Questions tagged [photodiode]

A photodiode converts light to an electric current.

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24 views

Does the photoelectric interaction occur mostly over the depletion zone of a photodiode?

It is important for some photodiodes like the PIN diode to have a large depletion zone. This is to achieve a large area that allows for convertion of photons to electron-hole pairs. Why does this ...
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57 views

Calculate intensity from a photodiode using voltage

I am running a photodiode through an op-amp circuit (trans-impedance amplifier.) I have been told I should characterize this device. I'm assuming he means using the voltage I get at a given distance ...
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248 views

Do AC input optocouplers require an ESD protection?

I intend on using a circuit I designed for detecting an AC input line for control purposes. One of the inputs will be accessed by third party users and a cable might be connected with a decent length(&...
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1answer
59 views

I want to register a small change of voltage of a photo sensing diode at bullet's speed

What I intend to do Estimate Accuracy of a Bullet Hit from the Bull's Eye: Use a row of light sensing diodes like BPW34 (or you suggest) spanning a feet vertically and horizontally or so with laser ...
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29 views

Instant LCD brightness control using an ambient light sensor

I'd like help building a circuit to control LCD backlight levels based on ambient light. The circuit must either be able to accomplish constant 12VDC current control between roughly 250-500mA or ...
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1answer
64 views

Are these scope traces normal for a reverse polarity LED hooked up to an NPN transistor?

I've been trying to make some cheap light sensors using some coloured LEDs and am using the schematic below. The idea is to hook up a bunch of LEDs (Red, Green, Blue etc.) to try and get an idea of ...
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38 views

How to calculate laser power on photodiode?

I am completely lost calculating the power of a laser diode and hope, that someone could help me. Here is my setup: OSRAM PL 520 (Type B1 = 50mW) Green Laser Diode OSRAM SFH 203 Photodiode The laser ...
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3answers
65 views

Design an RF amplifier for a photodiode

I've been asked to present a possible solution to design an optical system aimed at estimating the arrival time of the following light signal: $$s(t)=[\Sigma_{i=1}^∞rect(\frac{t-t_i}{T})]\cdot Acos(...
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36 views

Unclear block diagram of Hamamatsu's Hybrid Photo Detector

I am trying to understand what's happening in the block diagram of Hamatmatsu's Hybrid Photo Detector (HPD). The datasheet is available here. What exactly the two 2.5G Ohm of resistors doing there? ...
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5answers
98 views

Driving an LCD filter from a set of welding goggles - Optical modulator

I bought a pair of LCD welding goggles in the hope that I could re-purpose the switchable light filter for another project. Unfortunately, the circuit driving the LCD filter is way above my ability to ...
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86 views

Understanding the phototransistor

I am trying to learn how a phototransistor works, and I have made a schematic to show how I understand the photo-diode and NPN transistor to be linked in a phototransistor. I think that when light ...
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29 views

How to get the desired signal from a photodiode and phototransistor multisim?

The above is a visualization of an IR transmitter and receiver circuit I'm building. Sending a 2v and 1khz sine wave through a photodiode to a phototransistor. The figure above shows the outputs I ...
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1answer
91 views

Understanding how a NPN transistor works

I have been trying to understand how an NPN transistor works, specifically in the case of a photo-transistor. As far as I can tell, it should be something like this: I don’t understand how current ...
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1answer
83 views

Instability in photodiode amplifier circuit

I'm using a UV LED and a Schotky photodiode sensitive to UV light to get an estimate of the concentration of a vapor that passes through the space between the UV LED and UV diode, but I'm having ...
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1answer
39 views

Measurement of output current of a photodiode

I am a German student. My task is to conduct a characterization of a photodiode (KPEIMC-UDCOM by Kyosemi.) The photodiode will be illuminated by 850-1550 nm laser diodes. It would be good (but not ...
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2answers
86 views

Why is the N side thinner than the P side in a photodiode?

