Questions tagged [optoelectronics]
Components, circuits, or systems that convert between electrical and optical (light) energy.
269 questions
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Raspberry pi to sense voltages 12 to 24, what buffer is good?
Hello I’m looking to use my raspberry pi in an automotive application where it will be used to detect when the vehicles ignition is activated and de activated. I would like the system to be 24 volt ...
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Photodiode, analog electronic
I am a beginner PSPICE, in simulation electrical and electronics circuits. I want to simulate a schematic with the program Micro-CAP 12. I want to look for some graphics from a photodiode PIN which ...
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2
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464
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Optocoupler Reference
I want to use in my project an isolated optocoupler like this one to switch an IGBT.
In the following schematic, taken from this Vishay application note there's a "floating supply" in Vcc1 as you can ...
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3
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470
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Are optocouplers enough of a protection to sensitive electronics
There are certain lines in my car which I want to detect when hot. My initial thought was to hook a voltage divider to drop from 12v (or ~14 rather) to 3.3 and feed it to my pi but I soon realized ...
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786
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Ultra-narrow beam spread LASER diode
I want to build an optical position tracking system based on PSDs (Position-sensitive detectors). I searched online and found this PSD which has a sensitive area of 12 mm*12 mm. My goal is to allow a ...
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235
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What is this black, marking-less, 6-pin surface mount device?
Below you can see the device I'm trying to identify:
It is mounted underneath the expression pedal in one of these:
Basically, below the pedal there is a little plunger which gets closer or farther ...
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395
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Can I drive an optocoupler input with just 0.5mA (500 microA)?
Im trying to interface a keypad button in a device with a MCU, and they need to be in different circuits, with no shared GND.
This keypad button has 5V DC when not pressed, and 0V when pressed. I ...
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IR diode radiation spot area
How large is an IR diode radiation spot area?
I put some IR diodes (receiver and transmitter) in front of each other. I want each transmitter IR diode to only radiate on its reciever and not effect ...
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59
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Gate-Souce resistors needed?
I completed an IR emitter circuit with two selectable power settings. It's working on the breadboard and I'm asking if I need the gate-source resistors for stability? As the circuit is battery powered ...
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199
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Electroluminescent wire and EMC
I have been thinking about using EL wire in our house as a night light but I am concerned about electromagnetic compatibility and possible adverse effects on the inhabitants (we).
You can see these ...
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2
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300
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Photodiode not working in reverse bias
I'm using a photodiode module, model: coaxial InGaAs, Gtel.
I set it in reverse bias with 5V and tested it with a laser but it doesn't give any output voltage. Unfortunately I don't know the laser ...
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Optocoupler/isolater circuit for 24VDC sense that transfers switch status to 3.3VDC microcontroller
hope everyone is having a good couple weeks before Christmas, I was given this question for an assignment
How would you use an opto-isolator to sense a switch status in a 24VDC machine control ...
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2k
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Is this optocoupler driving relay circuit reliable and works great?
This is the circuit that I have, the optocoupler is an EL817 and the transistor is a BC817, the 24V relay is an Omron g2r_1_e, a 24V coil relay.
But when the optocoupler input is floating (not ...
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How do I model the optical coupling between two optoelectronic devices?
I'm building a circuit composed by two parts that are electrically isolating. One part has a LED (model: SIR333) and a phototransistor (model: SFH309FA). I basically have to model the optical coupling ...
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368
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Simple switch with TLP222A
Electronic newbie here.
I'm trying to use a TLP222A as a remote switch for a small signal (3V and about 150-200mA at most).
It's super simple, but I can't understand why the following happens:
I'm ...
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Are mechanical relay signal pins isolated from the output?
I am going to use a magnetic mechanical relay to switch 240v AC.
I am using MPC250D6Z05APT, in its specification it did not say that the 5V signal is isolated from its output upon failure of the ...
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523
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Optocoupler min collector-emitter voltage
I'm looking for an optocoupler but looks like I don't undersant their parameters well. What is "Optocoupler min collector-emitter voltage"?
For example, I found optocouplers like this but in the ...
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344
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How does one match irradiance to Luminous Intensity in Candela of source?
