Our customer installs domestic alarm systems and was finding that the installation
was often proving difficult and unsightly. Key problems centered around the need
to install a CE marked marked power supply, BT style master termination box in older
properties, repeater relay plus the option to use the power supply to charge storage
batteries. The original customer generated solution was based on fitting a number
of separate boxes and then wiring between them.
A new solution was designed by Impel that incorporates all of the required features
in one simple to install unit based on the readily available 47mm deep 2 gang pattress
box. When installed the unit blends in very well with all the other electrical fittings
in the house.
In the picture you can see a red coloured part, this is the jumper that can be moved
to switch the unit up to battery charger output.
One key issue that we had to resolve was the need to design an ADSL filter that could
be connected to the telephone line adjacent to any other ADSL filter without affecting
the ability of the network to support dual tone dialing which had proved to be a
problem with certain tone combinations being blocked. After many calculations and
tests we produced a filter with a front end resistive section to avoid reactive issues
with other external filters.