Analogue Optical Coupler

It is sometimes necessary to make an electrically isolated connection in a circuit. An optocoupler is usually the key component in such a situation. In most optocouplers, a single lightemitting diode (transmitter) and a single photodiode (receiver) are optically coupled inside the package. This solution is satisfactory for transferring digital levels (such as the control signals for a thyristor), since only two logical states (LED on or LED off) have to be transferred. An exact (analogue) coupling is thus not necessary.