Help please with rain detection for remote observatory operations?

[michaelmorris]

I’m in the process of trying to set up my roll-off roof observatory so that I can monitor imaging sessions from the warmth of my study. I am trying to achieve this with minimal cost.

As I see it I need five things to be in place before I can achieve this.

• The ability to run all the kit from the computer in my study
  
• The ability to monitor the scope so that I can see if it starts misbehaving and slewing dangerously.
  
• The ability to detect if it’s cloudy
  
• The ability to detect if there is likely to be a problem with dew
  
• The ability to detect if it’s raining
  

Here is my progress to date.

• The ability to run all the kit from the computer in my study – SORTED - Teamviewer software does this just fine.
  
• The ability to monitor the scope so that I can see if it starts misbehaving and slewing dangerously. – SORTED - http://stargazerslounge.com/topic/173875-which-scope-monitoring-webcam/
  
• The ability to detect if it’s cloudy – I have a Samsung SDC-435 video camera with a fish-eye lens attached, all enclosed in a weatherproof housing, which acts as an all weather meteor camera. I hope this will suffice as a way of monitoring cloud cover
  
• The ability to detect if there is likely to be a problem with dew – A cheap USB temperature humidity sensor should suffice
  
• The ability to detect if it’s raining – this is the one I’m having a problem with. I’m useless with electronics and have no programming skills at all, so a DIY rain detector is out. So far the only thing I’ve found that appears to fit the bill is this – http://www.auroraeurotech.com/CloudSensor.php. However, at over £200 this is presently well above my budget. Any cheap but reliable suggestions gratefully received.
  

Any comments or suggestions very gratefully received.

[upahill]

This seems like it might work for you

http://www.ebay.co.uk/itm/RAIN-SENSOR-RAIN-DETECTOR-SNOW-SENSOR-12vdc-/370740978722?pt=UK_BOI_Industrial_Automation_Control_ET&hash=item5651e26422

It uses heated sensors to evaporate what it detects, allowing you to detect not just rain, but when it has stopped raining.

[yesyes]

A rain sensor is still a project I have in the back of my head. I had started experimenting a while ago and plan to resume once my obsy is built.

The one I experimented with was a simple Vero strip board with all even traces connected to one wire and all odd ones to another wire. When this is dry this is basically "open", electrically. When water drops connect 2 traces it goes from open to a certain resistance. This can be measured and/or used to switch a transistor. The board would need to be heated when wet so that the water evaporates when it is no longer raining and open again.

Another idea I had was using a microphone under something like a camera dome and then detect the typical sound of rain (short spikes in signal when a drop hits the dome). This is just a theory in my head at the moment though.

Both would be very easy and cheap to build. The rest is software that I would be willing to share if I ever get to a stage when this would be working. ;-)

[michaelmorris]

This seems like it might work for you

http://www.ebay.co.u...=item5651e26422

It uses heated sensors to evaporate what it detects, allowing you to detect not just rain, but when it has stopped raining.

Thanks, I had already seen these, but I am struggling a bit to see how I can turn this into detector that alerts me on a remote computer. The best (only) idea I have come with so far is that the signal from the detector turns on a bright light and buzzer. These would show up as a visual and sound cue picked up by the webcam used for monitoring the scope. Whilst this could possibly work, the fatal flaw is that it completely relies on my ability to find the relevant circuit and to build it. I have almost zero electronics skills! (I own a soldering iron and I have lots of plasters ready to put on the burns).

[yesyes]

A visual alarm is pretty easy. Just let the relay in the sensor switch a 12Volt LED on and off that is in the field of view of the webcam. You'll need a 12V power supply for the sensor anyway so you could use that for the LED as well. No further "electronics" needed, just a bit of wire and a 12V LED.

[upahill]

Thanks, I had already seen these, but I am struggling a bit to see how I can turn this into detector that alerts me on a remote computer. The best (only) idea I have come with so far is that the signal from the detector turns on a bright light and buzzer. These would show up as a visual and sound cue picked up by the webcam used for monitoring the scope. Whilst this could possibly work, the fatal flaw is that it completely relies on my ability to find the relevant circuit and to build it. I have almost zero electronics skills! (I own a soldering iron and I have lots of plasters ready to put on the burns).

