Questions tagged [opto-isolator]

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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Only some of my inductive sensors are working with my board

I am working on a board which has six inductive sensors. I am using optocouplers for isolation between sensor output and MCU. Four of them work fine and two show very unreliable behaviour. When I ...
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45 views

How is this optoisolator being sensed by an input?

I'm trying to replace a mains input opto-isolator (pictured below) which is connected to an input on an industrial control board. I would have though shorting the input would be enough but this is not ...
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Help using an FOD3182 OptoCoupler

So this is the Optocoupler I will be using: https://html.alldatasheet.com/html-pdf/505064/FAIRCHILD/FOD3182/978/2/FOD3182.html My question is with the schematic of the data-sheet. Using Ni-multisim I ...
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48 views

Driving Power MOSFET with Optocoupler Problems (Component FOD3182)

simulate this circuit – Schematic created using CircuitLab So I am trying to build a BLDC motor controller using a Teensy4.0, FOD3182 Optocoupler, and some power mosfets. Currently I am working ...
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44 views

Driving optocoupler by a line receiver

I wanna drive TLP350 by a line receiver AM26LS32. I employed scheme 1, however, there was no signal on output. I found in line receiver datasheet that the current sign is negative so it is likely to ...
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54 views

Zero crossing detector output to another optocoupler

I will use the configuration below to build a zero crossing detector to connect to a PLC. I will change the output voltage to 24VDC and the correspondig resistor to 50K. The problem is that the input ...
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30 views

How to protect the circuit from Ethernet ESD, overvoltage, etc

Creating a carrier board for a RPI Compute Module4, I am not sure how to protect the circuitry from possible ESD /over-voltage coming through Ethernet connector. In normal circumstances, I would apply ...
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52 views

Can I change the voltage (12V) input into my optocoupler to 24 V?

simulate this circuit – Schematic created using CircuitLab I have an inductive sensor (LJ18A3-8-Z/BX,) normally open 6V to 36V 300mA. It is connected to a 12V 80kHz single channel opto-coupler. ...
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53 views

Why is the sensor value at the optocoupler wrong?

I am using six inductive sensors in my circuit. Four of them are working fine, but two sensors are showing very weird behaviour. I am using an optocoupler to read their output to the MCU for isolation:...
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How to test an ISO100 optically coupled linear isolation amplifier

I have these components and have to test whether it is functioning properly by building a test circuit. Not able to come up with an idea can anyone suggest please and provide some details about it. ...
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46 views

Can I upload a 24V to 5V optocoupler schematic from a module I bought?

I have the schematic for an 8 channel 24V to 5V optocoupler board I purchased. It uses the EL817. My input is an open collector input pulled up with 10K to 5V. I can't drive it to gnd to trigger my ...
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76 views

DC motor turns ON itself

I am driving a DC motor with driver DRV8871 and using optocoupler SHARP PC817 for the logic pin to the driver for isolating motor supply & MCU supply. I noticed very weird behaviour of the motor: ...
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83 views

Need help to correct circuit

I am using this circuit to detect whether or not electricity is being consumed. There are two sensor sources (CT1 & CT2 ) where a CT coil will be installed. When electricity passes through that ...
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129 views

How can I test a TLP582 optocoupler?

Have few of these components (TLP582) and I need to design a test circuit to test its functionality. Datasheet of TLP582 I have no idea how to make a circuit for this. What should I be testing in an ...
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23 views

Switching a relay with an Arduino using a transistor and an optocoupler

I want to switch a relay with an Arduino. The Arduino runs on 5V though, while the relay needs 12V. I want to use this circuit: Will this work and what transistor and optocoupler do i need to use?
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Problem in getting optocoupler output in Proteus

I am making a 5 level inverter in Proteus using 4N25 optocouplers but I am not getting any output from the optocouplers. I don't know what is wrong with this circuit. complete diagram
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48 views

Using an optocoupler to drive a pulse counter

I am trying to design a circuit to measure the RPM of a small internal combustion engine. The ignition on the engine is a simple magneto style ignition. These ignitions are switched off by grounding a ...
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43 views

Sensing 24v AC with 4N35?

