Connect with us

rain warning device

Discussion in 'General Electronics Discussion' started by shunhook, Jun 9, 2013.

Scroll to continue with content
  1. shunhook

    shunhook

    10
    0
    Jun 9, 2013
    I have joined your site in the hope that someone can help me. I keep an eye on an elderly blind lady who until recently has used an electronic warning device to let her know when it is raining, so that she can dash out and get in her washing.

    It appears to be a very simple device, a motherboard of about 2x3" which is suspended on an arm outside her kitchen and linked via a couple of wires to a buzzer unit in the kitchen. Currently it is not working, mainly because the terminal from which the wires lead to the kitchen is corroded and I cannot move the screws to replace the wires, one of which is broken.

    The RNIB used to provide such devices but, alas, no more. If there is anyone out there who can help we are willing to pay for a replacement.
     
  2. eKretz

    eKretz

    251
    27
    Apr 8, 2013
    Can you solder the wire where it has broken? Or failing that solder a new piece of wire to the old near the screw terminal? What is the RNIB?
     
  3. duke37

    duke37

    5,364
    772
    Jan 9, 2011
    The RNIB is the Royal National Institute for the Blind.

    I used to service the tape players but they do not need my help now that they have gone digital.

    If you are in the UK I could have a look at it for you. I am in mid derbyshire. I assume it could be easily posted. Send a private message if you want my details.
     
  4. glewis721

    glewis721

    49
    1
    Apr 30, 2013
  5. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

    8,393
    1,271
    Nov 28, 2011
    A photo of the failed unit might help.
     
  6. eKretz

    eKretz

    251
    27
    Apr 8, 2013
    It seems like the only problem is a broken wire, which should be easily fixable.
     
  7. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,497
    2,838
    Jan 21, 2010
    I recall a very simple "rain detector" from years gone past which consisted of a piece of veroboard at an angle (so the water would run off) with alternate strips connected together. The board was used to turn on a transistor which would in turn buzz a buzzer, light a light, etc.

    Pictures would be nice, since this is the device that popped into my head as soon as I read this thread.

    Some pictures would tell us if we're right and lead to a possibly quick and simple fix (as per multiple previous posters).
     
  8. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

    8,393
    1,271
    Nov 28, 2011
    Yes, I also thought of the stripboard with alternating strips connected together. But I think copper would corrode quite quickly. This is the problem with anything electronic that gets left outside. You would normally cover a PCB with conformal coating to protect it from the elements, but of course that would prevent the rain from making contact!

    Also I think you might need quite a large area, because you want the alarm to sound as soon as the rain starts, not when it's pouring down.

    Another method, like detecting disturbances to a beam of light across a large distance, might be better. But in this case, I think some photos of the problem board would be the next step.

    Alternatively, Google rain moisture detector board. There are products available that will replace the outdoor rain detector, and probably give improved performance.
     
  9. davenn

    davenn Moderator

    13,836
    1,951
    Sep 5, 2009
    ahhhh ... tinning them first does extend their life substantially ;)

    D
     
  10. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

    8,393
    1,271
    Nov 28, 2011
    Yes, of course. I wonder how long it would take to tin a 200x200 sheet of stripboard!
     
  11. davenn

    davenn Moderator

    13,836
    1,951
    Sep 5, 2009
    not what he meant by "quite a large area" ;)
    Kris was referring to the sensor size. A six in length of Veroboard should do the trick

    I remember making one of these a way back in the '70's

    Dave
     
  12. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

    8,393
    1,271
    Nov 28, 2011
    Well, of course, you could put the rain detector panel on the roof, but that would just make it inaccessible, and yield no advantages.

    If you mean that you could put a detector strip along the bottom edge of the roof (perhaps in the guttering) to collect rain that falls on the roof and slides down, I think that would be too slow, because on a normal roof, a lot of rainwater accumulates on the surface before it starts to run off. A sensor at the end of the guttering could be quite small, but would have an even longer detection delay because quite a lot of rainwater has to acccumulate in the gutter before it starts to flow.
     
  13. sirch

    sirch

    109
    1
    Dec 6, 2012
    A completely different approach would be to use something like a tipping bucket rain gauge – reasonably simple to build and has the advantage that all the electronics can be encapsulated if a reed switch (or hall effect switch) is used to detect the bucket movement.
     
  14. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

    8,393
    1,271
    Nov 28, 2011
    This is to detect rain so the lady can bring in the washing. By the time a tipping bucket rain gauge has tipped, the washing will already be pretty wet!
     
  15. sirch

    sirch

    109
    1
    Dec 6, 2012
    I get that and was just suggesting a possible alternative. I guess it depends how big the bucket and funnel are and to some extent the type of rain (drizzle vs large drops). A 1ml bucket under a 0.5m2 funnel would tip after a pretty short period of rain.
     
  16. shunhook

    shunhook

    10
    0
    Jun 9, 2013
    Thanks for your positive responses. As one of your number has kindly offered to have a look at the device I will take advantage of his offer.

    I have made some attempts to upload a picture. Making one more.

    Shunhook
     

    Attached Files:

  17. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

    8,393
    1,271
    Nov 28, 2011
    Are you TRYING to be dense? What is the point of climbing up onto the roof to put the sensor where you can't get to it, to check it, to clean pollution and bird crap off it, to remove corrosion, or for any other reason, when putting it on the roof gives NO ADVANTAGES compared to simply putting it somewhere else outside? WHY would ANYONE do that?

    Don't bother trying to answer...
     
  18. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

    8,393
    1,271
    Nov 28, 2011
    OK, that rain detector is just a PCB with interlaced tracks. If you can upload a photo of the track side, we'll be able to see whether they are protected in any way - tinned, for example. If the tracks are still in good condition, you just need to remake the connections to them.

    I don't have much experience with weatherproofing and weatherproof connectors, so I'll leave the suggestions to others on the forum.
     
  19. shunhook

    shunhook

    10
    0
    Jun 9, 2013
    Here is the other side.
     

    Attached Files:

  20. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

    8,393
    1,271
    Nov 28, 2011
    Hmm. There seems to be a large lump of something covering four tracks at the top. If it's conductive, it will make the rain detector report that it's always raining. If you can't remove it, you can disable that part of the board by cutting the second and fourth tracks (counting from the top downwards), to the left of the blob.

    From that photo, I can't say whether the tracks are protected in some way, or not. But as long as they still work, you only need to worry about remaking the two connections.

    Can anyone recommend a reliable weatherproof way to reconnect the wires to the PCB?
     
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day

-