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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40 views

Is it safe to use Vcc from processor side or use another supply

I have a Toradex Carrier Board. It has few GPIO pins. I need to use them as inputs. In our application we will give 12v input but as the pins can only take 3.3v so I have to design a simple board ...
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0answers
33 views

Fixed ratio dc to dc converter with isolation [on hold]

I am relatively new to electronics.I need to have a fixed ratio DC to DC converter with isolation in my design.(The ratio is approximately 6. For eg, 24 V input must output 4v). Is there a way to ...
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1answer
100 views

Cheap and small alternative to optoisolators: is there any?

Typical opto has several kV isolation voltage (which is not always needed), has relatively big cases (TLP291 in 4-SOIC is one of the smallest as I know) and typical price up to 1 USD in small amounts ...
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2answers
63 views

Opto-coupled PWM

Following on from this question: I have the task of setting a voltage V_set using PWM. The challenge arises from the fact, that V_set is referenced to a different ground than the MCU. My currently ...
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2answers
39 views

Opto-coupled PWM output

I have a circuit with two different ground levels. Using a optocoupler, I want to translate a PWM signal to the new ground level. Does there exist a easier method than the following? (Ideally with ...
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0answers
28 views

Optocoupler in reverse-active mode

I was recently reminded that BJTs can be used in reverse active mode. Can somebody enlighten me whether and to what extent the same is true for optocouplers? Do the same limitations apply to reverse ...
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2answers
30 views

Using a IR2125 to drive a MOSFET gate

I've done a good bit of experimentation and learned quite a bit from other members of the site here. I've built several circuits that drive an N-channel MOSFET on the "low side". But to build an ...
21
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5answers
7k 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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4answers
59 views

What's the difference in a digital optocoupler and a non digital

I'm looking at 2 different optocouplers.The Avaago ACPL-K44T and the ACPL-227. The ACPL-K43T states that it's a digital opto-coupler while Avago ACPL-227 doesn't. Schematically, they're a bit ...
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2answers
90 views

SCR which can conduct 230V AC at Zero gate voltage

As per the image, an operation for manual & Auto logic where manual can overwritten auto command and vice versa. The red circled area is an SCR(Silicon Controlled Rectifier). I'm looking for a ...
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0answers
39 views

FET Default on, Turn off with Optocoupler

I am relatively new to electronics and having trouble designing a circuit for a redundant power supply, which I would like to switch to battery if the voltage regulator turns off. This will be ...
0
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1answer
36 views

Triac connected CFL or Incandescent bulb or Electronic ballast tubelight FLASHES

I am building a triac based dimming circuit. Everything is working fine. The problem which I am facing is when I turn on or off any appliance (NOT CONNECTED TO TRIAC) in my any other room, the ...
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3answers
191 views

Interfacing open-collector optoisolator to 3.3V microcontroller

I have a bit of a puzzle on my hands trying to interface a Fairchild MID400 optoisolator (popular "logic level" optoisolator for mains detection) to a 3.3V GPIO pin. The MID400 is a 5V part [*] and ...
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2answers
40 views

Am I able to make a comparator on optocoupler?

Initially I'm trying to make over current protection scheme. So if the R2 current (and therefore R2 + D1 voltage) will go higher than some certain level I should have a signal to break the circuit. ...
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1answer
35 views

AC Line detection using MID400

I want to detect an AC Line Voltage (230V RMS, 50 Hz) and interface it with a microcontroller. I am aware about two solutions. Using an optocoupler like PC817 [datasheet] using MID400 ...
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2answers
86 views

Isolated 1-10V (or 0-10V) output

I need to control an LED driver with analog 0(1)-10V control input. This control device should be very cheap and compact so until now I made a schematic which uses the fact that those drivers have ...
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2answers
66 views

Is hobby relay adequate for air conditioner automation with microprocessor

I'd like to use a Beaglebone Black(3.3v Logic) plus a 3.3V to 5V logic level shifter(74HC125) to control an opto-isloated Songle Relay that has the following specs: Rated Resistive load: 10A ...
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1answer
29 views

AC Analog Isolation

Please excuse my limited knowledge of electronics, my problem is I've a circuit which is driven by a variable AC signal using LabVIEW it ranges from 100Hz to 100kHz (I can lower this to 30-50kHz if ...
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1answer
125 views

(schematic) Using a micro controller to drive Opto-coupler > 555 timer > MOSFET

I'm trying to use a micro-controller to activate an opto-coupler connected to 555 timer which is connected to a MOSFET. The circuit will drive a solenoid which draws 2amps at 12v. I'm new to circuit ...
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1answer
56 views

Which isolated ground should I use for an RF can/shield over an optically-isolating component?

