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Mechanical first rain drops detector?


I am looking for a mechanical' 'way of detecting the first raindrops of a shower or worse.

This detector then releases a mechanical alarm, which will alert folk who keep their washing on the line as long as possible, to bring it in.

The alarm could be sounded by a gravity falling weight (rock) or rewindable spring, driving a rattle, for example.

If possible, a windmill action could generate the power to reset the weight.

No electronics to be used in this if possible.

Kalrag3 years ago
I know that your avoiding electronics but thats going to be hard. You could find some sort of alarm that detects water and when that first drop falls it will let off an alarm. You could mount it on the roof so is out of the way of stuff.
orksecurity4 years ago
Ancient solution: Use a small piece of alka-seltzer, or some similar effervescent tablet, to hold back a spring. When water hits the tablet, it dissolves, releases the spring, and it powers whatever you were trying to activate. Of course this does have to be dried, reset, and equipped with a new "sensor" before it can be used again. But it does work.
Raymondo (author) 4 years ago
Thank you for coming up with your ideas. My limitation of not using electronics, was to see if anyone could come up with a solution using 'pure' mechanics. This could create some fun element into the garden. I have nothing against using electronics; but that is too easy. I like the Hygrometer approach. This may be arranged to become more sensitive when the humidity is raised. There still remains the problem of 'catching ' the first drops to trigger the 'alarm'. For the alarm, I quite like the marbles. They could be raised back up with a windmill driven 'conveyer belt'.
I first think of the drinking bird toy
dataphool5 years ago
1. Arrange a funnel over a clothespin so rain falling (from the shy) will be collected by the funnel. 2. The output of the vertical funnel causes the water to drop on an aspirin / anacin held between the jaws of the clothespin which are held open by the aspirin. 3. The first drops hitting the aspirin will cause it to dissolve, the clothespin will close. Choose your alarm: a stick of dynamite, or similar. 4. Note: the aspirin must be the old style, non-buffered, non-coated, a simple white pill that has been on the market for a hundred years.
I like dangerous ideas. lllolol
starwing1234 years ago
Your eyes? You could use a small strip tissue that holds a weight. When it gets wet, it breaks.
Or a convener belt of bathroom paper that goes out side. Spring loaded pins would push down not hard enough to go through, but will when wet. This activates a switch in between the belt that triggers a bell or alarm.
Kiteman5 years ago
I wonder if a hair hygrometer could be used?

Hair gets longer when wet - could it be possible to use this change in length to trigger a small mechanical device that then triggers a larger mechanical device (such as releasing a container of marbles to rain into a metal drum).

If your "no electronics" rule is down to concerns that a flat battery will cause a failure of the system, why not look into solar or wind power to trickle-charge a set of batteries?
That weather house article I linked to does mention that you can use hair instead of catgut. But good job finding the how-to. I am surprised Instructables does not have this already.
110100101105 years ago
make a lightweight roof above the cloth lines ? use just a big thin sheet of metal. when rain hits it it makes noise use a 1 X 1 M cone to collect more drops to fill small bucket as fast as possible with the first drops. then connect it to other mechanics make a small pad with cloth and make it very sensitive to weght. when it catches the firs drops it becomes heavier and pulls a lever down. this one may have lots of false alarms
I'd say it's possible, but sensitivity is an issue. A friend of mine has a little bucket and bell thing under his downspout. The bucket fills, tips over, and moves a hammer to strike a bell. When the bucket has dumped, it returns (via weights) to the normal position and does it again. Still, It takes a couple of minutes of pouring rain for it to go off, and it's not very loud. I've seen lots of other gadgets designed to be powered by rain or wind, but none that'd be sensitive enough to alert you before the clothes is soaked.
Electronics might be necessary here, to get a useful result.

The problem with a mechanical sensor sensitive enough to detect a few raindrops is that it would also be triggered by wind. Perhaps the sensor could be encased in a long tube with a funnel at the top?

Another solution a hygrometer. If the amount of water in the air is near the maximum amount that the air can hold at the current temperature, this tells you two things:
  • it is probably about to rain, and
  • your clothes were not drying anyway.
You can construct a hygrometer out of a string or hair that changes tension depending on the humiditiy. Another option is to use a piece of paper soaked in cobalt chloride, which will turn from blue to pink when the humidity goes up. (Cobalt chloride humidity test strips can be bought for a few dollars on Ebay. You could also buy half a kilo of cobalt chloride for $56 and make a few thousand test strips to sell to others.)
you could use a piece of paper towel holding up a weight (the rock) and when it gets wet from the rain it would tear, allowing the rock alarm to sound.
This would not be especially sensitive, even if it were bathroom tissue, but definitely an elegant solution.
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