just wondering if anyone could assist in choosing the right items i need to refine my ATO

using an air pump to pressurize a 5 gallon car boy, secondary airline coming out to sump

initially tried using a timer on it, the kind with 15min incremental notches you push down or up....turns out 15 minutes is too long, so instead of getting a digital timer i opted for a float switch activated pump

now i have seen the guys who have split one side of an extension cord, wired in the float switch, and called it a day, but not being a novice at electronics and what not, i realize right away the float switch is not rated anywhere near the amount of voltage coming through a typical AC 120v circuit, the only way those guys are getting away with this is because the air pump draws all of 2 watts of power from that circuit, so it works without burning things up

but i was thinking about adding in a 12v power supply and relay to actuate the pump when triggered by the switch to keep things safer and more reliable

according to my research a 12v 200 milliamp output DC power supply will be suitable, but i have not been able to find a specific part number for a relay to work with this setup, i work at an auto parts store so i have access to pretty much any 12v relay you could want, i just need someone to help me find which one is best to use and a simple wiring diagram would be nice too

anyone?

i believe i may have found the one, found one at radio shack that is known to work well for the application, and in the comments someone posted it is a direct replacement for a backup lamp relay for a 1993 Dodge Grand Caravan, so that gives me an application to lookup at work tomorrow, will check it out and post the part number in case anyone else comes across this thread in the future

ok guys, need some help understanding how this is going to work

i have a 5 gallon carboy for water supply

put two sealed stiff airline pieces through the top, one to the bottom of the carboy, the other is only a couple inches long so as to allow the carboy to be pressurized by the air pump

i have a Whisper 10 model air pump which is doing the job well right now, its a standard 110v plug in type air pump, rated at 1.5 watts, 120v AC

i got a 12v 30A SPST relay which i found somewhere else was recommended for this application

i have a cheap float switch on the way from ebay

i have a 110v AC to 12v DC power supply

so the idea is to power the relay with the 12v power supply and have it kick the air pump on and off...or to have the float switch trigger the relay to throw anyways.....but what i dont understand is how am i supposed to run a 110v air pump through a 12v relay????

i cant believe after hours of searching i cant find a simple diagram of how this was done.....basically didnt want to wire the float switch directly to the 110v AC source as the switch isnt made to handle that load, so i read that using one of these relays with a 12v power supply would convert it to a low voltage system....but i need a wiring diagram

You need a relay that has its coil switched by the float, powered by 12V, when the coil is energized (float lowers) the coil closes a 110V circuit turning the pump on, when the float rises, it cuts 12V power to the coil, opening the 110V circuit. This sort of relay.

ok so i have the wrong relay....any wiring diagrams to make this simple?

Unfortunately thats something I can't do for ya. The site I got the link from says to wire the floats and transformer to post 7 and 8 (in series it looks like), and the AC line to 4 and 6 on the relay socket, I'm not sure if the relay itself has those same numbers though.

hrm, the price of that aquahub kit is nearly cheap enough to just get the kit from them and wire it up, by the time i buy switches, relays, transformer, cord, etc.....i'd probably have that much in it anyways

Quite possibly, the premium kit does all the essentials, all you provide is tubing, pump, and a 94 cent extension cord from Walmart. Has 2 floats, so theres a backup if one fails, project box, and so on. I should have bought it, but I bought piece by piece from them, and will probably end up paying more by the time I get it all together.

just happened upon a member here selling a used deluxe aquahub kit with the three switches and even included a pump for water transfer for the same price as the standard kit new before shipping..thanks for the help

Cool, things usually work out in the end, glad a member was able to help out.