[volt-nuts] MicroVolt meter

[Dave M]

> 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