Uber Video Water Streaming Home Automation Thingy

Updated 2014.07.20

List of newly found excellent references


Tip122 from Arduino

Good quick reference (has all parts) of NPN PN2222A transistor


Update 2014.07.19 10.26 - Grrr

Grrr so - micro controllers a pretty whimpy for sourcing or sinking current. Regrettably, so is the PCF8574 io expander.  And more Grrr !     the 8 X Relay module are controlled by opto-isolators.  Ok, that "might" be good .. But .. and here is the double Grrr ! part - the modules come with another LED for a visual indicator (in addition to the opto-isolator) ..   So it adds up to be 50+ ma per input which needs to be sunk .. and the gutless PCF8474 can only sink 20ma :( 

I thought about desodering, or grinding off the LEDs .. but the PCF8574 is still probably too weak to sink the necessary current for the opto-isolator ..  Meh .. so I've got to add MORE COMPONENTS :(

8 x 2N2222 and 8 1K resistors

wired like this except up to a PCF8574 instead of an Arduino Uno

Update 2014.07.19

Raspi & I2C module both appear to be working. Yay !

Now it's time to install MRL - dropped the myrobotlab.jar - ran 

java -jar myrobotlab.jar -update

it didn't work - but the prelog does :P

Here the raspi is downloading all the services

This is one of my current top 4 things to finish on the Borg Todo List.

MRL will be controlling my sprinklers (it has for years - but since the electric valves were outside, winter destroyed them).  Since I need to replace the valves, it seemed like a good time to upgrade the hardware too.

Previously I used an Arduino controlling my own TIP120 transistor switches.  

I found some big 5VDC coil relays on the internet for very cheap.

But they drove me NUTS ! ..  Had to comb the internet for any documentation at all..  Finally a schematic which showed it supported electrical isolation with a phototransistor.  Ok, I hooked it up, but did not care about the isolation but it always behaved very strangly ... sometime it worky .. sometime no.

Now Boss#1 (wife) came home from Japan trip and found no automated sprinklers.  Oops.. ok so I had a closer look at the schematic and the printed board and realized that it HAS 2 GROUNDS !!!! even if you do jump together both sides of the 5VCC & JDVCC.  After tying the grounds together it works solid.

Quick trip to the Home Despot .. and I put together the Uber Manifold for the sprinkler systems.

I'm putting this together from re-cycled parts - so I happened to have a super-beefy 5VDC regulator which should be plenty power for the raspi, I2C digital io board, & the 5V side of the relay module.  Did not have the right molex connector, but nothing a quick solder can't fix.  

The whole thing will be fed by a salvaged 21 VDC power supply.  The valves are supposed to be 24V but I've seen them switch as low as 12V, so I think I'm good there.

Next will be to clip a micro usb connector and hook it up to the regulator - will be the power for raspi coming off the regulator.


PCF8574 - I2C Module $6 -