The BatLogger II
The Design and Construction of the BatLogger II
The BatLogger II
incorporates construction techniques I've developed
over many years of building field deployed data
I thought I would go
through what is involved in building a BatLogger II
and describe the elements that contribute toward it's
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
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
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
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
I hope this gives you some idea of how compact,
durable, and functional the BatLogger II package is.
Tony Messina - Las Vegas, Nevada
- email: T-Rex@ix.netcom.com
the BatLogger II was first published on this page in May, 2010
... last updated February, 2012