Questions tagged [optoelectronics]

Components, circuits, or systems that convert between electrical and optical (light) energy.

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Help modifying this circuit please [closed]

This is the circuit https://www.instructables.com/How-to-sense-220-V/ I can't find this phototransistor https://pdf1.alldatasheet.com/datasheet-pdf/view/45410/SIEMENS/LPT80A.html But I can get this ...
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How to drive this specific laser

I've done just a circuit to drive an old laser and it was like this one: I was wondering if it could be suitable for driving the laser whose datasheet is reported below. I have these requirements: ...
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Measuring low lux with ambient photodiode

For my application, I need to detect two light levels: pitch black (close to 0 lux) and a low ambient light level of about 0.1 lux (or higher). It seemed like the BH1680FVC ambient light sensor was a ...
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How to choose a phototransistor or photodiode?

I've found a photoresistor (yes, resistor, probably 30 years old) in my scrap box, attached it to an ATtiny as ambient light sensor, with a 100kΩ resistor as voltage divider towards +5V. On power on, ...
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2 votes
2 answers
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BT136 TRIAC waveform

I am using a TRIAC to switch an AC signal (a typical example is shown in question Triac Switch Circuit using MOC3021 and BT136). When a BT136 TRIAC is used to switch a pure sinewave signal, I want to ...
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7 votes
2 answers
906 views

How can we explain this strange phenomenon with an optocoupler switching?

Two optocouplers are connected according to the circuit below. The input voltage across the first optocoupler is a true square wave (3.3 V amplitude). The first optocoupler is an open collector output ...
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DVD burner laser identification

I just disassembled the DVD writer from a laptop and scavenged some parts. Around where the laser and mirrors and opto stuff are packed together, I extracted these parts. Which one is the laser diode ...
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Does this two opto-isolators circuit versions work the same way?

I'm doing a circuit to control a 10W Led driver by an MCU, and I need both circuits isolated from each other. So I need one pin from the MCU to control the led brightess by PWM (Arduino normal PWM ...
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3 answers
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What does the VCC pin do in this Optocoupler?

I have this optocoupler, and I am trying to figure out how it works. What is the VCC pin supposed to do? How does it supply current to the gate pin of the transistor? https://www.digikey.com/en/...
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3 answers
186 views

Using a LED as a debug serial port

I want to add a debug serial output port to a device that's sealed in epoxy. I plan to use one of three existing 3mm LEDs (red 617nm, green 568nm, or yellow 588nm), ±30° angle, that emerge from the ...
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If composite transparent materials thermal and electrical conductivity can be adjusted t what would be benefit?

Will it be provided less thermal and electrical gradient to support less dissipative system development for opto-electronics and related technologies? For thermoelectric design how it cold be ...
4 votes
7 answers
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Is it possible to control the frequency of light?

I mean, controlling directly in the source, not filtering the light or arranging density of the medium. For example, brightness can be controlled by current or voltage directly. However, when I came ...
4 votes
2 answers
1k views

Can anyone identify this chip which I think to be an optocoupler?

I'm trying to troubleshoot a Renishaw H-2000-5062-07-A optical receiver for a tool piece used in a milling machine. It has several of these 8-SOIC(?) parts and I very much suspect that they are ...
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How to track, measure, manipulate and/or synchronize the phases of trapped ion qubits [closed]

I am working on a simulation of the Honeywell trapped ion quantum computer. The papers say that it tracks the phases of the qubits using "opto-electronics" but it doesn't give any detail.
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2 answers
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Looking for 5mm discrete multi color LED [closed]

I want to make an electronic version of the Master Mind game as a hobby project. The challenge at the moment is to find right type of LEDs for the job. Below you ...
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1 answer
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Why are low band gap semiconductors (like silicon) not ideal for most solar cells? Are their atoms ionized by higher-energy photons?

Most sources on the web say that 1.3 eV or 1.4 eV is 'ideal' for most solar cells... What happens to lower-gap, gapless or overlap materials (conductors)? Are they ionized, rather than sending their ...
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1 answer
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How to know which opto-coupler is suitable for high current application?

