If you get a reading of infinity in both directions the LED is considered open and again the opto-isolator must be replaced. Now to test the phototransistor side of the opto-isolator. Set your analogue meter to the x10k ohm range. Place the black test lead on the collector pin and the red test lead on the emitter pin of the opto- isolator, you should get a resistance reading of infinity. Infinite reading with black test lead on collector and red test lead on emitter. Next place the red test lead on the collector and the black test lead on the emitter.
You should get a large resistance reading, typically around k ohms or so. Note: Testing shown is on a 4 pin opto-isolator , when testing a 6 pin opto-isolator use the same procedure, but double check the pin configurations for the particular opto-isolator. Method two: De-solder and remove the opto-isolator you want to test from the circuit it is in. Using alligator clips or some other method attach a DMM digital multimeter test leads to the collector and emitter pins of the opto-isolator, polarity does not matter.
Set the DMM to the resistance or ohms setting. The meter should read O. L Over Limit , infinity or something that indicates the resistance is beyond the range of the meter. Attach test leads to the emitter and collector pins, polarity does not matter. Set the DMM to the resistance setting, reading should be O. Now using you analogue meter set to x1 ohm range, place the red test lead on the cathode pin and the black test lead on the anode pin, you should get a low resistance reading on the analogue meter and also if you look at the digital multimeter it will now also show a low resistance reading.
With analogue meters black test lead on the anode pin and the red test lead on the cathode pin the DMM now shows a low resistance of This is the characteristics of a good opto-isolator. Method three: The third method requires assembling an easy to make opto-isolator tester. Place opto-isolator into proper section of the IC socket. The Optocoupler is just a small-sized circuit of infrared receiver and sender but in case of making it with externally by using IR sender and receiver cause many problems.
The optocoupler has many uses but due to increasing in IOT field from the optocoupler is now increasingly using in daily life to control the appliances. In IoT especially home automation or heavy load control, we need to control the AC load by the effect of change in frequency. To do so we will need a zero cross. The zero-cross is the method in which we receive the change in the frequency signal of the AC voltages. The change in voltage gives the ability to control the AC.
The basic features of optocoupler here is to give the change in frequency pulse. The DC voltages coming out from the resistance is lower in voltages but it has a noise that is not effective to use as the signal. To convert it to the proper signal we use the optocoupler. The optocoupler generates the same type of single pulse no matter how much the signal has noise. This single pulse is used to detect the events of change in frequency which is known as zero crosses.
This zero-cross allows the microcontrollers to control the HIGH ac load with the simple microcontroller. To use the dimmer we will need to use the microcontroller. Here we will describe a method to control the dimmer with an Arduino. The zero cross-pin will be used at interrupt pin and any digital pins can be used to control the signal. To control the dimmer with the Arduino the following code will be used:. The above code describes how the zero-cross can be used with the Arduino and how Arduino could control the high voltages.
The code is just for one dimmer to make it for multiple dimmers the code will require some modifications. Main features of PC High isolation voltage: V effective value;.
Compact dual-in-line package:. Linear optocoupler components. Optocoupler PC application circuit diagram 1. Optocoupler PC application circuit diagram 2. Optocoupler PC application circuit diagram 3. Optocoupler PC application circuit diagram 4. The PC is a commonly used linear optocoupler. It has the effect of completely isolating the upper and lower circuits without affecting each other.
Figure 1. Optocoupler PC pin diagram and internal circuit. Figure 2. Optocoupler pc application circuit. When an electric signal is applied to the input terminal, the light emitter emits light and illuminates the light receiver. The light receiver is turned on after receiving the light, and generates a photocurrent output from the output terminal, thus realizing the "electricity-optical-electricity" conversion.
Ordinary photocouplers can only transmit digital signals switch signals , and are not suitable for transmitting analog signals. Linear optocoupler is a new type of photoelectric isolation device that can transmit continuously changing analog voltage or current signals.
In this way, a corresponding optical signal will be generated as the strength of the input signal changes. Therefore, the conduction degree of the phototransistor is also different, and the output voltage or current is also different.
TL and PC are usually used for the voltage regulation feedback of switching power supply. If the output voltage requirement is not high, then Zener diode and PC can also be used. Let me illustrate the coordination of TL and PC through the following typical application circuit. The circuit diagram is as follows:. Figure 3. The value of R13 is not arbitrarily chosen, because two factors must be considered:. The dead zone current of TL is 1mA.
That is, when the current of R6 is close to zero, ensure that has 1mA. In addition, it is also a consideration of power consumption. R17 is to ensure the size of the dead zone current, and it may or may not be necessary. But there is one exception: when the output voltage is less than 7. The reason is that since R17 here provides TL dead zone current, it is only useful when the LED conduction voltage is insufficient. If the light-emitting diode can be turned on, it can provide enough dead zone current for TL TL is a precision voltage regulator source, and PC is a photoelectric coupling device.
In the switching power supply, the design of the voltage regulator feedback circuit usually uses TL and PC to cooperate. In the design of flyback power supplies, feedback circuits often use them as references. Figure 4.
0コメント