It means when you get your hole . BMC

It means when you get your hole . BMC

When people build systems that automatically turn on and off light bulbs and other mains-powered devices, they typically use a microcontroller to decide when to turn things on and off.

Alas, microcontrollers cannot be directly connected to mains power.

So these people typically build a system to allow the microcontroller to indirectly turn on and off the light bulbs:

First, the microcontroller turns on (or off) a small LED inside an optoisolator, when turns on (or off) the silicon switch inside the optoisolator, which turns on (or off) a triac.

The triac acts just like a light switch, turning on (or off) the light bulbs or other mains-powered devices attached to it.

The MOC3011 triac driver optoisolator is often used in such applications.

All you need to do is provide enough bias current thru the diode, usually less than 20 mA. Find a datasheet and look at the bottom for recommended circuits.

Usually there is an LED and a photo transistor, embedded in the same component. The package is usually a DIL with either 6 pins or four, for single devices.

The idea is, that a signal is sent to the LED and picked up with the transistor, held in a sealed encapulation.

The only connection between the two is LIGHT, no other electrical connection.

So it prodides ultimate isolation to prevent stray voltages getting into sensitive areas.

They are used in switched mode power supplies, to provide a feed back signal between the Low voltage side and the high voltage side.

They are also used in home telephones, to send the 50vac ring signal to the electronic warbler circuit. To isolate the user from any high voltage.

(I have known phones suffering lightning strikes, to have the top blown off the OptoIsolator!).