linear opto-coupler

The MOC 5010 opto-coupler may be used to isolate a circuit from the mains, as audio interface, in medical electronics, and in many other applications. Because of its high isolation resistance (1011ohms), the MOC 5010 is eminently suitable for applications where a circuit is connected directly to the mains, as, for instance, in most TV receivers. It can therefore be used to give enhanced perform- ance to the "TV sound interface" described in the April 1982 issue of Elektor. With a bandwidth stretching from 5 Hz to well over 100 kHz, there is no need to worry about the audio response as there was in earlier opto-couplers. Basically, the MOC 5010 converts a variation in input current into a varia- tion of output voltage. Input voltages are first transformed into currents. The circuit shown in figure 1 has an amplification factor of about 0.75. Its input should not exceed 2 V RMS, while the bandwidth is 118 kHz at the —3 dB points. Field-effect transistor T1 functions as a voltage/c...