Apr 25 2008
Building A Better Schematic
While working on our electronics projects I’ve read through a lot of schematics. And I’ve been endlessly annoyed. Error upon error upon error. It drives me up a wall, mainly because it means that I have to spend twice as long on a project. But also because it makes a beginners life so much harder.
Here are a couple of recommendations I have for the circuit designers our there. Most of these should be “no brainers” but I’ve seen so many errors that they are worth reiterating:
- Everything on the parts list should be clearly identified on the schematic.
- Everything on the schematic should be on the parts list.
- Be as descriptive as you can with components on the schematic. Labeling things “IC1″ or “R4″ is extremely frustrating. You should include the part # (IC1) along with a basic description (ex. CD4017). Even better, include a more detailed description. For example, IC1 CD4017 Decade Counter.
- Having jacks and terminal blocks on the schematics is okay, but you are mixing apples and oranges. A schematic should be an electronic representation of the circuit, not a physical one.
- If you do want to mix physical and electronic representations on a schematic, label properly. Don’t put “TB1″ (terminal block one) without indicating what it does. “TB1 DC In” and “TB2 Audio Out” are clear and simple.
- Check-double-check-triple-check. I’m honestly beginning to think that there are no proofreaders or editors left in this world. It is unacceptable that published (either book or magazine) work is not properly proofed. It’s gotten to the point of being embarrassing.
- Left to right. Top to bottom. That’s how we read in the West. That’s how we think. Nonstandard layouts, or inconsistent layouts, makes it very hard for a beginner to follow the “flow” of the circuit. If you can’t near-instantly tell where the power is, where the input is, where the output is, then you are doing it wrong.
- Constantly having to reference the text is annoying and error-prone. This goes back to being very descriptive on the schematic. If I have to go back and forth between the text, schematic, and parts list, then you aren’t doing a good job with the schematic.
- The text should supplement and expain in greater detail the contents of the schematic. You should not have to go to the text to determine what a part is. Only what it does.
One Response to “Building A Better Schematic”
You know, I don’t think I mind schematics laid out the same as the physical world. In fact, I think those are easier to explain. They are probably more helpful, too, when it comes to translating a schematic to a PCB or breadboard. It often takes a big conceptual jump to go from schematic to PCB. You can really see why people specialize in given areas.
I guess what annoys me most is the inconsistency. The apples and oranges. You see someone start in a more physical layout, then switch to a more logical setup. They start putting jacks here and there, and yet use logical gate symbols too (ex. triangles for invertors, instead of a DIP symbol).
They physical layout stuff is harder to do now, too, with all the surface mount stuff. You can get 6 different packages, with different pinouts.
Perhaps we need three levels:
* Logical Schematic (gate symbols, etc)
* Physical / Functional (package based)
* Production (PCB, breadboard, etc)