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Questions relating to designing PCBs
By t1d
#181622
The design with which I am working has four decoupling caps. Because C1, C6 and C7 are in such close proximity, I am wondering if the benefit of using three caps, to reduce the distance to their pins, is significantly better than the frugality of parts, reduction in heat and simplicity of design which would be afforded by using just one centrally located cap to serve all three pins. I am also wondering if the USB cap, C8, is of any benefit at all. Thoughts?
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By Ross Robotics
#181629
I would remove C1 and C7.. But it really depends on what this circuit will be doing..
By t1d
#181633
Thanks for your help, Codlink. It's just a demo board... Why is the cap at the USB helpful? Is it keeping the USB cable from being an antenna attached to the board?
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By Ross Robotics
#181635
It's for decoupling.
By t1d
#181644
I realize that the function of the USB cap is to decouple it, but I don't understand why it is necessary, as the chip pins on the power leg are protected by other decoupling caps. I want to learn why, so I will know for developing my own circuits.
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By Ross Robotics
#181647
It's for when someone uses the USB just for power. Some China supplies are CRAP. Also with some older PCs along with poor craftsmanship of said PC. For a part that cost pennies, it's called "rather be safe than sorry."

I know you're wanting to learn, but there are literally millions of webpages out there that contain this basic information.
By t1d
#181663
@ Codlink... Thank you for your help and patience. You are correct, I was able to find this answer by Goolging. Please forgive me. I do not want to become someone who has their questions ignored.

@ Valen... My apologies. My thinking was that each question was unique and that it would be easier for others to find the topic that they need by having individual threads for individual subjects. I will be glad to do as you asked.

Guys, I am embarrassed. I do not want to be troublesome. I am truly grateful for your help. You are very kind to help people; you create a better world by your generosity.

Creating the kind of world where we help each other, without requiring payment in the form of money, is something that I think is truly important. Accordingly, I participate in other forums where I can share in the areas in which I have the expertise and post tutorials on various sites. My thanks, again.