Questions tagged [photodiode]

A photodiode converts light to an electric current.

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322 views

I have made a photodiode circuit and measured using multimeter - still no change in voltage. What to do? [closed]

My photodiode is MTPD1346D-100 (InGaAs PIN photodiode.) What is the photodiode input voltage? This is my circuit schematic:
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230 views

Photon count with ADC, am I doing it right?

I have this LED and I want to characterize this photodiode. The LED should produce light of 370 nm, but I measured it and it is around 358 nm, and at that wavelength the quantum efficiency (\$\eta\$) ...
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2answers
514 views

Simple Op Amp Non-inverting Amplifier Circuit Not Working

I am only just starting to learn about circuits and electricity, so please bare with me. I am attempting to build the circuit pictured below: And this is my rendition of it: Here are the parts used:...
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231 views

Switching multiple photodiode inputs to an op amp

I am playing around with LEDs as (semi)wavelength selective photodetectors and have reproduced the circuit found in Forest Mims' Make article: I have an operational circuit using an LM358 powered by ...
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1answer
367 views

Photodiode to an ADC

Please bear with me as I'm not too experienced with this. I'm attempting to use an ADC to get readings from a photodiode. From what I understand, I should likely use an op-amp as the range of the ...
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2k views

Thin wall to block LED light from hitting photodiode?

I'm designing a small heart rate sensor using green smd LEDs and a photodiode. The photodiode needs to measure the reflected light, and not direct light from the LEDs. The LEDs are near the perimeter ...
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1answer
36 views

How are solar spectra simulators used and are they used to test photo-diodes and image sensors?

For example here is link to a Xenon lamp solar spectra simulator Xenon lamp AAA Class Solar Simulator. Two spectra are shown in the plot given in the link, one for the AM1.5G reference an other of ...
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1answer
122 views

Photodiode showing triangle waves instead of square? (re: need op amp?)

I'm trying to visualize an infrared signal using a IR receiver diode but my oscilloscope is showing triangle waves instead of square for the carrier frequency: One of the guys at EEVblog said I need ...
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1answer
265 views

Using an IR diode as an emitter and receiver?

At the recent Maker Faire Berlin, I was told that LEDs can be repurposed as photo diodes. I assume the same is true in the infrared range. This sounds like a nice solution for building a transmitter. ...
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298 views

PIN Photodiode gamma detection amplifier circuit - rectangular wave output

I've been working on a project recently, where I need to build a device which detects gamma radiation and can be used for gamma spectroscopy. I've done some research and found many interesting ways of ...
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87 views

Troubleshooting op-amp circuit and compactor for buzzer

I tried building a radiation detector (cheap photodiode Geiger counter) on perfboard: http://opengeiger.de/StuttgarterGeigerleThruHole_en.pdf More details here. With the circuit was turned on, ...
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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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189 views

Epoxy Resin Molded vs Hermetically Sealed Metal Can Packaging for LEDs and Photodiodes

Between epoxy resin molded vs hermetically sealed metal can packaging for photodiodes and LEDs are there any relevant functional differences I should be aware of when selecting between otherwise ...
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Understanding basic photoresistor circuit

I'm new to electronics, so I just can't wrap my head around how this photoresistor circuit works. I understand the following: the photodiode can be understood as a variable resistor (i.e. works in ...
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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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666 views

Irradiance sensor circuit

Im trying to measure the irradiance from the sun using the following TIA circuit: I'm using a BPW34 photodiode due to the good spectral range and for being cheap. Also the datasheet provides a ...
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1answer
200 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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123 views

What is the relationship between dark current and the contribution of dark noise in a photodiode?

For example, if I have a datasheet for a photodiode that lists a dark current of 1000nA. I have a transimpedance amplifier with 1kohm transimpedance and 1 mV voltage output voltage noise. Presumably ...
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243 views

How to filter out certain wavelengths of light [closed]

I am trying to filter out certain wavelengths of light and I was wondering if there is a way that you can filter them out. I am using Silicon Photomultipliers (Linked below) and I only want to detect ...
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1k views

Photodiode - circuit questions

I am a bit confused on a few things regarding photodiodes. Here are two circuits that I am referring to: or   For the second circuit the capacitor is not of importance. Here are my fundamental ...
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67 views

Do photodiodes break KVL?

I know what you are thinking, but hear me out. Let's do KVL in this loop: simulate this circuit – Schematic created using CircuitLab We get: $$ -V_{PD}+I(R_s+R_L)-V_1 = 0 $$ Now we solve for ...
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1answer
166 views

How much slower does a photodiode become in photovoltaic mode?

Take for example this photodiode, the main differences between using it in photovoltaic and photoconductive mode is the rise time and the Dark Current, aren't they?. I know exactly how the Dark ...
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1answer
104 views

How does the spectral response of a photodiode change with bias voltage?

Look at this data sheet, in the second page we have a graph for the spectral response. Now, I have learned that photodiodes must be reverse-biased in order to get a decent signal from them, but then ...
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56 views

How much does the Bias Voltage affect the NEP of a photodiode?

Look at this data sheet for example. Everything there is measured at 0V, including the NEP, if I connect that photodiode in reverse bias, how will that NEP change?. I'm inclined to believe that it ...
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1answer
63 views

In this semi-ideal photodiode, what would be the physical interpretation of this current?

A real photodiode can be expressed as a circuit made of several ideal components, it looks something like this: simulate this circuit – Schematic created using CircuitLab I copied it from here ...
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1answer
258 views

PCB design review: analog routing

I am designing a PCB with analog signals for the first time, and I would really appreciate any feedback on my layout and routing. The circuit is a light-meter, consisting of a photodiode connected ...
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3answers
2k views

Why are “square law” devices important?

