Empty Water Detector

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Introduction: Empty Water Detector

This project is an 'empty water detector' to tell you when the water is gone from a vessel - originally, I designed it for a christmas tree, but it will work for your dog's water bowl or just about anything else.

Parts list

  • 220k Resistor
  • Small Perfboard
  • 2N3906 Transistor
  • 2x or 3x AA Battery holder
  • 3mm Red LED
  • Extra wire for the probes

You can order the kit from Gadget Gangster & grab a PDF version of these instructions, here. You can also share your own projects on Gadget Gangster, too.

Here's a video demonstration

Step 1: Gather Materials

First, gather all your materials. If you've ordered the kit from Gadget Gangster, your project will come with a halfboard - put the halfboard in your vice, as shown in the picture. You'll also need a soldering iron and 2 AA batteries.

Step 2: Add the Resistor

Add the resistor from M3 to N7.
Bend out the leads on the other side of the board, flip the board over and solder the resistor down, and trim off the excess wire.

Step 3: Add the Transistor

Flip the board back and add the transistor from O6, O7, and M8. The flat side of the transistor should point to the edge of the board.
Spread apart the leads, flip the board over, solder & trim the excess wire, and flip back over.

Step 4: Add the LED

Add the LED from P6 to Q6. The longer lead goes into P6, shorter lead into Q6. Spread apart the leads, flip the board over, solder the LED down and trim the excess.

Step 5: Add the Probes

The probes are the wires you'll put in the water;

Take the red wire, cut in half, and strip the ends of each wire, & tin the ends (lightly twist the ends of the wire together, heat with your soldering iron, and add a bit of solder.
Once the wires are tinned, put on wire in P7, the other wire in Q8. These wires are the probes that you'll put into the water. You can tie the other ends of the wire in a knot, with one end a little shorter than the other.

Step 6: Connect the Batteries

Lastly, connect the battery pack. Thread the black and red wires through a few of the bigger holes on the bottom of the board for stress relief, and connect the red wire to Q23, Black wire to M22.
That's it! Add 2xAA batteries and insert the leads into the water you'd like to test. When the water's gone, the light will illuminate and you'll know it's time to add water!

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21 Comments

*I have no electronics background*

The link to your site doesn't work for anymore (for me at least). For a novice I wondered if you could make the schematic available? also how would you add a buzzer into this too?

Thanks,

Can you give a schematic diagram?

Great simple project, much better than sap!!! :-)

water does not trigger the system ? I put an alka-selzter tablet between the wires, that are squeezed by a spring clip, when water reaches the alka-seltzer tablet it crumbles and the wires touch, thereby completing the circuit. The fish upstairs, starts to sing and dance, and I rush down to the basement and turn off the main water valve and repair any leaks! Simple ! It works, tested it with water and the tablet. Asparin would also work. I like simple. Less work and parts to go bad!

I need to make this in reverse. I want to detect water if it leaks from my ancient basement boiler. My home has a concrete below ground basement. It has no drains or sump pumps. So if my boiler blows or a pipe leaks I will have a very ugly swimming pool! And all my workshop will be under water. So if I could nip any leaks in the bud, I would be much happier! Any simple DC plans would be deeply (no pun intended) appreciated! I have a catfish wall plaque that talksand moves. It has a 6V.DC battery box (4 AA @ 1.5 VDC each) power and 6VDC wall transformer too. I would like to run two small wires down to the basement and the plaque upstairs where I can hear it! All I need is a way to activate the catfish with a moisture sensor. Any wizards out there have a simple way to do this? I can do basic soldering and schematic stuff! But simple is better. Thanks.

I hope this helps. But if you use the plaque idea you'd have to take it apart and (im assuming it has a button to activate it) put 2 wires where the water would be (not touching though) and solder the 2 wires to the leads of the button.

SCHEMATIC.png

I need to make this in reverse. I want to detect water if it leaks from my ancient basement boiler. My home has a concrete below ground basement. It has no drains or sump pumps. So if my boiler blows or a pipe leaks I will have a very ugly swimming pool! And all my workshop will be under water. So if I could nip any leaks in the bud, I would be much happier! Any simple DC plans would be deeply (no pun intended) appreciated! I have a catfish wall plaque that talksand moves. It has a 6V.DC battery box (4 AA @ 1.5 VDC each) power and 6VDC wall transformer too. I would like to run two small wires down to the basement and the plaque upstairs where I can hear it! All I need is a way to activate the catfish with a moisture sensor. Any wizards out there have a simple way to do this? I can do basic soldering and schematic stuff! But simple is better. Thanks.

Question... Will this work with petrol / gasoline? I know it's a noobish question, but it's better to be safe than blown up. Thanks.

DON'T even think about that.
That's why they use floats in gas tanks.
It would be much simpler and probably cheaper but extremely dangerous.

Do it and let us know how it works out. A deep cycle battery would be great for that.