OPTOISOLATOR CIRCUIT HOW TO

The transistor within the optocoupler works slightly differently. When we apply a small voltage to the base pin, this will turn the transistor on and it will allow current to flow in the main circuit, so the main light turns on.īy the way we have covered how transistor work in detail in our previous article, click HERE. The transistor is blocking the current in the main circuit so the light is off. In a normal transistor circuit, we have the main circuit and a control circuit. The terminals are named collector and emitter, just like a normal transistor, except we’re missing the base pin. When we look at the symbol of this optocoupler, we see there is an LED symbol on the left and on the right side the symbol looks very similar to a transistor, that’s because it is a modified version of a transistor known as a phototransistor. There are a few variations of optocouplers but we’re going to stick with the basic photo-transistor version for this article. This allows us to control even higher voltages and currents and automate circuit control. We can expand the capabilities of the device by adding other components such as a transistor to the output of circuit two. The two circuits can therefore use different voltages and currents because of the separation.

They will also only allow electrons to flow in one direction because of the semiconductor materials inside. Why is that important? Because voltage spikes and noise on one circuit will not destroy or disrupt the other circuit. We can also use it to transfer a signal across, but the two circuits are electrically isolated from each other. This allows circuit 1 to control circuit 2. Circuit one is connected across pins 1 and 2, the second circuit is connected across pins 3 and 4. This device is basically a solid-state relay which interconnects two separate circuits. We use this to identify the type of optocoupler and also find the manufactures datasheet. On the body we also have some text, this is the part number. We also have a small circular indentation in the body next to pin 1, and we use this is identify the different pins. Pin 1 is the anode, pin 2 in the cathode, pin 3 is the collector and pin 4 is the emitter. In this version we have the main body with 4 pins. They are also known as optoisolators, optical isolators and photocouplers. Optocouplers are integrated electronic components that look something like this. Scroll to the bottom to watch the YouTube tutorial.

OPTOISOLATOR CIRCUIT HOW TO

In this article we’ll look at how they are used to control circuits, how they work and also how to design some simple optocoupler circuits to show the working principle.

Optoisolator circuit