Urban Survivalists

This weekend we decided to try making you guys some instructional videos for connecting the hoses to the reverse osmosis (RO) system instead of our standard text and picture based build instructions. The videos are hosted on YouTube and are pretty short. Let us know if you like them, hate them, or if you have any better ideas. We used Open Movie Editor to make these.  Many props to Richard Spindler and all those who have worked on the editor. It’s a great little program without a bunch of bloat ware. Does just what we need it to.

Alright, let’s get down to business!

Connecting two of the RO filter attachments

The RO system has four attachment points scattered about it. They go to the intake, outlet, pressure tank, and waste stream. First off, we will be showing you the intake to the piping we installed last week via a saddle valve.

Materials:

• One self-puncturing saddle valve. Preferably of the EZ-Quick attachment type. We didn’t get this one so we suffer. You’ll see.
• One RO system. You should have this already if you have been following along.
• One filter box.
• 1/4″ OD plastic tubing. Get the stiff stuff and not the rubber or fish tank tubing variety.
• 5/8″ spade bit
• Drill
• Carpenter’s square
• pencil

Steps:

1. Mark a spot three inches from the top left corner of the surface that the RO system is attached to and three inches from the left side.
2. Drill a 5/8″ hole at this point. This is where the tubing from the RO system will come through.
3. Watch the videos and follow along!

Attaching the second pump to the system (the clean water pump)

This pump will handle all of the clean water from the storage tank after the dirty water pump gets through pushing it through the RO system. It will be situated under the shelf. We know, not convenient but that’s how we are progressing through this. For those of you who are waiting, you can take things out of order and save yourself some effort.

Materials:

• Three 1″ sections of 1″ CPVC
• Two 8.5″ sections of 1″ CPVC
• One 7.5″ section of 1″ CPVC
• One prepared SureFlo pump with connection adapters.
• The partially complete filter box.
• PVC primer
• CPVC cement

Steps

1. Just follow the video! Note our mistakes and don’t make them.

Electronics

We also promised a rough draft schematic. This is the basic idea of what we are planning but it will change a lot as our design advances. This schematic was created with a program called LTspice. The program is free and allows the user to create electrical circuits. Highly recomended.

Anyway, let me explain what our ideas are. We will have an Arduino controlling the logic of the filter box. The large integrated circuit (IC) component is just a place holder representation of the digital pin outs of the Arduino. Into this, we will wire the float switches from the rain barrel and the clean water storage tank. When the storage tank is not full, (and thus the switch not on) we will pump water into it as long as the rain barrel has water in it (controlled by the other switch). To stop the pump from pushing water through the RO system, we set pin 1 on the Ardiuno to 0 volts and thus shut the sprinkler valve. The pump detects that it has reached 100 psi and it shuts down of its own accord. The sprinkler valve is controlled from the Adruino via a TIP110 power transistor to switch the heavier 24V 0.4A line. this is well within the transistor’s abilities and so we shouldn’t need a heat sink.

We have status LED’s on pins 4-8 that will indicate: power, rain barrel empty, clean water tank full, clean water pump on, dirty water pump on.

Supposing we want water from the system, we open the second to bottom silcock valve on the side of the filter box. The pressure in that line drops and the clean water pump turns on and we get water from the clean water storage tank. The only thing the Arduino controls is the solinoid (sprinkler) valve and the LEDs on the front panel.

Power will most likely come from a transformer at 24V and 20A which we send through the bridge rectifier shown. We will then send this through some sort of voltage regulator–haven’t picked it out yet–thus splitting it up into the 24V line, the 12V line and a 10V line. The 24V line will run the sprinkler valve and requires 0.4A. The 12 volt line goes to the two pumps and needs a minimum of 16A. The 10V line goes to the Arduino and will need no more than 500mA.

Since we have a lot of current coming out of our bridge rectifier, we will need to current limit it. For this we have the small circuit snippet to the right. It is basically an NPN power transister, a couple diodes, and a couple resistors. It limits the current through it according to the equation shown. This is a very common current limiter circuit and the components to it are very cheap. We will need to set up one of these for the sprinkler valve line and the Adruino line. For the heavy duty current needed for the two motors, we need another solution. We don’t really know with this is yet, however.

We are doing research on this right now and this is why this very early schematic is likely to change. Data sheets for all the currently specified IC’s are listed at the bottom of this post for any who are interested as well as the LTSpice file for this rough draft.

Also, the careful viewer of our videos above will notice that we’ve begun doing something with the mass of unruly wires coming from each motor and the sprinkler valve. We’ve simply put extensions on them to bring them to the area we think the control box will go and then sheathed them in braided black vinyl similar to the stuff used on computer cables to pretty them up. We aren’t going to give instructions on this as it is fiddly, time consuming and not really necessary. Sufice it to say, just run your cables nicely and neatle to where the control box will be and call it a day. More on that when we get to it.

Next week

Hopefully we have some more electronics junk to show you and maybe a test circuit or two. No promises as it is finals week and Stan is sweating a couple of tests. We will definitely have something we just don’t know exactely what it is going to be yet.

That’s it for this week. Stay green and sustainable!

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P&S

Links:

http://www.diodes.com/datasheets/ds21220.pdf

http://www.ligo.caltech.edu/~vsanni/ph5/Datasheets/BJT/TIP112.pdf

Rough Draft Filter Wiring LTspice

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