Path: ...!feeder3.eternal-september.org!news.eternal-september.org!eternal-september.org!.POSTED!not-for-mail From: "Don" 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: <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: When you rotate this sensor on its side it ought to work: 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.