An emitter is a device used to emit any signal, beacon, light, odor, liquid, fragrance, or any other type of signal. It is also called a dripper and is a device used in drip irrigation.
Some of the more notable manufacturers of emitter are:
In transistor technology, the emitter is the analog of the vacuum tube cathode, though the current flow through it may be either positive or negative, depending on the type of transistor.
An emitter may refer to an infrared LED used to emulate a remote control. It emitter can also be wired into the integrated receiver/decoder of a satellite TV unit, so that it can operate a VCR to record a TV show when selected from the electronic program guide. The wired emitter is stuck with an adhesive to the front of the VCR, and mimics the signals of the remote, eliminating the need to set the VCR separately.