Joyride
09-25-2008, 06:42 PM
I decided a while back that I wanted to build an automatic top off (ATO) for my tank, and have been slowly accumulating the pieces and parts necessary to do so. This project is loosely based on dfisch1's as well as some others.
I don't have room to do a gravity-fed system, so I needed something that employs a pump to pull water from a 5 gallon water container.
I wanted to use a float switch, but in my readings, I found a couple of references to float switches wearing out early if required to carry the full load of the switched device. This article (http://www.floatswitches.net/SpikingVoltage.html) provides the best explanation. As such, I decided to use a relay, the purpose of which is to allow the float switch to activate the relay, which in turn will carry the full current of the pump, sparing the switch. Granted, the Aqualifter has a very low draw of current, but in a situation like this, where failure can lead to water all over the floor of my house and my corals and fish shocked from hypo-salinity, I felt it best to do this as safely as possible.
Wherever possible, I also tried to use bits and pieces and scraps of stuff I had around the house. Half the fun of DIY projects is using that stuff you saved from the last project JUST IN CASE.
Before going any further, please don't do this project if you're at all uncomfortable with working with electricity. As with all electrical projects, this one offers you the opportunity to seriously injure yourself.
Supplies:
Tom Aquatics Aqualifter (http://www.marinedepot.com/ps_ViewItem~idProduct~OE1137~tab~1.html)
2x 1" PVC End Caps
3" of 1" PVC Pipe - thin walled
1-2 float switches (http://www.floatswitches.net/Miniature_Vertical_Mount_Float_Switches.html)
1 120VAC relay (http://marvac.com/detail.aspx?ID=25428)
1 Relay Socket (http://www.marvac.com/detail.aspx?ID=25794)
Black wire
White wire
1 Two-outlet electrical box
1 Outlet
Extension cord with female end cut off
Wire Nuts
Outlet Cover Plate
Zip ties
Overview of the steps I took:
Figure out how to wire the thing
Wire up the circuit and perform tests
Create the PVC housing for the float switch
Create the bracket to hold the switch
Wire it all together
Install
1. Figure out how to wire the thing...
I knew I needed a relay, but I had no idea how to wire one. The good news is that my brother was an electronics tech in the Navy back in the day (Desert Storm), so I tapped into him. After about 30 minutes of scrutinizing the schematics we found online (http://www.nteinc.com/relay_web/pdf/R12.pdf), we came up with a wiring approach.
Here's the wiring diagram that we came up with:
http://www.chenry.com/tankphotos/ATO.jpg
I'm sure this isn't an electrician-approved diagram, but I understood it.
The way the relay works is that when there's a circuit made between pins 13 and 14, it activates the coil in the relay, and moves the load bearing part of the relay from the resting connection on pin 1 to the activated connection on pin 5. So, I split the black wire coming from my power cable (represented by the "AC" in the drawing) and connected it to pins 5 and 13.
To complete the activation circuit, I connected pin 14 to the float switch, which I in turn connected to the Common (white) lead from the power cable. With this configuration, the float switch only bears enough load to activate the coil.
To complete the circuit the pump runs on, I connected pin 9 to the Hot side of the outlet, then connected the common side of the outlet to the white wire from the power cable.
2. Wire it up
One problem with all of this wiring is that I have never soldered a thing in my life, and I didn't think this was the time to start. I purchased a relay socket that has screw terminals for connecting the wires, and that made things much easier for me. If you're good at soldering, then you may not need the socket.
Here's a kind of blurry shot of the socket with the wire leads attached:
http://www.chenry.com/tankphotos/IMG_2152.jpg
Here's a shot of the socket with the relay installed
http://www.chenry.com/tankphotos/IMG_2146.jpg
Note: in this photo, the wire that's supposed to be on pin 5 is connected to pin 1 mistakenly.
When connecting things to the relay socket, I used wires cut to about 5" that were stripped on both ends. I didn't attempt to wire anything directly to the socket (other than the pigtails).
Here's a shot of the relay, outlet, power cable, and a light switch playing the part of the float switch (I used the light switch for testing purposes to make sure I had it all together the way I wanted)
http://www.chenry.com/tankphotos/IMG_2149.jpg
Next, I'll show how I built the PVC Housing...
