chipmunkofdoom2
Well-Known Member
Hello all, back again with more DIY scheming 
This next DIY for my pico is for an ATO (or Auto-topoff unit), however, since this guide "overbuilds" a little, this design can really work with any tank. Since I see this design so frequently and I see so many people making these wrong, this is going to be a step-by-step with detailed instructions, with all the whos, whats, whens, wheres and whys answered that I possibly can.
NOTE: this project deals with electricity in sufficient quantities to damage equipment, harm livestock, cause fires, and even KILL YOU. I am going to be as clear and concise as possible, but if you are at all unsure about what is shown here or you are not 100% confident in your ability to work with electricity, DO NOT attempt anything here. This is no joke.
Having said that, I have no professional electrician experience... I only know enough to keep me out of trouble if you're fairly handy, this is something that anyone would be able to do.
The Design
This design, like so many, is based off of the classic float-switch-wired-into-extension-cord-then-pump-plugged-into-extension-cord (like this OFFSITE build). The main difference is I will NOT be running the entire load voltage from the wall through the float switch.. instead I'm going to wire in a relay. You can read a few posts down on that off-site link for more info on why not using a relay is bad, but if you're not an electrician, suffice it to say that it's not good.
A decent simple analogy: not using a relay is like trying to run the return pump of your tank through a straw.. yeah, you can probably get enough converters and reducers so that it would physically work, and it may work out for a while, but the straw was never meant to take the beating of a pump rated for hundreds of gallons per hour. The straw is meant to delicately have a liquid drawn through it, by nothing stronger than the pressure the soft tissues of a human throat can create. It might last a week, it might last a month, it might last 2 years... the point is eventually you're going to come home with a burst straw and a mess. When you're dealing with electricity, it's a lot more dangerous than cleaning up some water...
How Does A Relay Help?
In a nutshell, a relay is necessary because it allows you to use a low voltage control current to supply full wall voltage safely. Using a relay only allows tenths of a watt to pass through the float switch, making it much easier on the connections in these delicate switches. A relay IS built to take the full beating of the AC load your outlets can provide.
Here's basically how it works: You have your relay (which is about a cubic inch size-wise), and there are 2 sets of terminals. The one set on bottom is for your control voltage (basically a small AC/DC adapter like an old cell phone charger) and the other you splice into your extension cord (up top). The float switch will will be attached to the end of the AC/DC adapter, then the AC/DC adapter is spliced into the terminals for the control input. When the water level drops and the float switch opens, the low-voltage current flows through. The low voltage current passes through the relay and activates an electromagnet. This magnet attracts a strip of conductive metal toward it, and in doing so, completes the circuit. When the float switch closes, the low voltage current stops, and the electromagnet shuts off, allowing the strip of metal to spring back to its original (off) position.
In the below diagram, the water level is at it's desired height, and the float switch is closed:
The following picture shows the water level dropped and the float switch in the open (on) position:
In the last picture, the float switch opened, and the current was allowed to flow from the AC/DC adapter to the relay, which activated the electromagnet, and allowed the wall voltage to pass through the connection.
Parts
Okay, so now that we have that out of the way, let's take a look at the parts list:
Float switch: $2.18 each (free shipping)
Relay: $6.75 (free shipping)
Any extension cord: Free (already had, $1.00 at the nearest Dollar Store if you don't have a spare)
AC/DC Adapter: Free (I have so many spare phone chargers from old cell phones that I'm actually happy to put them to some use)
That's pretty much it for the "meat" of the project, a total of about $10 for the electrical stuff. Other miscellaneous items you may need:
-A pump: I used a Tom's Aqualifter, but the great thing about this design is you can use just about any pump and not worry about how much electricity it needs, so long as it can plug into a non-grounded plug.
-A resivoir: something to hold the freshwater (for me, an old IO bucket)
-Tubing: to hook up to the pump
-Hanging bracket: this is something to hang the float switch from. I'm going to use a plastic wreath hanger, but as long as it won't rust, you can be creative and use whatever.
-Snail guard: for me, an old prescription bottle with holes drilled in it to allow water in
You may also want to get zip-ties. Basically, you can then drill evenly spaced holes in the hanger AND snail guard. Then you use the zip tie to choose the level you want it at and make sure it doesn't move, but can be somewhat easily repositioned with the help of a new zip-tie, if needed. Also, I already had a multimeter and a soldering iron and used both during this process. You could possibly get away without soldering and you might know the polarity of the AC/DC adapter you use just by looking at it, but I would try to borrow these items if you don't have them.
Construction
Now on to the actual construction! These steps can be done in somewhat different order, but this is just how I'm doing them
STEP 1: Attach Line Voltage to Relay
Here we connect the extension cord to the relay. The good thing about AC power is it doesn't really adhere to directions, so we can wire this any way we want. It's just basically completing the circuit anyways.
