Reed Relays & Optocouplers | Introduction
Reed relays contain an electromagnetic coil and reed switch. When power is applied to the coil, the reed switch is activated. They are ideal for applications requiring low and stable contact resistance, low capacitance, high insulation resistance, long life and small package size. They are also suitable for high RF switching and low current switching. Reed Relay applications continue grow every year despite severe competition from other small switching devices such as semiconductors and electromechanical armature style relays. Because the contacts in a Reed Relay are hermetically sealed, the contacts can switch low level signals as low as femtoamps and nanovolts.Reed Relays are ideally used for switching applications requiring low and stable contact resistance, low capacitance, high insulation resistance, long life and small size. For specialty requirements such as high RF switching, very high voltage switching, extremely low voltage or low current switching, again Reed Relays are also ideal.The optocoupler is composed of two circuits: an input circuit and an output circuit. A light emitting diode (LED) is the key input component, where the key output component is a photo-detector. Passing a current of approximately 10 ma through the two input terminals and through the light emitting diode, with the correct polarity, converts the electrical current into photons. The photons are then directed down a light tube or tunnel. At the end of the tunnel, the photons are incident on the photo detector that converts the photons back to an electric current. In this manner, the input information is transferred and amplified in the output detection circuit without any direct electrical conducting path. The longer the light tube the greater the distance between the metalized input terminals to the metalized output terminals. This insures a greater insulation resistance and high voltage isolation.