Optocoupler is a kind of optoelectronic device, relay is an electrical control device, generally speaking, optocoupler can directly control the relay, just pay attention to whether the voltage of the optocoupler and the relay match.
In fact, the optocoupler itself is a small relay, which can be used as a relay, but the load capacity is low, and the rated maximum current of the general optocoupler such as MOS3083, TLP3063, 3SD21, etc. is 1A, and the anti-impulse current time is very short, which is not as good as the special relay.
Now there is a kind of optocoupler relay, which is a combination of optocoupler and thyristor, which belongs to a kind of solid-state relay, which is a solid-state relay that uses optocoupler to control the state of opening light, this kind of relay has many advantages such as no electric shock wear, no action sound, no vibration and bounce, small size, etc., and is widely used.