First, we have to split the extension cord. I did this with a razor blade. Be careful not to cut into the wire that is staying intact!
Then cut one of the lines in half.
Lastly we strip some shielding off the ends of the cord.
The relay comes with metal plates secured with screws. These are really meant for quick release type connections, but I usually just wrap the wire around the screw and tighten it down, like so.
Both leads attached.
STEP 2: Attach Control Voltage to Relay
Here we connect the old phone charger to the relay. Notice the terminals are marked and it DOES matter where we put the negative and positive terminals so the magnet activates properly. I have a multimeter and tested it out, but typically red is positive, black is negative. In my case, white striped is positive and pure black is negative.
Same deal, strip off some of the plastic and expose the wire, then wrap around the screw. Then reattach to the relay. Now we only want to do this with the negative lead because we'll have to run the positive one to the float switch, then back from there to the relay.
Here's the finished relay. I attached the other lead just to test the relay, and the light comes on when the relay has control voltage.
STEP 3: Wire Float Switch
Here I've run some extra wiring to reach the tank and connected it to the float switch. Here it does not matter how we wire the switch, because this just bridges the gap and allows the electricity to flow through whatever direction it wants.
Here, we had to wire some power from the positive end of the relay to the tank because the adapter wires were a little to short.
STEP 4: Create "Snail Guard" And Mounting Bracket
This one took a little ingenuity, but I eventually found a pretty decent piece at the Lowes by my office. Basically, it's for hanging things off of doors. The piece meant to hang over the door (the large hook on the left) is way too big to hang over a tank edge. The hook on the far right, however, looked perfect.
I sawed off pretty much everything and left enough space so I could make the level adjustable.
Now that we have the mounting squared away, we have to make a "snail guard". Now you could most likely get one of these from an aquarium retailer, but I'm going for cheap here
I started with an old pill bottle and washed it thoroughly to remove the label and any residue. It contained hydrocodone from my appendix removal so if anything the fish and corals will get a little buzz and mellow out
Disassembled and drying:
Then I drilled plenty of holes to allow water flow:
I also drilled the top. Since the cap creates a seal, if you don't allow air to escape, water will only fill to the highest hole's level.
Next I drilled evenly spaced holes in the mounting bracket and the snail guard so that I could adjust the height with a zip tie:
I FINALLY got the float switches, almost 30 days after placing my order (darn Chinese shippers). So here they are, I ordered an extra in case the one goes out or something.
Next, I drilled a hole in the lid for the float switch to go through.
And here we have the fully assembled snail guard/float switch
And here you can see what it looks like secured to the hanger. The good thing about this design is you can move the bottle/switch assembly up or down as needed.
STEP 5: Wire Float Switch to Relay
This one's kinda hard to show, but basically, you connect the + from the AC/DC adapter to the one lead of the float switch, then you wire the other lead of the float switch to the + of the relay. The - on the relay goes to the - on the adapter.
And here we have everything all assembled, soldered, and taped!
Finally, time to put it into action!
Additional Considerations
In some builds, instead of using just one float switch, people use two. This give some redundancy, because in the case that one of the switches goes bad and sticks open (which is usually the position it dies in unfortunately, the other would still open and close normally, so your tank wouldn't overflow if one of the switches died. It would be difficult to determine if a switch had died or not without regular testing, however, so this is just something to consider if you don't mind the extra work and effort.
For a long time I sat and tried to think how I could clean this design up a little and make it more neat and tidy. The simple answer is I can't. You can program circuits and create circuit boards with built in AC/DC circuitry, but that goes beyond the realm of this DIY and my knowledge of electronics. This device might not be the most elegant, but it is a simple, darn good design when implemented properly.
All the items bought on Ebay were from Chinese sellers and were correspondingly cheap, however, the shipping takes 2 weeks+ from the time of order. Something to bear in mind. Comparable relays from other electronics sites cost $12, and that's not including the relatively high shipping prices of said dealer. Generally, these electronics are mostly made in China anyway, so it's really the difference between buying from a USA seller who's reselling, or just getting them right from the manufacturer.
You can use any float switch you want and any relay you want, just be sure the specs line up. For example, the float switches are pretty standard. Since you're only running a small amount of electricity through them, they can be rated for anything almost. The one I got for example was rated for up to 100V, .5A. Most phone chargers are only 5-12V (mine being 12v), and the relay will only pull as much current as it needs to, which again in my case is 3 - 25mA (.003-.025A). The float switch will handle this just fine. The relay is pretty simple as well, as long as it's rated for 10A or more and is rated for AC (mine is rated for 480V), you will be fine. for all but the thousands of gallons per hour pumps
Hopefully this clears up some confusion and de-mystifies the magical and, in my personal opinion, all-too-expensive ATO. Let me know if you have any questions, comments or concerns
This next DIY for my pico is for an ATO (or Auto-topoff unit), however, since this guide "overbuilds" a little, this design can really work with any tank. Since I see this design so frequently and I see so many people making these wrong, this is going to be a step-by-step with detailed instructions, with all the whos, whats, whens, wheres and whys answered that I possibly can.
