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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2answers
156 views

Filter 5v pulse from micro input

I am monitoring an external system which sends out a 5v pulse every 2 seconds when in normal mode. When the motor is working, it sends out a constant 5v designed to power a flashing light or LEDs as a ...
0
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1answer
182 views

SFH6916— SOP-16, Half Pitch Mini-Flat Package eagle library needed

I want to use SFH6916 ( Optocoupler, Photo-transistor Output, Quad Channel, SOP-16, Half Pitch Mini-Flat Package) in my circuit. I am using Cadsoft Eagle for layout designing. The package ...
3
votes
1answer
726 views

How to sense 24V AC (Thermostat) with a 5V Microcontroller

I'd like to detect thermostat events (heat, fan, ac etc) with an Arduino. I've done quite a bit of investigation but haven't found a definitive solution. Most projects I see involve controlling the ...
1
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2answers
194 views

Programming ATMega328 from arduino with separated power supply

I actually need to update the code on a project who use an ATMega328. I'm using an arduino as a SPI programmer. So, I need TX/RX and RESET pins to program the external ATMega328. My problem is, the ...
3
votes
3answers
336 views

How to float the output of an optocoupler when needed?

I want to have an opto-isolated output which can be driven high, low or left floating. I thought of the following circuit but I'm quite new to electronics so I don't know whether it makes sense. Do ...
0
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0answers
39 views

PCB design with 230VAC and 5VDC [duplicate]

I've developed a small circuit that aims to dim a lamp. Iit works fine on my breadboard, so now I'm building my own PCB. I never built a PCB with 230VAC on it and controlled by a 5V microcontroller. ...
2
votes
1answer
171 views

Unwanted “memory effect” on a bus with optocouplers

I'm working on a microcontroller driver for an equipment which can have up to 64 optically isolated digital inputs. The hardware was designed with an 8-bit bus in mind, so we have up to eight rows of ...
1
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1answer
540 views

MOC3010 & BT136 with Arduino as trigger to power AC light

I've spend days debugging this circuit and have exhausted all possible solutions. I'm trying to use an Arduino PWM pin to light a 120V AC lightbulb. In order to do this I'm using a MOC3010 ...
0
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1answer
417 views

Calculate Resistor Value for Optocoupler - 24VDC Anode

I'm looking for help and unfortunately stuck for time on a project, so hoping someone wouldn't mind helping me out. I am trying to calculate the resistor value required for an opto-isolator circuit. ...
4
votes
2answers
570 views

MOSFET controlled by optocoupler using Arduino

I have a question about using an Arduino to control a MOSFET with optocoupler. The question is, the supply voltage may vary from 5 to 36 Volts. For example, sometimes I will use a 5V switching ...
1
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0answers
455 views

Can You Drive Back-To-Back MOSFETs (aka a Solid State Relay) Without Using An Optocoupler?

I was wondering if there was any way of driving back-to-back MOSFETs (with their sources and gates tied together as shown in the following image) without using an optocoupler? The reason is that ...
1
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2answers
135 views

What is a reasonable isolation voltage for an optocoupler/digital isolator?

I need to isolate an input from my processor. What is a reasonable isolation voltage to look for optocoupler/digital isolator? I've pretty much decided to go with an RF isolator at this point because ...
0
votes
2answers
250 views

How to wire up optocoupler for digitally controlled UV (under voltage) input protection?

What I am trying to build is an under voltage input protection. It will always limit the voltage flowing into the output end to the microcontroller to be 3.3V, but when the input goes below 380V, it ...
0
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0answers
82 views

Optoisolation with make or break pneumatic contacts

The design I've been working on is based on the previous generation of the circuit that my customer has been using for many years. There are several pneumatic make or break switches that are triggered ...
11
votes
6answers
516 views

Using an Opto-Isolator to change an Op-Amp's Amplification

Consider this circuit, which is a standard non-inverting amplifier with an amplification of A = 1+R1/R2. I now want to be able to change this amplification value ...
2
votes
1answer
391 views

Controlling Triac w/optocoupler, need some help with optocoupler datasheet

Loads: Some baseboard heaters (1500W max, some motors, 12A max). I have no experience using Triacs and optocouplers. Triac: T3035H-6T, Datasheet: ...
2
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2answers
360 views

what is the voltage at the emitter of optocoupler 4N25?

simulate this circuit – Schematic created using CircuitLab I am using the emitter voltage to drive another transistor. But voltage is zero.
4
votes
6answers
432 views

Does opto-isolation matter when there's only one power supply?

