3

I accidentally knocked off and lost an SMD labelled "C9" from the Raspberry Pi Camera. The Camera still works, and I am unable to spot any differences. What is the role of the capacitor, and is it needed for proper operation of the camera?

  • 3
    Let us look at the schematic. raspberrypi.org/documentation/hardware/camera/schematics/…. I think C9 is a low pass filter, used to remove high frequency noise/spikes of the voltage regulator of the 24MHz clock. So if your environment is not that noisy, you won't notice anything if C9 fell off. – tlfong01 Jul 7 '20 at 3:32
  • 1
    Why dont you add this comment as an answer, so I can accept it? – Aayush Panda Jul 13 '20 at 0:42
  • 1
    thank you very much for your kindness. So I have drafted an answer. Please feel free to suggest anything to make my answer more newbie friendly. Cheers. – tlfong01 Jul 13 '20 at 2:15
  • 1
    C9 is a smoothing capacitor and the purpose is to protect the X1 from variations in the voltage supply. Since the value is quite high it will only protect against low frequency variations, if high frequency protections is needed there is also a low value capacitor in parallel with C9. – MatsK Jul 13 '20 at 9:09
1

Question

The OP accidentally knocked off a SMD component labelled C9 from his Rpi Camera. But his camera is working "perfectly" without any noticeable difference. How come?


Answer

Introduction

Well, usually in an electronics circuit, not all components are critical. If any one or more of those not critical components are removed, the system often still works, with or without any noticeable differences.


Rpi Camera Circuit Analysis

I googled the schematic as shown in Appendix A. Then I searched for any component labelled C9 and happily found it hiding in the very middle of the picture. Now I have put relevant circuit below for discussion.


clk gen

I think the SMD component labelled C9 is just an external 1uF bypass for the voltage regulator of the 24MHz clock generator. The voltage regulator usually has its own physically smaller bypasses. So the external bypass cap is not that critical.


Discussion and Recommendation

The SMD Bypass cap C9 for both V1.3 and V2.1 are easy to access. So it might be a good idea to replace the lost cap with an external one, say a through hole electrolytic/tantalum 1~10uF. Just use two jump wires to hang the external guy outside/nearby, instead of in place.

Warning: I am just a friendly hobbyist. No guarantee that no nothing won't melt down or blow up. Good luck.


References

(1) Rpi Camera Schematic v2.1 - rpi.org 2018apr24


Appendices

Appendix A - Rpi camera schematic

rpi camera


Appendix B - Rpi Camera Components

camera 2

camera components

  • 1
    This is fantastic! Thank you for your detailed answer! – Aayush Panda Jul 13 '20 at 16:39
  • Hi @Aayush Panda, You are very welcome. Thank you very much for your nice words and encouragement. Cheers. – tlfong01 Jul 14 '20 at 0:46

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.