# Water sensor

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#### Michaeneu

##### New Member
I'm looking to build a simple water level detector that will de-energize a 12VDC relay when the sensors detect water. Once the water level decreases the relay must energize. I saw your water activated alarm but I would prefer to stick to transistors and avoid IC's if possible.

Your help would be greatly appreciated.

Michael

#### crust

##### Member
Would a simple ball float work ... If not, perhaps supply us with some more detail as to what you would like to do.

#### dingo

##### New Member
That should work, haven't tested it. the first circuit might work with only one transistor I spose it depends on how wet your water is....... anyhow used a darlington pair to be on the safe side.

#### Roff

##### Well-Known Member
Dingo, you got your labels reversed. The circuit on the left turns the relay ON when the probes are wet, the one on the right turns the relay OFF when the probes are wet. You should include a 1k resistor in series with one probe lead to protect the transistor from excessive base current in case of a short, or really wet water.

#### Michaeneu

##### New Member
dingo said:
That should work, haven't tested it. the first circuit might work with only one transistor I spose it depends on how wet your water is....... anyhow used a darlington pair to be on the safe side.

Thanks dingo, the second circuit worked perfectly. I'm using it to purge air out of a water system. Once again, thanks.

Michael

#### e

##### New Member
I have a similar setup controlling the sump pump, oddly i didnt even need darlingtons, just standard PNPs and i did need to use a base current limiting resistor. Been working for about a year now..

#### mixos

##### New Member
Check this attacment also.

#### Attachments

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#### Hassan kabiru

##### New Member
water level control

I'm looking to build a simple water level detector that will de-energize a 12VDC relay when the sensors detect water. Once the water level increases the relay must energize. I saw your water activated alarm but I would prefer to stick to transistors and avoid IC's if possible.

Your help would be greatly appreciated.

#### Boncuk

##### New Member
Thanks dingo, the second circuit worked perfectly. I'm using it to purge air out of a water system. Once again, thanks.

Michael
How about using an automatic air bleed valve? It's used in heating systems and works perfect.

Boncuk

#### Boncuk

##### New Member
I have a similar setup controlling the sump pump, oddly i didnt even need darlingtons, just standard PNPs and i did need to use a base current limiting resistor. Been working for about a year now..
Wow! Your water must be darn wet!

Boncuk

#### neon

##### Banned
I'm looking to build a simple water level detector that will de-energize a 12VDC relay when the sensors detect water. Once the water level decreases the relay must energize. I saw your water activated alarm but I would prefer to stick to transistors and avoid IC's if possible.

Your help would be greatly appreciated.

Michael
GOD those things come from china for a $1 a pice to monitor trees moisture.$.99 cents stores got them.

#### Roff

##### Well-Known Member
How about using an automatic air bleed valve? It's used in heating systems and works perfect.

Boncuk
The post you responded to is nearly 5 years old...

#### Boncuk

##### New Member
The post you responded to is nearly 5 years old...
honestly I didn't check the date. How come this old post appears in a new thread?

At least it seemed to be a new one being posted on the first page.

Hans

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#### Roff

##### Well-Known Member
honestly I didn't check the date. How come this old post appears in a new thread?

At least it seemed to be a new one being posted on the first page.

Hans
Hassan put a new post in an old thread.

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