Optoisolators are often encouraged for isolating signals controlling higher voltage loads. The typical example is a low-voltage microcontroller controlling a motor or solenoid operating at a higher ...
0
votes
1answer
60 views

Looking for a medium power optocoupler

I have a project where I will control a 3 or 6 watt UV lamp DC with a microcontroller. I want to power my lamps with a AC/DC circuit and switch them on and off with a optocoupler, mainly because ...
3
votes
1answer
313 views

Optocoupler (Analog or Digital)

I have got few analog and digital signal that needs to be galvanically isolated. I am thinking to use H11F1M for analog signals. I am not sure how to rig-up the circuit using this device. Specifically ...
0
votes
1answer
294 views

RS232 and RS422 (Isolated and ESD Protected)

I want my RS232 and RS422 to be galvanically isolated and ESD protected. I have two options to implement this requirement. Option 1: MCU-->OPTO-->DRIVER-->ESD PROTECTION Use MAX3232 for RS232 ...
6
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3answers
221 views

unclean signal at the output of an optocoupler

I use a FOD260L optocoupler and here is its datasheet and diagram below pin 2 is connected to an atmega168a (supplied by 3.3V ) via 270 ohm resistor. pin 3 is connected to ground of the MCU. On the ...
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1answer
53 views

Simple switch with optoisolator - CTR related

I would like to use a optoisolator to act as a simple low current switch, however I'm slightly confused about how to apply the CTR. From this answer, I should be using the minimum value on the CTR ...
3
votes
1answer
148 views

Smoothing the on/off transition of mains LED lamps

A project with which I've been involved is an interactive portrait gallery, with seventy mains LED lamps, turned on and off using VO2223A optocoupler/phototriacs, driven by a microcontroller. The ...
2
votes
1answer
122 views

Optoisolator not outputting (DC switching)

Trying to reset, automatically, an HVAC speed control unit. The unit has an output pin H8 that goes to 24VDC when tripped, and 0VDC when running. There is no reliable ground pin (or other ground) ...
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2answers
2k views

Need help with 90vdc PM motor speed control circuit

I recently found a Permanent Magnet 90vdc motor, 2.5hp, 18Amps. It has simply two wires for voltage (red/black) and two for thermal breaker circuit i believe (blue/blue). It came out of an old ...
5
votes
2answers
377 views

Why is this optocoupling circuit useless?

Could someone explain me why I can't use the same ground when optocoupling? How can the uC get damaged if there is a short circuit in the phototransistor side?
5
votes
2answers
781 views

How to eliminate Bluetooth noise in electric guitar

After learning more about this problem, I have continued this question here. I am trying to remove noise from an electric-guitar circuit that I have created called the ArduGuitar. My circuit ...
2
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0answers
386 views

Using optoisolator and triac with mcu to switch light on/off--need low power alternative

I'm using the schematic below to control a lamp (light bulb) with a microcontroller and I'm running the mcu (and moc3010) off of AA batteries. I just realized the moc3010 has an LED in it that needs ...
3
votes
1answer
71 views

Determining the input current of an optoisolator based on output current and CTR

I have an optoisloator (CTR min:20% max:400%) in my circuit whose output current (Ic) is around 10 mA. To facilitate this much output current, how to decide the input current(If)? whether i have to ...
6
votes
2answers
2k views

Optocoupler input protection

I have to provide some isolated inputs that accept 12-24V. There should be some protection against reverse polarization, transient over-voltage and permanent over voltage (up to 40V) to some degree. ...
0
votes
1answer
172 views

Isolated closing contact other than relay?

I need an isolated closing contact, like a relay, but ideally solid state. Rating 24V 100 mA on the contact side would be plenty. 1 kHz operation would be enough as well. I will drive this from 5V 25 ...
2
votes
1answer
667 views

why does the microcontroller pin driving optocoupler is giving 2V even if it is set?

