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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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Parallel Triac driving same Inductive Load NOT Working?

As per the schematic two same value triacs and driver circuits are connected parallel, Triacs are BTA24 and Opto-couplers are moc3021 and the load is inductive, when i trigger the MOC U1 the Triac Q1 ...
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45 views

Ground Test with MID400 (Optoisolator)

I design my controller, one of the tasks of which is to check the operability of grounding in an AC line. The controller will be built on the basis of ATMEGA328P (Arduino UNO), in the high-voltage ...
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1answer
36 views

Opto-Isolater always on by higher voltage

I use an AQH3213 Opto-Isolater. When I use 3.3V on the 'dc motor side', everything works fine and it 'turns off and on in an interval of 1 second'. But when I use 5V, it's always on.... Do you have ...
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29 views

pwm 5v to 10v with optoisolator

i need to convert pwm 5v to 10v (eventually with an low-pass rc filter) now, the problem here it's that i want to have 5v isolated from 10v, so i don't think that i can use a mosfet. my idea it's to ...
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1answer
44 views

Noninverting optocoupler with a pulldown resistor

I am using a power MOSFET to switch a solenoid valve. The MOSFET is driven with a optocoupler (LTV-847) to isolate the 12V required to switch the valve from the 3.3V used by the microcontroller. ...
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1answer
83 views

microcontroller is “hanging” when it is feeding PWM to a DC motor controller

I am using linear potentiometer to control the speed of a DC motor. I am using the following schematic. An ATmega328P receives the value from linear potentiometer via analog read. This ATmega328P ...
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2answers
85 views

How series resistors influence clearance-creepage requirements?

simulate this circuit – Schematic created using CircuitLab I'm designing a circuit which should leak some amount of current from AC line to PE. The question is regarding clearance-creepage ...
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35 views

Powering both sides of an opto-isolator from the same power supply rail

I have an opto-isolator circuit to drive a 12v relay coil that controlled by a microcontroller. The microcontroller power supply is 3.3v that generated from a 12v power source (using voltage regulator)...
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3answers
1k views

No current through AC optocoupler

I am just testing this component MOC3021 optoisolator, its datasheet can be found here. This is my circuit in Proteus: Please forgive me for my ignorance of electronics, I have my background in ...
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0answers
24 views

phoresistor vactrol tremolo noise

I made an optocoupler by shrink tubing a generic photo resistor and a cold white led. Then used it in the following setup to be able to control audio level to achieve tremolo effect: simulate this ...
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1answer
22 views

Circuit to a/b switch like a relay would. So an analog or digital signal can be turned on or off or routed

I need to build an arduino-based switcher / router for a multi-arcade to route controls to different game boards, and also switch 2 vga inputs into one output. Without introducing any lag also. 3 ...
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104 views

Using optocouplers at the end of a twisted pair

I am designing a dumb "isolation box" that is to sit between a computer and medical data acquisition equipment. The purpose of this box is to inject power and to provide communications and digital ...
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2answers
54 views

What is optocoupler and how it is used? [closed]

Im curious about optocoupler. What is optocoupler,why and how it is used in electronic circuits ?
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1answer
40 views

What does “off-state output terminal voltage” in optocouplers mean?

I was looking at possible options of what optocouplers to use in my project. I was looking at these parts. https://www.fairchildsemi.com/search/?searchText=MOC3023-M#N=&&Nao=0&&Ntk=...
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1answer
44 views

Achieve -12~12V PWM Signal isolate

I have used IL300 to isolate 0~5V PWM signal before and it works great. The circuit is shown below. But now I need to isolate -12 ~ +12V PWM signal. Is there any possibility or suggested circuit to ...
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1answer
54 views

Transistor Reverse Biasing - AC

I am working on a project which require to activate a 24V Rated relay using a 3.3V rated IO. To provide adequate isolation I have added a Opto-isolater stage. In order to increase the current output ...
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1answer
74 views

Detect phone call termination

I am designing an automated telephone circuit that will work with the PSTN line. I already had a question to detect the incoming ring signal. Now I want to detect whether the opponent person in the ...
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1answer
29 views

Operating a 24VAC solenoid with a Triac. Protecting with TVS DIODE, RC Snubber or both?

