Getting back to topic. Here's a few bullet points on the habits that I've developed while prototyping during the years:

• It's been a long time since I've breadboarded an entire circuit before committing it to PCB. But I always test in a breadboard small subsystems of a circuit that I'm new or unfamiliar with, before incorporating them into a PCB's layout.
• Once the layout is complete, I check it thoroughly and make sure that:
  • All grounds go to each chip where they're supposed to go.
  • All power traces go to each chip where they're supposed to go.
  • Each chip has its own 100 nF decoupling cap between its power and ground pins, as close as possible
  • No traces of digital and analog signals run adjacent and in parallel with each other.
  • If there are different voltage levels being used in the PCB, make sure they go where they're supposed to go.
  • Always place an rc filter and a small tvs diode at the pcb where a far away digital sensor or component is connected to through a long wire.
• Always use ic sockets if possible
• DO NOT install any chips in the board until it has been powered up and all of the ground and power plugs in its ic sockets and critical nodes have been checked for correct voltage levels. It's a lot easier to diagnose and trace any possible shorts or discontinuities due to etching imperfections this way.
• Once the chips are in place, double check their voltage levels at their power and ground pins.
• If the board includes a UART or some other form of serial communications, use a very simple echo program to verify that the communication lines are indeed working properly.

 

• Once the layout is complete, I check it thoroughly and make sure that:
  • All grounds go to each chip where they're supposed to go.
  • All power traces go to each chip where they're supposed to go.
  • Each chip has its own 100 nF decoupling cap between its power and ground pins, as close as possible
  • No traces of digital and analog signals run adjacent and in parallel with each other.
  • If there are different voltage levels being used in the PCB, make sure they go where they're supposed to go.
  • Always place an rc filter and a small tvs diode at the pcb where a far away digital sensor or component is connected to through a long wire.

Regarding layout for analog circuits, I have a few other checklist items:

• Identify sensitive circuit nodes (e.g., everything connected to op amp inputs, all high-impedance signals, all low-level signals, etc.) and arrange components so those nodes are as absolutely compact as possible;
• Keep sensitive nodes as far away from digital and other high-level signals as possible;
• Keep digital and analog circuit sections separate;
• Route digital signals around analog sections rather than through them; and
• Arrange grounds so that high-current and high-speed ground returns follow a path completely separate from the grounds within a sensitive analog section.

Much pain and heartache is saved by following those rules, as they minimize unwanted capacitive and inductive coupling between circuits.

 

Regarding layout for analog circuits, I have a few other checklist items:

• Identify sensitive circuit nodes (e.g., everything connected to op amp inputs, all high-impedance signals, all low-level signals, etc.) and arrange components so those nodes are as absolutely compact as possible;
• Keep sensitive nodes as far away from digital and other high-level signals as possible;
• Keep digital and analog circuit sections separate;
• Route digital signals around analog sections rather than through them; and
• Arrange grounds so that high-current and high-speed ground returns follow a path completely separate from the grounds within a sensitive analog section.

Much pain and heartache is saved by following those rules, as they minimize unwanted capacitive and inductive coupling between circuits.

I would've hit the "Like" button twice for that one, if this place allowed it. I'll definitely keep those practices in mind for my next ADC circuit. Thanks!

 

When you are designing an schematic, pencil and eraser for hours, finish the thing, build, test and a happy performer, never forget to write the key part numbers and what the design was for on the schematic sheet.

Something I built and worked to perfection had to ship its IC to someone, and years later cannot discern what chip was even after wringing my brain to the extreme for years ! It has been my most frustrating obsession.

 

Finding a PC did not work properly or reliably because its fuse was like 10 Ohm resistive

 

When you are designing an schematic, pencil and eraser for hours, finish the thing, build, test and a happy performer, never forget to write the key part numbers and what the design was for on the schematic sheet.

Or join the 21st century and use software to design your circuit where it also creates a BOM.

 

Finding a PC did not work properly or reliably because its fuse was like 10 Ohm resistive

Wrong thread? What does this mean anyway?

 

Don't ever take your voltage rated work gloves off to shake hands with someone who wants to talk to you about what your are working on...

 

I worked in mass transit where the primary power is 600 VDC from overhead trolley wires.

The circuit breaker for the overhead wire was set to trip at 20,000 amps so a direct short across the line would be momentarily catastrophic. Occasionally, one of the trolley poles would short both wires at produce a flash and a boom which provided an example of arc flash and what could happen right in front of your face.

The rule was that the probes for you your meter were always plugged into the sockets for volts (not current), set the dial to OFF when not in use, and check the probes and settings before you did use the meter again.

 

Don't ever take your voltage rated work gloves off to shake hands with someone who wants to talk to you about what your are working on...

Or, never ask your idiot buddy to hand you the soldering iron while your head is under the dash when installing his car stereo.