The diagram below shows a circuit that uses an opto-coupler consisting of an LED and a phototransistor, for voltage level shifting. +5V +25 V 3302 22 ko 25 V out Ov 4N35 Optocoupler O NC OV 7408 (i) Explain how this circuit operates when a series of pulses shown are fed to the 7408 device input. (5) (ii) Sketch the waveform showing the phase, and amplitude of the voltage levels present at Vout in relation to the input. (4) (iii) If the LED requires 1.7 V to turn on, how much current does it consume? (3)