I have interfaced pin 1^1 of Atmel AT89S51 to optocoupler MOC3041 IC, I set this pin to logic high. I have connected 220 ohm resistor and red led and then pin 1 of the optocoupler and after that ...
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1answer
222 views

optocoupler help

I think I'm having a hard time understanding how an optocoupler works. I made a circuit based on example 15 if the Arduino projects book, but instead of trying to hack a button, I'm trying to just ...
0
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0answers
528 views

RS232 Ground-Loop Isolation: “creative” solution?

I have a RS232 connection that seem to suffer from different ground potentials at the two ends of the connection: The receiver signals a "break condition" in Realterm. As I understand it this means ...
7
votes
1answer
831 views

How is this 5-24V input circuit working?

Since I require some kind of wide range input (going to a microcontroller) for a new project, I looked through some designs that are already in use (or were considered at some point) for other ...
1
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3answers
1k views

Optocoupler | Why a resistor is required in the collector?

In this circuit, if the resistor in the collector R1 is 0 Ohms, the circuit doesn't work. That is, the output will be 12V DC signal as it is from the battery. And if R1 is non-zero, then the circuit ...
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1answer
618 views

Opto-isolator to directly drive load

I need to control 8 12V automotive relays with an arduino. I have two PS2502-4 optoisolators. The relays are 12V with a coil current of 75mA. The transistor side of the optoisolator can handle ...
0
votes
1answer
265 views

Sensing 12v inputs in 3.3v system

Sorry if this has been asked before, but I searched for a while and didn't find anything that exactly answered my question. I would like to sense the "dummy lights"(oil, neutral, etc.) in my ...
0
votes
2answers
714 views

Low power method to turn Raspberry Pi on or off using an Arduino

I want to use an Arduino to control power to a Raspberry Pi. The power supply to this system is a solar panel with rechargeable cells, and the Arduino will turn the Pi off to preserve power in ...
3
votes
1answer
210 views

How do I pick the right resistor for an optoisolator given a desired current?

This is a follow up to this question, but isn't specific to the other one. This is both an ohm's law question and a 'how does one interpret data sheets' question. I want to minimize the current I ...
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5answers
1k views

Using an Opto-Isolator to detect 120VAC on a Microcontroller

I am designing a system where I need to know whether or not 120VAC is present on a specific wire. The system is in line with a fuel pump system, and I need to check to see whether or not the pump is ...
2
votes
1answer
471 views

Controlling multiple triacs with microcontroller for light dimming: where to use optoisolators

I want to control (dim) multiple mains lights using triacs and a microcontroller. (One triac per light). I want to keep both the costs and component count as low as possible. Is it necessary to have ...
2
votes
1answer
335 views

Isolated vs non-isolated triacs

Bt136-600 is an example of a non-isolated triac, while BTA08 is an example of an insulated triac. What is the difference between an isolated and non-isolated triac? They seem to have the same symbol ...
0
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0answers
497 views

Ask a way to pass high frequency PWM trough PC817(PC847)?How to realise this goal trough push-pull?

I am using PC847(datasheet )to isolate a PWM control signal from CPLD. I will describe my design .When duty cycle changes from low to high, the forward current changes from low to high, so I have to ...
2
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1answer
746 views

Optocoupler with 220V DC

i need help from you. I want to use 220V DC input to microcontroller. For this purpose i have to use optocoupler, so how can i choose optocoupler with input for 220V DC? Thanks!
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0answers
74 views

Using TLP280-4 with STM32F1xx MCU

This is a continuation of my previous question. Olin Lathrop explicitly explained me the previous question, but also set thinking on the exact way of connection the optocoupler to a MCU input. I ...
2
votes
2answers
349 views

How to use electrically isolated weak signal for Arduino interrupt?

I'm trying to use the signal generator from a DSO Nano v2 to drive an Arduino interrupt for testing purposes. I have measured the output of the signal generator at approximately 13mA @ 2V DC. I have ...
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1answer
1k views

TLP280-4 Optocoupler on 12/24V inputs

There is a STM32 device which has to detect several signals from other devices. The voltage of these signals can be 12V or 24V. Also these signals can be positive (i.e. 12/24V) or negative (connected ...
2
votes
2answers
536 views

connection from an comparator to an optocoupler

I have the circuit below to decode a signal that is defined as Logic high >9.5 V and Logic low <6 V To determine the ...