I would like a suitable opto-coupler to use as isolation from a 12V and around 30A current and another for 5V and around 30A. Are there any good opto-couplers for those ratings?
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SSR for Attiny85 using Optocoupler and Triac

Looking for some advice, I am trying to create an onboard SSR to control the switching of a 120VAC load (heater/lighting), with an operating power of around 1500W max. I chose the following parts and ...
1 vote
3 answers
671 views

How to know the minimum LED current of an optocoupler?

I am going to need to use an optocoupler to isolate two circuits in two situations. In both situations, a MCU GPIO will be driving the LED of the optocoupler to send a signal on the other end. I am ...
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What is wrong/missing from the process subsystem? [closed]

My teacher told me to reconsider the process subsystem but I'm not sure what is really missing from it. background story: when a guy is standing on the porch, the LED lights up
6 votes
4 answers
3k views

What is the purpose of using an analog optocoupler?

What's the purpose of using an analog optocoupler in this circuit? Why not a digital one? An industrial battery charger. Normal operating voltage to monitor ranges from 120 V (Battery low) to 180 V (...
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2 answers
163 views

Amplifying a small signal from a phototransistor

I am building an amplifier for a phototransistor. It works well under normal lighting conditions. In my application, the light is very dim and barely produce any readable output. I tried to increase ...
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What is this component ? Negative tiny LCD glass?

I disassembled a ceiling projector clock to find out how it achieves its projection. I found a very small screen (or glass, see image) backlit by an LED. To build some projecting stuff, I would like ...
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2 answers
1k views

How do I simulate a short/open circuit in LTSpice?

I am trying to simulate open/short conditions for testing an optoisolator circuit I'm building. Essentially, I need to simulate SHORT and OPEN in order to verify that what I'm designing will output ...
1 vote
1 answer
60 views

Opto-Isolator FODM 8071 switching noise at output Issue

I am working with Logic Gate Output Optocoupler. I have tried removing 15pF capacitor but it didn't made any difference. On output port it is generating noise Any help would be appreciated..! Thanks ...
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1 answer
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How does this optocoupled smoke sensor circuit work? [closed]

This is an optocoupler module consisting of an infrared LED coupled to a phototransistor as smoke sensor. I got this circuit from this site. According to T.K. Hareendran says: For optimum ...
26 votes
7 answers
5k views

Is it possible to generate light with an antenna?

An antenna (e.g. a dipole) is able to radiate at a certain frequency thanks to the EM field generated by a current provided by a signal generator at such a frequency. So, for instance: Voltage source ...
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6 answers
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Why do we have a limited bandwidth in electronics?

I've been looking around a bit on optical communications and it is said that the main advantage in using optical communications, namely optical fibers, lies in the gigantic bandwidth available, when ...
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AQW610EAH-PhotoMos Relay

Can we apply voltage across 1 and 2 pins to control normally closed (N.C) and to pins 3 and 4 for normally open (N.O) at the same time in AQW610EAH ICs (pin diagram of that IC above)? Or only one N.C ...
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Can I use 1 optocoupler to drive 4 MOSFETs?

I've this circuit and works correctly, now I need to control 4 MOSFET instead of 2, is the second schematic correctly?
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1 answer
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Adjusting Voltage regulator with PWMed optocoupler

I have LD1084V adjustable voltage regulator powering servo and want to control its output from MCU. Optocoupler should behave as variable resistor so my thinking was : I am mainly concerned with gray ...
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1 answer
85 views

Opto-isolator/ optocoupler for electric isolation in IC design

I came across while reading the opto-isolator technique used for electric isolation in embedded systems/ Integrated Circuits design that " Opto-isolator is not recommended for electric isolation ...
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2 answers
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Help using an FOD3182 OptoCoupler

So this is the Optocoupler I will be using: https://html.alldatasheet.com/html-pdf/505064/FAIRCHILD/FOD3182/978/2/FOD3182.html My question is with the schematic of the data-sheet. Using Ni-multisim I ...
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263 views

How can I test a TLP582 optocoupler?