NOTE: this project deals with electricity in sufficient quantities to damage equipment, harm livestock, cause fires, and even KILL YOU. I am going to be as clear and concise as possible, but if you are at all unsure about what is shown here or you are not 100% confident in your ability to work with electricity, DO NOT attempt anything here. This is no joke.
Having said that, I have no professional electrician experience... I only know enough to keep me out of trouble
if you're fairly handy, this is something that anyone would be able to do.The Design
This design, like so many, is based off of the classic float-switch-wired-into-extension-cord-then-pump-plugged-into-extension-cord (like this OFFSITE build). The main difference is I will NOT be running the entire load voltage from the wall through the float switch.. instead I'm going to wire in a relay. You can read a few posts down on that off-site link for more info on why not using a relay is bad, but if you're not an electrician, suffice it to say that it's not good.
A decent simple analogy: not using a relay is like trying to run the return pump of your tank through a straw.. yeah, you can probably get enough converters and reducers so that it would physically work, and it may work out for a while, but the straw was never meant to take the beating of a pump rated for hundreds of gallons per hour. The straw is meant to delicately have a liquid drawn through it, by nothing stronger than the pressure the soft tissues of a human throat can create. It might last a week, it might last a month, it might last 2 years... the point is eventually you're going to come home with a burst straw and a mess. When you're dealing with electricity, it's a lot more dangerous than cleaning up some water...
How Does A Relay Help?
In a nutshell, a relay is necessary because it allows you to use a low voltage control current to supply full wall voltage safely. Using a relay only allows tenths of a watt to pass through the float switch, making it much easier on the connections in these delicate switches. A relay IS built to take the full beating of the AC load your outlets can provide.
Here's basically how it works: You have your relay (which is about a cubic inch size-wise), and there are 2 sets of terminals. The one set on bottom is for your control voltage (basically a small AC/DC adapter like an old cell phone charger) and the other you splice into your extension cord (up top). The float switch will will be attached to the end of the AC/DC adapter, then the AC/DC adapter is spliced into the terminals for the control input. When the water level drops and the float switch opens, the low-voltage current flows through. The low voltage current passes through the relay and activates an electromagnet. This magnet attracts a strip of conductive metal toward it, and in doing so, completes the circuit. When the float switch closes, the low voltage current stops, and the electromagnet shuts off, allowing the strip of metal to spring back to its original (off) position.
In the below diagram, the water level is at it's desired height, and the float switch is closed:
The following picture shows the water level dropped and the float switch in the open (on) position:
In the last picture, the float switch opened, and the current was allowed to flow from the AC/DC adapter to the relay, which activated the electromagnet, and allowed the wall voltage to pass through the connection.
Parts
Okay, so now that we have that out of the way, let's take a look at the parts list:
Float switch: $2.18 each (free shipping)
Relay: $6.75 (free shipping)
Any extension cord: Free (already had, $1.00 at the nearest Dollar Store if you don't have a spare
)AC/DC Adapter: Free (I have so many spare phone chargers from old cell phones that I'm actually happy to put them to some use)
That's pretty much it for the "meat" of the project, a total of about $10 for the electrical stuff. Other miscellaneous items you may need:
-A pump: I used a Tom's Aqualifter, but the great thing about this design is you can use just about any pump and not worry about how much electricity it needs, so long as it can plug into a non-grounded plug.
-A resivoir: something to hold the freshwater (for me, an old IO bucket
)-Tubing: to hook up to the pump
-Hanging bracket: this is something to hang the float switch from. I'm going to use a plastic wreath hanger, but as long as it won't rust, you can be creative and use whatever.
-Snail guard: for me, an old prescription bottle with holes drilled in it to allow water in
You may also want to get zip-ties. Basically, you can then drill evenly spaced holes in the hanger AND snail guard. Then you use the zip tie to choose the level you want it at and make sure it doesn't move, but can be somewhat easily repositioned with the help of a new zip-tie, if needed. Also, I already had a multimeter and a soldering iron and used both during this process. You could possibly get away without soldering and you might know the polarity of the AC/DC adapter you use just by looking at it, but I would try to borrow these items if you don't have them.
Construction
Now on to the actual construction! These steps can be done in somewhat different order, but this is just how I'm doing them
STEP 1: Attach Line Voltage to Relay
Here we connect the extension cord to the relay. The good thing about AC power is it doesn't really adhere to directions, so we can wire this any way we want. It's just basically completing the circuit anyways.