Basically I have sliding gate which has contacts to turn lamp when it's open or closed (two different ones) that are rated 24v AC max 3W. I would like to use those contacts to know if the gate is open ...
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33 views

Using optocouplers and programmable resistors to control a gamepad

Let me preface by saying that I'm a C developer by trade, with very little electronics/hardware design knowledge. I started working on a project to map Keyboard/Mouse to a USB HID gamepad with the ...
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34 views

How to detect AC or DC voltage from 9V DC to 250V AC?

I have a device that needs to detect the presence of voltages from 12V DC up to 240V AC RMS (Absolute maximum of 9V DC to 250V AC RMS) This device is going to have up to 8 channels that should be able ...
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38 views

Will optocoupler work if I use 4.7 k resistance to limit the current to the input of optocoupler from logic supply 3V

I am giving 3.3 V input to the optocoupler from my MCU and using 4.7 kΩ resistance in series to the input of the optocoupler will it work? R1 = 4.7 kΩ R2 = 4.7 kΩ Optocoupler: PC817 Vcc = 5 V CTR: ...
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Does a motor driver need a ground reference for logic signal with optocoupler isolation on logic pins?

I am using two power supplies, one for the motor driver (+24v), and the other one for my MCU (+5v). My concern is that in the datasheet of the motor driver (DRV8871) it is mentioned that GND needs to ...
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47 views

I want to regulate 52 volt to 44 volt with applying different pwm signal

I just want to regulate 52 volt to 44 volt with different pwm signal from arduino through a optocoupler 4n35.I just use this circuit in which i used 6 pmos and 6 optocoupler...i applied 52 volt and 45 ...
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62 views

Thermocouple simulator circuit : isolation & voltage reference

I'm designing a multi-channel (6-10) thermocouple simulator. For different reasons, all the outputs must be isolated to simulate completely the behaviour of the real-life thermocouple. To do the task ...
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23 views

common circuit to turn on/off ac motor of 110V AC or 230V AC using MOC3041 and BTA16 Resistor calculation

I am building a common circuit to turn on/off ac motor of 110V AC or 230V AC using MOC3041 and BTA16. How do i calculate both resistor value R and Rg ( With Wattage ). For accurate control of TRIC. ...
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43 views

How to build an audio mute button?

I'm planning on building a mute button that would physically cut the audio signal from or to my computer. This could be used for both input and output. I would like to be able to disconnect my ...
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33 views

Isolated gate driver for the Class D amplifer

I am trying to simulate the gate driver part for driving the MOSFETs in the class D amplifier with 4N25 optocoupler, not too sure if the connection between 4N25 and MOSFETs is correct.
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53 views

Opto-coupler IC internal voltage drop

I have a circuit where an 12 bit ADC IC is outputting 5V logic levels, which are going to be read by an FPGA inputs. The FPGA voltage is 3.3V so the 5V outputs from the ADC chip will switch the 3.3V ...
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74 views

Why this saw shaper circuit does not work in reality? [closed]

As part of the experiment, I decided to use an optocoupler in the saw shaper circuit. Although I managed to get the effect in the simulation, the actual design does not work on a breadboard. Please ...
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67 views

Circuit to replace a relay

I want to make a simple ladder circuit to control the on and off of a light bulb using 2 switches, but I am going to manipulate one of the switches by means of a microcontroller, and also I don't want ...
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2answers
49 views

Best way to AND all connected inputs to one output

I have an CNC router with 7 x SN04-NPN sensors connected in parallel with one control board input. The problem is obvious, i got random false endstop triggers due leaking of SN04. I know i should have ...
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40 views

Switching relay directly with an optocoupler

I have a relay network (more than 1 relay running in parallel), that I need to operate using a STM32 based MCU. The relay I am using is Omron G5V-1 (24v). I wanted to know if I can directly run these ...
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25 views

Isolated Triac Driving on Low RMS Current Load

I'm trying to drive a triac to control contactors. Here is the circuit I'm using: I have 3 different contactors which has series resistances like: 200R, 550R, 1.4k When using contactors with 200R and ...
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57 views

Opto-coupler output photo-transistor as normal BJT

I am currently using a 4N49 opto for command isolation (no speed requirements, just isolation for a slow 64ms signal). There is different section of the design which also needs a NPN transistor switch....
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76 views

Designing a transistor switching circuit with opto-isolation

I am working on a project where I want to switch a 12V DC LED strip(power consumption 300mA) using ESP32 having a complete isolation between LED strip power source. I came up with following circuit. ...
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115 views

Best way to manage multiple 12V inputs and outputs from Arduino?

