How to test optocoupler in circuit

how to test optocoupler in circuit

Optocoupler Circuits

Jun 28,  · Using the diagram in the right identify the pins; first the anode and cathode of the LED (in this case pins 1and 2), and then using an ohmmeterset on the ‘X1 Ohm’ domain, measure between pins 1 and 2, and you should get one reading measuring one way and no reading the opposite way (just like you check a diode). Part's Required: Multimeter or ohm meter, opto-coupler, Ohm resistor,push button,battery or power supply. Turn ON multimeter and select DC Voltage mode. Now, connect a resistor of a few hundred ohms ( ohms),Push button in series with the LED anode,after give .

An optocoupler device can be simply described as a sealed, self-contained unit that houses independently-powered optical light Tx and Rx units, that can be coupled together optically. Figure 1 shows the basic how to swing a hybrid golf club video of such a device. Here, the Tx unit is a LED, but the Rx unit may take the form of a phototransistor, a photo-FET, an opto-triac, or some other type of photo-sensitive semiconductor element; the Tx and Rx units are housed closely together in a single, sealed package.

Figure 2 shows the basic form of an optocoupler, together with a very simple application circuit. Here, when SW1 is open, no current flows in the LED, so no light falls on the face of Q1; Q1 passes virtually zero collector current under this condition, so zero voltage is developed across output resistor R2.

Major points to note about the Figure 2 optocoupler are that its output current is controlled by its input current, that a control circuit connected to its input can be electrically fully isolated from the output circuit, and that — since the input controls the output via a purely optical link — potential differences of hundreds of volts can safely exist between the input and output circuits.

Optocouplers can also be used to replace low-power relays and pulse transformers in many applications. The Figure 2 device is a simple isolating optocoupler. Figures 3 and 4 show two other types of optocoupler. The device shown in Figure 3 is known as a slotted optocoupler, and has a slot molded into the package between the LED light source and the phototransistor light sensor.

Here, light can normally pass from the LED to Q1 without significant what does symbol mean in excel by the slot. The optocoupling can, however, be completely blocked by placing an opaque object in the slot. The device shown in Figure 4 is known as a reflective optocoupler. Here, the LED and Q1 are optically screened from each other within the package, and both face outwards towards a common point from the package.

The construction is such that an optocoupled link can be set up by a reflective object such as metallic paint or tape, or even smoke particles sited a short distance outside the package, in line with both the LED and Q1. The reflective optocoupler can thus be used in applications such as tape-position detection, engine-shaft revolution counting or speed measurement, or smoke or fog detection, etc. One of the most important parameters of an optocoupler device is its optocoupling efficiency and, to maximize this parameter, the LED and the phototransistor which usually operate in the infrared range are always closely matched spectrally.

The most convenient way of specifying optocoupling efficiency is to quote the output-to-input current transfer ratio CTR of the device, i. In practice, CTR may be expressed as a simple figure such as 0.

It should be noted that, because of variations in LED radiation efficiency and phototransistor current gains, the how to get the muramasa in terraria CTR values of individual optocouplers may vary significantly from the typical value. This is the maximum permissible DC potential that can be allowed to exist between the input and output circuits.

Typical values vary from V to 4kV. This is the maximum allowable DC voltage that can be applied across the output transistor. Typical values vary from 20V to 80V. I F MAX.

Typical values vary from 40mA to how to market your idea. This is the typical maximum signal frequency that can be usefully passed through the optocoupler when the device is operated in its normal mode.

Typical values vary from 20kHz to kHz, depending on the type of device construction. Optocouplers are produced by several manufacturers and are available in a variety of forms and styles. Simple optocouplers are widely available in six basic forms, which are illustrated in Figures 6 to 8. Four of these Figures 6 and 7 are isolating optocouplers, and the remaining two are the slotted optocoupler Figure 8 a and the reflective optocoupler Figure 8 b.

The table of Figure 9 lists the typical parameter values of these six devices. The simple isolating optocoupler Figure 6 a uses a single phototransistor output stage and is usually housed in a six-pin package, with the base terminal of the phototransistor externally available. The phototransistor can, however, be converted to a photodiode by shorting the base pin 6 and emitter pin 4 terminals together; under this condition the CTR value falls to about 0. The Darlington optocoupler Figure 6 b is also housed in a six-pin package and has its phototransistor base externally available.

The dual and quad optocouplers of Figure 7 use how to download euro truck simulator for free full game output stages in which the base terminal is not externally available. Note in all four isolating devices that the input pins are on one side of the package, and the output pins are on the other.

This construction gives how to test optocoupler in circuit maximum possible values of isolating voltage. Also note in the multichannel devices of Figure 7 that, although these devices have isolating voltages of 1.

Isolating voltage values are not specified for the slotted and reflective optocoupler devices of Figure 8. Finally, the reflective optocoupler of Figure 8 b uses a Darlington output stage and has a useful bandwidth of only 20kHz.

