An optoelectronic device which combines an optical transmitter and receiver in a single package; commonly used in galvanic-isolated control applications such as power supplies.

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How to connect stages in digital logic?

Let's say I have a logic stage doing an operation on 2 inputs, giving me an output. How could I use this output to forward it into another set of logic stage, without having to put everything in the ...
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62 views

Optocoupler delay off MOSFET solenoid

This is to trigger a 12v solenoid (acting as a laser shutter) with 5v (JP2) thru an optocoupler. The problem is 5v line have bit fast interruptions on a laser show, so I'd like to add a bit of delay ...
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90 views

Using AC current to trigger Triac

I am trying to simulate the operation of an optocoupler with a triac to trigger the triac using the AC current. I have come across a few circuits that are all similar: My question is regarding the ...
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88 views

Is this an optocoupler ans how do I identify the pins?

I bought an Arduino starter kit with some basic components, and I know among them is an optocoupler. I need one for my project, and the only thing resembling it is a chip marked 'L1513 LTV4N35.' How ...
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221 views

In an isolated SMPS feedback design, how could optocoupler latency be higher than the switching period?

I often see this in practical SMPS designs. An optocoupler & voltage reference pair is used for informing the controller section about the output voltage level. However, when I read the datasheet ...
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115 views

Understanding optocoupler performance with collecor or emitter resistors

When using an optocoupler, is there a difference performance'wise whether using a collector or an emitter resistor? When using a normal transistor the base to emitter voltage gain is approximately 1, ...
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57 views

Reading ECU tacho signal with PIC MCU - noise issues

Am trying to read the frequency of a 0-12V square signal generated by a motorbike ECU with a PIC. Range 20Hz-300Hz I'm getting strange intermittent noise on the output of my optoisolator, and wondered ...
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175 views

How to drop 170V DC to 50V?

I have old flash that generates about 170V on it's trigger when it's charged and ready to fire. When flash fires, voltage drops to zero, and rises to 170V as flash charges... I need that flash ...
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69 views

Wiring an optocoupler to have both inverting and non-inverting output

Can an optocoupler be wired to give both inverting and non-inverting logic output without additional active components? I'd like to avoid using an inverter if possible, but also curious as to whether ...
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242 views

How do I choose an optocoupler for (19200 baud) serial communication between Arduino and RS422 transceiver?

I wish to read data from a Fronius solar inverter via the Fronius RS-422 Com Card option (part# 4,240,001). 1000 meter cabling length The Fronius communication uses a 5-wire RS 422 interface (`RX-`, ...
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132 views

How do I calculate maximum frequency supported by an optocoupler say for example PC817 and what factors it depends on? [closed]

I am currently working on isolating SPI bus.The SCLK for my non isolated version of design is 5MHz .How do I calculate whether the optocoupler is suitable for operation at this frequency of operation....
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233 views

How to provide an isolated ground for Arduino?

I am designing an EEG circuit at home using an Arduino. Now, the circuit calls for the use of a battery and an optocoupler-isolated ground for safety reasons. I am planning to use Fairchild ...
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103 views

SCR which can conduct 230V AC at Zero gate voltage

As per the image, an operation for manual & Auto logic where manual can overwritten auto command and vice versa. The red circled area is an SCR(Silicon Controlled Rectifier). I'm looking for a SCR ...
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187 views

Optoisolator, did I connected it right? (Arduino Uno)

Here is my connection for optoisolator, 2 wires, yellow and red are for AC current. Other 3 in my arduino, orange pin 2, blue ground and red 5V power. And ...
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193 views

How to test if zero crossing is working?