Have few of these components (TLP582) and I need to design a test circuit to test its functionality. Datasheet of TLP582 I have no idea how to make a circuit for this. What should I be testing in an ...
2 votes
1 answer
118 views

Driving a 14-pin with DFB laser using D2570H

For our project, we would like to use the D2570 DFB laser from Agere system since it has a built-in photodiode with a TEC sensor, thermistor and a bias-tee embedded in an 'all-in-one' package. However,...
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1 vote
1 answer
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Circuit to replace a relay

I want to make a simple ladder circuit to control the on and off of a light bulb using 2 switches, but I am going to manipulate one of the switches by means of a microcontroller, and also I don't want ...
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1 answer
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Understanding peak repetitive surge current

I have moc3021 optocouplers. The data sheet says it has a peak repetitive surge current rating of 1 amp, 120 pps. I was hoping to use a microcontroller to control 24V .800A AC with this optocoupler. ...
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2 answers
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Best way to AND all connected inputs to one output

I have an CNC router with 7 x SN04-NPN sensors connected in parallel with one control board input. The problem is obvious, i got random false endstop triggers due leaking of SN04. I know i should have ...
3 votes
3 answers
1k views

Position of current limiting resistor

I am designing a digital output circuit. I got confused about the position of the current limiting resistor of the transistor. I would like know where it should be. (After or before the pull up ...
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1 answer
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How to compare OLED and LCD brightness

I am trying to build a night clock projector, inspired by this project: https://microengineer.eu/2018/05/01/diy-night-clock-projector/ As I am more a computer scientist than an electrical engineer, I ...
6 votes
1 answer
101 views

Ham Transceiver to computer Interface design question

I am building a Ham transceiver to computer interface, which has the RS232 port controlling the PTT on the radio. The circuit currently calls out for a 1.2K resistor in series with the RTS line and ...
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1 answer
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Photon lifetime in an optical cavity

Hi I have the following problem and data for an optical cavity. Length \$ L=100 \mu m\$ Reflectivity \$R=0.33\$ Refraction index \$n=3.6\$ Inner losses \$p_i=20 cm^{-1}\$ Now I have to determine the ...
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Getting the optical power of a UV-LED using a spectrometer data

if it is possible can you let me know the way to get the radiated power of a UV-LED using the output data from the "Ocean optics- Maya pro 2000" spectrometer, or the calculations needed to ...
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what is the reason behind DC level shift of the optoisolator ouput(collector of photo transistor) terminal?

i am using SFH-610A optoisolator to switch 1KHZ PWM signal. on input side of opto i am triggering from micro controller with series resistor 500 ohms. and on the output side i have pull-up of 3.3V ...
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Resistor between vcc and control signal in a rpi controlled relay board

I have been researching to design a rpi controlled relay board and I found these two schematics from two companies. Personally I trust the company in the image above but I am confused about R3 (10k) ...
1 vote
1 answer
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How to share a digital signal between circuits?

Please see this : The Task I'm trying to create a single module which can safely share a single digital signal. The idea is that each (identical) module can monitor the status of the signal, and can ...
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Please help me understand how this inductive proximity sensor works

I'm trying to build out an optocoupler circuit to connect a new proximity sensor to my 3D printer and want to understand how it behaves before implementing. It's a Printrbot Simple Metal, Printrboard ...
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3 answers
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A laser driver (MLD203P1) with an external Bias-Tee for modulation

As the title says, I would like to add an external Bias tee to modulate a high frequency signal into a laser diode, because the laser driver I have chosen does not have a built-in modulation circuit. ...
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1 answer
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Opto-isolation amplifier output is too off

(As a follow-up to an earlier question answered by the community - thanks!) So I've got the test circuit setup using the HCPL 7520 (datasheet) now and planning to use an Arduino Uno to measure the ...
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Opto-isolation amplifier giving no output

First of all, thanks to the community for having such helpful answers here - don't post very often but here's one I could really do some help with. I want to measure a voltage range of 0-100V DC in an ...
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