First, we have to split the extension cord. I did this with a razor blade. Be careful not to cut into the wire that is staying intact!
Then cut one of the lines in half.
Lastly we strip some shielding off the ends of the cord.
The relay comes with metal plates secured with screws. These are really meant for quick release type connections, but I usually just wrap the wire around the screw and tighten it down, like so.
Both leads attached.
STEP 2: Attach Control Voltage to Relay
Here we connect the old phone charger to the relay. Notice the terminals are marked and it DOES matter where we put the negative and positive terminals so the magnet activates properly. I have a multimeter and tested it out, but typically red is positive, black is negative. In my case, white striped is positive and pure black is negative.
Same deal, strip off some of the plastic and expose the wire, then wrap around the screw. Then reattach to the relay. Now we only want to do this with the negative lead because we'll have to run the positive one to the float switch, then back from there to the relay.
Here's the finished relay. I attached the other lead just to test the relay, and the light comes on when the relay has control voltage.
STEP 3: Wire Float Switch
Here I've run some extra wiring to reach the tank and connected it to the float switch. Here it does not matter how we wire the switch, because this just bridges the gap and allows the electricity to flow through whatever direction it wants.
Here, we had to wire some power from the positive end of the relay to the tank because the adapter wires were a little to short.
STEP 4: Create "Snail Guard" And Mounting Bracket
This one took a little ingenuity, but I eventually found a pretty decent piece at the Lowes by my office. Basically, it's for hanging things off of doors. The piece meant to hang over the door (the large hook on the left) is way too big to hang over a tank edge. The hook on the far right, however, looked perfect.
I sawed off pretty much everything and left enough space so I could make the level adjustable.
Now that we have the mounting squared away, we have to make a "snail guard". Now you could most likely get one of these from an aquarium retailer, but I'm going for cheap here
I started with an old pill bottle and washed it thoroughly to remove the label and any residue. It contained hydrocodone from my appendix removal so if anything the fish and corals will get a little buzz and mellow out
Disassembled and drying:
Then I drilled plenty of holes to allow water flow:
I also drilled the top. Since the cap creates a seal, if you don't allow air to escape, water will only fill to the highest hole's level.
Next I drilled evenly spaced holes in the mounting bracket and the snail guard so that I could adjust the height with a zip tie:
I FINALLY got the float switches, almost 30 days after placing my order (darn Chinese shippers
). So here they are, I ordered an extra in case the one goes out or something.
Next, I drilled a hole in the lid for the float switch to go through.
And here we have the fully assembled snail guard/float switch
And here you can see what it looks like secured to the hanger. The good thing about this design is you can move the bottle/switch assembly up or down as needed.
STEP 5: Wire Float Switch to Relay
This one's kinda hard to show, but basically, you connect the + from the AC/DC adapter to the one lead of the float switch, then you wire the other lead of the float switch to the + of the relay. The - on the relay goes to the - on the adapter.
And here we have everything all assembled, soldered, and taped!
Finally, time to put it into action!
Additional Considerations
In some builds, instead of using just one float switch, people use two. This give some redundancy, because in the case that one of the switches goes bad and sticks open (which is usually the position it dies in unfortunately, the other would still open and close normally, so your tank wouldn't overflow if one of the switches died. It would be difficult to determine if a switch had died or not without regular testing, however, so this is just something to consider if you don't mind the extra work and effort.
For a long time I sat and tried to think how I could clean this design up a little and make it more neat and tidy. The simple answer is I can't. You can program circuits and create circuit boards with built in AC/DC circuitry, but that goes beyond the realm of this DIY and my knowledge of electronics. This device might not be the most elegant, but it is a simple, darn good design when implemented properly.
All the items bought on Ebay were from Chinese sellers and were correspondingly cheap, however, the shipping takes 2 weeks+ from the time of order. Something to bear in mind. Comparable relays from other electronics sites cost $12, and that's not including the relatively high shipping prices of said dealer. Generally, these electronics are mostly made in China anyway, so it's really the difference between buying from a USA seller who's reselling, or just getting them right from the manufacturer.
You can use any float switch you want and any relay you want, just be sure the specs line up. For example, the float switches are pretty standard. Since you're only running a small amount of electricity through them, they can be rated for anything almost. The one I got for example was rated for up to 100V, .5A. Most phone chargers are only 5-12V (mine being 12v), and the relay will only pull as much current as it needs to, which again in my case is 3 - 25mA (.003-.025A). The float switch will handle this just fine. The relay is pretty simple as well, as long as it's rated for 10A or more and is rated for AC (mine is rated for 480V), you will be fine. for all but the thousands of gallons per hour pumps
Hopefully this clears up some confusion and de-mystifies the magical and, in my personal opinion, all-too-expensive ATO. Let me know if you have any questions, comments or concerns
