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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47 views

Can I create a totem-pole structure by using two optocouplers?

I have two optocouplers. One of them uses NPN transistor and the other one uses PNP. Each of them explicitly give the base pin of their BJTs out. Can I make a totem pole structure by connecting them ...
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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 ...
6
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3answers
4k views

TRIAC dimmer, circuit design help (resistive load)

Okay guys, I've been tasked with making a light-dimming control system for a 240V heat lamp dissipating around 250W. I need to adjust the heat output on the lamp by control from a microprocessor. I'm ...
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2answers
466 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
68 views

Need an optocoupler for getting directly proportional output galvanically isolated from the DC input

I want to use an optocoupler to linearly step down a DC voltage which willy vary from 0V to 400V. That is, I want the output to be directly proportional to the input and I want it to be galvanically ...
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2answers
82 views

Detecting Zero Crossing of Mains (Sine and Square Wave)

I need to design a circuit that can measure and output pulses for a MCU at zero crossing of 220VAC waveforms. The application requires that that both square wave waveforms and sine-waves should work. ...
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3answers
67 views

Operation of PC817

I am studying a DC-DC converter circuit design which has PC817 photocoupler in it. I am confused with the way PC817 behaves. My friend says that it is an analog photocoupler. I have tested it myself ...
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2answers
179 views

Opto-coupled RS-232 receive circuit

I am looking into a implementing a low-cost RS-232/422 opto-coupled receive circuit. The aim is surge protection and tolerance to DC offsets. The challenge is that the inputs should be completely ...
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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
43 views

How to use LM56 to switch on/off a 2kW heater

I have an oil heater at 220V/2000W so lets say 10A. I was thinking of creating a circuit to switch the oil heater on/off with a LM56 (http://www.ti.com/product/lm56). Is it possible using a relay or ...
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2answers
77 views

Optoisolation and Mosfet combo

I want to switch a Thermoelectric Peltier Cooler (TEC1-12705) (12V - 77 Watts) using an Uno. I am an engineer but not an EE so I could use some guidance on circuit setup. There was a very good ...
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1answer
118 views

Two circuits with different voltages - should I use a transistor or an optocoupler as a switch

I am doing a project using the output of a Raspberry Pi GPIO pin (3.3V) to power a 12V remote control. If the two are on different circuits, can I use a transistor to switch on the 12V circuit or do ...
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1answer
58 views

Using PS2501A-1-A Optocoupler. Need help understanding datasheet

I'm experimenting with circuits to trigger my camera shutter and camera flash. My plan is to build a 2-stage trigger for high speed photography that triggers the camera a fraction of a second before ...
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3answers
76 views

Safe microcontroller input from 8.4V circuit

I have an airsoft rifle which uses an 8.4V battery to drive a motor when the trigger is pulled. The circuit is that simple, just a battery, motor and switch - there's also a 15A fuse. I want my ...
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2answers
362 views

How to combine PC's power and HDD LEDs?

I'm going to buy a PC tower case which has only one LED intended to be used as the power LED, thus no HDD LED is available. My intention is to have that single LED at about 50% of its intensity when ...
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0answers
51 views

Optocoupler for AC to DC current sensor

I am designing an AC to DC current converter. The specifications are as follows: input: 0 to 5A output: 4 to 20mA supply: 230VAC Now I want to isolate the input and output. What would be a ...
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1answer
289 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 ...
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2answers
402 views

Creating an opto isolator board for Raspberry Pi

I have a relay board which I bought from dx.com and I am not sure about its reliability. If it fails, then it may harm my Pi right? So I googled around and read that opto isolator provide complete ...
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2answers
147 views

Simple light bulb operated by button and optoisolator triac

I'm new to the world of electronics and I have a quite simple question. Can I control my light bulb with something like this schema? Power source is regular AC 230V (~320Vrms) source. Here is ...
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1answer
312 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 ...
2
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1answer
318 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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2answers
60 views

opto voltage specification question

The datasheet is here http://www.ssousa.com/pdf/SLC800.pdf . I need help on the following: Where is the maximum operating DC voltage is specified? It appears to be 500VDC but I am not sure. I ...
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4answers
2k views

Optocoupler with phototransistor base lead

I'm thinking about using 4N25 optocoupler - it has a separate lead for base of phototransistor. How do I use it? I suppose I can't leave it floating?
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2answers
232 views

Optocoupler design

I need to design a MOSFET control circuit which is driven from an FPGA through an optocoupler. Following are the conditions required to be met in my design: When the power is up initially and the ...
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2answers
52 views

