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Will my PCBs work?

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--- Quote from: inse on January 22, 2022, 03:33:31 am ---The golden rule of PCB design: first run will always need botch wire

--- End quote ---

Yup, one bodge wire was needed to make it work. :)


--- Quote from: Len on January 21, 2022, 08:34:56 pm ---These are the first PCBs that I have ever designed. Will they work?

--- End quote ---

Obviously not.  Something is missing.  Clue: You need to add the components.  :)

There are many reasons why a pcb might not work or not work correctly.
1/ Single ended nets that should be multiple ended nets.
2/ Tracks too thin.
3/ Interference between tracks or tracks and transformers/inductors or wires carrying HF and high current or even mains.
4/ Lack of shielding of wires.
5/ Poor grounding.

I remember a USB audio mixer project I did.
The pcb came back and on the output was 1VAC hum.
I narrowed it down to hum in the ground line.
Had a look at the schematic and I had mixed in power supply ground with audio ground.
The charging impulses into the smoothing capacitors were modulating the ground line and so the audio signal.

So separated audio ground and made power supply in one side and out the other and connected ground once at power edge connector.
Next revision came back totally different with very low noise level.

I designed a USB scope. Worked fine except for some 10KHz ripple on wanted signal.
I had run a signal track under a 7660 voltage inverter and its clock frequency was being induced into the track.

Similar problem with 8MHz on signal.
I had run signal next to 8MHz clock crystal and clock was getting induced into signal track.

Audio amplifier, simply didnt work.
I had forogt to add a tag to input ground track and it wasnt connected to power amp section ground and was floating.


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