I used circuit like this: On led I get: 3.3 mA and 1.3V What is the best way to test if zero crossing works with arduino or multimetar?
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266 views

Using optocoupler with MOSFET for dimming a LED

I have a blue LED which I want to dim using an Arduino, an optocoupler and an N-MOSFET. For achieving this I assembled the circuit on a breadboard as shown in the pictures, using a YwRobot breadboard ...
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1answer
173 views

Arduino input with CNY17 to sense 12v input

I have an Arduino Due and i am using a CNY17 optocoupler to sense a 12v brake signal from a car. The 12v signal is going thru a 1K resistor to the opto on pin 1, pin 2 to the ground. 3.3v is going ...
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135 views

Optocoupler w/ RasPi & Door Buzzer

I'm currently trying to make a system where sending a message to my Raspberry Pi from my phone will send a signal to my apartment's buzzer to open the front door, however I've been having problems ...
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72 views

Optoisolator Long term Reliability at HVDC

Most optocouplers spend most of thier time isolating mains voltages.They are reliable doing this and they are cheap and simple.How would things go if the same garden variety opto was isolating a DC ...
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87 views

4N32 Opto-Isolator Questions

I am looking into using a 4N32 opto-isolator and am struggling to find information on its pin 6. This looks to be the base of the transistor (darlington). I see example circuits where they appear to ...
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276 views

How Zero Crossing optoisolator to work with 220VAC?

I want to use a H11AA1 to detect Zero Crossing, but I am not sure how circuit should look like. How much voltage should LED receive inside H11AA1? Here is datasheet: http://www.vishay.com/docs/83608/...
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42 views

what is the best way to protect sinking inputs

I have a controller with sinking inputs ( should be grounded to activate) , I will use the system in a noisy environment, I want to protect these inputs from EMI and voltage spikes, what is the best ...
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455 views

Optocouplers with non-inverting logic

Here is the setup: I'm using the Arduino Mega's SPI functionality to send signals to multiple DACs. For digital isolation, I am considering the HCPL-2631 or the ACPL-064L. The problem with these two ...
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98 views

Power rating for opto-triac trigger circuit resistors

RHS will be using 220v 400watt bulb 2 simple questions 1- does the 360ohm resistors has to be of high watt too ? 2- all i can find is 5-10watt resistors, can i use them ? would they snub correctly ? (...
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173 views

Opto Coupler output voltage drop when connected to PLC

I have an input of pulse width 5 ms and which is fed to a Buffer IC and then the output of the buffer is FED to an opto isolator whose collector is pulled with a pull up of 7.5k resistor with an 24 V ...
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84 views

Using an opto-isolator in a car's circuit. How to ground?

So I have a microcontroller that will read some of the car's sensor output (0-5v) and i plan to send the signals through an opto-isolator. The problem is that when i simulate this, it seems i cannot ...
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86 views

Optocoupler Question

I'm currently trying to create a system to open my apartment's door (using the buzzer) using my raspberry pi, and thought that using an optocoupler would be the best solution - although I'm a complete ...
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110 views

uC-controlled high-side switch

I designed a circuit that powers on when the car is started (key is in ACC or ON). The circuit's uC then enables 12V from the battery by setting port PC5 high. The uC detects when the key is ...
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69 views

Totem pole opto-isolator TLP152 won't work as intended

I've been working on this very confusing problem regarding making a TLP152 opto-isolator to work as intended. Here is my circuit using a TLP152 to work as a IGBT gate driver. TLP152 circuit diagram ...
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50 views

Exceeding _Enable input voltage_ of optocoupler

I have microcontoller board with following optocoupler interface which is obviously made for input up to 5V. Based on datasheet I found, Vf = 1.5 V and ...
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236 views

Recommended capacitor rating for this mains zero-crossing detector

I found this zero-crossing detecting circuit here I want to recreate it, using the parts that I have on hand (or can get cheapest), but I'm not sure how to choose the correct 0.1uF capacitors. ...
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99 views

Timing Issues with Optically Isolated Data Signal

I have been working on a system that requires data transmission between two devices powered by separate supplies. I have based my design on the MIDI-hardware Spec, as I'm comfortable working with that ...
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426 views

Opto-coupler output

I am using this circuit for mains detection: The output fluctuates a little but capacitor and resistor values ensure that Output is logic HIGH when 220V mains is present. Once mains is not ...
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146 views

optocoupler output protection

I've got this circuit. The target generates an identical PWM signal to control the intensity of 3 LEDS. But I would like to protect the output of these optocouplers with this TVS: I'm not sure if ...
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208 views

Hey I am using 2 4N35 Optocoupler from Visha can I replace them with a single ILD615 from Vishay?

