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Old 2nd Jan 2019, 8:44 am   #1901
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Default Re: AVO Multimeter survey

Hi Aitor,

The Circuit Diagram of the Test Tool I think you are looking for is attached.

I built one of these, but modified it for use with both the older 1-12 Scales
and the 1-10.
Simply Circuit, but finding the 1 Ohm Resistors was a Task!

Also, I think the 0.05% tolerance might be a typo! Impossible to find at this level!
I settled for 0.2% which was the best I could achieve.

Ian
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File Type: pdf Mark V Scale Shape Test Circuit.pdf (19.7 KB, 116 views)
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Old 2nd Jan 2019, 9:08 am   #1902
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Default Re: AVO Multimeter survey

Ian, that’s very interesting. However it does rely on the cell being able to supply over 100mA without its terminal voltage dropping at all throughout the duration of the test. What type of cell did you use?
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Old 2nd Jan 2019, 9:24 am   #1903
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Thanks very much. I wonder that it could be better to use a power supply.

Why there are 2 variable resistors in series 20k and 100k??
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Old 2nd Jan 2019, 9:26 am   #1904
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Phil,

Yes, you are absolutely correct.
I cheated, my Circuit is running off a Regulated PSU for testing
at the moment.

It's actually not quite finished yet. As is so often the case, you
start a project and get side tracked!

The plan is eventually to run it off 2 x AA Cells (NiMh) and a Zener
Diode to bring it down to a fixed 1.5 Volts.
Got as far as fitting the Battery Box and it stopped there for a while.

Ian
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Old 2nd Jan 2019, 9:28 am   #1905
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Default Re: AVO Multimeter survey

The Two Variable Resistors are for Course and Fine Adjustment
of the FSD.
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Old 2nd Jan 2019, 9:57 am   #1906
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Thanks, I suppose so, but I was thinking that only with a higher one perhaps will work fine
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Old 2nd Jan 2019, 9:58 am   #1907
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Default Re: AVO Multimeter survey

Hi Ian. I think you’re probably taking the right approach by running the circuit from a regulated power supply. I’d do the same, unless you require portability. The reason I’m interested in circuits of this type is that I built a low-reading ohmmeter using similar principles. It worked fine using a D-size NiMH cell, but of course the duration of discharge is much shorter than with the cardinal point checker, which could be running for several minutes.

I presume from the high resistance values in series with the meter that Avo intended this circuit to be used solely for the Model 8. I’d like to build something similar that would test lower-sensitivity instruments with a similar degree of accuracy!
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Old 3rd Jan 2019, 12:29 pm   #1908
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Today I finally received my 36 range Avo. Serial number 26-5007
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Old 4th Jan 2019, 5:28 pm   #1909
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Avo 7 mk2

226-A-1061-F

With PF connectors
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Old 5th Jan 2019, 6:31 pm   #1910
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Ladies and Gentlemen,

Happy New Year to you all.

It's been a long time coming, and it's not finished by any means, but please find
attached a more complete version of the AVO Multimeter Survey Data.

I have no idea if this is even close to what SPCh envisaged back in 2004 when
this Thread was started, but I hope it will be of interest to some of you.

It is still my intention to improve on the Data recorded, in particular Case Styles
which has popped up several times recently, but I can't do this unless the Data
is still coming in.

Please feel free to comment (Good or Bad) on the Document, and offer any suggestions
for improving it.
There are a few more Meter Types that will be added shortly.

So, we are still looking for New Serial Numbers and Case details for Model 7's/ Model 40's and Model 8/9 Mk IV's even if their Serials have already been recorded.


Ian
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File Type: pdf AVO Multimeter Survey 2nd Edition.pdf (1.61 MB, 292 views)
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Old 5th Jan 2019, 6:46 pm   #1911
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Fantastic job. congratulations, it is easy to see the production month after month. Very useful and important this job!!!
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Old 5th Jan 2019, 7:57 pm   #1912
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Default Re: AVO Multimeter survey

Ian, what an absolutely fantastic job you have done. That's a real labour of love and a superb record for posterity. My thanks for all that hard work.

Is it possible that the last two entries for the Model 4 are actually the same meter?

And is the blurring of the data (looks like a picture import) deliberate, to stop scoundrels stealing it? If so, what about a good strong watermark all across the pdf?

Since your post containing the pdf document might become lost in the hugely long thread, could the moderators somehow link to it in the very first post?

Great job.
Jeremy
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Old 5th Jan 2019, 8:44 pm   #1913
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Hi Jeremy,

Thanks for the comments.

Yes, the last Two Model 4's are the same Meter. Dave's one as I recall.
It's one of those many things that slip through the Net, no matter how many times
you go through the Data.
It was reported twice in the Thread, so it slipped through.
Quite a few Meters have been reported more than once over the Years.
You might notice only 3 Model 4's are shown in the Stat's at the end.

The List does show up some interesting things. There appears to be another duplicate
Number on the Model 7 Mk II. Identical, but one states it's Braille. These were reported by
different Forum Members and I can only List the information given.

Regarding the resolution, no, it wasn't a deliberate ploy to stop copying, it was simply
a result of the way I was importing Data between Applications.
I decided it was good enough for the time being.
I hope to improve this on the next edition when I change over completely to Linux Applications.
The low Res was actually a surprise because I have been using all Microsoft Software up till now for this Project.

Anyway, it's great that errors are being picked up on, and I encourage that. Aitor has already highlighted another small error to me which has been corrected on the Master Database.

There are a few errors on it that I know about and will correct going forward, but I am happy to answer any questions if anybody has any queries and more than happy to have errors highlighted.
It's a Working Document after all.

Ian
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Old 5th Jan 2019, 9:16 pm   #1914
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.....It's a Working Document after all.Ian
No, it is a FANTASTIC working document after all!!

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Old 6th Jan 2019, 2:25 pm   #1915
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Thank you for embarking on a mammoth task and producing such a useful result. I see that item 16 is listed as a model 2, this is incorrect (my fault) it should be the rarer model 6 see here: http://www.richardsradios.co.uk/avo6.html
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Old 6th Jan 2019, 3:51 pm   #1916
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One more!. I think is not on the list, is not of my property, i found it on a electricity forum i think.

Model 8 serial number 96084-C-959
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Old 6th Jan 2019, 9:06 pm   #1917
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Just received mine, Model 8 MkIII No.25xx.666 the mark of the beast!!!
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Old 7th Jan 2019, 1:16 am   #1918
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There is a steel helmet that sits over the rear of the magnet/movement, which was covered with magnetic 'fur'. As well as giving physical/environmental protection, it appears to be able to grab and retain all magnetic matter that might otherwise jam the moving parts. The downside of this is every time the shunt is tweaked the helmet has to be replaced and screwed down, as calibration depends on it being in place.
Hello, have you got photos or more info about that "helmet"?

Thanks

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Old 7th Jan 2019, 9:36 am   #1919
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Default Re: AVO Multimeter survey

Ian, I’d like to add my thanks for your hard work in preparing and sharing the survey results. It is a superb work of reference and will be valuable to all of us who share this strange affliction!

One thought on the reason for duplicates - there may be meters that changed hands during the currency of this thread and were reported by multiple owners.
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Old 7th Jan 2019, 12:17 pm   #1920
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Seconded, well done Ian.

Aitor, i took a photo of the steel guard/helmet in the Precision Avometer, i will find it.

Dave
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