I don't have room to do a gravity-fed system, so I needed something that employs a pump to pull water from a 5 gallon water container.
I wanted to use a float switch, but in my readings, I found a couple of references to float switches wearing out early if required to carry the full load of the switched device. This article (http://www.floatswitches.net/SpikingVoltage.html) provides the best explanation. As such, I decided to use a relay, the purpose of which is to allow the float switch to activate the relay, which in turn will carry the full current of the pump, sparing the switch. Granted, the Aqualifter has a very low draw of current, but in a situation like this, where failure can lead to water all over the floor of my house and my corals and fish shocked from hypo-salinity, I felt it best to do this as safely as possible.
Wherever possible, I also tried to use bits and pieces and scraps of stuff I had around the house. Half the fun of DIY projects is using that stuff you saved from the last project JUST IN CASE.
Before going any further, please don't do this project if you're at all uncomfortable with working with electricity. As with all electrical projects, this one offers you the opportunity to seriously injure yourself.
Supplies:
Tom Aquatics Aqualifter (http://www.marinedepot.com/ps_ViewItem~idProduct~OE1137~tab~1.html)
2x 1" PVC End Caps
3" of 1" PVC Pipe - thin walled
1-2 float switches (http://www.floatswitches.net/Miniature_Vertical_Mount_Float_Switches.html)
1 120VAC relay (http://marvac.com/detail.aspx?ID=25428)
1 Relay Socket (http://www.marvac.com/detail.aspx?ID=25794)
Black wire
White wire
1 Two-outlet electrical box
1 Outlet
Extension cord with female end cut off
Wire Nuts
Outlet Cover Plate
Zip ties
Overview of the steps I took:
Figure out how to wire the thing
Wire up the circuit and perform tests
Create the PVC housing for the float switch
Create the bracket to hold the switch
Wire it all together
Install
1. Figure out how to wire the thing...
I knew I needed a relay, but I had no idea how to wire one. The good news is that my brother was an electronics tech in the Navy back in the day (Desert Storm), so I tapped into him. After about 30 minutes of scrutinizing the schematics we found online (http://www.nteinc.com/relay_web/pdf/R12.pdf), we came up with a wiring approach.
Here's the wiring diagram that we came up with:
http://www.chenry.com/tankphotos/ATO.jpg
I'm sure this isn't an electrician-approved diagram, but I understood it.
The way the relay works is that when there's a circuit made between pins 13 and 14, it activates the coil in the relay, and moves the load bearing part of the relay from the resting connection on pin 1 to the activated connection on pin 5. So, I split the black wire coming from my power cable (represented by the "AC" in the drawing) and connected it to pins 5 and 13.
To complete the activation circuit, I connected pin 14 to the float switch, which I in turn connected to the Common (white) lead from the power cable. With this configuration, the float switch only bears enough load to activate the coil.
To complete the circuit the pump runs on, I connected pin 9 to the Hot side of the outlet, then connected the common side of the outlet to the white wire from the power cable.
2. Wire it up
One problem with all of this wiring is that I have never soldered a thing in my life, and I didn't think this was the time to start. I purchased a relay socket that has screw terminals for connecting the wires, and that made things much easier for me. If you're good at soldering, then you may not need the socket.
Here's a kind of blurry shot of the socket with the wire leads attached:
http://www.chenry.com/tankphotos/IMG_2152.jpg
Here's a shot of the socket with the relay installed
http://www.chenry.com/tankphotos/IMG_2146.jpg
Note: in this photo, the wire that's supposed to be on pin 5 is connected to pin 1 mistakenly.
When connecting things to the relay socket, I used wires cut to about 5" that were stripped on both ends. I didn't attempt to wire anything directly to the socket (other than the pigtails).
Here's a shot of the relay, outlet, power cable, and a light switch playing the part of the float switch (I used the light switch for testing purposes to make sure I had it all together the way I wanted)
http://www.chenry.com/tankphotos/IMG_2149.jpg
Next, I'll show how I built the PVC Housing...