The mission that was set before Dave and myself this week was to create a functional prototype of our system interfacing with the valves through the relay and to actually control the flow of liquid using our CO2 powered system.
Tube Coupling, the finer points
The first task was to find fittings and or couplings to attach a length of 3/16″ inner diameter tubing to our 5/16″ inner diameter regulator output on our CO2 tank. This was finally accomplished after a few trips to the local Lowe’s and acquiring a few pipe threaded barb fittings and a length of 5/16″ inner diameter tubing. What this allowed me to do was connect that piece of tubing to the regulator and then connect the other end of that tubing to a 5/16″ ID barbed fitting that had a 1/4″ threaded pipe fitting on it. Next I connected a similar piece of hardware to the length of 1/8″ ID and using a 1/4″ Female to Female pipe coupler was able to have a successful “down-scaling” of tube sizes.
Pumping, the cap saga
The biggest issue yet to resolve is to find a solution for connecting this tubing to a bottle cap or stopper assembly. For this prototype I simply drilled to 1/4″ holes in a bottle cap and hot glued two lengths of 1/8″ ID tubing into place. Then I connected this assembly to the CO2 lines and also to a 12VDC valve. Next I connected the power to the valve and ran the ground wires through the relay terminals, this way when the relay is turned on (or the “switch” is closed) a connection is actually made and current is allowed to flow and to open this normally closed valve.
PHP, a useful timer
As of last week we had a working proof of concept that we could run C code through PHP and manipulate the ports on the relay. This week I took it a step forward and using PHP’s built in date function wrote a small script that checks the start time and then keeps checking back for a predetermined length of time to elapse. This method can be accurate down to the millisecond and we are currently experimenting as to whether this is the best method to use. I made my script run for 10 seconds, ran the script and collected the pumped liquid in an empty container. I found that this method, in conjunction with a controlled 5 p.s.i. pressurized system made for very consistent pours. The amount of variance was practically undetectable to the naked eye and that result made me quite pleased with our progress.
Onward and Upward
Next I plan to further investigate timing and calibration methods as well as further research on a permanent cap assembly. One other thing that I will be attempting is pumping 2 different liquids to make a test “mixture”.
Note: as soon as I find my camera charger I will be uploading a video of the prototype working! 