Thursday, February 4, 2016

Worm Bin Monitor Live: Part 3

I am continuing to refine my flow-through worm bin temperature monitoring system.  In part 1 and part 2 I started prototyping what the system would do based on a couple of third party tutorials that I combined.

Worm Bin Up & Running

I am now have everything working in the real world.  To do that I needed

  • a decent wireless network signal outdoors to talk to the system from inside my home
  • more permanent electronic connections so things don't fall apart if moved
  • a bin full of worms
  • mild protection for electronic components

dust-resistant enclosure

Outdoor Wi-fi

I have an indoor wireless access point but it does not get me very far outdoors.  I needed to get good network access at least 250 feet though many large pine trees to monitor anything.  To do this I purchased and installed a wireless access point designed for outdoor use.

I mounted this AP on the outside wall of my second story.  I had my doubts it would work very well, but I was really surprised that it does.

I also boosted the reception of the Raspberry Pi at the worm bin with a USB wireless adapter with an external antenna.  The downside of this particular antenna is that it requires a powered USB hub to stay well connected.

I purchased the EnGenius ens202-ext Outdoor Wireless Access Point and found a powered usb hub on Amazon.  The connection is working great.

Stabilizing The Electronics

In the working photo above, the red circled area is the air temperature and humidity sensor.  The green area is the solder less breadboard I used in previous steps to setup the sensors temporarily.

I had to learn to solder to make it all stable.  I have never soldered so I checked out some how-tos on the subject.  This soldering Instructable got me going.  I was in a hurry so I went down to the local Radio Shack (mine is still in business but has limited supply).

I picked up some 0.35 leaded rosin core solder, a pack of cheap circuit boards, and some 22 gauge solid core wire.  I already had a 25 watt soldering iron I had used years ago for something else.

Soldering takes practice but I was able to recreate my two sensor circuits on a small board.   I removed all the wires and resistors off of the original white breadboard .  I left the breadboard in place so I can add new sensors in the future (soil moisture sensor?).  I soldered wires onto the air sensor (red circle) to extend it outside of the foam box.

My worm bin is outdoors but under cover.  I am not too worried about moisture and dirt but do want some modest protection from dust.  I opted to reuse a foam food container to house the electronics.

Incidentally, these foam boxes are a major sore spot for me because locally all the restaurants hand them out for take out and leftovers.  In California, where I am from, Styrofoam has been illegal for many years.  The southern US is way behind on environmental awareness, so it's nice to re purpose things when I can.

Adding The Worms 

Finally...the worms are added.  I ordered 10K red wigglers online.  They came plump and lively.  I added them to the bin 24 hours ago.  

10 lbs of Eisenia Foetida worms

Final Thoughts on the Benefits of Environmental Monitoring

Our recent North Carolina temperatures have been unseasonable.  In February, we are seeing highs in 70s F and lows in 20s F.  My initial monitoring is demonstrating that the insulation and warming cable is keeping the bin temperature stable.  It's currently in the 50s.  By tomorrow evening we will see temperatures in the lower 20s.  

steady soil temp so far

Since I am a relatively new worm owner with a lot invested in worms I want to react quickly to problems.  The worm bin monitoring system will tell me how far temperatures rise or fall and for how long.  I can see measurable results for my efforts to control temperature with more heat in the winter, ventilation changes, recent feedings, and the addition of ice bottles in the summer months.

Raspberry Pi Model 2

I decided to replace the Raspberry Pi B+ with a Model 2.  It's much faster loading the page now.  However, there was a problem with the DHT (soil) sensor not working with the Adafruit library as I had installed it.

I made sure this was installed:
sudo apt-get install build-essential python-dev

Then reinstalled the Adafruit library to make sure.
cd /home/pi/sources/Adafruit_Python_DHT
sudo python install 

Now all is working correctly.


  1. can you go into details about this part please:
    "or even better yet, run the command above with a cron job then edit the worm bin web page to read the data (/home/pi/projects/temp-and-humidity/public/index.html) "

    1. On linux you can schedule commands like "python grabserial | ts > /home/pi/projects/temp-and-humidity/sensor-values/moisture.csv" to run at specific times of the day or every so many minutes/hours etc. I added a link to a tutorial above

    2. by the way...I think you meant to comment about cron on "Worm Bin Moisture Sensor with Arduino" not this post.