiN · « **Reply #138 on:** October 14, 2016, 04:53:35 am »

Revive!

I have module with heated dual LTFLU coming my way

. (No, not the 732)
Time to give those LTZs a worthy rivalry, what you folks say?

If anyone has ideas or theories to check on real circuit, let me know. I'd be happy to do that for upcoming article.

Vgkid · « **Reply #139 on:** October 14, 2016, 05:24:08 am »

Is it the precursor to the 732, the 735...

zlymex · « **Reply #140 on:** October 15, 2016, 01:28:24 am »

Is it the Fluke 5440B

ManateeMafia · « **Reply #141 on:** October 15, 2016, 02:16:14 am »

Quote from: Vgkid on October 14, 2016, 05:24:08 am

Is it the precursor to the 732, the 735...

You mean one of these ? I only know about two in the wild. A member on volt-nuts group bought the other.

Sorry, this was taken late at night.

Vgkid · « **Reply #142 on:** October 15, 2016, 04:52:48 am »

Looking into both the 731(I would assume te 735C is closer to this one), and the 732. I would say that zlymex is correct. I don't spend much time learning about those newer calibrators.

zlymex · « **Reply #143 on:** October 15, 2016, 07:05:33 am »

Quote from: ManateeMafia on October 15, 2016, 02:16:14 am

Quote from: Vgkid on October 14, 2016, 05:24:08 am
Is it the precursor to the 732, the 735...

You mean one of these ? I only know about two in the wild. A member on volt-nuts group bought the other.

Sorry, this was taken late at night.

Then you must bought that unit on ebay on March 2014.

zlymex · « **Reply #144 on:** October 15, 2016, 07:08:36 am »

Quote from: Vgkid on October 15, 2016, 04:52:48 am

Looking into both the 731(I would assume te 735C is closer to this one), and the 732. I would say that zlymex is correct. I don't spend much time learning about those newer calibrators.

Newer calibrators such as 5720A also use heated dual LTFLU.

Vgkid · « **Reply #145 on:** October 15, 2016, 07:46:38 am »

That is certainly interesting, like a single oven variant of the 732.

ManateeMafia · « **Reply #146 on:** October 15, 2016, 06:01:03 pm »

Quote from: zlymex on October 15, 2016, 07:05:33 am

Quote from: ManateeMafia on October 15, 2016, 02:16:14 am
Quote from: Vgkid on October 14, 2016, 05:24:08 am
Is it the precursor to the 732, the 735...

You mean one of these ? I only know about two in the wild. A member on volt-nuts group bought the other.

Sorry, this was taken late at night.
Then you must bought that unit on ebay on March 2014.

That was me. Do you have any information regarding the 735C? I have no idea what the specs are but I am guessing they are close to the 732A.

zlymex · « **Reply #147 on:** October 16, 2016, 09:02:55 am »

Quote from: ManateeMafia on October 15, 2016, 06:01:03 pm

That was me. Do you have any information regarding the 735C? I have no idea what the specs are but I am guessing they are close to the 732A.

I have almost nothing about 735C except some photos from eBay and one cut from probably an article and I forgot the source.

ManateeMafia · « **Reply #148 on:** October 16, 2016, 10:23:10 am »

I have that same article. I guess a teardown will have to be planned on this.

Another big difference is that they used ni-cd batteries that are expensive to replace.

TiN · « **Reply #149 on:** October 16, 2016, 05:46:55 pm »

Quote from: ManateeMafia on October 16, 2016, 10:23:10 am

teardown will have to be planned on this.

My screwdriver is ready!


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Author Topic: The LTFLU (aka SZA263) reference zener diode circuit (Read 197043 times)

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