BOTH TIMES I have used it as soon as I hit "hide UI" and take the screenshot it fucking freezes and I like progress.
At least I got a cool shot but now I have to do this fight all over again
Holy shit photomode*
I am implementing a balanced optical receiver and I’m not sure how to characterize what I’m observing. The implementation is to place two BPW46 photodiodes in series between GND and 5V and use the midpoint as the negative input to an op-amp. The positive input to the op-amp is set as close as possible to the ‘resting’ value observed on the negative input when both photodiodes are occluded. No feedback or other components are used.
This implementation is passing basic acceptance, but I have some questions about the ‘resting’ value. I’m seeing it be about 0.2V. Occluding one diode or the other offeres a 0.4V swing. I’m not sure how calculate what the resting value should be from the datasheet for the BPW46 diodes. I need a way to set the comparison value without using a trim pot and direct observation to set the comparison value. How is this calculation made?
I know any diode connected exposed to light will act like a photodiode at least somewhat, with potentially mediocre results. I'm looking to implement a photodiode in TSMC 130nm without any sort of opto-process. Can anyone point me towards any resources in terms of how to estimate the eventual performance.
Never had to do this in particular before so with me luck.
I need to use a Vishay K857P quadrant photodiode for laser steering. I only want digital output indicating if top/bottom and left\right are illuminated more.
A balanced optical detector is very simple when only two photodiodes are being compared. (1x opamp) The only viable design I have that does the equivalent for a quadrant detector requires 4x transimpediance amplifiers, 4x buffers, 2x summing amp, 2x difference amp. I suspect there may be a way to simplify this if I only want digital output.
Given the extra circuity needed for the quadrant detector, its actually easier for me to send the received laser beam through a beam splitter, and use two quadrant detectors: one for horizontal and one for vertical and use the single op-amp comparator circuit. Unfortunately, these units have a common cathode instead of having four individual diodes, and thus can't be used this way as-is. I'm looking for ways to get around the common cathode and enable single bit output for left\right and top\bottom with simple circuitry.
I checked on two segment diodes and they also have the common cathode as well. Are there segmented diodes out there that don't have a common anode or cathode?
Does anyone have any good resources for designing a photodiode. I'm trying to use TSMC 130nm for my next chip (no opto-process just bare bones basic) as it's especially cheap and I'd like to use something a little smaller than my typical AMS 350nm.
Does anyone have any design resources for how to design/ estimate the photosensitivity of the process. Like I know that so long as the diode is exposed to light it should function as a photodiode (admittedly poorly), I'd like to be able to get a rough estimate of the sensors eventual performance before fabricating the chip.
Hi guys, I'm a scientist helping to set up an EEG lab and I was given this circuit diagram for building a low latency light sensor, but several parts are no longer available. The purpose of the light sensor is to assess timing variability between onset of a visual stimulus and onset of a digital event code that is supposed to mark when the image appears on screen.
- What specs should I match to build an equivalent (or similarly functional) circuit with different component parts?
- Given the specs of the component parts, how would I compute the rise time / latency to voltage change in the presence of light? I am hoping to get < 1 ms latency if possible.
- Any recommendations for walk-in electronics stores where I could buy the parts? I am hoping to build this by Friday afternoon since that's when I can borrow an oscilloscope, but that precludes online ordering.
Thank you so much for help with any of these questions!
Edit:
Here's a list of the ICs:
http://www.digikey.com/scripts/dksearch/dksus.dll?vendor=0&keywords=pnz102-nd (This part is now obsolete.)
http://www.digikey.com/product-detail/en/2N3904TFR/2N3904D26ZTR-ND/458818
http://www.digikey.com/product-detail/en/74LVU04N,112/568-7874-5-ND/1232028
The inverter is apparently used so that a high TTL signal indicates a bright light
https://preview.redd.it/0xy27lw7liq71.png?width=550&format=png&auto=webp&s=79c52ba7121c5f67ec2888f95999092d03755a30
I have an application where simplicity is critical. I need a simple compare of the photocurrent of two photodiodes with only digital output. Can I simply point the photodiodes to the inputs of an opamp with small resistors to ground in open-loop mode and expect predictable results?
I need to make 4 comparisons of 4 pairs of photodiodes, which would entail 8 transimpedance amplifiers. This gets space and cost limiting quickly, so I'm looking for ways to be more clever. Would this or something similar work reliably?
Alright so I am currently working on a light meter project to use with my film cameras. I have successfully made an incident meter using an Arduino and a BH1750 ambient light sensor. However I shoot a lot of landscape photography and this calls for the use of a reflected light meter. Being that the incident meter was an easy project, I thought the reflected one would be too. I was very wrong. The deeper down the rabbit hole I go the more I see how complicated it is.
So anyways someone helped my out by providing me with a formula:
P = I*Ssrc*Alens
Where: P is equal to power, I is the luminance in cd/m^2, Ssrc is the solid angle of the source and Alens is the area of the lens. A problem arises when I plug a value for luminance into the formula. A normal daylight reading for luminance gives back a value for power in watts. From what I understand this is impossible according to the datasheet of the silicon photodiode that I plan to use (BPW34). I also know that you need an op amp running in zero bias or reverse bias mode. What I need to know is how the value of power that comes out the op amp relates to the value of power expressed in the above formula. Any help will be greatly appreciated.