Even so, the device has a typical minimum CTR value of only 0. Optocouplers are very easy devices to use, with the input side being used in the manner of a normal LED and the output used in the manner of a normal phototransistor. The following notes give a summary of the salient usage points. The input current to the optocoupler LED must be limited via a series-connected external resistor which, as shown in Figure 10can be connected on either the anode or the cathode side of the LED.

If the LED is to be driven from an AC source, or there is a possibility of a reverse voltage being applied across the LED, the LED must be protected from reverse voltages via an external diode connected as shown in Figure This resistor can be connected to either the collector or the emitter of the phototransistor, as shown in Figure The greater the value of this resistor, the greater is the sensitivity of the circuit, but the lower is its bandwidth.

In normal use, the phototransistor is used with its base terminal open-circuit. If desired, however, the phototransistor can be converted into a photodiode by using the base terminal as shown in Figure 13 a and ignoring the emitter terminal or shorting it to the base. This connection results in a greatly increased bandwidth typically 30MHzbut a greatly reduced CTR value typically 0. Alternatively, the base terminal can be used to vary the CTR value of the optocoupler by wiring an external resistor RV1 between the base and emitter, as shown in the Darlington example of Figure 13 b.

Optocoupler devices are ideally suited for use in digital interfacing applications in which the input and output circuits are driven by different power supplies. Figure 14 shows how to interface two TTL circuits, using an optocoupler circuit that provides a non-inverting action. This snag is overcome in the Figure 14 circuit by fitting an external pull-up resistor R3 as shown. Consequently, these devices can be interfaced by using a sink configuration similar to that of Figure 14or they can use the how do you set ringback tones configuration shown in Figure In either case, the R2 value must be large enough what is pid in medical terms provide an output voltage swing that switches fully between the CMOS logic-0 and logic-1 states.

With the computer output high, the optocoupler LED and phototransistor are both off, so the motor is driven on via Q1 and Q2. When the computer output goes low, the LED and phototransistor are driven on, so Q1-Q2 and the motor are cut off. An optocoupler can be used to interface analog signals from one circuit to another by setting up a standing current through the LED and then modulating this current with the analog signal.

Figure 17 shows this technique used to make an audio-coupling circuit. This terminal is DC-biased at half-supply volts via the R1-R2 potential divider, and can be AC-modulated by an audio signal applied via C1. On the output side of the optocoupler, a quiescent current is set up by the optocoupler action in the phototransistor, and causes a quiescent voltage to be set up across RV1, which should have its value adjusted to give a quiescent output value of half-supply voltage.

An ideal application for the optocoupler is that of interfacing the output of a low-voltage control circuit possible with one side of its power supply grounded to the input of a triac power-control circuit that is driven from the AC power lines and which can be used to control the power feed to lamps, heaters, and motors.

Thus, when SW1 is open, the optocoupler is off, so zero base drive is applied to Q1, and the triac and load are off. SCRs silicon controlled rectifiers and triacs are semiconductor power-switching devices that like transistors are inherently photosensitive.

Such devices are readily available, in both simple and complex forms; some sophisticated triac types incorporate interference-suppressing, zero-crossing switching circuitry in the package. Figure 19 a and 19 b show the typical outlines of simple optocoupled SCRs and triacs which are usually mounted in six-pin DIL packages ; Figure 20 lists the typical parameters of these two particular devices, which have rather limited rms output-current ratings, the values being in the examples shown mA for the SCR and mA for the triac.

Figures 21 to 23 show various ways of using an optocoupled triac; R1 should be chosen to pass an LED current of at least 20mA; all other component values are those used with a V AC supply. In Figure 21the triac is used to directly activate an AC line-powered filament lamp, which should have an rms rating of less than mA and a peak inrush current rating of less than 1.

Figure 22 shows how the optocoupled triac can be used to activate a slave triac and, thereby, activate a load of any desired power rating. This circuit is suitable for use only with non-inductive loads such as lamps and heating elements, using a triac of suitable rating.

Finally, Figure 23 shows how the above circuit can be modified what is the capital of riga use with inductive loads such as electric motors. The R2-C1-R3 network provides a degree of phase-shift to the triac gate-drive network, to ensure correct triac triggering action, and R4-C2 form a snubber network, to suppress rate-of-rise rate effects.

An optocoupled solid-state relay SSR is a device that can be used as a superior replacement for many types of low-power electromechanical relays. Siemens are the present market leaders in the optocoupled SSR field. The device has an isolation voltage rating of 3. Other devices in the Siemens optocoupled SSRs range include ones that have outputs that act as single-pole or two-pole NC, NO, or change-over switches.

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Popular Stories Wirespondence! Turing Machines s Radio Applause Cards. Learning Electronics Need to brush up on your electronics principles? Basic form of an optocoupler device. Basic form and application circuit of a typical optocoupler. Typical simple a and Darlington b isolating optocouplers.

