[volt-nuts] Homebrew DVM
stan.katz.hk at gmail.com
Wed Nov 16 01:47:45 UTC 2011
I would think that Ron Tipton's 6 1/2 digit diy DVM, based on LTC2400 and a
statistical pool of Thaler(now Cirrus) VRE305A's would be the baseline
design to beat in this thread's quest for excellence. Yes?
On Tue, Nov 15, 2011 at 7:20 PM, Fred <pa4tim at gmail.com> wrote:
> The ADC I am gonna use is the LTC2400. A friend who is a digit-nut made
> the pcb and will make the software for me.
> About the dual slope experiment. I could look better as it is. The
> arduino died before I could do more tests but first results amazed me.
> Remember it was just breadboard, no Vref (just resistive divider from
> Vcc and, I do not dare to say, but the measurement pictures were taken
> after I blew up my last 4066, so I used optocouplers to switch and
> strange enough that went very well.
> The drift you see in the measurements is more because the powersupply I
> measured the voltage from, is not realy stable. Noise I do not know.
> The experiment was after a discussion on a Dutch forum. There was some
> talk about multimeters and ADCs and the a member who works at ST as an
> EE told the top meters used dual slope about how easy it is to make a
> dual slope ADC. He told us to just try it on a breadboard and gave some
> tips. A few of us including me started experimenting with it and I was
> trilled it was so easy to get it working like it did. Was fun too. I'm
> now reading a lot of literature and your interesting discussions to
> learn more before I build my meter using the LTC2400. So thanks for all
> the valuable information. As a beginner I appreciate it very much.
> Fred PA4TIM
> Andreas Jahn schreef op di 15-11-2011 om 23:19 [+0100]:
> > Hello Fred,
> > I asked for the 26 bit (24 bit usable) ADC.
> > Do you really get this (noiseless) resolution with a simple dual slope
> > With best regards
> > Andreas
> > >
> > > http://www.pa4tim.nl/?p=2482 there you see the schematic and some
> > > ( the top one is from the circuit that, i was told, turned out to be a
> > > converter)
> > >
> > > Fred PA4TIM
> > >
> > >> I am looking now for a converter with less noise.
> > >> So what ADC are You using?
> > >>
> > >>>
> > >>> Now I have a 26 bit ( 24 bit usable) ADC waiting to be used
> > >>> to the arduino, I am making/experimenting with some Vrefs and have
> > >>> for a compound chopper based on a LT1052. But the realisation will
> be up
> > >>> in the future, first gathering more knowledge about percision and
> > >>> volt techniques.
> > >>>
> > >>> Fred PA4TIM
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