Photodiode Sampling: How Does Wavelength Affect Plate Saturation

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Discussion Overview

The discussion centers around the effects of light wavelength on the saturation of a photodiode, specifically one sourced from a CD-ROM drive. Participants explore the characteristics of the photodiode, its potential configurations, and the implications for measuring light input.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions how the wavelength of light at 800nm affects the saturation of a 1mm² photodiode plate.
  • Another participant suggests that the device may not be a photodiode but rather an optocoupler, raising concerns about potential eye damage from infrared light.
  • A participant shares measurements taken from the device, indicating a voltage of 35mV in daylight and near zero when covered, speculating about the function of the device's legs and the presence of transistor junctions.
  • Concerns are raised about the lack of a part number and the risk of damaging the device due to improper connections, with suggestions that it may contain a built-in amplifier.

Areas of Agreement / Disagreement

Participants express uncertainty about the exact nature of the device, with some suggesting it is a photodiode while others propose it may be an optocoupler. There is no consensus on the device's identity or functionality.

Contextual Notes

Participants note limitations in their understanding due to the absence of a part number and the unclear pinout of the device. There are also concerns about potential damage to the device from previous connections.

Who May Find This Useful

This discussion may be of interest to individuals working with photodiodes, optocouplers, or those involved in experimental setups related to light detection and measurement.

BrockLee
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I am curious how does the wavelength of light let's say 800nm/s collected by a photodiode results from the saturation of the plate 1mm. sq.

I have this photodiode from a cdrom and it has 6 legs, two do not have a bias-junction, the other four do, and the collector is slightly greenish. I don't know what kind of photodiode it is but its from a class two laser cdrom. I plugged in two junctions into my microphone port, unpowered, I don't know how to amplify this so i won't until i get advice, and I get a small peak around 30Hz, but that's about it. Is there any other sampling, like dividing the noise by multiples of expected light input?
thanks.
 
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You will need to get data on that device before you can use it.

6 pins sounds more like an optocoupler than a photodiode.

You may even have a laser. These are Infra Red in a CD writer so you could damage your eyes without even knowing it was working. So, don't apply power to it until you are sure of what it is.
 
I did meter the legs and on 4 of them in any combination, Irecieved at full day light 35mV and close to zero when covered by my hands, now this is not too intuitive, but I think that its made to be amplifyed by two of the legs, and the other four, which have small black dots inbetween the traces leading them to the plate in the center, have to be transistor junctions. But I have no way of testing these junctions as I do not have a ICEO/ICBO tester.
 
What package is the device in? Do you have a part number? If you don't know the pinout of the device and have already connected it to things like a microphone jack in full sun light its very possible that you may have already damaged it.

vk6kro said:
6 pins sounds more like an optocoupler than a photodiode.

I think its probably just a photodiode (or some photodetector) with a built amplifier.
 
Topher925 said:
What package is the device in? Do you have a part number? If you don't know the pinout of the device and have already connected it to things like a microphone jack in full sun light its very possible that you may have already damaged it.
I think its probably just a photodiode (or some photodetector) with a built amplifier.
No part number and package type is unidentifiable Silicone cased traces, So see through, with traces tintish looking.
If i had some battery's I would post a picture.
 

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