anyone know where i can find some rain-sensors (for house windows)?
i keep my windows open at night … don’t want it raining inside the house while i’m asleep. i probably would position the sensor on the window-sill … and the rain would set off a buzzer. nobody leaves their windows open at night? i have found several websites offering certain types … rain-sensor is different than water-sensor (impurities).
surprised radio-shack/sprint doesn’t offer one.
You could also use an enuresis alarm
Many modern cars have a sensor to start the wipers when it starts raining. Maybe you could find one in a scrap yard and rig something with that.
Did you try a Google search for “rain sensor”?
Every major irrigation supplier manufactures a rain sensor that will trigger a solenoid. And if it can trigger solenoid it will trigger an alarm.
I find this a little murky. Most rain sensors I’ve seen (and put on) irrigation controllers are low-voltage/low-current and simply signal the control box that free water is falling from the sky and thus expensive water from the ground need not be added.
With a little electronics knowledge, any of them could be adapted to a rain alarm. Maybe with very little knowledge, if one of those handheld alarm units like Rat Shack used to sell is used.
The irrigation rain sensor I took apart consisted on a plastic housing containing a number of water absorbing discs threaded on a screw or rod. As the discs absorb water they swell, pulling the rod up until it trips a switch. The trip point is adjustable so that you can adjust the amount of rainfall needed to trip the switch. It takes quite a while for the discs to dry out again (depending on how much water they soaked up) so the switch mat remain closed for several days.
I don’t think this type of sensor is appropriate for the OP. First, it takes a considerable amount of rain to trip the switch (a short shower won’t do it, but a short shower could get the inside of the house pretty wet). Second, there is a time delay between when the rain starts and the sensor trips, since it take a while for the discs to absorb water. Finally, it will take a while before the sensor is ready to sense the next rainfall.
If you really want to do a good job, you could also fit an electric window opener. (There must be an American equivalent) so you won’t have to get out of bed.
You may be right but in my experience the better makers had faster-acting, more sensitive rain sensors. (In general, if you’re going to install or replace a sprinkler controller, the Home Depot brands should be avoided entirely, but commercial grade controllers like Irritrol are great.)
My Irritrol installation in California seemed very responsive to rain changes - but as you say, that may not be as fast and sensitive as the OP needs. I suggest stapling a cat just inside the windows. Cats are well known for howling when they get wet.
This looks like it would fit the bill, but it only seems to be available in Australia:
This might also work:
wanted to thank everyone for their input … and, yes, i am not electronically inclined. marvin_the_martian, you and i had come across that same australian website/product.
however, what is offered in the marketplace seems ridiculous, primitive and ineffective. as a few of the respondents have suggested … we get cloudbursts down here in texas … pads soaking up water and then having to dry out for the next cloudburst … very inefficient how they design the hardware. i’d be looking for something almost instantaneous.
we all learn, in grade-school science, electricity conducts easily through water … shouldn’t matter spring-water or treated-water. if a grid of miniature gold-plated* electrical wires is placed on a medium … the space between any one element would be one micron … as soon as one tiny water-droplet lands on the medium … the area of that droplet would span at least two wires and, thus, would cause a “short” … which would then close the circuit.
since the “bamboo-weave” design of the grid has inherent limitations (crossing wires) … would have to separate them … similar to how they create lithium batteries … stacked elements separated using paperboard or plastic or other inhibitor. probably would be less costly keeping all the horizontal wires on top … rather than a front/behind/front scheme.
bellow is just a crude representation i came across while surfing the web:
linked image
again … wanted to thank everyone for their contribution and time.
*gold-plated because non-corrosive and excellent transference … copper would corrode too quickly.
ooops … missed one typo in the word “below”.
we all learn, in grade-school science, electricity conducts easily through water
Pure water is actually an insulator - however rainwater will have mineral ions from dust particles in the atmosphere and so will be a conductor.
Personally, I’d go with the $60 optical sensing unit from rainsensors.com
Well that seems a little harsh. The sensor in question is designed for irrigation applications - the desired operation is to not trip until a certain amount of rain has fallen, then remain tripped for a duration (days) proportional to the amount of rain that has fallen. While the sensor is in the tripped state, operation of the irrigation system is suspended. The “swelling discs” design is a simple and elegant solution to this design problem. No need to denigrate it just because it does not solve your problem.
When designing a sensor, preventing false positives is as important as sensitivity. The rain sensor you describe would be very sensitive, yes. But it would also react to any >1 micron conductive particle that lands on it. That may include soot and fog (mist).
And as Marvin the Martian said, faster & more sensitive is not always better. It may be better for your applications, but for other applications, you may only want it to react to a substantial rain (not just a 5-minute sprinkle).
The leak detectors that Isilder linked to sound very close to what you’re looking for. I have one and it works well. It won’t respond to a “tiny water droplet” but when there’s enough moisture to conduct between the two electrodes it will sound an alarm.
–Mark