Flipping Output Logic

I have the following circuit: The diagram above has a pot between VCC, LM393 and Ground, on my board pictured below this is replaced by a voltage divider with two 10k pots. It looks like this: ...
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1answer
214 views

Isolating PWM From H-Bridge

I have a H-bridge based on FAN7392 drivers. This bridge works at 350VDC to output a approximately 240V 50Hz waveform. This circuit is isolated from rest of the board and I would like to maintain the ...
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1answer
205 views

Optocoupler TVS Protection for digital input module 24V 220V

I have two digital input modules that must match: IEC 61000-4-2 ESD Contact 6kV and Air 8kV IEC 61000-4-4 EFT 1kV IEC 61000-4-5 Surge Line to line 0.5kV and Line to Earth 1kV First module: 32 digital ...
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2answers
400 views

How can I use optocouplers with function generators?

I am using optocoupler PC817 to create optical isolation between my digital signal and arduino due and arduino mega 2560 . And I am using external pull-up resistor connected with 3.3 V (to pull up ...
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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
175 views

Why I can't get a clean signal from my opto-isolator?

I am trying to get working my first Mosfet H bridge. My H bridge characteristics are: 12v power supply 3.5A max current I need to control the bridge from a microcontroller 5V output About 30KHz PWM ...
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2answers
176 views

Debugging a garage door opener circuit with an optocoupler and mosfet

There seem to be many related questions, but I can't quite find the answer I'm looking for. I've got a garage door opener switch. There's 16V across the wires, and when you short them, the garage ...
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3answers
410 views

How do I drive a MOSFET working under high voltage while keeping it insulated from the rest of the circuit?

I want to drive a MOSFET with a 50Hz, 50% duty cycle clock pulse. The voltage to be switched is as high as 300V DC. The section inside the dashed lines will stay electrically isolated from the rest ...
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3answers
247 views

How to drive optocoupler with BJT properly [schematics]

Recently I asked a question about optocoupler: Shematics: optocoupler controls a transistor and doesn't work as expected I have one more question related to the topic. PWM input comes from the ...
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4answers
195 views

Shematics: optocoupler controls a transistor and doesn't work as expected

I'm applying optocoupler TLP521 to decouple microcontroller Atmega88 (on the left of the schematics) from the power circuit. I have a problem understanding why the schematics below doesn't work in ...
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2answers
112 views

How are the values for the resistances and capacitor chosen in the circuit below

In the circuit shown, the optocopuler is used as a solid state relay and the triac acts as a switch. i would like to know how the resistor values and capacitor value was chosen.
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1answer
130 views

What are important design parameters for Opto-isolators? [closed]

I want to use an opto-isolator in my circuit. I found Opto-isolator 6N135 matching with my design voltage requirement. datasheet (http://www.vishay.com/docs/83604/6n135.pdf). But datasheet seems to be ...
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1answer
94 views

What is this Circuit's function? Does it involve Isolation?

My question is: Does this circuit isolate the "X Volts" lines from ground (1) If not, how should I implement an opto-coupler to provide isolation between the data lines ("X Volts") and ground? ...
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1answer
179 views

LED and photodiode characteristics at very low currents

I'm trying to understand the coupled characteristic of a classic 4n35 optocoupler, used in reverse biased photodiode mode (I'm only using the B-C junction only). Over 1mA input forward voltage, the ...
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2answers
987 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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2answers
200 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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1answer
154 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 ...
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3answers
145 views

High frequency mains sensing

I want to sense mains voltage at a frequency faster than 5000Hz, with a microcontroller. The idea behind this is to visualize the actual shape of the AC voltage, and eventually to compare it with the ...
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3answers
99 views

Light controlled h-bridge?

I was wondering if it would be smart to control a power H-bridge, with light. Imagine an opto-isolated power stage, where the opto-isolators are sawed in 2 parts connected by an optic fiber. I think ...
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3answers
2k views

Shift Register output to Relays

sorry for the length. This is a continuation of my recent question. I have an optocoupled 8-relay board that I’m trying to connect to my microcontroller. I have placed a 74HC595 shift register inline ...
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3answers
253 views

Optocoupler Issue - Not sure why it isn't working - help needed [closed]

I have used an optocoupler/isolator before in a similar circuit, can't figure out why it isn't working in this instance, any help would be much appreciated. I am using the Siemens SFH615A, link to ...
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2answers
141 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 ...
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4answers
7k views

How do I select the accompanying components for an optocoupler?

I'm using an optocoupler (MOC3021) to sense the On/Off state of an electrial appliance using a microcontroller ATmega16L. How do i go about doing this? My mains supply specs are 230V, 50Hz. How do I ...
2
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1answer
525 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 ...
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2answers
151 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 ...
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1answer
167 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 ...