martin_h Posted May 24, 2015 Share Posted May 24, 2015 Anybody used one of these in their projects? If so any good??http://www.maplin.co.uk/p/kemo-rain-sensor-dc-12v-n21dd Link to comment Share on other sites More sharing options...
swag72 Posted May 24, 2015 Share Posted May 24, 2015 That looks just like the one I bought from ebay Martin. I have it connected to a buzzer and a light switch to turn on and off and it works a treat. Link to comment Share on other sites More sharing options...
cathouse42 Posted May 24, 2015 Share Posted May 24, 2015 Maplin in general are overpriced, best to shop around especially when dealing with Maplin. You can generally save quite a bit on their prices.http://www.amazon.co.uk/s/ref=nb_sb_noss_2/279-6313677-3017856?url=search-alias%3Daps&field-keywords=rain+sensorHere is a bunch of rain sensors on Amazon. Link to comment Share on other sites More sharing options...
pete_l Posted May 24, 2015 Share Posted May 24, 2015 It's important to realise that this is a very small device: the sensor area is about the size of my thumb. Plus, you still have a significant amount of DIY to, errr ..... do yourself. Added to which, there's the price of a power supply.The description carries an implied admission that the sensor may not detect direct rainfall if your rain is too "pure".So although I've not used one, it doesn't sound like a device I'd be willing to trust to keep ££££'s of equipment dry. Link to comment Share on other sites More sharing options...
cathouse42 Posted May 24, 2015 Share Posted May 24, 2015 It's important to realise that this is a very small device: the sensor area is about the size of my thumb. Plus, you still have a significant amount of DIY to, errr ..... do yourself. Added to which, there's the price of a power supply.The description carries an implied admission that the sensor may not detect direct rainfall if your rain is too "pure".So although I've not used one, it doesn't sound like a device I'd be willing to trust to keep ££££'s of equipment dry.And also minimal false positives in the sensor, once they are wet, how can they determine whether that is old rain or new rain Kemo's product page is here http://www.kemo-electronic.de/en/House/Garden/M152-Rain-Sensor-12-V-DC.phpData sheet here http://www.kemo-electronic.de/datasheets/m152.pdfYou probably don't want to have these placed near a roof where water can drip down onto the sensors thus sending more false positives or shield them from the actual rain (probably placing them at an angle will help the old rain run off the sensor ).Perhaps multiple smaller cheaper sensors spaced about and a voting system between them will reduce false positives. Would be a fun Arduino project or something (or this $9 CHIP computer coming out). Link to comment Share on other sites More sharing options...
swag72 Posted May 24, 2015 Share Posted May 24, 2015 To be fair with this system I've had 2 false positives in about 2 years. It informed me there was rain when there wasn't. Link to comment Share on other sites More sharing options...
Gina Posted May 24, 2015 Share Posted May 24, 2015 I like the look of this optical rain sensor from Amazon - I don't like the price though Mind you, if it detects very light rain or drizzle that others don't, it would be worth the money to save your expensive astro equipment. Link to comment Share on other sites More sharing options...
michaelmorris Posted May 24, 2015 Share Posted May 24, 2015 And also minimal false positives in the sensor, once they are wet, how can they determine whether that is old rain or new rain Most have a small heater that is constantly on. This slowly evaporates rain that accumulates on the sensor. It's also a good idea to mount that sensor at a slight angle to aid rain drops running off. Link to comment Share on other sites More sharing options...
cathouse42 Posted May 24, 2015 Share Posted May 24, 2015 So say for example, if I bunch together an odd number of cheap sensors (odd number makes voting easier, no tie-breaker situations), say three, that should reduce false positives to near zero, wouldn't it? Assuming they are placed at differing angles (slight not huge angle) and spaced out far apart. Three should be enough to get very reliable readings. Link to comment Share on other sites More sharing options...
michaelmorris Posted May 24, 2015 Share Posted May 24, 2015 So say for example, if I bunch together an odd number of cheap sensors (odd number makes voting easier, no tie-breaker situations), say three, that should reduce false positives to near zero, wouldn't it? Assuming they are placed at differing angles (slight not huge angle) and spaced out far apart. Three should be enough to get very reliable readings.Assuming that the reason for false positives are glitches in individual sensors or their electronics and not a design flaw/feature in the design of the sensors, then this would seem a logical way of reducing false positives. Link to comment Share on other sites More sharing options...
cathouse42 Posted May 24, 2015 Share Posted May 24, 2015 Assuming that the reason for false positives are glitches in individual sensors or their electronics and not a design flaw/feature in the design of the sensors, then this would seem a logical way of reducing false positives.And each sensor being different brands, batch, or models.How well do these work with HAIL? Link to comment Share on other sites More sharing options...
michaelmorris Posted May 24, 2015 Share Posted May 24, 2015 No idea how well they work with hail. Link to comment Share on other sites More sharing options...
cathouse42 Posted May 24, 2015 Share Posted May 24, 2015 No idea how well they work with hail.They probably won't work with hail on it's own, that will be a different sensor, because hail bounces and will need to handle that. Link to comment Share on other sites More sharing options...
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