November 19, 2018

An optocoupler or opto-isolator consists of a light emitter, the LED and a light sensitive . I use latch 74hc and put 8 optocoulpers pc in 8 inputs of latch . PC Series. PC Series. High Density Mounting Type. Photocoupler PC Anode mark. PC Internal connection diagram. PC PC PC PC Photocoupler has a transistor which is controlled based on light (photon). So this IC basically has an IR LED and a photo-transistor inside it.

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Optocouplerr up or log in Sign up using Google. There pull-up resistor 1K acts as a load resistor. By clicking “Post Your Answer”, you acknowledge that you have read our updated terms of serviceprivacy policy and cookie policyand that your continued use of the website is subject to these policies.

v – How to get output voltage in PC opto coupler? – Electrical Engineering Stack Exchange

Taimoor Ali 83 How can I get 3. This is more than the 5mA minimum required to drive the 2N into saturation. I have tested it with 5 optocouller, means when Optockupler was giving 5 volt on 4th pin and when I was checking voltage on 3rd pin it was 4. Sign up using Email and Password. You have both sides sharing a common ground, therefore they’re not isolated, therefore why do you need the opto-isolator?

Do you have resistor between 12 V and Pin 1?

Module 5.2

If you connect your PC as shown below you should be able to achieve a “non inverting” output. The output will not get high as soon as the input logic is made low and vice versa. Skip to main content. The main purpose of an optocoupler interface is to completely isolate the input circuit from the output circuit, which normally means optocoupker will be two completely separate power supplies, one for opotcoupler input circuit and one for the output. How to do that? The graph of CTR vs.


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You need a pull-up resistor at pin 4. To saturate optocoupled phototransistor and produce a logic 0 less than 0. Manufacturers will normally quote a range of CTR values for different output phototransistor collector voltages V C and different ambient temperatures T A The CTR will also vary with the age of the optocoupler, as the efficiency of LEDs decreases with age over s of operating hours.

Learner Learner 11 5. This will short the collector and emitter opticoupler hence the Logic Output voltage will become zero. I am using PC opto coupler. This comes in very handy when you are trying to isolate a noisy signal from your digital electronics, so if you are looking for an IC to provide optical isolation in your circuit design then this IC might be the right choice for you.

Bipolar Junction Transistors 4. By clicking “Post Your Answer”, you acknowledge that you have read our updated terms of serviceprivacy policy and cookie policyand that your continued use of the website is subject to these policies. Having found an approximate figure opgocoupler the CTR, which suggests that input and output conditions should be similar, at pd817, the next task is to calculate the values of R1 and R2.

In my experience, a lot of opto devices are worse than this so try driving the opgocoupler a little harder maybe 20mA and try increasing the output resistor from 1k to 10k. I am getting an output voltage of 3. But I dont know what is happening in case of 3.

The graph in Fig.

This way the logic input will be reflected at the logic output and still provides and isolation between the two. The below waveform shows the time taken for the output to transit from one state to another. Note also the effect of using a 74HCT14 Schmitt inverter at the output; any rounding of the square pulses is eliminated and although the optocoupler output only falls to 0.

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The Schmitt inverter at the output performs several functions; it ensures that the output conforms to HCT voltage and current specifications, it also provides very fast rise and fall times for the output, and corrects the signal inversion caused by the phototransistor being operated in common emitter mode. The problem is lessened by ensuring that the external circuit is fully isolated from the computer and an optocoupler such as the PC is a cheap and effective assuming no major user errors solution.

Understand the requirements for a typical optocoupler application. However, that’s still a lot of current, and might load the output connected to IN3 too much. I would not opt for that option. First of all the Optocoupler forward voltage is 1.

Describe basic applications of optocouplers: The Emitter pin 4 is grounded. I cannot post the schematics but i can tell you the resistor value.

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This is where the isolation occurs. Forward Current for a Optocouper The Web This site. Pls post all resistor values along with the schematics to give a possibly useful answer. Optocouplsr up using Facebook.

LSTTL or CMOS types may have different logic voltage levels and different input and output current requirements, and optocouplers can provide a convenient way of interfacing two circuits with different logic levels. The digital signal given to the IR LED will be reflected on the transistor but there will be no hard electrical connection between the two.