Diy ato

[Mdj]

Setting up my ato I have a small 24v pump and wallwart I am using would I need to put a relay on the float since it is a small pump or could I wire it directly through float.

[der_wille_zur_macht]

I don't think it's ever good practice to put power through a float switch, they should really be operating at signal levels only. In other words, use a relay. Assuming you're using one of the standard float switches seen in this hobby (Madison M8000 or a knockoff), they're pretty fragile, we need to do whatever we can to protect them.

[Mdj]

That's what I figured was hoping I might be able to save a plug with a small pump will go get like 3v plug in and relay thanks for your help

[Mdj]

That's what what I figured was hoping to save myself a plug with a small pump guess I will go get a small 3v wallwart and a relay. This hobby sure takes slot of plug spots

[cwetherford]

Thanks for the insight... I’m doing the same thing

[outy]

autotopoff.com is the best place to get cheap ATO parts. mine are a decade old and still in use.

do it right the first time, and be done. No worrying on a very important piece of electronics

[der_wille_zur_macht]

You can use the 24v power supply for both the pump and the signal circuit (assuming you have an appropriate relay), you just don't want the full current powering the pump to be running through the switch.

[Mdj]

Would I just need to run a resistor in the line to float to lower current. Wallwart t off wire resistor to floats back to relay then other side of t back to relay. What type of resistor would be best to restrict power from wallwart through float switches ?

[mcgyvr]

You do not need a resistor at all..The coil of the relay is basically the resistor
The relay "draws" (pulls) only the current it needs and that small current travels through the float.
The float is capable of switching the small current the relay is drawing to operate but typically the current that a pump is drawing is too much for the float to switch reliably..

[der_wille_zur_macht]

The signal side of the relay and the power side would be wired in parallel. They'd both get their own 24v from the power supply, and the current through each branch of the circuit would be completely independent.

[mcgyvr]

Here is a quick diagram of your wiring..

[Mdj]

Thanks I can run that guess my brain was just thinking the 24v would be going through switch didn't know it would only send what the relay needed. Guess that's why I don't work with electric much normally.

[mcgyvr]

yep thats a very common misconception.

An LED though on the other hand needs that resistor (or constant current power source) to "spoon feed" it the current it needs or it will let out the magic smoke..

[der_wille_zur_macht]

Originally Posted by Mdj

Thanks I can run that guess my brain was just thinking the 24v would be going through switch

To be clear, the full 24v will actually be applied to the switch. It's not the voltage that's a problem (within reason), it's the current the pump would pull. When you wire loads in parallel, each gets the full voltage, but each parallel branch of the circuit is completely independent in terms of current. The pump can pull all the current it needs, and the switch will only see the current required to hold the relay closed (which is typically very small).

[mcgyvr]

Originally Posted by der_wille_zur_macht

To be clear, the full 24v will actually be applied to the switch. It's not the voltage that's a problem (within reason), it's the current the pump would pull. When you wire loads in parallel, each gets the full voltage, but each parallel branch of the circuit is completely independent in terms of current. The pump can pull all the current it needs, and the switch will only see the current required to hold the relay closed (which is typically very small).

I went with the assumption that they really didn't mean voltage but good you posted it when I was too lazy to

[Mdj]

Think it makes more since to me know so since I am hooking up 2 floats all I need to do is split wire going to float from diagram above then run both floats to the relay so they will work independently for a fail safe. I am also wanting to put a float on reservoir to kill the pump if it gets to low on water could I put this float before other 2 floats so they run through it or should I run another relay to kill pump if water gets low in resevoir

[mcgyvr]

Originally Posted by Mdj

Think it makes more since to me know so since I am hooking up 2 floats all I need to do is split wire going to float from diagram above then run both floats to the relay so they will work independently for a fail safe. I am also wanting to put a float on reservoir to kill the pump if it gets to low on water could I put this float before other 2 floats so they run through it or should I run another relay to kill pump if water gets low in resevoir

All 3 in series.. One in ATO fresh tank flipped over (inverted operation)
Note you can either just flip the whole sensor over to invert but IMO its always better to keep the spot where the wire enters the connector dry at all times and you can flip the "bobber" upside down by removing the plastic ring (or whatever your version has) to invert the function..
I always run my wires through some vinyl tubing that fits snugly over the threaded portion right where the wire enters and even apply a bit of silicone to seal it even better..
The can/do fail because of a faulty seal so I do that to hopefully mitigate that issue..

[Mdj]

Ok now I am a bit confused what is purpose of backup switch if ran in series if 1st float sticks won't it stop the secondary float from working if it is stuck open or am I missing something that is why I assumed running in parallel would be way to go so all switches would work independently even if failure occurred will the other switches work as a backup if switch one sticks in series

[perkint]

If they are in parallel, any one of the float switches being closed will run the pump (so if one sticks, the pump still runs). If they are in series, they all need to be closed, so any one sticking will only run the pump until the next one opens the circuit

Tim

[Mdj]

Ok so the fail safe is intended to keep display from flooding but it will not protect me if a float sticks not allowing the pump to kick on from loosing to much water in display will it or am I just way over thinking this i am going to use the diagram with the 3 floats from above should float 1 be set just higher than 2 or did I get it backwards

[perkint]

As you say, running them in series with one float higher than the other prevents over filling but not under filling. To be honest, IMO if you want that, use a controller (an Arduino nano).

Tim

[Mdj]

I am eventually going to tackle a controller but for now I must go without I think I am going to need a whole lot more research to diy a arduino controller and box controllers are just way out of my budget as of now but this will at least prevent me from topping tank off manually twice a day thanks so much for your help

[perkint]

To be fair, developing an ATU controller is a pretty good first Arduino project

Tim