ischwartz
Posts: 1
Joined: Wed Jun 10, 2020 4:29 pm

Detecting Photodetector Voltage with RasPi0

Wed Jun 10, 2020 4:52 pm

I am trying to build a voltage feedback system using the Raspberry Pi but am not incredibly familiar with it. I was really hoping somebody more experienced could make sure I'm not completely lost.

To provide a bit of background, I will be measuring a pulsed source of light with a photodector, whose output will be in a current. There will be milliAmp spikes during the pulses with microAmp levels between these pulses. I want to keep the power of the light between the pulses as low as possible (in an ideal world it would be zero).

My thinking was to use an electronic switch (something like sn74auc1g66) to block the current during pulses so I only see the current between pulses. I'd then convert the tiny current into a more readable voltage using AN1494, and then convert this signal to digital (I was heavily considering the RasPi0 Analog Zero). I would then use the Pi to measure this voltage and output a corresponding voltage to either raise or lower the light.

My question is: does this seem possible in the way I described? Will the I-V converter be necessary? Is the RasPi0 my best choice for such a task?

I would love to hear input from others on this, especially to make sure I am not in way over my head! Thank you!

boyoh
Posts: 1468
Joined: Fri Nov 23, 2012 3:30 pm
Location: Selby. North Yorkshire .UK

Re: Detecting Photodetector Voltage with RasPi0

Fri Jun 12, 2020 10:33 pm

ischwartz wrote:
Wed Jun 10, 2020 4:52 pm
I am trying to build a voltage feedback system using the Raspberry Pi but am not incredibly familiar with it. I was really hoping somebody more experienced could make sure I'm not completely lost.

To provide a bit of background, I will be measuring a pulsed source of light with a photodector, whose output will be in a current. There will be milliAmp spikes during the pulses with microAmp levels between these pulses. I want to keep the power of the light between the pulses as low as possible (in an ideal world it would be zero).

My thinking was to use an electronic switch (something like sn74auc1g66) to block the current during pulses so I only see the current between pulses. I'd then convert the tiny current into a more readable voltage using AN1494, and then convert this signal to digital (I was heavily considering the RasPi0 Analog Zero). I would then use the Pi to measure this voltage and output a corresponding voltage to either raise or lower the light.

My question is: does this seem possible in the way I described? Will the I-V converter be necessary? Is the RasPi0 my best choice for such a task?

I would love to hear input from others on this, especially to make sure I am not in way over my head! Thank you!
From BoyOh
I'm a bit lost on what you want to do, I understand you want to transmit pulses of light , and detect only the light pulses
and Ignore any light between pulses, Could you transmit the light through some Optic Fiber tube.
Only jest a suggestion

Regards BoyOh
BoyOh ( Selby, North Yorkshire.UK)
Some Times Right Some Times Wrong

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