A remote extender is a gadget which allows you to use a remote control from a location which is not within range of the device you want to control. It will normally be used in conjunction with a video sender which carries wireless audiovisual signals around a property. It can also be used in a setup which uses cabling to carry the signal to a second TV screen.
The remote extender is almost always used in a home where the user has routed video signals from a device such as a DVD player or cable box to be seen on a second TV in another room, either by cables or wirelessly. Some such set-ups include technology to re-route remote control signals. Others need a separate remote extender.
The terminology used with a remote extender can vary depending on the exact system. Using one set of terms, there is a base unit which is located in the same room as the audio/video device to be controlled. There is also an extender unit which is located in the room you want to use the remote control in. The instructions from the remote control are received by extender unit and then carried via wireless signals to the base unit.
There are several different setups that allow the signal to get from the base unit to the audio/video device. One way is for the base unit, which is often pyramid-shaped, to be placed on a table or other surface and pointed towards the remote sensor on the device. Another method is to have the base unit placed on or near the audio/video device with a small wire running along the top of the device and a small transmitter about the size of a bean hanging in front of the device's remote sensor. With such set-ups it may be necessary to tape the wire in place to make sure the transmitter is able to "see" the sensor. A third, rarer, option is for the base unit to be connected directly to an input on the audio/video device; this will usually only work on devices designed to receive signals in this way.
One downside of using a remote extender is that both the base unit and the extender unit will need an external power supply. In most cases this will mean a main lead, since batteries will not be powerful enough. The power drawn by the units is relatively low, so will not be too costly. It is, however, worth switching the units off when not in use. The main drawback of the power demands is that the units each require a power socket, though with such low demands this is unlikely to cause problems when used in a multi-socket adaptor.