Backyard Aquaponics
A place to discuss aquaponics

Not sure if the cheapest but little bird haven't let me down yet, this would appear to be an ideal product http://littlebirdelectronics.com/products/seeeduino-stalker-waterproof-solar-kit-1

I've been playing around with Arduino stuff. I made a Nano clone powered temperature/light logger with three DS18B20 digital thermometers (waterproof with 1 m leads), an analog thermometer that resides on the board, and a photodiode that pokes out of the enclosure. I installed it a few days ago and it's logging time-stamped temperature outside and inside the greenhouse along with water temperature and light level to an SD card every 10 minutes. The analog thermometer was leftover from testing, so I just left it as a sanity check. Assembly and coding was pretty straightforward, though I can't say I fully understand all the OneWire stuff.

Nano was about $15, SD shield $20, waterproofed DS18B20s $6 each, and the rest didn't add up to more than a few bucks. I have a bluetooth module I'm playing with, but it doesn't add much functionality unless you have a dedicated computer to receive/log/display your incoming data. I'm liking the Raspberry Pi with wifi as the next step.

Jake, you have done almost exactly what i'm about to do. I have the uno, I ended up getting that data logger. I have the same 1m long waterproof sensor. all for around 100 bucks delivered.

now I just have to put it all together like you have and see what it does.

Where on earth did you get 18x20 sensors for $6? I paid something like $15 each from Element14 (used to be called RS components) and I had to do the waterproofing myself...

Also it looks like you're using 5V power for each sensor, and a separate "one wire" for each sensor, is this correct? Not parasite power and a common communication line?

Nice work, looking forward to seeing some data from it.

http://www.adafruit.com/products/381

I got mine for 10 bucks, including the pull up resistor. Seemed like a good enough deal

infact I got all my kit from these guys.

Waterproof for less than AUD $1.50....

http://www.ebay.com.au/itm/High-Quality-Waterproof-Digital-Temperature-Temp-Sensor-Thermal-Probe-DS18B20-/190738017226?pt=AU_B_I_Electrical_Test_Equipment&hash=item2c68df2bca&_uhb=1

individual units AUD $0.76....

http://www.ebay.com.au/itm/10-x-DS18B20-Digital-Temperature-Sensor-TO-92-TO92-3V-5-5V-/130586168086?pt=AU_B_I_Electrical_Test_Equipment&hash=item1e678acb16&_uhb=1

Need to add shipping to those, but sure beats $15 each.

Of course you should be supporting your local hobby electronics shop if you can anyway

If you don't mind waterproofing them yourself they are free from the manufacturer as samples

If you only need 3 that is

that is cheap from hong kong.

so the one I brought from adafruit has the following specs



what am I meant to do with the 4th wire thats connected to the shielding?

Connect it to ground, or leave it floating. It doesn't matter.

Is anyone else using the extra routines that give you a full decimal place of temperature data, instead of just .0 or .5?

They seem quite reliable for me, despite the way that they are calculated...

I used the test library directly as listed which I think gave me 2 decimal places. worked a treat. the waterproof reads about 1/2 a degree lower than the DHT-11 that I got at the same time.

http://www.pjrc.com/teensy/td_libs_OneWire.html

I dont know enough C++ to determine whether there is a better way to calculate the actual temperature, but it works, and can read quicker than once every second, so its enough for me anyway, i'll probably only read every 5 mins in the end anyway.

Have you bought from that place? I'm just about to buy a few things (like a 1$ SD card module) and was wondering if they were reliable.

I cant remember if they were those ones specifically, but i have found that ebay sellers that are stores tend to make sure you are happy. It is very easy to asses them on ebay...

i've had less trouble with hong kong sellers in general than i've had with local ones. shipping is normally quicker too

There's some really inexpensive stuff out there.

Would you people buy a $1.39 delivery included SD card reader/writer or would the quality be too poor?