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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1answer
207 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 ...
0
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2answers
60 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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3answers
102 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
144 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
113 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
106 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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2answers
92 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
79 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
78 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
88 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
139 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
146 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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3answers
113 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 ...
0
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3answers
72 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 ...
2
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3answers
177 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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1answer
93 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
105 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
75 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 ...
2
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1answer
279 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
95 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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3answers
173 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 ...
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0answers
36 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
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1answer
142 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 ...
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0answers
207 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
95 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
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2answers
246 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 ...
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0answers
295 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 ...
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2answers
84 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
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2answers
134 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 ...
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0answers
73 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 ...
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6answers
351 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 ...
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0answers
170 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
106 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
185 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
236 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
46 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 ...
2
votes
1answer
206 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
164 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
183 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
41 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
140 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
115 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) ...
0
votes
1answer
952 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
288 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
535 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 ...
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0answers
268 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
51 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
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2answers
815 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
110 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
457 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 ...