Auto stop 12v pump (no float-switch)?

Hi guys, i got a very urgent question,
I need a mini small water pump just as the wiper pump 12v  but the most important thing  I need it to stop when the water tank is full (auto-stop) with no need of a float-switch.
So how can i find this type of pump and what is their right name of the pump
or what is the key-words that could give me the right on google

 this is my first question link

Thanks, Pls instructables community help me !!

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Peter's circuit's a good way to do it.

vwtm2006 (author)  steveastrouk3 years ago

thanks guys, but i need something simple , i am searching for a mini pump 12v that have a pressure sensor or on demand system

i need the name of this type of pumps

thanks community

simple is a float switch. Pressure switches arenot going to work without a lot of tricky work, because the thing won't have enough discrimination - you have 2 metres of height, and your tank is 200 mm high.. There is 10 percent pressure change in 1/5th of a Bar. The sensor is not cheap, or simple

Maybe a water switch (two exposed wires close to each other on which the water closes the circuitwhen touching it) and if needed a relay.

You know I never thought about the important question until red Steve, Rick and Petecd comments.

What kind of water and will it have living things in it?

Small amounts of current bother and can kill living marine life in fact it only takes 4 ma to kill a person.

I never rely on waters continuity, distilled water is an insulator until you add a trace element just like a semiconductor. If you take pure water electricity won’t pass through it, add salt or acid to the water and electricity will pass through it just like a semiconductor.

So what kind of water?


All reliable water controls use some kind of float system just all float
systems don’t use floats.

Take a washing machine for example the float is air, as the washing mashing fills with water it seals and fills a tube with air sealed to a diaphragm switch the higher the water level the higher the air pressure in the tube. When the air pressure reaches the desired point it trips the diaphragm switch to turn off the filling solenoid turning off the water.

Yes I was an appliance repair man.

It is a simple diaphragm switch but it can be complicated to set up, you may need a large tube pushing air into a small tube to create the air pressure needed to
trip the diaphragm switch.


petercd3 years ago

This is what I used as the auto fill circuit on a 12V washer pump for one of my hydroxy cells, the fet came out of a 14" monitor with its own heatsink.

Washer motor control.JPG
rickharris3 years ago

Use a couple of wires to turn a transistor on/off when they are in the water/dry

like these