I'm building a PCB that uses an optically-isolated voltage-sensor IC which takes an input voltage of -0.2V to 0.2V on one side and generates an isolated, proportional output that ranges from 0V to ...
0
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2answers
100 views

AC/DC optocoupler wiring

Looking for some clarification on the proper wiring of an AC/DC optocoupler (HCPL3700, datasheet) when working with 120vac. From what i read online it looks like a need a resistor on the hot side ...
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1answer
83 views

It makes sense to use an optocoupler with the same ground?

I've a microcontroller and I want to have some protection for a digital output, but I only have one power source so I was thinking on use a diode to prevent backward currents. It's reasonable to use ...
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3answers
196 views

Why does this optocoupler circuit work without getting destroyed?

This circuit is being used for mains detection. Input is being fed directly from 220V 50Hz mains and output goes to Arduino which is running on 3.3V. Theoretically the optocoupler LED should burn out ...
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1answer
30 views

Smps feedback method [closed]

Hello all I have seen some smps use output secondary for feedback using via opto coupler. And in other smpa i have seen they use primary aux winding feedback only. Which one is good to use and easly ...
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2answers
285 views

Driving a 24V isolated load from a 3.3V MCU

I am looking to drive a 12-24V purely resistive load from a 3.3V MCU. I would like to use an opto-isolator to separate the circuits electrically. I've drawn up the following circuit, but I'm not ...
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1answer
114 views

Substituting Arduino for ESP8266 in a (Yet Another!) Garage Door Controller

I have a garage door opener with two leads that will activate the motor if the leads are shorted. I hooked my multimeter into the leads and measured ~24VDC and triggered the motor ~50mA. Using an ...
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1answer
45 views

connect a triac to optoisolator

I want to use a current sense from the CR2550 connected to optoisolator LDA 110 and drive the gate of a triac. How do I connect these two systems with out killing either? Update Thanks for all the ...
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1answer
52 views

How to calculate the resistors to convert 24V to 3.3V using a TCMD4000

I would like to convert a 24V signal to a 3.3V signal using a TCMD4000 optocoupler. Datasheet: http://www.vishay.com/docs/83513/tcmd1000.pdf How can I calculate the resistor's value on the input ...
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2answers
33 views

FOD053LR2 Opto coupler resistors

I have a opto coupler to detect 12v and use this on a micro controller at 3.3v Used the 4N25 before and they worked fine but i switched to the FOD053LR2 wich has 2 opto inside for better space usage. ...
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3answers
124 views

Difference between optoisolator(optocoupler) and solid state relay?

I have been looking into relays and optoisolators. I am aware that there are different optoisolators, with some having a transistor on the detector side which allows current to flow in one direction ...
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2answers
79 views

AC dimmer- triggering triac using moc3041. lamp always remain on, and does not change its intensity

Below is schematic. 1) Problem is lamp always remains on,even if i haven't provided the Anode A terminal with power through micro controller. 2) Also please explain me the need for R7 resistor. 3) ...
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1answer
48 views

How to connect stages in digital logic?

Let's say I have a logic stage doing an operation on 2 inputs, giving me an output. How could I use this output to forward it into another set of logic stage, without having to put everything in the ...
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1answer
55 views

Optocoupler delay off MOSFET solenoid

This is to trigger a 12v solenoid (acting as a laser shutter) with 5v (JP2) thru an optocoupler. The problem is 5v line have bit fast interruptions on a laser show, so I'd like to add a bit of delay ...
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2answers
62 views

Using AC current to trigger Triac

I am trying to simulate the operation of an optocoupler with a triac to trigger the triac using the AC current. I have come across a few circuits that are all similar: My question is regarding the ...
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1answer
75 views

Is this an optocoupler ans how do I identify the pins?

