Path: ...!feeder3.eternal-september.org!news.eternal-september.org!eternal-september.org!.POSTED!not-for-mail
From: "Don" <g@crcomp.net>
Newsgroups: sci.electronics.design
Subject: Re: Damned Projects!
Date: Sun, 29 Dec 2024 18:28:24 -0000 (UTC)
Organization: A noiseless patient Spider
Lines: 49
Message-ID: <20241229b@crcomp.net>
References: <gqarmjlh9gc54qu1mg410hivqqt7vtg0kn@4ax.com> <000463@dontemail.com>
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Injection-Date: Sun, 29 Dec 2024 19:28:25 +0100 (CET)
Injection-Info: dont-email.me; posting-host="0e0a6e7642294639adf1952c81c1c704";
	logging-data="1188670"; mail-complaints-to="abuse@eternal-september.org";	posting-account="U2FsdGVkX18+f5EHDyeKOUWG35nwF4X4"
Cancel-Lock: sha1:5GfaSg5p4tWSnpSlzfYxVWMFXeE=
Bytes: 2992

Wanderer wrote:
> Cursitor Doom wrote:
>> Gentlemen,
>>
>> I'm currently in the process of building a device which will shut off
>> the power to a washing machine in the event of a hose failing and
>> spewing water out all over the floor. This is an eventuality which has
>> always caused me considerable angst, so I finally decided to do
>> something about it. After all, those flimsy 'exhaust' hoses go brittle
>> over time and having one split 'in action' could cause a significant
>> amount of damage to the surrounding area in a very short time. Having
>> something to cut the power off instantly as soon as the water hits the
>> floor would be a very worthwhile addition to the utility room and
>> beyond.
>> I came up with a pretty simple design which I've already proven to
>> work first time at the breadboarding stage. However, turning this
>> concept into a practical proposition is taking *far* longer than I'd
>> imagined. I am getting there, but *slowly* and was wondering whether
>> other people here have the same sort of problem as I invariably do
>> with these little personal projects they undertake?
>>
>> Your hydrophobic pal,
>> CD
>>
>
> The way I've seen water detectors done is with an LED angled to reflect off
> a piece of glass to a photodiode when the glass is dry. When the glass is wet
> the index of refraction of the glass/water is different from the glass/air and
> allows the light to pass through and not hit the photodiode. That's how automatic
> windshield wiper raindrop detectors work.

Here's the physics of a rain sensor:

<https://www.yoctopuce.com/EN/article/how-to-build-a-rain-sensor>

When you rotate this sensor on its side it ought to work:

<https://www.instructables.com/Measuring-the-Refractive-Index-of-Liquid-at-a-Defi/>

If it's high enough, you probably can fabricate (print) it as a single
piece and leave the cover off altogether.

Danke,

-- 
Don, KB7RPU, https://www.qsl.net/kb7rpu
There was a young lady named Bright Whose speed was far faster than light;
She set out one day In a relative way And returned on the previous night.