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Topic: Engineer/Programmer for Prototype temp/RH logging (Read 3 times) previous topic - next topic

liudr

Just curious, what is the temperature range your tanks are at, max, min, and what resolution are you looking to achieve.

For temperature alone, I've done a project with a few students using thermochromic liquid crystal sheets and a digital camera. FYI, a thermochromic liquid crystal sheet changes color at different temperature so you can attach a patch on every tank and just use one camera to get everything in one shot and keep grabbing frames. All depends on how accurately you want and the range of temp.

smh3w

First of all thanks very much to everyone who replied!

robtillaart

Excellent information!

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One Arduino can sample 4 sensors - once per 10 seconds or so - ; add an ethernet to post all the sensor data to a PHP page on a PC which stores it in a MySQL database or a logfile per sensor per day or so.. You can use this data to make nice graphs


So... one Arduino UNO can monitor 4 of the SHT15's and transmit the data wirelessly (thanks PaulS) via an XBee (of some sort) to a computer? Will the computer end of the transmission require another Arduino UNO, power supply (not through USB?), and XBee device(s)?

Is there a way for a solid state relay to operate something with higher voltage (regular household current) such as a: http://www.amazon.com/gp/product/B000WEIJ7K/ref=pd_lpo_k2_dp_sr_1?pf_rd_p=486539851&pf_rd_s=lpo-top-stripe-1&pf_rd_t=201&pf_rd_i=B000BKGOM2&pf_rd_m=ATVPDKIKX0DER&pf_rd_r=0C34ZQGDHZT2991M5TTC

PaulS

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My questions were more for getting you to think about the requirements, than to criticize anything. Writing a good requirements document is critical to successfully developing a project.


They were good questions. I didn't mean to sound defensive. Sometimes it's hard for me to communicate clearly what I have in mind to others.

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As Rob's price list and wiring comments shows.....really doesn't need to be an Arduino at each tank.


I guess I just do not really have that firm of a grasp of how all this stuff works. All I need are an SHT15, XBee, power supply, and sensor wiring/casing at the tank, and with appropriate receiving equiptment (?? another XBee?) at the computer?

My assumptions that I can't possibly do this on my own are being very strongly confirmed! :-X

My intention is not to sell a system like this just to make money. If I could somehow manage to put the components together I would sell at near cost to other hobbyists. I think people would be interested in the basic function of temp/RH logging.

liudr

Nominal temperature ranges are usually between 70 F - 78 F during the day along with a drop in temperature to around 62-65 F at night. As for resolution, to the nearest tenth. I'm sure people would get their jollies from as accurate a reading as possible (hundredth).

The experiences I've had with thermochromic liquid crystal sheets is that it can be hard to differentiate between the reading as the temperature of the object it is mounted on (i.e. glass) or the ambient temperature (which is what I need)



Anyone want to make one for me?  :'(

I would really like to learn about how to put something like this together, but I would be basically starting at square one zero. I have no experience soldering, reading wiring diagrams, deciphering very complex data sheets, programming in whatever language the Arduino uses, etc.

I don't mean to sound childish, I guess I can just be impatient.

PaulS

#7
Jan 10, 2011, 01:10 pm Last Edit: Jan 10, 2011, 01:11 pm by PaulS Reason: 1
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So... one Arduino UNO can monitor 4 of the SHT15's and transmit the data wirelessly (thanks PaulS) via an XBee (of some sort) to a computer?

Yes.

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Will the computer end of the transmission require another Arduino UNO, power supply (not through USB?), and XBee device(s)?

The PC end could consist of an XBee and a USB explorer (or there is a dongle version).

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Is there a way for a solid state relay to operate something with higher voltage

That is the function of a relay, solid state or conventional.

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All I need are an SHT15, XBee, power supply, and sensor wiring/casing at the tank, and with appropriate receiving equiptment (?? another XBee?) at the computer?

That is one way of doing it. It has advantages in that the sensor is close to the sender.

It has disadvantages in that the XBee has a smaller number of digital and analog pins, compared to an Arduino with XBee, and the XBee can't make decisions. The Arduino would be able to handle more inputs and make decisions, rather than the computer.

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Anyone want to make one for me?

I'd be willing (PM me if interested). I have XBees and Arduinos and all the shields. The only things I don't have are the temperature/humidity sensor and solid state relay to control the fans/heaters.

robtillaart

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o... one Arduino UNO can monitor 4 of the SHT15's

Yes, but if you don't mind plenty of cables, one MEGA - http://arduino.cc/en/Main/ArduinoBoardMega2560 - has 70 I/O lines so it can handle approx 20 temphumid sensors and fans.  It sells for ~$65 ...

I like the XBEE architecture proposal as it keeps the room clean of cables. But is it part of the requirements?

If you do XBEE I think you want one XBEE per tank, that has one sensor + one fan.

XBEE - $30 (including some board thingie)
SHT  - $38
FAN  - $6
Power supply - $10
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$85 - so almost equal in price but no wires and maximal modular. So the price we can say the price will be approx $100 per tank no matter what architecture. So which architecture to choose depends on the other requirements of the system than price

So Steven, can you sum up the requirements for us (single sentence per requirement please)

Here are some as a starter, some may apply some not up to you Steven.

- the system must monitor temperature per tank
- the system must monitor humidity per tank
- the system must activate a fan at XX degrees F/C per tank
- the system must deactivate a fan at XX degrees F/C per tank
- the system must have settings per tank
- the system must have a manual override for all fans [ON/OFF]
- the system must sample temperature every 10 seconds
- the system must sample humidity every 60 seconds
- the system must apply a warning when temperature is outside the range [XX..YY]
- the system must apply a warning when humidity is outside the range [XX..YY]
- the system must have a local feedback about its working condition  (might be a blinking LED (without delay :) )

- the system may not be noisy at night (not explicit enough)

- the system must be save for the frogs (not explicit enough)
==> - the system must work on 5Volts

- etc ...
Rob Tillaart

Nederlandse sectie - http://arduino.cc/forum/index.php/board,77.0.html -
(Please do not PM for private consultancy)

rocketgeek

Here's a thought for a probe/controller board that goes in each tank and reports to a central base station. Prices are for single quantities:

1 x SHT11 (cheaper and slightly less accurate SHT15): $25
1 x SF1 (protective cover for SHT series): $5
1 x Atmega32: $4
1 x AT86RF230 (2.4 GHz 802.15.4 tranceiver): $4

This, along with a power supply and all the random ancillary stuff should fit on a very small board. Add a couple of transistor outputs to drive relays and you're good to go on most of your requirements, and for a lower retail price than a probe along from the Herp Keeper folks. Those ICs are rated for operation up to 85 deg C, which is more than enough temperature headroom. The center hub can be any 802.15.4 device that can easily be plugged into a PC, along with an LCD and a few buttons. I'm working on a shield-compatible Arduino clone with an onboard 802.15.4 radio, the Zigduino (www.logos-electro.com/zigduino) that would work well with a datalogger shield and an LCD shield like the Freetronics LCD shield (http://www.freetronics.com/products/16x2lcd) to fulfill your display requirements.

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