Hi, I am trying to build the amplifier circuit with the photodiode. I am referencing the circuit below. Note I only built the photodiode amplifier circuit around the LM358. I do not have a boost converter (U3) or linear regulator (U5) connected. My code also measures A1 and I have switched R1 with …

Do you have a common ground? You need a common ground. Do you have a multimeter? Unconnected, the analog input will float to an undefined voltage so a reading of 400 (or almost anything) is perfectly normal. But it's quite a coincidence that the op-amp would be putting-out the exact same volta…

I think some of your code is missing.

Please post a hand drawn schematic of the actual circuit you have constructed, showing the Arduino connections as well. As an aside, the LM358 is a very poor choice for a transimpedance amplifier, especially operating at 5V. It has very limited range of input currents and output voltages. Excellent…

Thank you for the advice. I will look into the fet amplifier. I attached a hand drawn circuit to my original post

Yeah... I've never built a transconductance amplifier (or really studied them) but I'm pretty sure you need high gain for a photodiode and high gain usually means "trouble". You generally need low noise components, and good PCB layout in a shielded case, etc. (Most of my experience with high-g…

There is no common ground between your circuit and the Arduino. And there is no decoupling on the supply of the opamp. Leo..

Your amplifier cannot swing negative; a negative supply is needed or refer your diode to a power supply mid(ish) point.

As with most of the "text book" circuits, the power supply is not shown, and is assumed to be bipolar (+15 and -15 volts)!

[image] madman87: problem is that my serial output gives a constant value (~400 counts). What do you anticipate, higher AD counts with increasing light on the sensor? Are you attempting to linearly map counts to light levels? Other than transimpedance and amplification, I am unsure what the…

[image] mrburnette: What do you anticipate,. . . Some background -- [image] Problems with op-amp for photodiode Sensors Hi all, I am trying to build the op amp circuit from this paper here (go to Fig. 3). All the components I have are same as stated in the paper. H…

Cant power transimpedance amp for photodiode with dc power supply?

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mrburnette July 29, 2022, 4:47pm 13

Thank you runaway_pancake.

... Was there a x-post somewhere or what? I never saw "here" ... but no matter.

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Cant power transimpedance amp for photodiode with dc power supply?

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