Electric Gates Sensor

[shabba]

Hi,
I am using a reed switch and a mini pro (5v until my 3v ones arrive) that I want to use to detect when our electric gates open. I am going to just base it on the binaryswitchsensor sketch.
I was wondering about weather proofing the sensor setup. It goes below freezing here maybe a couple weeks a year (West coast of Ireland) so I guess this would affect battery life. I may be able to siphon off power from the gate itself but still need to weather proof either way. What should I be looking at?

Thanks!

[bjornhallberg]

@shabba A simple reed switch could probably be run for a year at least on 2xAA alkaline batteries, no regulator or anything. The nrf24 and the atmega are good down to 1.9V. I've had my motion sensor outdoor over the winter and that thing has survived, despite all the limitations of the HC-SR501 (relatively high quiescent current, wont work well as the voltage starts dropping, certainly wont work down to 1.9V anyhow).

Weather proofing is an interesting issue that we haven't discussed all that much on the forum. My understanding of weather proofing is that you either go completely sealed (which is downright impossible for us normal folk) or we allow some ventilation, so hot air wont condensate inside as temperatures drop rapidly. If you want to go completely overboard, there are gore-tex vents that can be installed, or you just have to drill some holes in strategic places. I have used the plastic boxes (http://forum.mysensors.org/topic/444/battery-powered-motion-sensor/13) that are available from Ebay. They're pretty ok, you could probably make them a bit more ventilated, but the main problem is that the included screws rust like crazy. A real problem with a lot of the China stuff. I realize they're not supposed to be stainless or anything but they oxidize a lot faster than equivalent stuff bought locally. Could be hard to replace. Haven't checked the threading but I fear they might be some wonky american thread?

[tbowmo]

@bjornhallberg said:

Haven't checked the threading but I fear they might be some wonky american thread?

:d

[shabba]

@bjornhallberg Thanks - I could use a box without screws by using magnets (and maybe tape) as I will be attaching to a gate. I could then punch a couple holes in bottom on gate side to allow condensation out. I could also allow the reed switch wires through these holes or if I can get the box close enough just leave them inside the box.

[bjornhallberg]

@shabba Sure, neodymium magnets could work. If you can make them stick with glue. Wiping the grease off might help a lot. Apparently they don't like heat so hot glue is out of the question though. I guess they wont interfere with the electronics, but I'm not a radio expert. Or you could buy magnets with a hole in the middle and screw them down or use rivets.

Also, there is adhesive velcro. I've bought the cheap stuff you can often find with sewing supplies. I don't know what sort of glue they use on the back of those but it is practically impossible to pull off once it has stuck.

The plastic boxes are also available without those "tabs" at the ends if you look around.

[bjornhallberg]

@tbowmo The last time I needed a non-standard thread (for a camera tripod-like mount) I had to go to Würth. They charge about an arm and a leg for a few screws, but on the other hand the metal is probably very high-grade and resistant to corrosion.