I have been reading that a photodiode is built by sandwiching a very thin N type semiconductor togther with a thicker P type. Why is that so?
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Photodiode IC giving non-intuitive outputs

I am using a Photodiode IC (CXA2586M). This PDIC has multiple photodiodes but all of them have the same circuit. I have supplied voltages as per the datasheet (i.e Vcc = 5V, Vc = 1.5V) (See default ...
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1answer
82 views

Photodiode operational amplifier's strange temperature behaviour

I have two identical circuits (see attached schematic for example) residing on one PCB. Each circuit amplifies the signal from a silicon pin photodiode VEMD5080X01 . The diodes are sitting in a black ...
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47 views

IRFZ44N with Arduino works fine on breadboard but not when directly connected with wire

I have a circuit that looks like this in the picture below. I am getting 5V to power Arduino Nano BLE 33 from the powerboost 500 module that is connected to the 450mAh lipo battery and the wireless ...
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1answer
52 views

How to simulate the CNY70 IR reflectometer with TINA or LTSpice

How can I model the CNY70 IR reflectometer from Vishay (click here for datasheet) using TINA or LTSpice. In particular, I would like to simulate the circuit shown below: The 4pins on the left side ...
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1answer
38 views

Switch Configuration for Variable Gain Photodiode Amplifier

In this article here: https://www.analog.com/en/technical-articles/optimizing-precision-photodiode-sensor-circuit-design.html# It states: However, I don't understand the rather critical line "...
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48 views

Why when i put a voltage through my photodiode its sensitivity doesn't change?

I have a photodiode that I want to experiment; the problem is that when no voltage is applied to the circuit I get a voltage through the resistor of around 0.3V that change if I apply light. For any ...
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2answers
61 views

Confused about photodiode current

I am confused about the photodiode current voltage diagram. According to this diagram the current at zero bias is down->reverse current.How is that even possible? At photovoltaic mode isnt the ...
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48 views

IR modulation with photodiodes multiplexing

I have 100 IR photodiodes that I would like to multiplex to one (or the fewest achievable) transimpedance amplifier(s), both for space and price constraints. I am aware of the capacitance and noise ...
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615 views

Amplify difference between two photodiodes

I have two adjacent photodiodes in photovoltaic mode, with two transimpedance amplifiers. Unfortunately, my MCU (nRF52840) is one meter away, and I expect a fair amount of noise to enter the system. ...
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1answer
19 views

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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69 views

Photodiodes: Measuring Low Optical Power vs Dark Current Contradiction

Taken from: http://www.geni-uv.com/download/products/GUVV-T20GD-U.pdf I'm trying to do some estimates here and I've run into something that seemingly doesn't make sense. In the table above, it states ...
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3answers
761 views

How to select LEDs for use as colour selective photodiodes?

When selecting LEDs for use as photodiodes, are there general guidelines that one can use to increase the odds that a more suitable LED is selected? For example: Does diffuse or clear impact ...
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33 views

Monitor Photodiode polarity convention

I have Monitor Photodiode specs that claim the following: MPD Reverse Voltage: -10V Min, -3V Max MPD Forward Current: 0mA Min, 10 mA Max What is the convention for measuring this voltage and ...
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1answer
79 views

Analog circuit for a photo sensor

I'm personally developing an analog circuit for a photo sensor using very cheap op-amp. My biggest motivation for my circuit is to design it cheaply as much as possible. My main op-amp is a TL071. ...
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2answers
60 views

Not accurate readings when connecting OpAmp AD822 to ADC MCP3008

for my project, I am using a photodiode, that I connected to the AD822 OpAmp. This OpAmp should then be connected to the MCP3008 ADC. I am reading the data from the MCP3008 with a RaspberryPi. I am ...
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1answer
142 views

Small feedback capacitor in photodiode amplifier

I'm designing a transimpedence circuit with a photodiode. Op-amp: LTC6268 (GBW = 500MHz) Photodiode: SFH2700 A1 (C_j = 4.6pF, max current = 1.5uA) Required bandwidth: 2MHz Using the calculation from ...
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2answers
154 views

Simulating Photodiode sensor in LTspice

I am designing a current source that is going to control LED. With help of the DAC and microcontroller, I generate a voltage that goes to OP-amplifier, and afterward, I am opening my NMOS transistor. ...
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65 views

Photosensitive Diode or photo resistor?

