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14 sensors on a stick

This is a stick of 14 sensors on six ICs, that's meant to go into the middle of a beehive. But it could be interesting for other uses. It runs on low-power 3.3V, and uses a single I2C data bus.

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WRT to the choice of sensors, there's redundancy for the T + RH sensors, because we've had so much trouble with RH sensors (it's a test platform). It has a barometric-pressure sensor, a CO2 sensor, and two volatile organic gas sensors. The latter use miniature hot plates, briefly drawing up to 75mA. An 800M:1 dynamic-range light sensor is to help explore interesting night-time hive activity (but we didn't add proximity detectors). (I also resisted temptation to add a lightning detector.)

As far as the bewildering array of IO connectors is concerned, that's to handle a variety of uses.

--
 Thanks, 
    - Win
Reply to
Winfield Hill
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Anyone who wants to play with one of these sticks, I may have extras in a month or so.

--
 Thanks, 
    - Win
Reply to
Winfield Hill

I don't have a need for one, but might be interested if it comes conformal coated in honey. :)

Nice looking design. Hope it works out for you!

Reply to
mpm

Or one at the bottom of the jar of honey like the worm in Tequila.

--

  Rick C. 

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Reply to
Rick C

Thank you! Yes, I enjoyed working on this design, and admired the amazing sensors, but in the end, I just selected simple sensors that can be drawn as a box with four pins, and wired up supply and ground, along with the two I2C pins in parallel. Two 1.8-volt sensors added a hint of complexity. There was quite a bit of mucking around, finding various small parts, making weird PCB footprints, learning about FFC flat flexible cables, etc. And the Institute mathematician has spent several weeks working on software to talk to the sensors. Tomorrow we'll power one up and see what happens.

--
 Thanks, 
    - Win
Reply to
Winfield Hill

dl=0

What is it you are looking for with these sensors? I kept a hive for 5 years, temporarily retiring it two years ago for lack of time but planning to get two hives going again in a couple of years - we are running low on honey :-). If I were to monitor my hives electronically the first thing I would want is a scale and means for daily hive weight logging to an MQTT broker which I could check from computer or phone, the second might be a microphone and logging of a few FFT bins for swarm prediction:

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While looking for this I found a note on honeybee hearing which I probably posted somewhere before:

Honeybees hearing is also sensitive to displacement rather than pressure. For many years it was a mystery how an insect with no ears could respond to the sound of the wingbeat of guide bees preforming the "dance" which communicates direction to food source (by direction of the central tail-waggle portion of the dance), distance (by the speed of tail waggle), and quality (by wingbeat frequency). It was eventually determined that hearing was done with an organ within a joint of the antennae, and by testing in a standing wave tube shown that honeybees can hear at the displacement maxima (pressure nodes) and not at the displacement nodes (pressure maxima). This hearing is limited to a few hundred Hz by the size of the antennae, which is much larger than the MEMS displacement microphones.

My source of this information, The ABC-XYZ of Bee Culture, references Towne, W.F. and W.H. Kirchner, Hearing in honey bees: detection of air particle oscillations. Science 244: 686-688, 1989

Glen

Reply to
glen walpert
[...]

A few hundred Hz? The bees might enjoy some rap or didgeridoo music :-)

After all, Kobe cattle is listening to Mozart I believe.

--
Regards, Joerg 

http://www.analogconsultants.com/
Reply to
Joerg

Thanks for your comments.

This sensor stick plugs into our bee-hive monitor, which has about 60 other sensors, including weight, all bee trips in/out, temp, RH, and two microphones. Running this last summer on seven hives, I learned a lot, but I'm not sure how valuable it would be to experienced bee-hive operators. We're still feeling our way along, including this summer improving rapid reporting, easy data visualization, analysis, etc.

As far as sound is concerned, we can make detailed recordings, do FFTs, etc., but mostly we just save minimum sound intensity every 10 minutes.

We only got one set of recordings on a hive abscond event. The hive seemed healthy and things looked pretty normal, up to just before the event. But we had seen the unusual markers before, and without a follow-on abscond event. One thing that we saw the night before was guarding level suddenly way down, virtually stopped. It's possible the absconding had already started, and took two days. That's what the weight and bee-trip data implied.

After the abscond, within a day or two, robber bees arrived. But robbers never bothered to guard the hive. One night about 60 bees were trapped in the hive (they didn't know well how to navigate any of the 24 counting-channel tunnels in the dark), but they all escaped in a rush at 3am, into driving rain and pitch black storm. Dunno what happened.