As yesyes said, as simple 12V LED across the relay would work as a visual indicator, but you could get it to do pretty much anything you wanted with a few add on circuits. 12V Buzzer, or use it on something like an Arduino to send you a text message when its raining, control your roof - ooooh endless possibilities hehe.

Whats your desired outcome? IE if it starts raining what do you *want* to happen - then maybe we could choose the best circuit/device combo to help

[michaelmorris]

As yesyes said, as simple 12V LED across the relay would work as a visual indicator, but you could get it to do pretty much anything you wanted with a few add on circuits. 12V Buzzer, or use it on something like an Arduino to send you a text message when its raining, control your roof - ooooh endless possibilities hehe.

Whats your desired outcome? IE if it starts raining what do you *want* to happen - then maybe we could choose the best circuit/device combo to help

Thanks, the simple buzzer and light would do grand for now.

I *want* the sensor to automatically summon my massed ranks of Cloudy Pixeis to brush the clouds away with their mystic rain brooms. However, in the real world I simply need something to prompt to get me off my fat a**e and go and park the scope and close the observatory roof. :grin:

[russellhq]

Could you use another webcam to look though a window on the roof for rain droplets?

[upahill]

Maybe getting it to trigger a doorbell inside the house, could possibly even get a wireless one (although that stretches beyond my electrical capabilities)

[pete_l]

Cars use light reflected by raindrops on the windshield to detect rain droplets. Obviously once you've detected rain, you'll need the equivalent of a wiper to be actuated.

Have a look at this link http://en.wikipedia.org/wiki/Rain_sensor

[Islander]

These are supposed to be pretty good and not that expensive either:

http://www.rainsensors.com/

[michaelmorris]

These are supposed to be pretty good and not that expensive either:

http://www.rainsensors.com/

I looked at these as well. I would have to add the postage VAT and import duty on to the price, so I'd guess I 'd end up spending around £60-£70. Whilst they look good, I won't have much of a clue where to start in terms of turning this into a switch for a 12v light and buzzer. Whilst I might be able to work it out, I might also just end up with a lump of plastic!. The rain gauge on Ebay looks easier to make something out of and it's half the price.

This project to allow for remote monitoring of an imaging run is just a nice little add-on to operation of the observatory, it's not essential, so I don't want to spend too much money on it. I'd like to spend less than £100 on the entire project. So far I've spent just under £18. A Temper Hum sensor will add another £28, leaving no more than £54 for everything else.

[upahill]

What about something like this?

http://www.ebay.co.uk/itm/USB-WIRELESS-WEATHER-FORECASTER-STATION-LCD-TOUCHSCREEN-/400389932688?pt=UK_Home_Garden_Weather_Stations&hash=item5d39198690

That would give you everything, wireless-ly, only thing I cant work out is if it just gives you the rainfall amount in the last hour, or if it can tell you if its actually raining right now.

Worth a look though imo.

[michaelmorris]

Could you use another webcam to look though a window on the roof for rain droplets?

That's a nice idea, but how would I turn this into an alarm? I would have to watch it constantly.

If I have a loud audible alarm, the webcam microphone should pick this up and transmit the sound to the laptop or mobile phone I am using to remotely run the observatory computer using the free Teamviewer software.

[russellhq]

Yes, but how would I turn this into an alarm? I would have to watch it constantly.

I thought you were watching constantly to monitor the mount for misbehaviours?

[Gina]

Interesting thread I'm looking for a rain detector for my obsy.

[keithatrochdale]

What about something like this?

http://www.ebay.co.u...=item5d39198690

That would give you everything, wireless-ly, only thing I cant work out is if it just gives you the rainfall amount in the last hour, or if it can tell you if its actually raining right now.

Worth a look though imo.

You can set alarms by using Cumulus free software.