Typical dual a and quad b isolating optocouplers. Typical slotted a and reflective b optocouplers. Typical parameter values of the Figures 6 to 8 devices.

The LED current must be limited by a series resistor, which can be connected to either the anode a or the cathode b. The input LED can be protected against reverse voltages via an external diode.

An external output resistor, wired in series with the phototransistor, can be connected to either the collector a or emitter b. If its base is available, the phototransistor can be made to function as a photodiode aor its CTR values can be varied via RV1 b.

Simple non-synchronous triac power switch with optocoupled input. Typical optocoupled SCR a and triac b.


The following takes the PC optocoupler detection as an example to illustrate the detection method of the digital detection circuit is shown in the figure below. When testing, connect the anode 1 and the cathode 2 of the optocoupler diode to the c and e jacks of the digital multimeter's hFE. Sep 17,  · How to Check an optocoupler. A common type of Optocoupler consists of an LED and a photo-transistor in the same opaque package. In electronics, an optocoupl. Nov 28,  · In order to perform the functionality test, place the IC in the female headers so that the emitter of the phototransistor & IR LED anode pins of the IC are connected to the GND of the circuit, while the IR LED cathode & phototransistor collector pin of the IC is connected to the 4V VCC. Now, Connect the circuit to power.

Difference Between 1N, 1N and 1N Author: Iggy Date: 24 Feb PC optocoupler has been widely used. You can see it in computer terminals, thyristor system equipment, measuring instruments, photocopiers, automatic ticketing, household appliances, such as fans, heaters, etc. Its signal transmission between circuits completely isolates the front end from the load, and its purpose is to increase safety, reduce circuit interference, and simplify circuit design. PC is a commonly used linear optocoupler.

It is often used as a coupling device in various functional circuits that require more precision. It can completely isolate the upper and lower circuits without affecting each other. 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. Circuit diagram of TL and PC used together.

Next, using Figure 4 as a reference, various parameters in the circuit diagram will be analyzed and explained. To understand the relationship between the two, you must first determine the values of the four parameters R1, R3, R5, and R6 in the TL part of Figure 4. Suppose the output voltage is Vo, and the auxiliary winding rectified output voltage is 12V. This circuit compares the output voltage with the reference voltage formed by TL, and controls the C pole of the TOP tube through the current change of the photocoupler PC, thereby changing the PWM width to achieve the purpose of stabilizing the output voltage.

According to the technical manual of TOPSwicth, the current Ic flowing into the control pin C is inversely proportional to the duty cycle D, as shown in Figure 5. Figure 5. Relationship between TOPSwicth duty cycle and control current.

Therefore, the current Ice of the triode should also change within this range. The figure below is a circuit diagram of the TTL control signal input circuit for turning on or off a 12V DC motor using a commonly used optocoupler PC Figure 6.

TTL control signal input circuit. PC Datasheet. This IRED is coupled to a photo transistor optically and not electrically. It is closed in a four 4 pin package. This package is usually available in two different forms. When used correctly, an Optocoupler can effectively: Remove electrical noise from signals. Isolate low-voltage devices from high-voltage circuits.

Allow you to use small digital signals to control larger AC voltages. In PC photoisolator IC circuit , the IR receives the noisy signal as a power from the one circuit and passes it to the other part through the IR signal.

The other part receives the signal and then performs according to the circuit design. Irene 20 Feb IntroductionThe LM device is an adjustable three-terminal positive-voltage regulator capable of supplying more than 1. In addition, it has the adva Continue reading ». Iggy 19 Apr The 78L05 is a three terminal integrated regulator.

Its excellent internal current limit and thermal shutdown characteristics make it particularly suitable for overload conditions. When used to repla Mia 2 Feb It is made up of semiconductor material and carries low forward drop voltage. Mia 13 Oct I IntroductionHere, you can learn about the AD instrument amplifier circuit.

Besides, you can also browse AD main features, working principles, and applications. This blog generally discusses th Billily 3 Nov It consists of seven NPN Darlington pairs with a high voltage output and a common cathode clamp diode for Alliance Semiconductor Co Ametherm Amphenol Aerospace Operat Main features of PC 1. High isolation voltage: V effective value; 3. Compact dual-in-line package: PC is a single-channel optocoupler; PC is a dual-channel optocoupler; PC is a three-channel optocoupler; PC is a four-channel optocoupler; 4.

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 circuit diagram is as follows: Figure 3. Generally, this current is about 2uA. In order to prevent the current at this end from affecting the voltage divider ratio and avoid the influence of noise, the current flowing through the resistor R13 is generally more than times the reference segment current, so the resistance should be less than 2. Requirements for standby power consumption. Circuit diagram of TL and PC used together Next, using Figure 4 as a reference, various parameters in the circuit diagram will be analyzed and explained.

Why is Optocoupler Used? What is a PC Pinout? How Does PC Work? Photo Mfr. Leave a Reply Cancel reply.

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