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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How to read 0 current during unavailability of signal at line and neutral? [closed]
I want to read 0 current when there is no signal coming to line and neutral. How do I do it? Do I need to change the optocoupler resistor value or what?
When there is no power connected to L and N ...
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Circuit to work around optocoupler's output voltage limit
I have an application that calls for an H11D1 optocoupler. This part has a maxmimum output voltage of 300V. The optocouplers I have on hand have a much lower output voltage rating.
Is there a way to ...
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How do I replace or modify this circuit to run on 7.4VDC?
I’m trying to replace the power supply of a CCTV camera with something that will accept a 7.4V battery.
The part I’m stuck on is using or replacing the optocoupler with something that can be driven by ...
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Troubleshooting a ZCD TRIAC circuit
Can someone see what's wrong here? My 50 W LED light doesn't shine.
Here is my code from the Arduino IDE:
...
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What is the best way to wire this specific optocoupler to drive a MOSFET gate?
I am using an FOD3180 optocoupler. I want to use the IRFP250 MOSFET to drive a 30V motor. I'm going to power the MOSFET with a separate 12V power supply. Can anyone show me the specific circuit ...
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24 VDC signal to Raspberry Pi GPIO input via optocoupler not working
I am new to the whole universe of electric circuits and could not get my head fully around my problem. Please bear with me.
I have a 24 VDC signal that is switched on and off by a relay. My Raspberry ...
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Optocoupler / 5 V, 1 A DC [closed]
I am looking for an optocoupler capable of handling 5 V, 1 A DC continuously, in SMD format. I must be doing it wrong or I don't know how to search properly, but I can't find any reference. Do you ...
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Is this behavior realistic for bipolar loads on optocoupler outputs?
Background:
When using LTspice to simulate such a circuit (the opto-model is called PC357NT and is part of some exhaustive lib called "ZZZ" which I downloaded a long time ago. The PC357NT ...
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PLC output optoisolation with mosfet output
I'm wondering if this circuit i've made is correct.
Basically i want to separate PLC transistor outputs from loads.
I need 500mA output current for LEDs but also for relays etc.
PLC and loads are ...
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Is this the correct way of making a non-inverting optocoupler?
Requires to read 24 V input signal, and output to an Arduino as 1, at the same time it lights up the LED indicator. Is this circuit viable?
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Is there a way to approximate an optotriac in CircuitJS / Falstad?
Falstad does not have an optotriac part. I've opened a feature request issue on the CircuitJS GitHub to ask for one to be added, but is there a reasonable way to emulate an optotriac given the ...
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AC 220V MCU TTL Level 8 Ch Optocoupler Isolation Test Board Conversion to 24V
I am trying to add a sensor to my 8 underfloor heating actuators (24V) so I can monitor when they are 'On'. I thought this would do the job, although I'm only sensing 24VDC.
Input goes through MB6M ...
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Trigger feedback from camera hot shoe to embedded controller
I am trying to build a circuit using the signal from a Fuji XT-20 camera hot shoe to drive an interrupt input pin on a Teknic ClearCore controller.
My understanding is that all the hot shoe does is ...
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Isolation on bidirectional I/O pin
On the PCB we are currently designing we have two isolated grounds, one for the sensitive electronics (including a Jetson Orin NX SoM), and one for the outside-facing connections.
The difficult part ...
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Translate voltage between line/neutral potential and ground potential (between primary and secondary side of PSU)
I would like to know how to translate a voltage difference between two independent reference potentials, as accurately as possible.
backstory:
We are building a active power measurement station for ...
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Calculating resistors in circuit with optocoupler and triac
I'm trying to build circuit with optocoupler and triac, but i dont know how to calculate R2.
For R1 it was easy, since Led Trigger Current is 15mA-30mA, so with 330Ω and 5V i will get 15mA (or am i ...
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Isolated high voltage FET switch
I want to design an isolated FET switch. The schematic is shown below.
The optoisolator datasheet is here.