I went through both datasheets and i think it should work. Basically I am asking if the dual channel version of 4N35 is the 8 dip ILD615. Thanks. edit: I have added the picture. my circuit is like ...
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146 views

normally open or normally closed OptoMos

In the following OptoMos datasheet the OptoMos is defined as Normally closed, when there is no input the output is closed. But in other OptoMos like the SFH618A-2 i can't find if the OptoMos is NO or ...
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80 views

How to use same 'input' for two circuits

First of all, please excuse my complete lack of knowledge in electronics :) Let's start with a little bit of context. I am trying to modify a machine that already uses a photo-interrupter to measure ...
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0answers
60 views

Adding resistor in parallel to digipot

I'm trying to control a device using a digital potentiometer (AD5245S). In my application I can't tie the low-ref of the potentiometer and ground, so I'm using an I2C optical isolator (ISO1541) to ...
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149 views

Converting 5 volts to 12 volts using a photocoupler

i have an arduino and i need to convert 5 volts to 12 volts in order to trigger a 12 volt Rele, i am considering to use the circuit that i attached here (below), if the "input" square is 5 volts, what ...
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62 views

Do I need TVS with Optocoupler relay

I am connecting digital output from a camera to a light source using a relay (see below). The relay uses SONGLE SRD-5VDC-SL-C Optocoupler: RELAY DATASHEET The camera manual says "Uses an open-...
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1answer
103 views

Voltage Regulation

I am a young engineer and I need a help from you. I need to design a driver circuit which must power-up a LED (OC) if the measured volatge is greater that 50V (Voltage to be measured can be upto ...
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111 views

OptoIsolator Reliability?

I have heard it from multiple people over the last 5 years that Optoisolators are failure prone and should be avoided when able. I'm working on a project (for personal use) that I was going to put an ...
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2answers
81 views

Severe Voltage Drop When Applying a Load to Opto-Isolator Circuit

The circuit below uses the Vishay ILD213T optocoupler (datasheet). The load in question is a 5V solenoid valve with a resistance of 46Ω. The circuit is configured with "IN1" connected to a GPIO pin ...
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219 views

Opto-isolator output from collector vs. emitter

I have an Isocom ISQ2X quad opto-isolator (datasheet) that I will use to drive a logic input. The opto-isolator's simplified model given by the datasheet is pictured below. The transistor base pin is ...
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294 views

Use a PC123 optocoupler for MIDI input

Im trying to connect a MIDI input cable to an arduino. To do that, I need an optocoupler, that secures the internal circuits from damage. This is the schematic as shown by the MIDI specification: ...
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114 views

Design of AC measurement circuit

I posted a question earlier, How to measure AC voltage without a voltage divider using microcontroller and I got some very useful answers, one of those was to implement this for isolation http://...
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31 views

Optical switch operation point derivation

I have an optical switch part opb840W and I am failing to derive the required information for my application from there. The intended use would be as in the following circuit: simulate this ...
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623 views

What is the correct way to measure voltage with an optocoupler?

I'm using an optocoupler to measure a voltage, I'm making a current loop to control the current through the LED, so I'm using three op-amps: one to measure the voltage, one to set up a current offset ...
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2answers
302 views

Driving a 24V isolated load from a 3.3V MCU

I am looking to drive a 12-24V purely resistive load from a 3.3V MCU. I would like to use an opto-isolator to separate the circuits electrically. I've drawn up the following circuit, but I'm not ...
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52 views

Accidentally outputting to an optoisolator

It's your friendly electronic hobbyist again. I am designing a board where I am reading input from an optoisolator like this. IN7 is connected to a peripheral parallel port chip of an old 8-bit ...