A light source has an Irradiance of about 1.6 W/m²/nm at wavelenght 385nm and an LED:
Peak Wavelength 385nm
Viewing Angle 30 °
Luminous Intensity 80 mcd
If this light source shines on a ...
user132893
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201
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Great Scott LED VU Meter circuit
I'm looking to complete one of my first electronics projects so I was looking for inspiration from youtube Great Scott and this project caught my eye.
In short, his project converts the stereo signal ...
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Can I use Highspeed Opamp as differential clock driver?
I want to use high speed Opamp LT1364 as +/- 15V clock driver of same voltage instead of typical CMOS / CCD clock drivers with lower voltage and slew rate.
CMRR : 90dB
PSRR : 100dB
Slew rate : 1kV/uS
...
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8
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4k
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Reflect IR beam off reflector instead of emitting straight to TSOP receiver
I have a working set-up to detect beam breaks using an IR LED, modulated at 36kHz, and a TSOP receiver connected to a comparator. It outputs the count via Arduino. The range is about the width of a ...
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532
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How to use 4N27 optocoupler? [duplicate]
I was wondering why the 4N27 optocoupler has a pin for base of the phototransistor - and of course how to connect it.
I've usually dealt with PC817 optocouplers and connected them according to the ...
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Signal low delay for specific amount of time / hardware - equivalent of Arduino pulseIn() function
I have a circuit similar to the following:
(Source: electronicsforu.com - Shadow Alarm: Light Sensitive Circuit)
In the circuit, the output from op-amp pin 6 goes low when a shadow falls or light is ...
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2
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273
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How does a fiber optic receiver convert the optical signal to an electrical signal?
A fiber optic receiver needs to convert the incoming optical signal to an electrical signal so it can be sampled. How is this achieved in practice?
I believe a photodiode is used, but would a ...
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Three terminal LED pilot. What's the matter?
Long story short, I've purchased a 24VDC LED pilot and I've got a 12VDC pilot with three terminals instead. I was wondering what are each one of those three terminals for, the terminals have standard ...
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233
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What could be the reason SPICE is outputting very different CTR curve for this optocoupler?
For a 4N25/26 I tried to plot the CTR vs LED Current graph by simulating the following circuit. To obtain results similar to the one in the datasheet I keep Vce constant at 10V and sweep the forward ...
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884
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Opto-coupler circuit - selection of resitor [duplicate]
I have a circuit like below.
I wanted to know how these resistance values were calculated. I wanted to use 12V/24V in place of 9V.
Let me know selection of opto-coupler and resistance value.
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242
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Interfacing a microcontroller digital IO
I'm working with some microcontrollers, and I'm quite confused about how to interface the digital I/O. I've already see some projects with opto-couplers on outputs, other ones with buffers, so I'm ...
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Relation for the current generated by a photo-diode in photo-conductive mode
If a photodiode with responsivity R is operated in photo-conductive mode with
reverse bias voltage Vb and load resistance Rld what relation gives the output current from the photo-diode flowing ...
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58
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Esp8226 with opto mosfet switch LBA110
I want to switch AC load by LBA110 because it has NC switch pole and tiny side. I tried to read datasheet, but with my bad knowledge about electric, I can not find out how to make it work. Is it work ...
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201
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Increase LED Brightness
The schematic shows one row of my 16(row)x32(Col) LED matrix. Each row has 32 LEDs.
I'm Scanning rows @ 1/16th rate.I'm using a PIC micro controller. I use 3V LEDs. The problem is LEDs are dim.
How to ...
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350
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What bias voltage is applied to a PIN photodiode when connected only to multimeter
If I take just a PIN photodiode (e.g. BPW34 FAS ) and connect a multimeter to its terminals to measure current, for example: expose the photodiode to the sunlight and read current of ~1 mA on the ...
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Photodiode current vs. irradiance and finding upper limit current
1.) What equation could be used to calculate, or make a decent estimate
of the current produced by a photo-diode from incident irradiance and its operating parameters. For example for this PIN photo-...
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566
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Reverse function optocoupler in series with physical NC switch?
I've read this answer
(reverse function optocoupler) but my case is different:
I've got a CNC mini lathe.
