Capacitor C1 burns when I switched the Power On

[AbidHussain70]

No description provided.

[RobertGawron]

@AbidHussain70: could you please say what the problem was? You closed the issue so I think you resolved it by yourself, the info about issue would be good for me and maybe other people who try to build the same device.

[AbidHussain70]

I made a new PCB. When I receive the PCB I will solder the components and will update.

[AbidHussain70]

Hi,
I made a new PCB and I solder the components, I am getting almost 2.4 V in the photo-diode, and almost 3.6 V across C4 capacitor, when I switched On the power. But after sometime the voltage across C4 jumps to 5 V and the voltage the photo-diode terminal goes under 1 V. These are measurement without attaching photo-diodes to the terminal.
What should be the voltage across the photo-diode terminal? And does the voltage of the C4 varies with the load? (I mean if I attached the photo-diodes).

[AbidHussain70]

I attached the photo-diodes and now the voltage across photo-diode is 2.5 V.

[RobertGawron]

@AbidHussain70:

What should be the voltage across the photo-diode terminal?

By "terminal" you mean + input of operation amplifier (I mean pin 3 of U1) measured in reference to GND? If yes, then + and - pins have the same voltage measured to ground and - pin has voltage created by voltage divider R1+R2 = half of the power supply voltage.

If by terminal you mean pins of the photodiode, it should be (I'm not sure here):
half of the supply voltage - 4x12V

And does the voltage of the C4 varies with the load? (I mean if I attached the photo-diodes).

The voltage will be always the same - it should be -4x12V (measured on pins of C4). It's -4x12V because you have four 12V batteries connected with "+" to the GND.

1. What is the voltage on pin 3 of the U1?
2. What's the voltage on pin 2 of U1?

[AbidHussain70]

By terminal I mean the input voltage for photo-diodes.

I made a small socket for Photo-diodes, and placed a connector on main board. The socket will be installed on the connector.`

Here is the picture of small socket. My aim is to check the results with different number of photo-diodes. `

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What is the voltage on pin 3 of the U1?

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U1 pin3 gives 6V.

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What's the voltage on pin 2 of U1?

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U1 pin2 gives almost 0V.

I am using 12 volt power source directly from power supply.

[RobertGawron]

@AbidHussain70: I see you created your own PCB and modified a a bit schematic. Cool :)

What is the purpose of D1-D4 and are they connected in correct polarization? Can you check if voltage on terminal (I marked is as 1) is roughly -4x12V?