Questions tagged [photodiode]
A photodiode converts light to an electric current.
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What are the pros and cons for the various photodiode circuit arrangements?
I've been messing around with photodiodes do measure relative light intensity from very low light to very bright conditions. My search for information on photodiodes and the circuits they are ...
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Strange noise in analog laser pulse detection circuit
I have laser radiation detection and amplification circuit, whose actual circuit is not know due to property restrictions, so i was trying to understand and re-construct it from board by reverse-...
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Characterizing a PIN photodiode's 3 dB bandwidth
I'm currently attempting to characterize a PIN photodiode's 3 dB bandwidth. The photodiode input is a laser source that is being modulated by an ESA RF output that performs a frequency sweep from 0-1....
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Modeling a solar cell with a voltage source and a resistor
For a project, I have to model a solar cell just with a voltage source and a resistor (Thevenin equivalent model.)
I searched on the internet and all of the models I found are with a current source, ...
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IR frequency counter
I want to deign a frequency counter in this way:
A specific frequency (33 kHz) is radiated by an infrared transmitter from a distance of 10 m to the infrared receiver for 100 ms.
After amplifying the ...
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Simple circuit analysis
I am trying to figure out what the output voltage (V1) of this circuit is. Is the photodiode in reverse bias in this case, which means the current is flowing in (opposite of what is shown here)? Is ...
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Photodiode circuit to compensate for LED temperature drift
I'm trying to create a stable light source using 5000K white LEDs. In researching this I've discovered that LEDs drift with temperature by a non-negligible amount. Further research leads me to believe ...
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Collecting photodiode current in specific capacitor
I want to be able to measure the amount of light that hits a photodiode during different timeslices specified by particular signals. For example, below when S1 is high I want C1 to charge, and when ...
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Why would a photodiode with an op-amp be very linear?
I read here mentioned
The configuration in Figure 1a creates a very linear response in terms of the irradiance of the light source.
Would this configuration of photodiode not be linear? Why?
The ...
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Any theoretical reference for empirical equation for estimating oxygen saturation (% SpO2 = 110 - 25*R)? [closed]
The empirical equation used to estimate % SpO2 is based on the observation that the ratio of the red and infrared light absorbed by arterial blood (represented by R in the equation) varies linearly ...
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Can bright light sources like LED flashlights damage the photodiodes of optical heart rate sensors used in smartwatches?
Suppose a 3 - 3.3 V white (or any colour) LED with 800 Lm (theoretical max 1800 Lm), 5592 Cd or more is shone into the optical heart rate sensor on the back of a smartwatch at close range (< 10 cm) ...
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Is this light sensor circuit correct?
I want to be able to accurately measure the light which hits a photodiode, during a specific exposure time.
The exposure is switched via MOSFET via input A. The idea is that you drive A high for a ...
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Is this an LED or IR receiver?
I want to make a trigger for my project. I saw this PCB for triggering the RF part of the PCB. I think one PCB has an IR receiver and the other part has an IR transmitter so they can trigger the RF ...
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Optocoupler with cascaded photodiodes
simulate this circuit – Schematic created using CircuitLab
Is there a component like in the dashed box? It may supply gate voltage for a source-to-source pair of N-channel MOSFETs. Speed is not ...
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Choosing the right LED IR and the photodiode for optical beam sensor
I need to design an optical beam sensor for about 15-20 cm of distance - any obstacle between an emitter and a detector would trigger an interrupt for a microcontroller.
I was thinking about using a ...
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For multiple photodiodes looking at a different angle could I connect them to a 4071 ic or something similar?
I want to make many photodiodes at different angles and I want to be able to tell where IR light is coming from. I am designing a PCB using a Teensy 4.1 and would like to be able to identify from what ...
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Difficulties with multiplexing PPG signal in pulse oximeter
I've designed pulse oximeter circuit. When one LED lights continuously, I got perfect PPG (Photoplethysmogram) signal.
Then I measure PPG while blinking LEDS, like that:
I got stuck. There is no ...
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BPW34 Photodiode TIA amplifier
I have a problem with circuit, for some reason I always have 4.8 volt in output.
Like a:
4.8 V - when I put finger on photodiode
4.83 V - in room light
8.27 V - when I light it with IR laser
What am ...
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PIN diode - what setting to detect the frequency?
My question regarding the use of the PIN photo diode, I could not understand what would be the best configuration using an integrator operational amplifier for frequency detection if it is the photo ...
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About a non-inverting photodiode amplifier in photoconductive mode
The classic photodiode amplifier in photoconductive mode looks like this picture:
Negative -5V seems to be necessary.
I have a idea to make a single rail photodiode amplifier:
Could it work well?
I ...
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Avalanche photodiode current limiting/optimum APD bias point indication
I am trying to design an avalanche photodiode driver using the MAX1932 APD bias supply IC. Everything looks pretty understandable except selecting the APD current limit.
I looked through all APD ...
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Low pass filter (?) in Thorlabs PDs
What is the purpose of this circuit in all Thorlabs PDs? It looks like a second order low pass filter to me, but shouldn't it be two resistors in that case?
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Voltage output range of PSD circuit
I saw this circuit the other day on here: What is the basic circuit to wire up a position-sensitive detector, or PSD?
From what I understand from the answer given, the voltages X1 and X2 can be used ...
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Simple Time of Flight distance threshold design
I want to make a basic TOF distancing circuit inspired by the square-wave phase shift method
here.
But I don't know how to measure charge stored in capacitors.
However, I thought of a simplification. ...
