Monday, December 21, 2015

30: "Smart Home," "Internet of Things," Blah, Blah

Cnet has equipped a house as a demo Smart Home. I recently read their bit about protecting the house from water main flooding. Their article mentioned a wifi-enabled solenoid valve which could be used shut off the input supply. The suggested device was listed as $400. That figure got my attention.

Last summer, I installed a Particle Photon-based system for my granddaughter's demonstration farm. The setup includes 2 soil moisture sensors and a solenoid-operated water valve. I initially installed a 1/2" plastic valve for irrigating the 100' x 30' hoop house. That turned out to be too small so I changed it for a brass 3/4" model.

Anyway, here's my version of how to protect a home from water damage caused by a pipe breaking, water heater leak, etc. Note: Wifi and Internet are assumed in all cases.

Cnet's device--

1. Wifi-enabled solenoid water valve, 1": $400
2. Pipe adapters: $30
3. Plummer to cut it into main service pipe: $150?
4. Wifi-enabled water sensor: $50?
5. Power supplies: 5v: $5, 12v: $15?
6. Controller for house: ?
Total: $650+

My way (version 1)--
1. Solenoid water valve 1": $40
2. Pipe adapters: $30
3. Plummer: $150
4. Water sensors: $5
5. Power supplies: 5v: $5, 12v: $15?
6. Particle Photon controller: $20
Total: $250

My way (version 2)--
1. Stepper motor to rotate existing house turn off valve 90 degrees: $40
2. Motor mounting bracket + 2 limit switches: $20
3. Plummer: (not needed)
4. Water sensors: $5
5. Power supplies: 5v: $5, 12v: $15?
6. Particle Photon controller: $20
Total: $110

Sunday, December 13, 2015

29: Portable Sensors

I have ideas for several of these. The one I'm building just now will provide temperature, humidity,  dew point and soil moisture readings from a flashlight-sized device. Here's the breadboard mess:

And this is my crude wooden enclosure (soil probe not shown):

I'm using an Arduino Nano and a DHT22 temperature/humidity sensor (etc.). The readout is to a 4 digit 7-segment LED. Power from a 9-volt battery. The cheap 4-digit LED takes all of the digital pins 2 through 12. So I have just one left for the DHT (unless I use TX and RX which leads to problems). The moisture probe uses analog, luckily.

My Sketch displays each reading for a second at a time, as in-- "F 74", "h 39", d 42", "S 11" (I can fudge those 4 letters in 7 segments).

I'd really like to find a source for enclosures so I don't have to waste time building crappy ones of my own. Any suggestions?
28: More About Secure Wires

Way back in my Raspberry Pi blog ( post 59 I discussed "Bare Conductive Electric Paint." I had hoped to be able to draw circuits on paper with the stuff. Well, not quite. But it was a sort of conductive glue (slow drying, not very strong).

Anyway, the stuff has stiffened up in the tube to where it won't come out the narrow spout anymore, but now I have a new use: sticking breadboard wires M-to-F or M-to-breadboard. Just dip the wire (M) end in the "paint" and insert as usual. And after 20 minutes the connection will be pretty secure AND the contact will be good. Also, since the glue isn't too strong, you can get it out if you need to make a change.

Note that wisely, most glue is insulating, not conductive -- probably a good idea.