This shield circuit is suggested by Motorola, using a 4N26 type coupler and an MC1733 type operational amplifier. However, the configuration can be experimented with an equivalent component. With this configuration the switching times can be reduced from 2 to 3us to 100ns typically. The operational amplifier must receive symmetrical power and the input signal must be rectangular with an amplitude of 3 V. For this type of signal, the output rises from 10% to 90% of 0.6 V in approximately 100 ns.
