©2019 Open Acoustic Devices

Dec 26, 2018

About protective measures

4 comments

hi, I intend to put this instrument in the field to collect the sound of birds. Do you have any advice on protective measures?

Hi, For short deployments (a couple of days) we normally use small plastic bags and these work fine. For longer deployments you'll find lots of discussion on the forum from people who have made small enclosures from off-the-shelf electronics housings. We're in the process of getting a proper housing designed, but this won't be available until the middle of the year probably. Alex

Hello Alex, I am about to test my AudioMoth device and I would like to ask you, when you mention the plastic bag, I wonder if you refer to normal transparent plastic bags (like those used for food conservation). Do you normally make a hole where the mic is or do you leave the bag as it is? Do you think we an also wrap the device in cling film?

Thanks,

Alessia

@alessia portaccio Hi, We use small ziplock bags that electronic components and small parts come in. They generally have quite thin plastic walls so we don't make a hole, we just put the AudioMoth inside the sealed bag. These seem fine to lightly weatherproof the device but it won't stand up to strong rain or wind. We've seen a few people who put them in open boxes and then cover the top with cling-film. These seems to work fine as well. Alex

New Posts
  • Hello all. For those who are looking for some inspiration: I found a cheap yet practical shock-/waterproof case. Available in three colours (beige, black orange) in the Geek/Wish store. With some minor adaptations it’s ideal for the AudioMoth. The inner lining consists of foam in which the shape of the AudioMoth can be easily cut out. For the fixation of the membrane I was inspired by the Aurita design and used a PVC shoulder washer. After drilling a hole just above the mic I enlarged it until the washer fits tightly. Since the materials (plastic vs PVC) are difficult to glue I used butyl tape to attach the shoulder washer. The membrane, standard cling film (10 micron), is mounted on top of the washer. In order to prevent damage by the sharp edges there there is an O-ring on top. The second O-ring stretches the membrane over the first one and provides extra protection against water ingress. I also provide a silicagel packet to prevent condensation on the membrane and as extra safety in case of the membrane is compromised. It is advised to check the membrane after each battery change because the cling film degrades due to weather conditions. Also the O-rings suffer from UV-degradation after a time so be sure to check their condition as well. The box has two ‘eyelets’, very convenient to attach the box. The box costs 2€ and together with the other stuff you have an excellent enclosure for less than 5€ and 15 minutes crafting.
  • Having recently got my v1.1 AM in GG round7, I'm really pleased to report that the recessed card and switch, means it fits really well in this case sized 85x58x33mm: https://www.ebay.co.uk/itm/Waterproof-Plastic-Electronic-Instrument-Project-Enclosure-Box-Case-US/253320952007 The width is a perfect snug fit, with small fillets of (camping mat) foam for the length in either end of lid, and also on the base. As was used in the recent British Bat Survey 2019 SW pilot (BBS19) I have used two layers of metal mesh treated with NicWax over the Mic- https://www.inoxia.co.uk/products/mesh/sheets/500-mesh Pros of this case: - Small sized, but has thick plastic making it strong. For example a bit smaller and much stronger than the OBO Bettermann Junction Box (A8 75x75x36mm ) used for the BBS19 survey, and also here . - A proper waterproof compressed rubber seal, mean this is very likely to be fully waterproof case - Not as cheap as the OBO A8, but at around £1.50 GBP its not expensive Cons: - Four small screens to lose in the field, and screwdriver to carry. - AMv1.1 only., It is too narrow for a AMv1.0 Overall I think I'll use these case for AM v1.1 in damp, or less secure situations. But if it is a dry and secure site I think I'll stick with the convenience of the OBO A8 case.
  • The guide (https://github.com/kitzeslab/opensoundscape) states that the enclosure must be "acoustically transparent over the mic". In this regard: 1. When using the provided bag, should we try to get the mic in contact with the plastic? 2. Are all "Ziploc baggies" made of the same material and are actually equivalent in terms of "sound transparency"? 3. Could anyone post which "Ziploc baggies" brands have been successfully used? 4. In general, are there tests on recording quality degradation using the different enclosure alternatives? Should we not have a consensus test of the type "recording an standard sound without any enclosure, with the standard enclosure and with the proposed enclosure"? Cheers! Agus
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