H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
H03K17/51—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used
H03K17/78—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used using opto-electronic devices, i.e. light-emitting and photoelectric devices electrically- or optically-coupled