I have never designed this kind of circuit before. Can someone advise if this is correct in ...
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What is the safest way to control another circuit?
From my custom board with an MCU I need to connect to an Interlock Pin of another circuit. I have a lot of options, but I don't know what is better.
Using an optocoupler, but I'm afraid the output ...
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Frequency-independent way to determine AC mains RMS voltage
I'm looking for a circuit to determine the RMS voltage of the AC mains supply regardless of its frequency.
The monitoring circuit needs to be isolated from the AC mains, and I can't use a transformer. ...
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Designing a simple controller for a hot plate
I have a hotplate with a TS port meant for an external temperature control unit. The manufacturer's customer service told me that this port is not connected to anything internally in the model I own. ...
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Controlling a 5 V input with a 3.3 V ESP8266 via an opto-isolator
I want to control a 5 V input on another device with a ESP8266 by using a PC817 opto-isolator. I am using the following wiring:
The output pin is connected to an Arduino-like microcontroller. I need ...
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24V I/O (PLC) to 3.3V interface with opto and PCF8574
I am more of a software guy, and I want to make sure my design works before sending it off to fabrication.
I need to interface with 24V PLC I/Os. I want a simple design for now, as I can add ...
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What resistor values should I use for an optocoupler switching a MOSFET?
Final Update
I believe this to be correct now. I also have simulated this circuit on the circuit here: Link
Please feel free and tell me if anyone sees anything else wrong.
UPDATED Circuit:
Based ...
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DIY voltmeter safety concerns
I would like to build a voltmeter using an ATMEGA328P that measures AC mains voltage. I came across the following schematic which appears to be what I am looking for:
The top part of the circuit goes ...
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How to isolate the AM2301 sensor with a small footprint and low-cost isolator (digital or opto)?
Looking for a solution for isolating the AM2301 sensor with either digital or opto-isolator. I have space and cost constraints. Thank you .
AM2301 is accessed via a single bus / single line interface ...
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Mains AC detection circuit - will it work?
I´m trying to detect mains voltage (230 VAC) across AC_SENS_L and AC_SENS_N.
AC_SENS_IN goes to an Arduino input with pull-up.
I only need to detect if voltage is present, not what voltage.
Any ...
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What component is needed to collect injector pulse?
I am planning to convert this pulse to a digital signal (apx. 5 V for MCU input) based on voltage level. The maximum voltage of this pulse is 12 V when the injector nozzle is closed and 0 V otherwise. ...
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MOSFET not driving a relay
I've been trying to drive a 24 V SMD relay with an internal coil resistance of 2880 Ω and an isolated 3.3 V logic input.
I selected the 2N7002 MOSFET (Ic=115 mA) to drive the relay; the relay needs 24/...
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Does a general purpose optocoupler such as CNY17-4 support clean 25 kHz PWM?
I've "scanned" through all possible combinations of values for the current-limiting resistor for the LED input of the CNY17-4 optocoupler, as well as the output pull-up. At 25 kHz, I couldn'...
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Optocoupler with cascaded photodiodes
simulate this circuit – Schematic created using CircuitLab
Is there a component like in the dashed box? It may supply gate voltage for a source-to-source pair of N-channel MOSFETs. Speed is not ...
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Isolated DC-DC converter
We have a design in which we need to isolate a communications signal coming from a TTL serial port and going to a DUT sitting on a bed of nails (functional tester).
The supply voltage ranges from 2.5 ...
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Is this BJT based optocoupler current limiter a good idea?
I have been thinking about how to produce an optocoupled input that works well over a wide voltage range, say 3V to 30V and I came up with the following schematic.
According to the simulator in ...
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13.75V (AC) Door bell ringing signal to Raspberry Pi GPIO - Am I on the right track of which components I need? (Beginner)
I'm in the making of a RaspberryPi doorbell. It will have to possibility to send events and receive actions/commands via a Telegram bot (already working). The approach is to connect it to the handheld ...
