[Stoves] humidity sensor resources
Marc Pare
mpare at gatech.edu
Mon Feb 4 05:27:44 CST 2013
Here are a few notes on a related area: fuel moisture sensors. We
researched this a bit for measuring the moisture content of rice husk
quickly in the field.
It was easy to find wood moisture sensors in the market, but nothing was
suitable for rice husk. It turns out that the operating principle behind
moisture sensors is pretty simple: you stick two leads into a materials and
measure the voltage drop across them (a resistance sensor). You can also do
it with capacitance.
The dead simplest way to implement is two rusty nails and a multimeter. But
here's a slightly better way:
"DIY Cheap soil moisture sensor"
http://www.cheapvegetablegardener.com/how-to-make-cheap-soil-moisture-sensor-2/
For rice husk, we would end up needing to use plates to get enough contact
area for a reliable reading. I think that's how the lab instruments for
this stuff work e.g. "Moisture spear"s
http://www.qclabequipment.com/SINARSPMOISTUREPROBE.html
Ended up not getting past the parts collection phase of this project!
Marc Paré
B.S. Mechanical Engineering
Georgia Institute of Technology | Université de Technologie de Compiègne
my cv, etc. | http://notwandering.com
On Mon, Feb 4, 2013 at 1:37 AM, Charlie Sellers <csellers42 at yahoo.com>wrote:
> Frank, good to see you at ETHOS (here is a quick video I took of the
> Sunday outdoor stove demo session http://youtu.be/KuJLf2ALMG4) and I
> agree that we have a need for something like this for fuel drying
> applications (such as when trying to prepare batches of feedstocks with a
> consistent moisture content - e.g. for use at regional stove testing labs.
> Here is what I have experience with, or found available:
>
>
> - I couldn't track down much at all about those oven sensors - either
> some sensor characteristics, or sources of them that might provide somedescription of what they are or how they work - so I worry that we won't be
> able to find enough info on their associated circuitry to use them easily
> (but the big ferrite magnets found in each oven are well worth
> harvesting).
> - When I was doing medical device development we used Sensirion's
> super quality SHT line of tiny CMOS sensors (they throw in a DTS
> temperature sensor for free), but while they are now a tenth of what we
> paid for them... they are still ~$25 at places like Sparkfun. For the same
> price, or much less, you can get consumer-grade weather station
> "instruments" complete with remote LCD readouts.
> - This bare sensor example caught my eye because its is so absurdly
> cheap ($3-$6) and often readily available -
> http://www.amazon.com/Virtuabotix-DHT11-Digital-Temperature-Humidity/dp/B0066YD3GM.
> You need some circuitry to use it or any other one, but hackers have
> published exactly how to do it using a variety of microprocessor platforms
> - for computer-aided data logging:
> http://embedded-lab.com/blog/?p=4333
>
> If anyone can suggest alternative methods (and applications for them in
> our arena) then I'd like to hear about them. Or about experiences with
> inexpensive drying in bulk of things like wood chips, for TLUDs or similar.
>
> Charlie
>
>
>
>
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