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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355 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: ...
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0answers
142 views

Relay/TRIAC for water heater switching

I'm designing a remote controlled switch for my water heater and I am bothered by the following questions: Should the switch be DPST, or can I just switch the phase line (dangerous?) ? can I do it ...
2
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2answers
328 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.
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6answers
394 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
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1answer
58 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
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1answer
302 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
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1answer
271 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 ...
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3answers
212 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
50 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
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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
120 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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1answer
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 ...
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2answers
356 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?
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2answers
735 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
359 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
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1answer
63 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 ...
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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
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1answer
162 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
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1answer
629 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
208 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
512 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
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1answer
767 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 ...
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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
559 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 ...
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1answer
244 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 ...
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2answers
692 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
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1answer
192 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
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1answer
444 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
304 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 ...
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455 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
709 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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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
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2answers
331 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 ...
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2answers
507 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 ...
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2answers
177 views

how many resistance do i need to safe the LED of PC814?

if i have a input of 5v (arduino HIGH) on the LED of a PC814, how is the value of the resistance that i must use before that, so i don't burn the led? ...
9
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1answer
7k views

Criteria behind selecting pwm frequency for speed control of a dc motor?

I'm working on a speed control circuit for a brushed dc motor (24v, 500rpm, 2A, 4kgcm). The main components that I plan to use are PIC16f873, 4n25 optocoupler, IRFZ44N MOSFET, BY 500 - 800 diode(for ...
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2answers
816 views

How to switch between a solar panel and battery?

A 12v battery is being charged from a solar panel. When battery is 12v solar panel is disconnected from battery and connect the load with battery. And again solar panel is connected with battery when ...
5
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1answer
215 views

Why is there a minimum Ic for a optocoupler?

I got confused when I saw this on a HCPL-181 optocoupler datasheet. You can get the datasheet here: HCPL-181 datasheet. So what would happen if the collector current goes below 2.5mA? (In fact I ...
2
votes
2answers
2k views

How to de-couple DMX512 with opto-isolators?

I'd like to build a DMX512 device. The problem I have is how to decouple the device from the bus. I decided to use opto-isolators, but how should I wire the diode part of the isolator? Since I need ...
3
votes
1answer
316 views

Optoisolator always on on the high-voltage side

I am building a simplified version of this circuit: As far as I can tell, it is a pretty standard design. The load will be a dumb resistive heater (this is a sous vide project). For now, the ...
5
votes
1answer
568 views

How to connect RS232 (“Opto-RS232”)

--Background-- I'm setting up a pretty standard RS232 interface from a digital caliper to a microcontroller, via a MAX232 chip (or in my case, MAX3222, which is the 3.3V-supply variant with 2 ...
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1answer
528 views

How to implement a delay OPTOcoupler input there by the circuit remain on for the next 1 second

I have another new project , the project is simple one when a call lands to the mobile an ac machine is triggered and it turns off when the mobile ring stop , for that i have used this circuit The ...
2
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1answer
2k views

how to put led to indicate the signal is functioning

I want to connect an input signal to pc817 and the output to a microcontroller. I don't know how to put the LED at the input to indicate that the input signal is working. For example my input is ...
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1answer
472 views

What is “Saturated CTR” of an optocoupler?

For example, in the datasheet of 4n27: . So what is saturated and what is non-saturated CTR?
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3answers
602 views

An opto-coupler/triac oddity — is it a problem, and is there a solution?

I'm using VO2223A opto-coupler/phototriacs to drive some low-current mains lighting with a PIC controller. All are working fine, but when the (DPST) mains switch is first turned on during system ...
6
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2answers
3k views

driving a relay with transistor and Opto-isolator

I am very new in electronics. I am controlling a relay with stm32 micro controller. For the isolation I have used a 4N33 opto-isolator. As my relay coil needs around 250 mA, I used a mps222 ...
17
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4answers
2k views

Why are relays so frequently driven by optocouplers?

Since the advent of the many microcontroller development boards, like Arduino, there have been a number of relay modules sold to drive mains AC loads. A lot of these seem to use an optocoupler, ...
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1answer
776 views

How do I select an optoisolator to both provide zero crossing to a uC and controll a triac?

This application note states that zero crossing detection can be achieved in an AVR with just a couple of resistors. However, it forgoes galvanic isolation and this is not acceptable for me. I would ...