Questions tagged [optoelectronics]

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

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2answers
97 views

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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1answer
66 views

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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1answer
69 views

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 ...
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0answers
128 views

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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0answers
70 views

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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7answers
1k views

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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0answers
349 views

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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1answer
57 views

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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1answer
49 views

How does a fiber optic receiver converts 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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1answer
307 views

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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1answer
103 views

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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1answer
471 views

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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1answer
104 views

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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1answer
26 views

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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1answer
30 views

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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1answer
166 views

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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2answers
103 views

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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1answer
198 views

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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1answer
224 views

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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0answers
61 views

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 ...
2
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1answer
315 views

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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2answers
159 views

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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1answer
84 views

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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3answers
207 views

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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2answers
319 views

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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1answer
259 views

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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0answers
2k views

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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2answers
371 views

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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2answers
47 views

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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2answers
2k views

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 ...
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2answers
121 views

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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2answers
216 views

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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1answer
92 views

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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2answers
163 views

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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1answer
394 views

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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2answers
75 views

optical path resonance distance measurement device, super useful for open source hardware if it would work [closed]

My head just tends to be full of open hardware and open manufacturing stuff, and one idea I have had for years and always wanted to try, but never could for want of access to an electronics lab, is a ...
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1answer
747 views

LOGIC GATES and logic circuits in a calculator

i am tasked to do a circuit using logic gates regarding the work of a calculator. it is said that how can we make number 3 shown in a calculator represented by logic gates. can someone help me? i ...
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2answers
110 views

Identifying mystery dual channel opto detector?

How do I identify if a component is a photo diode or photo transistor? I have a three lead component removed from an old mouse where it was used to do quadrature encoding of the scroll wheel (a normal ...
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1answer
250 views

MID400 used in “Unsaturated” Mode

I've been spec'd a MID400 in a high voltage A/C power monitor circuit. After receiving the prototype (board is done), I've determined this device is for power on/off application. Problem is I need to ...
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1answer
328 views

What is comparison of readout times of global and rolling shutter cameras? [closed]

Rolling shutter will take more time because of sequential readout and global will take less time.But what are the exact values of image readout time?
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4answers
2k views

Why we use two photodiodes as optoisolator or optocoupler?

Why do we need two photodiodes in order to create an optoisolator or optocoupler? Many sources say that it is to compensate for the non-linearity of the diodes, but is there any explanation based on ...
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2answers
1k views

24 VAC Detection Using Optocoupler

I have been using an HCPL3700 to detect 24VAC, but they are large and relatively expensive. I have tested the design shown in the figure (AC input to the diode, and measuring output collector-emitter ...
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1answer
696 views

Design of output stage for CNY70 reflective sensor

I have built the following circuit for a reflective sensor: The resistor \$R_D\$ has been given the value 200 \$\Omega\$ and the resistor \$R_T\$ is to be dimensioned. \$V_{CC}\$ is 5 V. I have ...
2
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1answer
234 views

Questions about CNY70 Reflective Optical Sensor datasheet

I am using the CNY70 for a project, but i need information from the datasheet. In Figure 11, which i have added below, the relative collector current, \$I_{Crel}\$, is shown versus the displacement, s,...
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2answers
225 views

Automatic room light controller with IR sensor

(Schematic source: Electronics Hub) In this circuit sensor is not working.using (4*1.5)v cells as supply.without connecting the transmitter and receiver elements,in the o/p led glows.i have connected ...
2
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1answer
1k views

SWD optoisolation problem

I have designed the following optoisolator for SWD interfacing with an STM32 device and J-LINK programmer: This is the generic schematic: And this is a single optoisolator schematic: I am not able ...
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2answers
1k views

Typical wavelength range for solar cell measurement

Why is a wavelength range of 300nm-1100nm usually used to investigate the properties of solar cells (EQE, current generated, etc.)? Is it to reduce spectral impact? I also don't understand what is ...
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1answer
369 views

Detect if the load is present on this circuit

Is there a way to detect if the load is conected on the circuit above? (The other load should be connected to the F Pad, sorry for the mistake).
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0answers
172 views

Low cost low speed fiber optic connection for embedded applications

I would like to use a fiber connection to send data between two nodes. The nodes would typically have a 8 or 32 bit micro controller. I need data rate of 2 Mbps or higher and distance is about 100 ...
5
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1answer
475 views

Q: Check if an LED in my circuit is still “good”

I have an electrical circuit which uses an LED, connected to a µC, to show the status of an x-ray source in another room. Obviously this LED is important to have in a working condition. Now, LEDs can ...