Urban Survivalists

This week, we are going to show you how we got the pumps in the filter box to work. We showed you an electronic schematic last week, but later found a more efficient way to do things using a car battery charger as suggested by somebody in our local Dorkbot group. The contents of the battery charger had everything we needed to convert the AC power from the socket to DC for the water pumps at 12V and up to 10A. You can see the components of the battery charger hooked up to the pumps in the video, and water is actually flowing through the pumps! wahoo!

Here you can see the battery charger that we bought to make this work, it only cost $33 from our local Harbor Freight. We highly recommend using this approach as it is the cheapest option we have yet found. It’s pretty easy too!

The images below just show you the original components of the battery charger before we started to mess with things. The last photo here shows the input pin set up needed to power the pumps at 12 volts. This took some fiddling with the switches to figure out which coils were being used but it wasn’t too hard.

Now we remove the shortstop. This is a circuit breaker. Make sure things are unplugged before attempting this. Normally we would keep this in place but we don’t know what it is rated at. We need a 10A time delay fuse in line for each of our pumps. We will add our own later.

Next, we are placing the electrical components in an electrical box so that people and pets don’t bump this thing while its running. We realize that most people don’t usually have an electrical box laying around, but we strongly encourage enclosing this system because it runs 10 Amps through it! It only takes 1 Amp to kill you if arced through your heart, so be careful people! Seriously, this isn’t just a sharp little zap from a wall socket.

Below are some pictures of our electrical box. These photos just to show you how we organized the components even though you probably won’t be able to replicate this with our exact electrical box dimensions. Wiring is a fiddly thing. Find yourself an enclosure that seems to fit everything and just stuff the electronics in there. Route the wires nicely using barrier strips to keep things removable for later upgrades and changes. It’s also important to screw things down to the box. In our case, we have a removable plate for this.

Next Week and Beyond!

We will continue putting the wiring together for the power supply. We intend to bring the AC power line into the box and connect it to a barrier strip and then to the intake on the transformer. We’ll then split three 12V lines off of the output through a barrier strip. Two lines will run to the pumps and one will power the Arduino and the 24V solenoid valve. Since we only have 12V, we need to use a voltage regulator to step this up to the necessary 24V at 0.44A the solenoid valve requires. This should be a fairly simple circuit so we don’t anticipate many problems with it…famous last words!

After all this tedious wiring, we will need to write a little Arduino program to control everything based on the input of a couple of float switches housed in our clean water barrel and our rain barrels. This shouldn’t be a problem and really requires no work from you other than downloading what we write and loading it onto an Arduino. Good times.

That’s it for this time. Sorry it’s so short but we’ve been scrambling around trying to get our electronics lined up. Harder than it looks here. Be safe and sustainable!

P&S

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