[time-nuts] Poor man's oven

Poul-Henning Kamp phk at phk.freebsd.dk
Tue Jun 6 15:01:35 EDT 2017

In message <CABbxVHuzd5riV+SBQA0CnsVFCzVb7Ub-dfLJLTob0TZt-pRrzQ at mail.gmail.com>
, Chris Albertson writes:

>The next step up the complexity scale would have you place an I2C
>interlaced ADC inside your oven.  These don't cost much and have several
>ADC channels.

ISOtemp made a version of their OCXO-107 which a built in DAC, but
I've been told the result was less than stellar.

When you do stuff like that, you need to pay a lot of attention to noise.

Personally I would avoid I2C, in preference for SPI to avoid the
sharp flanks required by I2C.

I would also run the SPI as slow as I possibly could and put low-pass
filter the digital signals at the boundary.

SRS uses an interesting trick in several of their instruments, where
they shut down parts or even all of the digital circuits when not
needed, see for instance their digital "all analog" lock-in amplifier.

Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.

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