[time-nuts] Environmental sensor recommendations

Edesio Costa e Silva time-nuts at tardis.net.br
Thu Apr 5 10:15:38 EDT 2018


If you use an "interchangeable" NTC like
https://br.mouser.com/ProductDetail/US-Sensor/PS103J2 you can skip the
calibration part.

Edésio

On Thu, Apr 05, 2018 at 09:20:56AM -0400, Bob kb8tq wrote:
> Hi
>
> By far the highest resolution sensor you will come across is a thermistor. It also has a pretty
> narrow range in terms of maintaining high resolution. That???s fine for something with a target
> temperature ( OCXO oven) and not so fine for monitoring outdoor temperature year round.
>
> If you want something that is pre-calibrated, then the IC based parts are the way to go. They
> are a much better answer to the ???general purpose sensor???? question. Mounting them and hooking
> up to them ??? errr ???. not quite so easy.
>
> One basic answer is to buy a bag of cheap thermistors and calibrate them yourself. They may
> have odd curves, but so far the entire bag looks about the same. That???s been true for a couple
> of bags bought randomly here and there. For a lot of things, a simple three point calibration will
> do pretty well. You still need to do a rational curve fit, but even that isn???t to crazy over limited
> ranges.
>
> Bob
>
> > On Apr 4, 2018, at 8:58 PM, Mark Sims <holrum at hotmail.com> wrote:
> >
> > I recently (mostly)  finished adding external environmental sensor support to Lady Heather.   You can use the sensor as the primary "receiver" device or in conjunction with any of the "receivers" that Lady Heather supports (except currently the HP-5071A which uses the same plot queue entries as the environmental sensors).  Heather supports humidity, pressure, and two temperature values.
> >
> > I am currently using a dogratian.com USB-PA sensor with temperature, humidity, and pressure.  I am also designing a Heather specific board (BME280, two thernistors, temperature controller interface, maybe a couple of ADC channels, etc).   Are there any recommendations for other off-the-shelf sensors worth looking at?
> >
> > The main requirement is that the sensor should send data over a serial port or virtual serial port or maybe ethernet.   Ideally it would stream readings at 1 Hz, but a polled device (like the dogratian.com devices) can be accomodated.    Also, it would be very nice if the temperature sensors are small, responsive, and on leads that could be attached to whatever is being monitored.
> >
> > Attached is a screen dump of the USB-PA running.   Can you spot the furnace cycling and sunrise?
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