In the literature, I often see the notion of square law devices. Why are these devices important, to the extent that they have their own characterization as square law device? In what context does ...
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141 views

how does single supply op-amp work while its non-inverting input is connected to ground?

In HCNR200 Datasheet, the page 11, figure 13-A, there is a sample that confused me. In this sample, the Vin is applied to the inverting input and if the electric current passes through PD1, PD1 ...
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1answer
183 views

Photodiode current equation

The current in photo diode because of generation rate G and depletion width W is given as qGW (neglecting diffusion currents). When the light is incident on the diode excess carriers are generated in ...
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76 views

PCB dual LED emitter, TIA and voltage regulator (beginner)

Does this PCB look good for this operation? The schematic is attached. I have a voltage regulator connectected to an LED emitter. Voltage regulator to TIA . TIA then is attached to active high pass ...
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2answers
156 views

Driving Avalanche Photodiodes (PCBs)

I am using Avalanche Photodiodes and I was told that they use a much higher voltage then standard photodiodes and I was wondering if I need a High Voltage PCB to drive them? I am currently just using ...
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2answers
222 views

Photodiode Output measurement

I'm using Hamamatshu s8559 photodiode to convert x-rays into it's respective energy. I'm using a 10 bit ADC converter. The problem I'm facing is I have no relationship between the Photo-current ...
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2answers
653 views

Very low current (<10 microamps) darkness detector circuit that turns off in light

I've made a device that lights an LED at a very low current (<10 microamps) as a very dim indicator for use in the dark. At its simplest, the circuit is a 3V coin battery + resistor (300K-1M ...
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1answer
54 views

How to use my bits to transmit this photodiode signal in the most efficient way possible? [closed]

Suppose I have photodiode with a Dark Current of 5 pA and that using the NEP of that photodiode at some frequency \$\lambda\$ I determined that the smallest signal I could detect was of 1 pA. First ...
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1answer
122 views

Phototransistor and Photodiodes capacitances when some in an array sense light

I'm using phototransistors to sense low speed data (about 7 bits a second). With one phototransistor and a 300K resistor, I found my sweet spot and can transmit correct data with lazer. I find if the ...
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1answer
1k views

Can you connect multiple photodiodes in parallel and treat it as one?

Im working on an IR sensor based off of the Texas Instr. particle sensor (TIDA-00378). They use just one photodiode in their design. I would like to use multiple photodiodes, lined up with multiple ...
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80 views

making a photodiode module

I am trying to do stimulated Raman scattering microscopy. In this experiment two pulsed laser beams are used . The wavelength of these two laser beams is tuned to match a specific Raman frequency of ...
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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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418 views

Please explain this formula for the relationship between bandwidth and the temporal response of a photodetector

I am reading "Optoelectronic Sensors" by Didier Decoster and Joseph Harari. At section 1.8.2 they start explaining the relationship between rise time and bandwidth, and they give a very weird formula ...
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2k views

Forward drop of diode vs forward drop of LED

It is always said that forward voltage drop in the diode is around 0.7 volts. LED also being a diode, why does it have a greater forward voltage drop of around 3 Volts? What is the model of LED that ...
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1answer
234 views

LED output with Photodiode and Function Generator

Some of my student and I are designing a Physics experiment involving a high power LED, a square wave from function generator (50 ohm output impedance) and a digital oscilloscope (1 MOhm imput ...
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62 views

How to calculate the current produced by a solar panel?

The equation for calculating current when given voltage and temperature is known as the 5-Parameter model ie. \$I = I_{ph} - I_o[\exp(\frac{V + R_sI}{nV_t})-1] - (\frac{V+R_sI}{R_{sh}})\$ Since this ...
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1answer
79 views

How does a camera pixel accumulate charge (colour)?

I refer to the Wikipedia entry for a CMOS camera sensor's individual pixel. There is a schematic like so:- and a statement that:- The read-out transistor, Msf, acts as a buffer (specifically, a ...
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1answer
52 views

Explanation of 5 Parameter Model for Solar Cells

I am having a hard time understanding this equation, the 5 Parameter model for photovoltaic cells. \$I = I_{ph} - I_o[\exp(\frac{V + R_sI}{nV_t})-1] - (\frac{V+R_sI}{R_{sh}})\$ My goal is to apply a ...
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109 views

Estimate minimum detectable light pulse in a photodiode (5 ms, 44 kHz modulated)?

I'll use an IR LED modulated at 44 kHz to illuminate particles in air or water, and will use a silicon photodiode to detect weak pulses of scattered light as they pass through the LED's collimated ...
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1answer
40 views

Output changes wildly with input voltage in photodiode circuit

I am currently analyzing a photodiode sensor input circuit (not designed by me, but schematics drawn from a commercial product). I am currently simulating the circuit on TINA TI. While experimenting ...
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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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1answer
125 views

How does this op-amp photodiode circuit behave?

I am trying to understand the inner workings of a photoelectric object sensor I have in my hands. (modulated with 24 kHz) Here is the very beginning of the receiver part: simulate this circuit –...
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149 views

Making LED flash from steady-state signal

I am looking to design a simple circuit that detect objects placed in a spot. So far, the circuit uses simple IR LED and photodiode to detect the object placed between them. The voltage developed in ...
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1answer
129 views

Resistor on transimpedance amplifier input?

I am currently examining an expired patent file of a photoelectric sensor. The file includes the circuit, I am trying to understand it with my limited analog electronics knowledge: Patent no: ...

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