Also if someone could link me to a reliable photodiode op amp circuit to use.
Alright so I am planning to make a light meter for photography that measures luminance. I have so far successfully made an incident light meter using an ambient light sensor and an Arduino. From my limited research I have found that a reflected light meter that measures luminance instead of illuminance is more difficult. Could anyone point me in the right direction on where I can find information on how to calculate a value for the light intensity using a photodiode. I understand that it uses the photoelectric effect but it also relies on the angle of the cone of light, the angle at which the target surface is at and I believe the surface area of the sensor. Also I think that there is some constant used in place of the angle at the target surface as this is impossible to measure as the target is almost always at infinity. I am planning to use a Si photodiode that is sensitive to visible light as that is what the camera will work with. The ultimate goal of this project is to replicate what Sekonic and other light meter brands can do but cheaper and most likely less accurate. Apologies if my post is not specific, I am very new to this area and I don't know where to start. Many thanks.
I’ve been using some BPW34 photodiodes as mini solar cells on a couple of projects. String 10 of them together in series and you have 5v and can drive an ATTiny85 and a couple of LEDs. I’m wondering if there is an unpackaged version or SMD version. It would be great for a project I’m thinking of using a clear glass pcb.
Hi!
I have a setup with a large format high power LED. I use some lenses and diffusers in the setup, which is in a tube-like mount.
I would like to monitor the light the Power of the LED. I thought that maybe just putting a simple photodiode in a random position inside the system might be enough? I don't need a calibrated, exact measurement, I am thinking only in relative power monitoring.
For example I measure the system's power after the setup, and correlate it with the photodiode. If later on I notice that the power on the photodiode decreased by 20%, I would assume that the system's power also decreased by 20%.
Is this a feasable idea?
https://preview.redd.it/mjnojgjydys61.png?width=653&format=png&auto=webp&s=04e76e52325c7a4e35c80be29af5647f381eca3a
I've been having some trouble getting reliable results with an IR photodiode. Essentially I'm trying to use it as a beam-break detector, so it needs to be fast, which rules out analogRead.
At the moment I'm trying DATAPIN --> PHOTODIODE --> GND, then setting INPUT_PULLUP on the pin.
I have a feeling this isn't the best way. My next thought is to use a transistor but with no experience with them, I wouldn't know where to start.
Online searches show a confusing amount of options which go way over my head as I'm quite new to electronics.
Any thoughts or ideas?
The goal is to convert the light intensity measured by a photodiode into a digital signal I can manipulate and perform calculations on. I have a microcontroller dev board with an ADC pin (accepts -3.3 to 3.3 V) that I'm hoping to do this with.
From what I've gathered online, mainly from this PDF from Vishay Semiconductors, you can put a resistor in series with the reversed photodiode. Since the current generated by the photodiode is proportional to the amount of light received by the photodiode, the voltage across the resistor will also be proportional, and you can use that to estimate light intensity.
But how do I make sure that the voltage across the resistor stays under 3.3 V? Is it already guaranteed if my source voltage V_s is 3.3 V? Or do I just look at the maximum reverse current of the photodiode (looks like it's 10 uA?) and make my resistor value (3.3)/(10e-6)? Or should I also be factoring in the photodiode's max reverse voltage (looks like it's 20 V) and make my resistor value (3.3 + 20)/(10e-6)? Or is there some other solution more suited for this task that I should be using instead?
I have a BPW34 PIN photodiode i cut one of them in half (that why the photodiode look a little shattered) and take some close up photo with a microscope to see each layer. Im not sure if its right but for now i have seen 6 different layer and i would like to know which is layer is what , for exemple which layer is the P ,I ,N ect im not even sure if we can see these layers since i know there a very small but that why i make this post also the pink label layer is the layer that receive the light.
https://preview.redd.it/cciy9jq0j3r61.jpg?width=1280&format=pjpg&auto=webp&s=2e905d43f8c5ca6a9613fbaaa9239f278d32f06f
hi i have a Photodiode connected to A0 via a LM393, all is working fine except the Lux reading is inverted, max light is 0 lux and no light is 200 lux, guess its just a error in the code (attached)
- platform: adc
pin: A0
name: "Brightness"
unit_of_measurement: lux
update_interval: 5s
filters:
- lambda: |-
return (x / 10000.0) * 2000000.0;
Not sure if this is the right place for this question, but I want a fast optical sensor to open/close the drain-source on a MOSFET. I got some parts and have been running tests out in my barn using 9v on my supply(constant voltage simulating a 9vbatt). Results were not what I had expected. The current generated by the photodiode aimed straight at my emitter is just under 1mA, which seems pretty terrible! I know I've seen circuits with photodiodes driving MOSFETS, so what gives? I feel like I am missing something stupid here...
I need to do a presentation on PIN photodiode but im not really sure to understand why putting a voltage through a reverse biase photodiode will increase is response time what physics phenomena is the cause of that
