Products > Test Equipment
Some old school instruments showing how it's done (HP 3325A and Fluke 8506a)
SilverSolder:
The manually tuned A/D converter is both good and bad: good, in that it is possible to tune it... and bad, in that it needs tuning in the first place!
joeqsmith:
--- Quote from: garrettm on February 18, 2021, 12:07:23 am ---Here's the output of my meter on the 10V range after power up using each binary type. The decimal representation given below the hex values uses my code for the conversion.
| Vs | 3-byte | 5-byte | 6-byte |
-------------------------------------------------------
|+10V | 10 00 00 | 00 FF FF 99 01 | 00 FF FF C2 00 01 |
|-10V | F0 00 00 | FF 00 00 89 01 | FF 00 00 84 00 01 |
-------------------------------------------------------
|+10V |+10.00000 | +9.99994 | +9.999963 |
|-10V |-10.00000 | -9.99992 | -9.999921 |
I would be curious to see the output of your code with what's shown here.
--- End quote ---
No problem. For the 3-byte, do you want me to scale the data for the range? Again, I have not tested that part.
***
For the 5-byte,
9.9999386072 / -9.9999183416
***
Interesting about the 3-byte is that the document you link has been corrected from my manual where they had dropped the sign.
10.0000000000 / -10.0000000000
Using the manuals example of 0xF7,0xBF, 0xFF
-5.1562595367
***
Note that I do not have support for the range scale factor.
joeqsmith:
With the meter now basically working, I wanted to run a longer term stability test in the lowest range (what started the whole mess). I was looking in my stash around 1-5 ohms that was somewhat stable. I found some old Shallcross parts marked JRBR71S. Searching for some sort of data sheets that would show the drift, I came across this article on resistors that I found interesting.
https://www.edn.com/the-last-half-century-wirewound-resistors-part-one/
https://www.edn.com/the-last-half-century-wirewound-resistors-part-two/
I never located a data sheet or figure out what the tempco is.
SilverSolder:
--- Quote from: joeqsmith on February 20, 2021, 02:04:48 am ---With the meter now basically working, I wanted to run a longer term stability test in the lowest range (what started the whole mess). I was looking in my stash around 1-5 ohms that was somewhat stable. I found some old Shallcross parts marked JRBR71S. Searching for some sort of data sheets that would show the drift, I came across this article on resistors that I found interesting.
https://www.edn.com/the-last-half-century-wirewound-resistors-part-one/
https://www.edn.com/the-last-half-century-wirewound-resistors-part-two/
I never located a data sheet or figure out what the tempco is.
--- End quote ---
Was that written by the same Mr. Pettis who is an EEVBlog member? - he seems to know his stuff!
SilverSolder:
So I got the Batronix programmer, took 4 days to ship in from Germany.
It's about the same size as the TL866.
It feels super solid, metal cabinet. And it is able to put 21V on to the Vpp pin of the EPROM:
I tried both Intel and TI NMOS 21V chips, and both worked first time.
Bottom line, it works like a charm... I feel it is good value at EUR 159, given the obvious care and attention that has gone into everything (hardware, software, and chip database that goes into extreme detail, even listing the EPROM variants with different timing).
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