[volt-nuts] MicroVolt meter

[shalimr9 at gmail.com]

Another part worth looking at is the Analog Device ADUC7061.

It is an ARM-7 core with 24 bit ADC and a lot of other goodies. They have a $35 eval kit (look for ADUC7061 minikit). Programming is via the USB so there is no need for a separate programmer.

I believe gcc will create ARM-7 code, so you should not have to use the expensive Keil or IAR tools, at least once you become familiar with the architecture. Debugging under gcc/gdb is certainly not as much fun as it is under Keil or IAR (if it were ever fun.)

If your needs are modest, you may be able to do what you need with the sample code and eval software they provide with the kit.

That would be the cheapest 24 bit to USB converter you can buy.

Didier KO4BB

Sent from my BlackBerry Wireless thingy while I do other things...

-----Original Message-----
From: "Dave M" <dgminala at mediacombb.net>
Sender: volt-nuts-bounces at febo.com
Date: Wed, 4 May 2011 09:55:12 
To: <volt-nuts at febo.com>
Reply-To: Discussion of precise voltage measurement <volt-nuts at febo.com>
Subject: Re: [volt-nuts] MicroVolt meter

> From: shalimr9 at gmail.com
> Subject: Re: [volt-nuts] MicroVolt meter
>
> There are 24 bits ADCs available. One I have used is the MSC1210 from
> TI. It is actually an ADC with an 8051 processor integrated (with
> Flash and RAM). There are many more. You can probably buy a cheap
> development kit. I paid $50 for mine.
>
> Didier KO4BB
> Q
> Sent from my BlackBerry Wireless thingy while I do other things...
>
> -----Original Message-----
> From: Fred Schneider <pa4tim at gmail.com>
> Subject: [volt-nuts] MicroVolt meter
>
> Am I a dreamer if I think there must be a way to build a digital or
> analogue meter that has a resolution of 0,1 uVDC and a max input of 2
> V in that range, and 1 uV at a 20 V range.
> Used bench meters with that resolution are scares and new ones made
> of plain gold.
>
> I was thinking of using a modern chopper opamp. LTC1051 with LT1007.
> Or a TL7652.
> Maybe two that split up the voltage and then to two ADC's. Wilkinson
> version ? The result to an Arduino for the readout and combining of
> the most and least significant digits.
> But I'm an RF head, i can make 1GHz oscillators, but digital stuff is
> rather new for me ( I can program a little in C).
>
> Other idea
> A 845AB meter can reach 1 uV full scale, but that is nice as null
> detector. You can not measure the voltage of a 1 V calibrator direct.
> There should be a way to use that thechnique. For instance make
> something for that meter, a sort attenuator or divider or subtractor
> and let it switch automatic through it ranges. The 845 stays in 1 uV
> range but the Attenuator switches from the 10 V to 1 uV range. The
> measurements from the recorder output to a uProcessor that combines
> all the results. So in the 10 V range it measures 3.53V, we keep the
> 3.  in the 1 V ranges it sees 0,534V. We keep the 5, in the 1 mV
> range it sees 0,0346, we keep the 3 ect upto 0.1 uV.
> A sort of sample and hold that we use in a later stage to subtract
> from the next input.
>
> Fred PA4TIM

The 24-bit ADC is a good idea.  I was investigating the MSC1210 a couple of 
years ago when I ran into medical problems, and just never got back to it.
I did a quick search for the eval kit but couldn't find any available.  Does 
anyone know of a source (reasonably priced, of course)?

David
dgminala at mediacombb dot net




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