The BatLogger II incorporates construction techniques I've developed over many years of building field deployed data collection systems.

I thought I would go through what is involved in building a BatLogger II and describe the elements that contribute toward it's durable construction.

If you would like more detailed information on the construction of the BatLogger II, you can download the full 2 megabyte PDF construction document .

Field gear needs to be durable and weather resistant to be of use. I tend to think of NEMA 4 rated electronics enclosures when I start a new project. I particularly like the clear, polycarbonate, weather tight, UV stabilized NEMA cases, like the ones shown above. These cases are available in many sizes, and are easily machined for adding wire glands, connectors, etc. They also have internal bosses that can be used for mounting circuit boards, and have protected mounting holes to facilitate mounting the finished device to whatever surface it will reside on in the field.

It is worth the extra cost, and effort, to make well designed and constructed printed circuit boards.

Heavy traces and double sided boards make for very durable electronics. The extras, silk screening and solder masks, make the board easier to construct and maintain over the many years it can be in service.

Custom boards also ease assembly when the whole project comes together ... all the holes are in the right place, and the board fits perfectly - with little wasted space.

The BatLogger II has all of the electronics for the detector and PIC data converter on a lower layer circuit board. The HOBO logger is mounted on an upper circuit board, which also holds the parts for a nocturnal light sensor. The space in between the circuit boards accomodates the internal wiring and connectors.

By mounting the bottom board with threaded standoffs, additional mounting points for the upper board are provided.

The components used to get wires and sensors in and out of the device are also important. We started out with a weather resistant enclosure ... you want to keep it that way.

Here you see a cable gland being used to bring out the power wires from the BatLogger II. A rubber washer in the gland crimps down on the wires when the cap-nut is tightened to seal out the weather.

Here, another cable gland is used to hold the temperature probe for the HOBO logger.

To the right of the temperature probe is a weathertight cable connector used to connect an earphone to test and setup the bat detector at the time of deployment. The connector is even more protected due to the use of a cap that snaps in place when the connector is not used.

Even the external adjustment that is needed to set up the bat detector sensitivity can be made weather resistant.

This control is a special, hermetically sealed "Knob Pot", that contains a variable resistor element inside the same housing as the adjustment knob. Weathertight seals on both sides of the mounting plate make this an ideal way to provide an external adjustment to a device without compromising the NEMA integrity.

Here is a side view of a BatLogger II, showing how all of the elements have come together.

The HOBO logger attaches to the top mounting board with industrial strength Velcro strips. This enables the logger to be easily removed when its battery needs to be replaced.

It is not necessary to remove the logger to launch and offload data though, as the data connector is easily accessible when the NEMA cover is removed.

I hope this gives you some idea of how compact, durable, and functional the BatLogger II package is.