The most common application of Optocoupler is signal isolation. It provides complete isolation because its input side is not electrically connected to the output side. Its input side is a light source which is commonly a LED, while the secondary side is a photo transistor. A photo transistor is also a transistor but without a base current. The absence of
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In optocoupler, CTR stands for current transfer ratio. This is comparable to the current gain beta in BJT. This is the most important parameters of an optocoupler to function normally. There are several factors that affect the CTR, read here. In this article we are going to focus what is the disadvantage of using Optocoupler with low CTR particularly in
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When you already heard about Optocoupler devices, you may be heard also about CTR. CTR stands for current transfer ratio. In bipolar junction transistor this is the so called current gain or simply beta. It is the ratio of the collector to forward current of an Optocoupler. In circuit design involving optocoupler, you may be dealing with the device CTR
READThe optocoupler operation as switch is similar on how to configure BJT as switch. For a BJT to operate as switch it must be set to function in saturation and cut-off. Optocoupler as well. However in BJT circuit the base current must be high enough to drive the transistor into saturation; but in Optocoupler it is the forward current. In
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There are several ways on how to determine Optocoupler operation. The old school method is to build an actual circuit and measure the collector-emitter voltage. If the reading is low enough (equal to the saturation voltage of the device) or ideally zero, the Optocoupler is operating at saturation. If the reading is higher than the specified saturation voltage but lower
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Actually, Optocoupler circuit design is not that difficult as some thought. It’s just like you are designing a BJT circuit. If a BJT has its beta or current gain, optocoupler has its CTR or current transfer ratio. Once you know what a CTR is and learn how to use it, then Optocoupler circuit design is that easy. Current transfer ratio
READHow to bias optocoupler is even simpler than bipolar junction transistors. However such device is not well discussed in the universities making people believe that it is a difficult device to deal with. Here I will reveal the methods and techniques on how to bias optocoupler. Before jumping to the main topic on how to bias optocoupler, let me touch some
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In linear power supply design output regulation is not a question because it is easily done by the linear regulator inserted before the load. Nowadays linear power supply is not anymore widely used. What is drawing more attention now is the switch mode power supply. How switch mode power supply regulates its output is different from what linear regulator does.
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In power supply the term voltage regulation is often mentioned and this is a very important thing actually. Nobody will buy a power supply with an output that has a voltage swing of 10% or even higher. Imagine for a 12V output the voltage can go as high as 13.2V and as low as 10.8V. This is ridiculous. In today’s
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In this article we will learn the ways on how to sweep temperature in LTSpice. In voltage, current and resistance sweeping you need to declare a certain parameter inside curly braces. In temperature sweeping you don’t have to. When a temperature sweep is used, LTSpice automatically vary the properties of components with respect to desired temperatures. For instance, the forward voltage
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