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Hello I need someone to build a simple water activated circuit for me

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First I am not a electronics expert and am having a tough time with it. I need someone to build a circuit that is water activated by two contacts that closes a circuit when submerged in water. Then I need that circuit to cause an elecric motor to turn on. The battery power is 1.5 volts or 1 double "A", and the motor is a 1.5 - 3 volts. I seem to be able to find plenty of schematics for this setup only it uses a buzzer instead of the motor, and I believe the resistors and transistor are specific to the buzzer used in those schematics. If anyone is able to help in lamen terms then I would be eternally grateful. Please remember when responding I have very little experience with elecronic circuits.
 

blueroomelectronics

Well-Known Member
How much does it pay?

A simple solution is a float and a switch.
8801-drawing_FS-H.gif

This is a nice magnetic one.
https://www.reed-sensor.com/Other_Sensors/Horizontal_Float_Switch.htm
 
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blueroomelectronics

Well-Known Member
Just use the motor the same way as the buzzer. A toy1.5V motor probably won't have much torque.

What's it for?
 
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well im running test with tap water with a small amount of salt added to lower the resistance somewhat. and I cant use the float setup because the device is tossed into the water and it needs to activate itself
 

shimniok

Member
I did a rain gauge project way back when ... it is doable. I just don't remember the schematic (this was like 11-12 yrs ago) but it was ridiculously simple. Just a bunch of independent LED lighting circuits with leads at different heights in the collector. Whee :D I imagine you're not going to see a lot of current through the water but some.
 

Raul

New Member
sounds like you want the device to detect the presence of water not respond to some level of water, using a very fine level of detection of the delta between a the charge or potential of a body of water and the sensor. sort of like what Saw Stop uses to activate their blade brakes.

The Saw Stop unit senses the delta between the human and the saw's basic electrical charge or s something like that and reacts by slamming an aluminum blade brake into the teeth of the blade while also activating the trunnion and lowering the blade at a rapid clip.
The result is you can't cut yourself so long as the saw is working correctly.

If it's worth it to you, you might order one of their brake cartridges and reverse engineer it.
 

MrDEB

Well-Known Member
maybe I misinterperted wrong

but it sounds like the op wants to measure the resistance of water, then add salt to change the resistance.
I'm thinking a voltage comparator connected to two contacts.
adding salt changes the waters resistance thus changing the voltage input to the comparator.
problem would be a very sensitive comparator unless a PIC is utilized then go with ADC circuit??
maybe doable??
 

BrownOut

Banned
I did this once. You need to use AC current to make the measurement sensitive.
 
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