As part of a project I am controlling 24VAC solenoid sprinkler valves like this https://rayshobby.net/wordpress/understanding-24vac-sprinkler-valves/ using a triac (BT1308W) http://www.mouser.com/ds/2/...
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3answers
68 views

Problems sizing series input resistor for this optocoupler

Under the electrical characteristics, the optocoupler 4N26 typical "forward voltage" is given as 1.2V. But for sizing the input resistor Im have hesitations. In my application as a control signal I ...
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2answers
88 views

how do I use H11L1 correctly to receive MIDI?

I was following this schematics. This is the first result on google images My Arduino Serial Monitor received nothing. I tried to replace the H11L1 with LED, and it does blink. but as soon as I ...
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2answers
57 views

A question about using optocoupler instead of FET for longer signal wires

After my previous question I had concluded to use the following circuitry to operate this solid state relay: But now I found out that, from the micro-controller(Arduino UNO) digital output pin to the ...
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1answer
75 views

Overvoltage protection for AC relay dilemma

I am currently designing a safety-related device that has to open a relay when a certain event occurs. During most of its life, this relay will be closed, and only open if the safety event occurs, ...
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2answers
37 views

Isolate a digital signal that changes its amplitude

I have to isolate a digital signal that has the following characteristics: frequency: between 1 and 1000 Hz amplitude pk-pk: 12V offset: 0-6V With "offset" I mean the actual voltage may change from ...
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2answers
89 views

Component values

Can somebody clarify the following points for the MOC3041 sample circuit given at their datasheet: What are the wattages of resistors at the HOT side What is the difference between 360Ω and just 330 ...
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2answers
120 views

Is this optocoupler front-end safe?

This is a follow-up to Is this line detector safe? I'm re-designing the front-end based on some great feedback from the community. I've decided to move to the following topology: The phase of the ...
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4answers
140 views

Is this line detector safe?

I'm thinking about building a basic AC mains voltage detector. I'd like for it to be both protected and isolated, so I have a zener TVS and an optoisolator. R1 and R3 are chosen so that between them,...
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44 views

How to use an opto-isolator in my circuit?

I am very new to electrical isolation, and I have to build an electrooculogram circuit in which I use an optical isolation system (with diodes) to provide protection to the user. I have only found ...
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1answer
77 views

Measuring individual cell voltages in a series cells Battery

I'm making a 600V battery, and I'm trying to design a Battery Monitoring system, that measures (and keeps log of) each cell's voltage turn by turn, in a series configuration of 162 lithium cells. 162 ...
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64 views

Creepage Distance in Altium Designer

I have a design with a high voltage and a low voltage part. Between the two I need to have a creepage distance of 8mm. Some optoisolators I use in my design are not wide enough on the PCB footprint, ...
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1answer
28 views

Driving multiple loads with a single TRIAC and multiple optoisolators

I simulated this circuit in multisim. It is working fine. However, I am just curious to know if it is possible to drive multiple loads with multiple opto-isolators with single TRIAC? Something like ...
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1answer
55 views

TRIAC won't turn on/turn off

I'm trying to make simple lamp switching circuit to work, but it just doesn't want to work as intended - question is, why? I'm using MOC3021 random phase optotriac with BT136/600E sensitive gate ...
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1answer
36 views

Trigger input with varying input voltages

Currently I am trying to build a circuit, with the goal of triggering a pin of an ESP8266 from varying input voltages (in the range of 5 to max 15 volts it should get triggered). Also the input should ...
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47 views

How much current does an LED in optocoupler draw?