--
 Thanks, 
    - Win
Reply to
Winfield Hill

Great work and great sharing. The fraternal sharing of experience, lessons learned, is precious. Engineering

-like life- should be a continuing education. Too much of our industry is closed off, sensitive to competition, separated by "oceans" - so places like S.E.D. our vital. I hope our younger peers keep it going. Cheers, Rich S.

Reply to
Rich S

=0

Very interesting project

I was just checking out the schematics, you have 2 sensors that monitor gas es/VOC

For a private project, I am looking for a sensor that would detect mold, so I could have a sensor that could track/detect where the mold origin is. As far I can see PM2.5 sensors (more or less dust sensors), are the preferred solution, but that said, I am not fully into the subject yet

Why did you decide for VOC and not PM2.5 sensors?

Also, how do you calibrate the sensors. From what I gather, the VOC sensors are difficult to use if they are not calibrated to a known reference first

Cheers

Klaus

Reply to
klaus.kragelund

We're doing some high-Z optical sensors for detecting sparks in cotton harvesting equipment. There's a 200 Mohm TIA in there, so we care quite a lot about water inside the box, which leads us to put T/RH sensors inside to give early warning of water ingress.

Could you tell us more about your RH sensor experience?

Thanks

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC / Hobbs ElectroOptics 
Optics, Electro-optics, Photonics, Analog Electronics 
Briarcliff Manor NY 10510 

http://electrooptical.net 
http://hobbs-eo.com
Reply to
Phil Hobbs

WE had only one brand that failed (one you wouldn't use); I can tell you more after working with our four new brands.

--
 Thanks, 
    - Win
Reply to
Winfield Hill

Very nice!

If you have extras in a moth or so, I have a chicken coop that needs instrumented!

--bob

Reply to
artie

OK, Bob, send me an email to hold a place.

--
 Thanks, 
    - Win
Reply to
Winfield Hill

I don't think it's small enough to be in a moth.

:)

Reply to
Clifford Heath

Thanks for the details, sounds fascinating. I am in no way a bee expert, my last two hives absconded without me noticing, and I have decided not to try again until I can be around to take care of the 2 hives rather than one, doubling my odds of making it through the winter. I trust you will let us know of any interesting findings from your research.

Thanks, Glen

Reply to
glen walpert

A short beekeeper blog about two hive abscondings.

Mikek

Reply to
amdx

I'd be interested too. (though I have no project in mind) I went looking for info on how humidity sensors work, and found precious little. this,

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and this,
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talked about how they work.

I found nothing about how they work in the vendors data sheets.

George H.

Reply to
George Herold

On a sunny day (Mon, 3 Jun 2019 08:28:55 -0700 (PDT)) it happened George Herold wrote in :

Here in detail explained:

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I have 2 humidity sensors logging 24/7. the first one is a variant of this one, and uses a DHT11 resistive sensor:

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DHT11 resistance decreases when moisture increases.

The other one

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uses a cheap Chinese wireless indoor / outdoor sensor an USB DVB-T stick as receiver and some software to decode 433 MHz signals: panteltje12: ~ # rtl_433 -d 0 -R 19 | weather_sensor_to_xgpspc -xy Registering protocol [1] "Nexus Temperature & Humidity Sensor" Registered 1 out of 101 device decoding protocols Found 1 device(s)

trying device 0: Realtek, RTL2838UHIDIR, SN: 00000001 Found Rafael Micro R820T tuner Using device 0: Generic RTL2832U OEM Exact sample rate is: 250000.000414 Hz Sample rate set to 250000. Bit detection level set to 0 (Auto). Tuner gain set to Auto. Reading samples in async mode... Tuned to 433920000 Hz. ... 2019 06 03 17:29 t 31.0 / rh 17.0 \ t_min 16.8 at 07:00 t_max 31.0 at 17:29 rh_min 17.0 at 17:28 rh_max 88.0 at 06:44 ... been hot here outside.

I opened it up (modified for li-ion battery (it sucks current) and it seems a very similar sensor to the DHT11.

rtl_433 is a nice program (written by somebody else) that decodes many 433 MHz device protocols. weather_sensor_to_xgpspc just processes the output and then forwards it via ethernet to a Raspberry Pi, I wrote that.

I once worked with capacitive humidity sensors used to measure humidity of grain in silos, that was long ago, big and expensive units, do no remember who made thsose.

Bees no... Very few insects here this year, flowers bloom, but hardly any insects.

Reply to
Jan Panteltje

Thanks Jan. I guess I always want to know more. Why do these things measure RH (relative humidity) so well? I'd think they some how would measure the amount of water in the air. (absolute humidity) Which changes dramatically with temperature.

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Yeah we had some wild bee hives in our woods, but they died off, and now no honey bees at my house. :^( (fewer apples on the trees.)

George H.

Reply to
George Herold

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