As I understand it, a photosensitive diode generates a small current with light. I ordered these off Amazon: https://www.amazon.com/gp/product/B01F3TU2XC/ref=ask_ql_qh_dp_hza These change resistance ...
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1answer
73 views

Can the direct current output of a photodiode pass through a capacitor? If so what effect are they having in this circuit?

I am studying RC filtering in order to try and understand this circuit which was previously discussed in(What kind of filtering does this op-amp perform?). The answers gave advice on testing the ...
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1answer
71 views

Transfer Function of Photodiode

I am trying to obtain the transfer function for a photodiode. Since I couldn't find any standard result online, I figured I would try to obtain it from the circuit equivalent shown below, but I am ...
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1answer
53 views

Measuring Voltage from Photodiode with OpAmp

I am trying to measure the voltage coming out from my OpAmp after connecting it to my Photodiode. As a Photodiode I am using the BPW34S from Vishay and the Op Amp is the AD822ANZ from Analog Devices. ...
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1answer
44 views

Bias T for modulation of VCSEL laserdiode

For my project, I would like to design a Bias Tee for a VCSEL laserdiode, because a modulation is required. The bandwidth is 20 KHz - 10 MHz. My steps are shown below: As a reference, I have used the ...
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45 views

Operational amplifier - why average voltage is not stright related to pulse to duty cycle?

I have a strange problem, that I cant find an answer. I have slow photodiode (about 2MHz) and fast, pulsed laser light source (pulses 10 to 500ns). Im trying to measure optical output power. To do it ...
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3answers
83 views

Can LED strips be used as photodetectors?

As I did not find any photodiode/PD strips available, I am wondering if it would be possible to use LED strips as photodetectors. And if yes, which type of LED strip could be used for that purpose? My ...
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2answers
81 views

Will this photodiode circuit filter this frequency?

I have the following circuit with a photodiode and an LM358P where I intend to blink an LED at around 20kHz. I want to work on it. I have made a calculation through 1/(2piRC), and got something around ...
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1answer
38 views

is it possible linear response photodiode amplifier using 2n3819

This is a typical jfet circuit to amplify the photodiode signal. Is this simply the photovoltaic voltage generated by the photodiode? My understanding is this is highly non-linear since the voltage ...
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46 views

Understanding photodiode modes and practical effect on noise vs response time tradeoffs for audio applications

I am an experimental musician with admittedly very little electronics experience (but I do have a mathematics degree) trying to find a decent photodiode for a project where I send audio signals via ...
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21 views

carrier concentration of PN junction [duplicate]

i am trying to calculate these formulas: -and- (p-side: x < -xp , n-side: x > xn) But i wonder, how can i find pn0 and np0 Thanks in advance.
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132 views

Increasing sensitivity of photodiode amplifier

I have build a 2-stage amplifier circuit for amplifying the current from an InGaAs photodiode. It uses 2 OPA4350 op-amps. The first stage is a TIA with a feedback resistor = 1MΩ. The 2nd stage is a ...
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30 views

Photodetector and low noise amplifier acting as low pass filter

I need some basic advice for impedance matching: I have a photodetector (Det01CFC from Thorlabs, https://www.thorlabs.com/drawings/275cb418cdc2cf1f-A2E46103-D9C0-3581-4553E3D3CA93AD83/DET01CFC-Manual....
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1answer
45 views

Impedance matching for broad bandwidth voltage amplifier

I need some basic advice for impedance matching: I have a photodetector (Det01CFC from Thorlabs) that generates a current. For my experiment, I would like to amplify this signal with an amplifier. The ...
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2answers
67 views

Parallel resistor before voltage amplifier

For my project, I would like to amplify the output from a photodetector for subsequent analysis with an oscilloscope. The output of the photodetector is a current. Since we are using a voltage-...
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71 views

Current sensor that works in 0nA-250nA range?

Is there any current sensor capable of sense very low current ranges from 0nA to 250nA? I would need to sense the current produced by this photodiode: GVGR-S11SD (http://www.geni-uv.com/download/...
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53 views

carrier concentration - distance graph of PN junction

i am trying to plot the distance-carrier_concentration graph above with these formulas: -and- (p-side: x < -xp , n-side: x > xn) But i could draw only red lines on the graphs with these ...

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