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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63 views

Optoisolator not turning off

I'm using an optoisolator for high side switching a Nixie tube. For some reason, the optoisolator is not fully turning off, allowing the a very minimal amount of current to flow through the Nixie ...
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51 views

Need help on proper circuit connection

I am trying to test IGBT switching using the following circuit but the IGBT smoked out. I am using MSP430 with g2553 chip, NMK0505SAC dc-dc converter, FOD3184 optocoupler and IRG4BC20UD. Please help ...
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61 views

high speed optocoupler circuit

I have 4n35 optocouplers, I am using these to isolate a motor driver circuit and the Arduino controlling it. I put one on the slave select pin and one on the tx line to the motor controller (there is ...
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2answers
87 views

How to drive an IGBT with an optocoupler?

What's the proper schematic for driving the IGBT (IRG4BC20UD) from a microcontroller (MSP430-g2553) pin through the optocoupler (FOD3184)? I am going to design a full bridge inverter to drive 9W CFLs ...
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1answer
59 views

Will replacing the MOC3024 with MOC3021 make any change

I'm student of 10th grade and new to electronics I'm trying to make a switch to control appliances which runs on AC mains and I don't want to use any relay see the circuit diagram from the link to ...
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96 views

Optocouplers for purposes other than galvanic isolation?

In the diagram below there are two modules, A and B, which are separated by a physical distance of about 15m. Module A has a 12V DC power input. Module A powers module B (they share a common ground). ...
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78 views

Using an optocoupler to put an AC signal on a DC bias

Expanding from this question Can an opto-isolated input be analog?: Can you use an optocoupler to take an AC signal and attach it to a DC bias? More specifically, can you take something like a 1V ...
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82 views

Solid state relay (or equivalent/alternative) to drive 6V DC from a 3.3V micro

I have to open/close two wire from a closed device. I cannot open due to it's under warranty, and the only part that I can open and modify is an external button that connects the two wires. Firstly I ...
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4answers
168 views

Sensing analog voltage on Arduino without loading the input circuit

I want to design a voltage divider for my Arduino Analog input pin, to be able to sense the change in voltage in a 9V, 250mA circuit (without loading it). Ive programmed the Arduino so that as soon ...
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1answer
68 views

Application of AC optocoupler [closed]

I found this circuit for an AC optocoupler: For this circuit, what would be the criteria to choose the correct resistors and capacitors? Why were these values chosen? How do I select the right ...
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2answers
120 views

Are IC sockets suitable for mains voltage?

I need to derive a low-voltage galvanically isolated 50 Hz signal from 230 V mains. I'll use an opto-isolator for this. I'd like to use IC sockets for all ICs in this personal one-off project. ...
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157 views

Is this use of optocoupler wrong?

This is nearly not exactly how the circuit looks like, but I have a feeling that this circuit could cause problems while working. My feeling is that initially as Q1 would be in ON position, the ...
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134 views

Opto coupler schematic

I am analyzing following circuit, but I am not getting its flow. In the following schematic SW1 is coming from controller and connected to opto coupler ( cathode of LED ) and J4B is connected to ...
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82 views

Pull up resistor on Schmitt trigger IC input?

I have two different circuits on two different boards. The output of board A, let's say, is optocoupler based and hence, it has a pull up on it. This signal is connected to board B through an ...
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3answers
139 views

Debugging a PIC16F84A interface with a 4N25 optocoupler

I have a PCB board that I'm trying to repair, the principle of this circuit board is to switch an oven relays one at a time only with a constant rest time, and the switching time is predefined by the ...
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1answer
41 views

Opto-isolator flow in following circuit

In the OPTO-Isolator used above, I am not getting flow of ckt. According to my understanding, in case of PS8821-2, RD ( of MC ) will connect to SCL( of TPS2384 ) and MC_SCL ( of MC ) will connect ...
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4answers
114 views

Can an opto-isolated input be analog?

