Turning LED's into photodiodes?

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In summary, you would need to connect the photodiodes to a current-to-voltage converter circuit in order to convert the photocurrent to an output voltage.
  • #1
petitericeball
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I think that's what they're called. I was guessing that you just put them in backwards, but I'm betting its more complicated than that?
 
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  • #2
In theory, although you would be better off with real photodiodes.
 
  • #3
mgb_phys said:
In theory, although you would be better off with real photodiodes.

You will connect the LED or photodiode up to a current-to-voltage converter circuit, in order to convert the photocurrent to an output voltage. See the example opamp circuit on this page, for example:

http://sales.hamamatsu.com/assets/html/ssd/si-photodiode/index.htm

Using a high reverse voltage across the photodiode or LED will help it to operate faster (detect higher frequency signals), because the high reverse bias decreases the capacitance across the depletion region.
 
  • #4
how would i go about sending these "impulse" type things into a computer?
 
  • #5
People who have green 532nm lasers have been known to try to test the output power by using green LED's. It works but it is not a very accurate way of approaching this problem.
 
  • #6
petitericeball said:
how would i go about sending these "impulse" type things into a computer?

What impulse type things?
 
  • #7
Sorry that was very vague.. bad day.. Okay, so how would i hook up the photodiodes up to a computer so that the computer can understand the signals that the photodiodes are sending out?

Okay, so I'm trying to create some sort of a computer targeting system (nothing fancy) with lasers and photodiodes. I want to be able to be able to "track" the movement of the laser using the photodiodes. Later on I hope to somehow make the laser track movement.

I know this is a terrible explanation, but I don't totally understand how I am suppose to do this..
 
  • #8
The traditional way would be with some data acquisition and motion control modules, connected via RS-232 or USB to your PC. Here are three companies that make such modules:

B&B Electronics http://bb-elec.com/

Omega http://www.omega.com/das/index.html

National Instruments http://www.ni.com/

You can also "roll your own" modules, but you need to be fluent in RS-232 or USB interface hardware, and comfortable programming your own uC and data acq and motion control hardware.
 

FAQ: Turning LED's into photodiodes?

1. How can LED's be converted into photodiodes?

LED's can be converted into photodiodes by reversing the direction of current flow. This means that instead of providing power to the LED, the LED is exposed to light and the resulting current is measured. The light-sensitive nature of the LED allows it to function as a photodiode.

2. What is the difference between a LED and a photodiode?

A LED (light-emitting diode) is a semiconductor device that emits light when a current is applied, while a photodiode is a semiconductor device that produces a current when exposed to light. In other words, LED's emit light while photodiodes detect light.

3. What are the advantages of using LED's as photodiodes?

Using LED's as photodiodes can be advantageous because they are readily available and inexpensive. Additionally, they have a wide spectral response range and can be easily integrated into electronic circuits.

4. Can all LED's be used as photodiodes?

No, not all LED's can be used as photodiodes. Only certain types of LED's, such as those with a transparent or clear casing, can function as photodiodes. Additionally, LED's that emit light in the visible spectrum are typically more sensitive to light and therefore better suited for use as photodiodes.

5. What are some common applications of using LED's as photodiodes?

LED's used as photodiodes have a variety of applications, including in light sensors, optical communication systems, and barcode scanners. They can also be used in industrial applications for detecting and measuring light intensity and in consumer electronics for touchless gesture control.

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