![]() ![]() The optoisolator improves the reliability of the system, as it filters out some kind of electrical noise. Figure 3: Optocoupler circuit example with amplifier circuit at the output So no digital IC gate is present in this circuit. Transistor BC337 does the current amplification. There is a trade-off between the speed and sensitivity of the circuit.įurther, figure 3 shows a circuit diagram example for the optocoupler circuit with an extra amplification stage. The value of the resistor connected to the collector decides the speed and sensitivity of the circuit. The base of the phototransistor may be connected to the emitter (pin 4) using a high-value resistor (not shown in the circuit). Then, this inverted “B” signal becomes a normal signal with the help of a “NOT” gate.įurther, the waveform Vo or signal ‘C” in the above diagram indicated the normal output. Signal “B” is the output of the optocoupler circuit. The output current of the IC flow through a 10K ohm resistor. A resistor of 3,3K ohms provides the current limit in the diode input of the device. In the above circuit, Vin the input signal. Figure 2: Optoisolator use in a circuit example Optocoupler circuit examplesįigure 2 shows a simple electronic circuit for signal isolation. The selection of components depends on the voltage level and delay in the circuit requirements. This voltage drop across the resistor is the output of the circuit. Subsequently, the current generated in the phototransistor passes through an external resistor. This current transistor is approximately proportional to the LED current.Ī resistor of the appropriate value limits the current flow in the input LED. ![]() ![]() Then an electric current results in the output of the transistor. This light falls on the input of the optically sensitive phototransistor of the output stage of the optocoupler. This light emission takes place inside the optocoupler. How optocoupler worksĪs electrical current flows through the input LED, the LED emits light. The diagram in figure 1 shows the simple symbol of a phototransistor-type optocoupler without a base of the phototransistor. Figure 1: Optocoupler symbol without base It is also called Photocoupler or Optoisolator. The base of phototransistor – experience-based knowledgeĪn optocoupler is an electronic semiconductor device that interconnects two separate isolated electrical or electronic circuits using a light-sensitive optical interface.Nowadays optocoupler finds use almost everywhere in electronics and power electronics circuits. I also will explain the applications, types, and a circuit diagram explanation with signal, and also experience-based knowledge of the optoisolator. In this post, I will explain what is an optocoupler, and how an optocoupler works. ![]()
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