Homebrew PCBs

--- In Homebrew_PCBs@yahoogroups.com, "Herbert E. Plett"
<cachureos@...> wrote:
>
> 
> 
> > <John.Craddock@> wrote:
> > >
> > > Hi Philip,
> > > Yes, I read the article and have been doing some research of
> > thermocouple interfacing. ...
> 
> why so much complication?
> 
> hardware is dead simple using a 1-wire interface from Dallas-Maxim.
> thermocouple feeds directly into an ADC (DS2761) that directly
digitizes with a
> resolution of 15uV, measures digitally its own temperature and
connects to a uP
> via one pin (and ground). also has a 2-5V ADC that can be fed
directly from a
> pot (ie, setpoint).
> 
> so, all is needed is this chip 
> ( http://www.maxim-ic.com/quick_view2.cfm/qv_pk/3468 ) plus a microP
(I use
> Atmel Tiny), plus an opto-triac/triac pair or a solid state relay
and a few
> passives, switches and a pot with a large knob.
> 
> the process is all digital and the micro has the chance
(responsibility) to
> implement whatever algorithm fits (from on-off to self adjusting)
plus any
> bells and whistles (LCD display, serial logging, profile, etc).
> BTW, it DOES fit on a 1" x 2" board (exclusive of power and relay).  
> 
> I kept following this discussion in the hope somebody would come up
with a two
> chip reasonable analog solution, but no, no such... (at least yet)
> 
> 
> 
> 
> 
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Hi Herbert.

If I am reading it correctly, the DS2761 is a "High-Precision Li+
Battery Monitor". The datasheet says that its voltage measurement
channel does so with a resolution of 4.88 millivolts resolution.
Typical thermocouples have a resolution of around 40 to 50 microvolts
per degree C.

So obviously I am missing something from your description below. Could
you elaborate please?

Regards,

Ross McKenzie
ValuSoft
Melbourne Australia