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Detection of mechanical relay sticking
I'm exploring new methods to find if relay contacts have been stuck together without using auxiliary contacts of the relay. while searching I find out this block circuit:
at this Toshiba page
as far ...
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Ćuk converter implementation
I am trying to design a 50 W non-isolated Ćuk converter. I am using the IRF540N MOSFET which is driven by a 555 timer-TLP250 setup, using the fast-recovery BY399P diode.
I am trying to find a design ...
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Optocoupler as UART communication
I am using the LTV-816S optocoupler for isolated data communication. When I give 4V supply to U1.1 then I get 3.3 at RX. but when I give a signal (4V) at U1.2 pin then at Rx I should get 0 but I am ...
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Optocoupler selection for detecting 24 VAC input with ESP32
I'm looking to detect HVAC thermostat calls using ESP32 GPIO inputs. I have a total of six inputs (two compressor speeds, blower, reversing valve, and two aux heat levels). Nominally 24 VAC, but my ...
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How does Whitebox labs get isolated sensor boards when they are using a single power supply?
Whitebox labs makes "Electrically Isolated EZO™ Carrier Boards" which are isolated boards for Atlas Scientific sensors such as pH.
I don't understand how can you get an isolated board if ...
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Drive long cable directly with opto isolator 6N137 (open drain OP)
I would like to use serial comms between atmega328p microcontrollers over lines up to about 20 meters long, at speeds of around 9600, with the first choice of cable being cat5. Opto isolating them ...
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Microcontroller digital input isolation using optocoupler
In my project I'm using an STM32F401 controller. I want to provide a digital input to one of its GPIO (3.3V maximum) pins to read an industrial sensor output. I'm advised to provide isolation between ...
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Reading neutral gear from F150 transmission range sensor
We're converting an F150 to hybrid, and I'm working on having our system be able to tell when the truck is in PRND. Primarily, I'd like to know when it's in neutral - the others should come as a ...
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How to drive a 15 Vdc relay coil from ESP8266 3.3 V logic
I want to control a series of Zettler AZ2100–1A–15DE relays with an ESP8266 Wemos D1 Mini microcontroller.
I thought I could do this with an optocoupler, so I bought an 8-channel PC817 board from ...
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Will this 24 V relay driver work?
I am not sure about the 24 V which drives the transistor base. Is this circuit correct? Do I need some modifications?
The current rating for D2 is 200 mA. Is that high enough?
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M-Bus optocoupler application
I'm designing an M-bus circuit and when I look at the datasheet, it says I need to use a UART. You can see the connection by looking at the first schematic:
When I looked at the same circuit with the ...
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Choose appropriate opto-isolator for 230 Vac zero-cross detection circuit
I struggle to understand the datasheet for opto-isolators. I am making a 230 Vac circuit with a full-bridge rectifier. What should I look for when choosing an appropriate opto-isolator?
I've been ...
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ESP32 opto-isolated relay board not working - PC817 opto-isolator, 2N3904 NPN BJT and SRD-05VDC-SL-C relay
I have just finished soldering my "custom designed" ESP32 PCB board that I'd like to use for management of 6 x 24 Vac irrigation valves.
Given my limited electronics knowledge, for ...
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Designing a galvanically isolated analog transmission circuit with IL300 and different power supplies on both sides
I'm having trouble understanding how this circuit (suggested in the datasheet of the IL300) would behave with a different power supply on both sides of the opto-coupling.
The datasheet assumes that ...
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Connect 3 mm jack with 4N25 optocoupler to 8 Ω speaker
I want to take an audio signal from a smartphone's 3 mm jack plug, pass it on to a 4N25 optocoupler,, and get the sound from an 8 Ω speaker. I don't know how to connect them to each other. Can you ...
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TLP3556A MOS switch doesn't seem to turn on
We are using this photo MOS relay in one of our designs. This design is in production and we test every relay in QC. Recently I came across a failed unit with one relay not turning on.
I checked the ...
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