I am planning to actuate the relay (opto-isolated) using the GPIO pins of Nodemcu. NodeMcu's datasheet says that maximum current that can be drawn out of a GPIO pin is 12 mA. Any load more that may ...
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1answer
80 views

Sense 230V - voltage

Brief sum up (you can go directly to the end if you already read the sum up in the other question) For a home project I'm making a controller to drive a two-direction 230V motor. For those unfamiliar ...
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4answers
2k views

Detect 220 VAC with a Raspberry Pi

I want to build a simple device to check if the light is on or off. I found some schematics but I need to be sure that it is safe. Source : How to detect 220 VAC voltage using an opto-isolator My ...
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1answer
66 views

Control 24VAC solenoid with arduino using a octocopuler and a Triac

Following a previous question I implemented the following schematic on my PCB. The schematic : My PCB: I have been unable to make it work, if I measure the voltage on j13 it's allways 25v, i know ...
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24 views

High Speed Piezoactuator Driver-Unexpected (Low) Voltage Output

I'm working on a project that requires charging and discharging a piezoactuator (150V, 1.5μF) extremely fast, IE total slew time allowed ~50μs (so somewhere around a 11A pulse). My background is in ...
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31 views

Low Voltage Marx Generator Switch

I have a low voltage Marx generator which is connected to a coil inductor, eventually forming an LC oscillator. I want to find a way to switch the circuit on, but because the voltage is low I cannot ...
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2answers
73 views

Automotive signal isolation - alternatives to optocouplers

I'm working on an automotive project, where I'd like to interface various digital signals to an MCU. The signals can either be ON/OFF (e.g. radiator fans) or measurements of pulse frequency, width, ...
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1answer
109 views

Latching/Non-Latching Relay Driver Circuit with darlington optocoupler

I'm designing a circuit where an ESP8266 controls two types of relays, a single coil latching relay and a normal non-latching relay. The relays are power relays use to control low power electrical ...
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1answer
482 views

4 channel optocoupler [duplicate]

I was designing a dual H bridge board which uses some logic signals to drive 8 mosfets. Initially I was using 8 optocouplers per board which was really annoying to wire up. after a bit of searching, I ...
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2answers
69 views

“Fast” pulse (8µs) low current (10µA - 100µA) amplification for optocouplers

I got this problem where a inverted pulse of 8µs has to be amplified because the pulse only delivers 10-100µA. The signal will be transmitted over a optocoupler and sent to a mc that interrupts upon ...
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3answers
721 views

How does Galvanic isolation work?

I am unable to understand how does galvanic isolation work either via an optocoupler or a transformer. In an optocoupler, the input side current caused LED to emit infra red light which basically ...
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1answer
150 views

Driving a 24VAC solenoid with arduino using a octocopuler and a triac

Following a previous question I have redesigned my schematic: I'm trying to energize a solenoid used to open and close a 24VAC sprinkler valve I have the following questions : 1) The GPIO leg can ...
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1answer
86 views

logic level conversions for opto-isolators in digital input acquisition

This isn't my usual job, I'm not an EE, but I want to give it shot... This question concerns developing an interface board to connect a device (DUT) to a test system in a manufacturing scenario. ...
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2answers
63 views

Current loop protection from wrong connection of the wires

I have built a current loop protection circuit based on the topic Using a microcontroller ADC to measure a 4-20mA sensor It works good. The next step is I want to protect the input of the circuit ...
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2answers
69 views

Bidirectional (opto?) isolators for any protocol?

I would like to isolate digital serial communication between 2 circuits. I don't know much about the protocol between two circuits. It is not a common protocol such as SPI or I2C. Shortest pulses are ...
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1answer
89 views

Avoiding turn-off of zero-crossing optotriac

I'm designing a circuit that switches a load using a regular TRIAC (say, a BT-137) being fed by a MOC3063 - an optotriac with zero crossing detection. The circuit being fed by the TRIAC can be either ...
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1answer
78 views

Bypassing DSLR battery to power camera from power supply cheaply with bidirectional optocouplers

I am trying to power my Nikon DSLR with a permanent power source instead of the battery for long captures (overnight) without buying the overpriced battery adapter. I can't simply connect a AC-DC ...
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1answer
173 views

AC Voltage Detector with MID400 optocoupler

The task I am trying to achieve is as follows: I am using a MID400 optocoupler to send either a 5V or 0V signal to a pi plate depending on if there is AC voltage present. I am using 120V AC from a ...