photoelectronic relay - switches up to 1750 VA

switches up to 1750 VA Motorola ICs 3040 and 3041 enable the construction of a simple elec- tronic relay that in spite of its simplicity has some interesting characteristics. For instance, the ICs IC1 MOC 3040 MOC 3041 have an internal zero crossing detec- tor that saves quite a few external components. Moreover, the ICs have an isolation voltage of not less than 7.5 kV which enables the relay to be connected to any circuit operating from mains voltage. The ICs may be compared with a normal opto-coupler in which the usual phototransistor has been replaced by a phototriac (100 mA/400 V at 25°C). The advan- tage of this is that virtually all types of silicon-controlled rectifiers (SCRs) may be used in the circuit, which would not be possible if a phototran- sistor were used. The choice of type of SCR depends on what is to be switched by the relay. If the load is resistive, a TIC 226D/400 V will do fine. If, however, inductive loads have to be switched, a 600 V SCR, for instance, a ...