I have a limit switch on one of the lathe's axis ends (X+) wired as NC to my Gecko G540 ...
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Can't get my led bulb to turn on using triac and optocoupler
I have made the below circuit but my LED bulb won't turn on, although circuit works fine if replace the led bulb with a small led and ac supply with 5v dc supply.
Can someone guide me in a right ...
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627
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Driving IRF9530 MOSFET with 5V
I want to drive the IRF9530 P-Channel FET with 5V PIC microcontroller. My load is 3.2A. schemtic shows one row in my LED matrix. Scanning @ 1/16th rate, so peak current per LED will be 64mA and the ...
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2
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417
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Improve Brightness in LED Multiplex
I’m doing a 16 rows & 48 column LED matrix design. The attachment shows only one row & some columns.
I’m scanning rows @ 1/16th rate. Designed for 4mA average current to the LEDs. I’m doing a ...
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200
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Is this opto input current sized wrong and can it have such symptoms?
I have been using 4N26 opto for some time for a trigger input of a module. Vin is fixed 40Hz 0..5V pulse with %50 duty cycle. OUT goes to trigger of a module.
Below is the schematics:
Among ...
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3
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631
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LED Matrix Leakage LEDs
I'm doing a LED matrix design and it's a cathode row design. Attached is a picture of my matrix design.
The design works ok and I can show any pattern in the matrix.
The problem is when a leak LED ...
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what limits the maximum voltage of this optocoupler (6N137)?
In the datasheet it is stated that the maximum VCC voltage is +5.5V.(https://www.vishay.com/docs/84732/6n137.pdf)
Because ive been told to question everything (and i have enought of them to kill one ...
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Why isn't the saturation current of a photodiode the same as its short circuit current?
The formula I see everywhere is:
$$
I_{sat} = \frac{V_{bias}}{R_L}
$$
But this seems incomplete for the following reason:
The larger the resistance is the smaller the saturation current, it stands ...
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5k
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Optocoupler 24V input misbehaving
I have an optocoupler circuit that is used to accept 24V input (100 ms pulses) and interfaced to a microcontroller.
The schematic is as follows:
Opto: BL817C or TLP621.
TLP621 datasheet
As per my ...
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803
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Optocoupler to drive LEDs (maybe with transistor)
I wonder if there is some simple solution to drive LEDs powered from single rectified voltage.
Assume AC is 220 V, each LEDs is 3.0 - 3.2 V 150 mA. I reckon series connection made it simpler but not ...
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60
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How will the resistance of this Evaluation Module affect the measurements of the current produced by this photodiode?
A little context: This is part of a bigger project about glowing algae, my job is to design a photodiode array to measure the amount of light the algae produce in response to movement.
I have a good ...
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2
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5k
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Help understanding power ratings in optocoupler datasheet
I want to understand this the datasheet for the Everlight EL817 optocoupler but don't know what is the maximum power can the output hold.
I see an optocoupler as a kind of switch that closes a ...
user54073
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Better resolution with photodiode (LTR-536AD)
I want to build something like a fog-sensor.
I'm using a laser and on the other end (~20m) I have a LTR-536AD photodiode. I hooked the photodiode to an arduino and was monitoring the voltage.
My ...
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777
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Measure laser with photoresistor (LDR)?
I want to make a simple setum, where I can measure the opacity of air. I want to use a simple laserbeam, which I shoot across the room, and on the other side I want to measure how much is blocked/...
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163
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How is optimum series resistor of an optocoupler sized?
I want to learn how to size the series resistor for this optocoupler which has a high CTR.
I will use Arduino's 5V digital output pins for eight of this coupler so I really want to source necessary ...
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320
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Trouble changing an optocoupler without changing circuit functionality.
As a part of a circuit an optocoupler was driving the gate of a MOSFET as follows:
Now I need to change the above opto with a 4N46 darlington one.
I'm not familiar with these much and having ...
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1k
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What does "off-state output terminal voltage" in optocouplers mean?
I was looking at possible options of what optocouplers to use in my project. I was looking at these parts.
https://www.fairchildsemi.com/search/?searchText=MOC3023-M#N=&&Nao=0&&Ntk=...
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