I have a low light source that I would like to convert to an electrical signal. I have tried the pin silicon photodiodes without success. I believe I need an Avalanche Photodiode to make my project work. I am not an electrical engineer, so I need help and advice before I purchase. I would like the APD to collect light in the visible range.
I have noticed that the APD has three pins. Is the third pin and input? Will I need a special power source to supply the APD?
I have noticed that range finder APD are much cheaper than other APD. Do they have any value other than for range finders?
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\$\begingroup\$ So we can give you a useful answer, can you link to datasheets for examples of the 3-pin devices and "range finder" devices you're looking at? \$\endgroup\$– The PhotonCommented Nov 8, 2017 at 20:01
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\$\begingroup\$ Hi, Photon. I recognize you from physics. Here's the ebay link:ebay.com/itm/… \$\endgroup\$– LambdaCommented Nov 8, 2017 at 20:10
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\$\begingroup\$ Here's the other one:edmundoptics.com/testing-detection/detectors/… \$\endgroup\$– LambdaCommented Nov 8, 2017 at 20:12
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\$\begingroup\$ "I have a low light source that I would like to convert to an electrical signal." Did you considered using a phototransistor? \$\endgroup\$– mguimaCommented Nov 8, 2017 at 23:14
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1 Answer
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For pont (2) The data sheet gives pinout.
The third pin is the metal case of the diode. In general it should be connected to ground.
There will be a small amount of capacitative coupling to the photodiode itself (not specified in the data sheet) so the ground connection should be clean as any noise could couple to the active electrodes.
An APD needs to be biased at a high stable voltage close to its breakdown so that the photo-generated carriers are multiplied by avalanche action. For this diode it can result in an amplification of up to 1000 times.
The actual bias required is shown in the data-sheet and will probably require adjustment for each diode and may need temperature compensation.
answered Nov 8, 2017 at 20:31
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\$\begingroup\$ Thanks for your answer, Kevin. So it sounds like I will need a power supply like this one? rover.ebay.com/rover/0/0/… \$\endgroup\$– LambdaCommented Nov 8, 2017 at 21:26
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\$\begingroup\$ @Lambda - possibly. That doesn't specify the voltage range it covers. I couldn't find information about that supply. \$\endgroup\$ Commented Nov 8, 2017 at 21:33