Relay help. ATO

Snaz · #1 09-18-2010, 04:17 PM

I have an existing DIY ato than uses a float switch to activate a battery powered air pump which pressurizes a bottle of fresh water and tops off the tank nicely. Now what I want to do is replace the battery air pump with a regular one that plugs into a wall socket but the float switch is not rated for full house current. I know a relay would solve this but i'm not sure which to buy and how to wire it.

I found this on ebay, not sure if this is what I need.
http://cgi.ebay.ca/5-X-JQC-3F-T73-DC...item4cf00a223e

banditpowdercoat · #2 09-18-2010, 05:46 PM

What voltage goes to your Float sw? You need to match the relay control voltage to your ATO/Float sw voltage. then the relay contacts to the voltage you want to switch. That relay used 9V DC to operate, and will sw up to 250V AC It will work fine, if your ATO/float operates on 9Vdc

Snaz · #3 09-18-2010, 06:14 PM

The float switch is currently setup with two D batteries so that would be 3v but I was thinking of using a 9v battery or 12v power supply for this new setup.

Bloodasp · #4 09-18-2010, 06:33 PM

I wish they'd include schematics on those or which pins are what but anyway just by looking at it I would guess the 2 pins on the left are the ones that are going to be connected to the 9 volt source. In series with that on the positive side of your 9 volt supply would be where your float switch will be connected. The 3 pins on the right would be where the ac voltage would go. One pin would be normally open (NO), which means it is not powered when the relay is not activated, one is normally closed (NC) and one is common (C). Connect one of the wires on your AC plug to the outlet where you are going to connect the ATO to and the other wire to the NO pin and the C pin goes to the Outlet. Not sure which is NO, NC, or C from the 3 pins. I guess you have to test out which if no diagram is given.

http://www.embed4u.com/?p=380

there's a schematic there, which shows a better way of wiring it.

Snaz · #5 09-18-2010, 09:07 PM

Makes sense. How does one attach the wires to these poles? I guess the relays are designed to fit in a circuit board, can I just solder the wires to these poles? Doesn't sound the safest way to do it. Thanks for the help.

banditpowdercoat · #6 09-18-2010, 09:17 PM

Yup, they for soldering into a CB. You can just solder onto the pin's no problem. I would wrap the whole thing in elec tape after, to cover the 120V solder connections. I have stuff like that all over my house LOL But then again, I'm an electrician and I tinker alot

mike31154 · #7 09-19-2010, 08:06 PM

Instead of making things more complex with a relay, have you considered making it simpler instead? I have a similar ATO with an air pump pressurizing a container but use a mechanical furnace humidifier float switch to limit the fill level rather than an electrical float switch to turn a pump on and off when the level drops. I use a regular, small aquarium air pump plugged into a timer which cycles on for a few minutes every hour. This keeps the top off container sufficiently pressurized to keep up with evaporation, while the mechanical float switch keeps the level from rising above the set/desired level. Once you've got the timings dialed in to keep up with evap, it works like a charm and if the pump happens to run a little longer, no harm done, the float valve prevents any likelihood of overfilling. Less electrical around water = more warm & fuzzy safe feeling.