You could also use it to predict when condensation is likely to occur and switch on dew heaters etc.

[upahill]

For that eBay rain sensor I found this which might help.

[Islander]

I looked at these as well. I would have to add the postage VAT and import duty on to the price, so I'd guess I 'd end up spending around £60-£70. Whilst they look good, I won't have much of a clue where to start in terms of turning this into a switch for a 12v light and buzzer. Whilst I might be able to work it out, I might also just end up with a lump of plastic!. The rain gauge on Ebay looks easier to make something out of and it's half the price.

This project to allow for remote monitoring of an imaging run is just a nice little add-on to operation of the observatory, it's not essential, so I don't want to spend too much money on it. I'd like to spend less than £100 on the entire project. So far I've spent just under £18. A Temper Hum sensor will add another £28, leaving no more than £54 for everything else.

If it's out of your budget range then fair enough. Connecting one of these is simplicity itself - 4 wires, 2 for supply and 2 for either a normally open switch contact or a normally closed one - it provides both. It can be treated as a simple switch. There's a link to the installation instructions here:

http://www.rainsenso...nstructions.pdf

The quality of construction is superb too.

The eBay sensor will do the job though.

[michaelmorris]

I thought you were watching constantly to monitor the mount for misbehaviours?

No, whilst I would occasionally check it at other times, I would probably only check it constantly whilst slewing.

[michaelmorris]

What about something like this?

http://www.ebay.co.u...=item5d39198690

That would give you everything, wireless-ly, only thing I cant work out is if it just gives you the rainfall amount in the last hour, or if it can tell you if its actually raining right now.

Worth a look though imo.

Thanks for the link. It looks as though it's a rain gauge, rather than a rain sensor. A rain guage tells you how much has fallen, a rain sensor tells you it's raining now (what I need). Thanks anyway.

[michaelmorris]

For that eBay rain sensor I found this which might help.

That's brillaint, thanks. Where did you find it?

[upahill]

That's brillaint, thanks. Where did you find it?

Its from a wholesalers site, in another language I am afraid, original link here http://www.kemo-electronic.de/en/House/Garden/M152-Rain-Sensor-12-V-DC.php

The part number is M152 so googled "M152 Rain Sensor"

Only thing is, the relay appears to be latching, so once activated it will stay on until the rain dries up (even with the heater this could take a while) - the problem therefore is that if you connect a lamp, or buzzer in this fashion it will stay on (or worse continue making a noise) until the rain is gone. You could wire a switch in paralell I guess to "turn off" the notification, but alas not perfect.

Someone smarter than me could probably advise a timer circuit which when the relay switches to the ON position sounds the buzzer, and then turns it off for a period of time, after the set time has elapsed it would check the state of the relay and if its still ON then it would remind you again and if its OFF it would do nothing.

Its been quite a few years since I played with Logic gates/555 timers etc so I cant help any further, but this does sound like a fantastic Arduino project.

Sam

[Gina]

Thanks for the link. It looks as though it's a rain gauge, rather than a rain sensor. A rain guage tells you how much has fallen, a rain sensor tells you it's raining now (what I need). Thanks anyway.

It's a weather station - I have that and it's alright for telling the outdoor temperature, humidity, wind speed and direction and how much rain has fallen. They're good value for their purpose and I can reccommend the Cumulus software by Sandysoft but it can't tell you the exact moment it starts raining nor does it have any extra add-on sensors. Some of the more expensive stations do have add-on leaf moisture sensors that employ strip board type sensors but these cost 500 quid or so upwards. For anyone who's interested in that nice cheap WS from Maplin etc. (direct or ebay) or anything weather related, the Cumulus message board has lots of info. http://sandaysoft.com/forum/index.php

[russellhq]

Its from a wholesalers site, in another language I am afraid, original link here http://www.kemo-elec...sor-12-V-DC.php

There is also a UK supply here:

http://www.brocott.c...odule-m152.html

Or Amazon if you wish:

http://www.amazon.co.uk/Kemo-M152-detector-module-sensor/dp/B000NI2QJC