For a bowling alley I am going to make a circuit using an Arduino Mega to turn on arrow lights(1-4 bulbs in each) given the bowling pin lights that are lit up at the moment on a masking unit. AMF no ...
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72 views

Suppress noise on digital signal

Tasked with improving on an existing design, I need to read pulses using a reed sensor excited with a magnet, placed on the front wheels of motorbikes. The system's core has changed, moving from a PIC ...
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2answers
64 views

Relay circuit with MOC3021 and BT136

I am designing a relay circuit with MOC3021 and BT136 from this datasheet. I know the importance of snubber circut(39ohm resistance and 0.01uf capacitor). But I have no idea why 360,470 ohm ...
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77 views

Replacing optocoupler with a more reliable and durable device

I am working on a project where I need to have some sort isolation from a machine sending out highs and lows in terms of 24vdc to 0vdc respectively. And I'm using a microcontroller like ESP32 that ...
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2answers
51 views

Can this be done with the TLP2368 optocoupler (open collector)? (Toshiba)

I have tried to write to Toshiba technical service, but no one responds. I have the layout of this optocoupler (TLP2368). According to the datasheets, the VCC voltage to GND is a maximum of 6V, so I ...
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1answer
34 views

Driving an opto isolator where ground can swing between 30V and 0V

I have a motor controller that outputs a fault by pulling down its I/O pin (PIN 10). It will also go into fault if you external pull the pin down too. The MC has two configurable pullups: A: The ...
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109 views

TRIAC confusion

First for some quick background: You might be aware of my other threads in which I pose a problem with micro-controller to WiFi-command an existing coffee machine which had (as happens with a lot of ...
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voltage level handled using optocoupler [duplicate]

I want to program at89c2051 chip. I am referring circuit diagram where the optocoupler is used to handle the 2 voltage levels (+12V and +5V). i didn't understand how Pin A0 and A1 will control the ...
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32 views

Circuit design for triggering multiple optocouplers at constant voltage level

I have theoretical understanding of general electronics basics, however I do not have any practical experience in circuit design. Therefore I need some advice of what would be the best practice on how ...
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1answer
142 views

Detect 10V…To.. 260V AC/DC with HCPL-3700

I want to detect voltage between 10V and 260V AC / DC, I have thought to use the HCPL-3700 but if I put the 47k resistors the output is activated, but if I apply 12V the output is not activated. Does ...
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3answers
50 views

Reading Optocouplers datasheet: current transfer ratio (CTR)

So I am working with an optocoupler at the moment, and having trouble understanding what CTR value to use in my calculations. The datasheet states 50% Min and 600% Max, which is a huge difference. Do ...
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1answer
46 views

Voltage divider on optocoupler emitter output

I am trying to control a load switch from the GPIO pins of an STM32 which outputs 3.3V. They need to be isolated using the optocoupler shown. The problem is that the isolated voltage supplied is 24V, ...
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138 views

Optocoupler to switch 24V using Arduino

I am currently redesigning a circuit to switch a spring applied brake using an Arduino Micro. The current circuit looks like this (please excuse if I'm using wrong symbols, I'm learning by myself): ...
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49 views

Proteus simulation error

I am getting these errors while running simulation in proteous. [SPICE] transient GMIN stepping at time=7.87403e-006 [SPICE] TRAN: Timestep too small; timestep = 1.25e-019: trouble with node #00004. ...
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1answer
77 views

Controlling AC load from a microcontroller GPIO with triac

I have the above question and I don't know who to ask. I looked around here, while most have no answers but there are a couple that kind of applies but went a little over my head, like these: ...

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