I bought an Arduino starter kit with some basic components, and I know among them is an optocoupler. I need one for my project, and the only thing resembling it is a chip marked 'L1513 LTV4N35.' How ...
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2answers
196 views

In an isolated SMPS feedback design, how could optocoupler latency be higher than the switching period?

I often see this in practical SMPS designs. An optocoupler & voltage reference pair is used for informing the controller section about the output voltage level. However, when I read the datasheet ...
3
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3answers
104 views

Understanding optocoupler performance with collecor or emitter resistors

When using an optocoupler, is there a difference performance'wise whether using a collector or an emitter resistor? When using a normal transistor the base to emitter voltage gain is approximately 1, ...
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1answer
47 views

Reading ECU tacho signal with PIC MCU - noise issues

Am trying to read the frequency of a 0-12V square signal generated by a motorbike ECU with a PIC. Range 20Hz-300Hz I'm getting strange intermittent noise on the output of my optoisolator, and wondered ...
11
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4answers
26k views

Digital Dimmer With Microcontroller

I want to build a digital dimmer for resistive Loads. I have found this circuit for that: The input voltage is 220VAC 50Hz. The red box in the picture is for ...
0
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3answers
168 views

How to drop 170V DC to 50V?

I have old flash that generates about 170V on it's trigger when it's charged and ready to fire. When flash fires, voltage drops to zero, and rises to 170V as flash charges... I need that flash ...
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3answers
64 views

Wiring an optocoupler to have both inverting and non-inverting output

Can an optocoupler be wired to give both inverting and non-inverting logic output without additional active components? I'd like to avoid using an inverter if possible, but also curious as to whether ...
4
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1answer
188 views

How do I choose an optocoupler for (19200 baud) serial communication between Arduino and RS422 transceiver?

I wish to read data from a Fronius solar inverter via the Fronius RS-422 Com Card option (part# 4,240,001). 1000 meter cabling length The Fronius communication uses a 5-wire RS 422 interface (`RX-`, ...
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1answer
381 views

How to fix Arduino optocoupler + LED that doesn't light up?

I'm having a hard time understanding how an optocoupler works. I made a circuit based on example 15 if the Arduino projects book. Instead of trying to hack a button, I'm trying to just light an LED on ...
4
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1answer
7k views

How do I choose my optocoupler to drive a solenoid with a MOSFET?

I need to drive a solenoid with a MOSFET. The solenoid is an 8W solenoid and it will be connected to a +12V voltage. And this drive command have to be isolated with an optocoupler but I don't know ...
5
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4answers
8k views

120VAC 60Hz Zero Cross Detector

I'm designing a digital phase-controlled light dimmer, and I need a zero-crossing detector circuit. From what I've read, it's a bad idea to wire the AC main directly to the microcontroller through a ...
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3answers
15k views

How to connect a Inductive Proximity Sensor Switch NPN DC6-36V to PIC18F4550 5V

I have got a LJ12A3-4-Z/BX Inductive Proximity Sensor Switch NPN DC6-36V with this Specifications: Model: LJ12A3-4-Z/BX Theory: Inductive Type Sensor Wire Type: Cylindrical DC 3 Wire Type ...
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1answer
106 views

How do I calculate maximum frequency supported by an optocoupler say for example PC817 and what factors it depends on? [closed]

I am currently working on isolating SPI bus.The SCLK for my non isolated version of design is 5MHz .How do I calculate whether the optocoupler is suitable for operation at this frequency of ...
0
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1answer
190 views

How to provide an isolated ground for Arduino?

I am designing an EEG circuit at home using an Arduino. Now, the circuit calls for the use of a battery and an optocoupler-isolated ground for safety reasons. I am planning to use Fairchild ...
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3answers
170 views

Optoisolator, did I connected it right? (Arduino Uno)

Here is my connection for optoisolator, 2 wires, yellow and red are for AC current. Other 3 in my arduino, orange pin 2, blue ground and red 5V power. And ...
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2answers
172 views

How to test if zero crossing is working?

I used circuit like this: On led I get: 3.3 mA and 1.3V What is the best way to test if zero crossing works with arduino or multimetar?