Title says it all: can an opto-isolated input be analog or are they intrinsically digital? Why: I am looking to purchase a relay control board and am deciding between a few options. Here is my ...
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59 views

Explain operation of solid-state relay

Link for Datasheet: http://www.ixysic.com/home/pdfs.nsf/www/CPC1230N.pdf/$file/CPC1230N.pdf This is the relay I am using in my circuit, but I am not getting how it connects/disconnects and flow of ...
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159 views

Relay alternatives that are silent and support 500mA+

What can I use as a silent "general-purpose" relay alternative? There are various scenarios where I will need a relay-like device that allows me to control one circuit with a separate isolated ...
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2answers
55 views

Do I need a current limiting resistor for MAX383 digital logic?

I'm trying to control a MAX383 analog switch using a Raspberry Pi, through an optocoupler (Sharp PC817), to separate digital logic from the analog section. On the analog side, I will have a bipolar ...
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1answer
42 views

LED with opto-isolator does not work

schematic_1 schematic_2 schematic_3 If I wired like schematic_1, L1 and L2 are lighting. But, in schematic_2, L1 is not lighting even though L2 is lighting. When I wired in series as ...
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121 views

When do we prefer isolator over optocoupler?

Today I have learned that a device called "isolator" exists (eg: SI8712CC-B-IS). Its function is very similar to the optocoupler's. On the good side, it is much much faster. While it is very hard to ...
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111 views

Under what conditions does an optocoupler work fastest?

I want to use the optocoupler FODM452R2 in my design. I want this optocoupler to run as fast as it can (i.e.; work with minimum propagation delay and least rise/fall times). What is the optimum R1, R2 ...
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100 views

Is it possible to use capacitor for isolation instead of optocoupler?

I designed a Buck converter which drives several LEDs. The PWM signal, which has a certain fixed duty cycle, is generated by a 555 timer IC. The circuit which drives the Buck MOSFET, including the ...
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1answer
133 views

Water pump with opto-isolator MOC3063M and triac BT137

I have designed a circuit for water pump. Please correct me if I am wrong with schematics. The idea is to to switch on/off AC motor pump with 230V and 7.5A, when water is detected. I have used ...
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1answer
118 views

Normally closed SSR won't work with grounding out a magneto's primary to ground

I've been trying to find a device that will ground out a magneto's coil (primary kill wire) in a normally closed state without using a mechanical relay because I want my circuit to be all solid state. ...
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124 views

Arduino controlling high voltage DC source, Opto-Isolator

I need to create a circuit that I can use an Arduino to control a 400~500 DC voltage source. I am not used to opto-isolators, but I was thinking about using it to separate both systems. But I cant ...
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29 views

How can I control an IR204E in a PK543A to remotely operate this apartment door buzzer? (What relay do I need?)

My apartment door 'suite station' (buzzer) is a TekTone IR204E (pdf). It has an option for talk, listen, and open door. It contains four wires labeled 1, 2, 3, and X. My research leads me to believe ...
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1answer
60 views

How does this motor drive circuit work?

The Drive terminals are connected to a PWM signal generated by an arduino micro controller. The purpose of this circuit is to isolate the arduino from the motors to avoid too much current being drawn. ...
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1answer
24 views

Cell Voltage Relaying in a Battery Management System

Question: If I have 48 lithium cells connected in series as a pack, how would I best go about physically implementing a system to measure, isolate, and relay cell voltages to a centrally managed ...
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84 views

Dimming SSR Circuit - Verification

I am designing an SSR circuit for the purpose of controlling Christmas lights. Specifically I have the following two goals. Switching & Dimming incandescent strings Switching LED strings - I ...
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3answers
118 views

Very wide range high voltage measurement with optical isolation

I have a voltage source I'd like to measure, it is from 0V to 1kV, any value in that range. The accuracy isn't that important, but measuring with an accuracy with 1-5% would be perfect. This has to be ...
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76 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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2answers
182 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
219 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
230 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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298 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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1answer
87 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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117 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
100 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
100 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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1answer
239 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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0answers
84 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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2answers
745 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
229 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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73 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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275 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
341 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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531 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 ...