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Reading 100s photodetectors
I'm trying to measure light intensity at a lot of points in a project. I have about 250 photo detectors (BPX 65). When I had just 1, I tried connecting it to an Arduino board. But I'm not sure, what ...
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How does the RC component of a organic photodiode impact the response speed? [closed]
As I hate abstractions, I'm trying to understand at the physical level how capacitance forms within photodiode and how it decreases the performance with resistance.
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Transconductance photodiode?
I'm having trouble finding a theoretical explanation about the transconductance photodiode behavior, the materials I find on the internet they talk about the connections, but not the behavior, in case ...
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Portable LED staircase light
I need to make a portable LED staircase light that uses a BPW34 photodiode. It should enable the LED driver when incoming light is below an adjustable threshold, and disable the LED driver when ...
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Photodiode arrays: how can different wavelengths be compared?
In DAD (diode array detector), aka PDA (photodiode array) detectors, the light is dispersed and different wavelengths fall onto different diodes. This allows finding out which wavelengths were present ...
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Multiplex array of photodiodes [closed]
I have a linear array of 10 photodiodes that I want to connect to a single transimpedance amplifier to produce signals.
I'm envisioning some sort of analog switching circuit (U2 in the diagram below) ...
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Photodiode detector 2-stage amplifier design
I found the post with circuit diagram I wanted to build: circuit diagram.
The resistors values, gain and filter frequency are enough for me.
I wanted to measure light intensity as DC voltage, so ...
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Feasibility of high-speed omnidirectional communication through infrared light
I am currently working on the design of a low-cost communication system based on IR LEDs and photodiodes for my research project. The goal is to transmit data with ~100ns pulses across ~0.5m distance (...
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Low intensity UV light detector
I wanted to build low light UV detector, I mean the measurement of light with wavelength 405 nm. I found two schemes:
First circuit:
And the second circuit:
I wanted to use operational amplifier ...
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Input bias current calculation
I have a VBP104FAS connected as above with the LMP7721 opamp to produce an output voltage from the photodiode's small input current. I am trying to calculate the input bias current I need as I am ...
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Transimpedance amplifier circuit with uniform light input gives a sine wave output
I am trying to build a transimpedance amplifier circuit on a PCB (as in the figure below).
Although I have run a SPICE simulation and got the desired results, I wanted to test it out on a breadboard ...
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How to improve output swing of an NMOS pixel circuit?
This is a standard pixel circuit:
It works just like one would expect. When the reset signal on the gate of the PMOS is low it is conducting and charges the capacitor to 5V, then when the signal turns ...
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DC transimpedance amplifier feedback capacitor
I am designing a simple photodiode light sensor circuit. The circuit will use a transimpedance amplifier to generate a usable voltage from the light level detected by the photodiode. The most basic ...
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500 mV p-p noise in two stage photodiode amplifier output
I have problem with power supply noise finding its way to op-amp output. Power line (+ and -) noise is 40 mV p-p. Is this due to poor pcb layout or poor filtering and what to do to make it better.
I ...
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Photodiode speed limitation
I have a system which demands optical data transmission since rotating parts are present. A mixed mechanical-electrical engineering project has led us to use photodiodes to receive data from one ...
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Can very small currents be accurately measured using only standard analog electronic components on an IC? [closed]
Let's say, for example, that I have a photodiode, which produces electrons in response to the amount of light.
What is the theoretical lower limit that can be accurately measured only using basic ...
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Why is this op-amp outputting such low voltage?
Why am I not getting the expected gain out of my op-amp?
I m using a 16-pin TI OPA4322SAIPW op-amp with a Advanced Photonix 019-141-411-R photodiode and this circuit:
where Rin is 1.8 kΩ and Rf is 27 ...
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How to use LEDs to communicate using a UART
I am using a UART to communicate between two Raspberry Pi Picos, and want to use LED / photodiode pairs rather than wires.
I have two SunLED XZMOK54W-8 610 nm LEDs paired with two Advanced Photonix ...
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Why is my SCR controlled by a photodiode pulsing when supplied with high voltage
I am working on a circuit which when a photogate (consisting of a photodiode and a corresponding LED) is interrupted, an SCR is triggered which discharges a capacitor through a solenoid. I built and ...
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Distinguish if this component is a PIN Photodiode or an APD Avalanche Photodiode
I am experimenting with a DFB Laser salvaged from a scrapped GPON Router. Laser works fine, but it comes with what looks like a "Built in InGaAsP monitor photodiode" incorporated into the ...
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Light reading diode?
I’m trying to think of a device to measure amount of UVA & UVB daylight for plants in my shed and so trying to work out what I could use to measure:
The amount of light
Its type
Its time
Be able ...
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APD (Avalanche Photodiode) Active Quenching Circuit (AQC) Waveforms & Circuit Behavior
I am reading a paper tiled Avalanche photodiodes and quenching circuits for single-photon detection
The paper presents an Active Quenching Circuit schematic, briefly describes its operation, and shows ...
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Open circuit photodiode energy
Where does a photo-diode use the energy it collects from light and other EM waves when not loaded? Does it dissipate it as heat, reflect it or something else?
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Photodiode bias in TIA?
When I see TIA schematics, I can see either the photodiode to GND or against VCC. What is the difference?
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Photodiode circuit unstable measurements on MCU ADC [closed]
I'm working on a fluoresce detection circuit. I have a lot of unstable measurements on the output of my second amplifier with the ADC. With the multimeter I have stable measurements.
How can I smooth ...
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Measuring <10 pA of photocurrent using transimpedance amplifier
I am working on a project that measures low intensity light.
The photodiode I am using an OSD35-5T. This is a large surface area photodiode. The idea is that the large surface area would absorb/...
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