Sketcing a circuit while prototyping - Any suggestions?

[TheUnnamedNewbie]

We have CAD now. CAD is great. It allows us to make nice schematics (if we know what we are doing) that look neat and are readable quickly.

However, often while "thinking up" a circuit, you need to quickly be able to visualize a schematic (or at least I do). I still prefer old-skool paper and pen for this - if I have to do them in CAD, I always feel like I'm wasting a good bit of time drawing the pinouts/schematic symbols for parts I might not even use. But at the same time, with paper it gets really messy really quickly and even more so when you start "replacing" or "inserting" stuff into your schematic. (examples of this would be "oh hey I think we are going to need a compensation capacitance here" or "perhaps we can use a voltage divider here so we can use a different reference voltage there" etc).

So I was wondering if there were any ways to do "quick" schematic sketches in CAD (without feeling like I spend 50 % of the time making a symbol for yet another amplifier etc.), or alternatively, any ways to make better hand-drawn sketches. What are your tips/Experiences/etc?

[plazma]

For a quick sketch I use Eagle and use correct parts if available or replace them with a similar part with a similar symbol.

For simple circuits I some times use Every Circuit on Android.

If better simulation is needed then I use LTspice.

[ikrase]

THere's always the Falstad applet. With simulation!

[Zero999]

I use LTSpice for quick stretches .

[tszaboo]

Pencil. With rubber pencil eraser. B2 works well.

[plazma]

Pencil. With rubber pencil eraser. B2 works well.

Pilot Frixion pens are good for paper sketching. Just don't solder or use hot air above the drawings

[Fludo]

Visio studio from Microsoft is very good for sketches, it's very easy to create and manipulate custom components.  It's more like a graphical editor but has a fairly large selection of circuit and engineering components.  I use it for drawing cable and wiring diagrams with non common plugs and connectors.

[T3sl4co1l]

Pen and paper.  (My prototype drawings have lots of scribbled-out sections, yes. )

It may be a acquired or innate skill to imagine the circuit as you go, keeping track of it; I probably do this the most, with the downside that, when I put down a circuit for a couple of days and forget to write it down, I'm left staring as a breadboard.   (Or if it's not fully written down, because I made a small change here or there and forgot to note it.)

Tim

[RoGeorge]

Paper (a notebook would be even better) and pencil. No fancy pens. Pencil marks will still be readable forever, some other fancy chemical pens might fade out after a few years, or in contact with heat or other chemicals.

It doesn't matter if the draft get messy. It will be cleaned up later, in CAD. Also, paper sketches are of an enormous help when you go back to a design after a few years. A CAD page will tell you nothing, you might not even recognize that that was your own design. The paper sketch will make you remember the whole project history in a glimpse.

Another issue with CAD in the long run is that the support changes, as in floppy disks, CD, DVD, BluRay, USB drive, whatever, the data format changes, the CAD software changes, and you might not be able to run the old software on a new machine, and so on.

Also against draft design in CAD is the extra burden that comes with editing, minor details that you don't think they are hard, but overall they will slow you down.

Paper does not need power, and as long as you don't set your notes on fire and you don't loose the notebook, you are good to go, with instant access. No viruses, no lost files, no hard disk failures.

One more thing to add, stay away from online (cloud based) CAD tools at all cost. I've seen too many companies and cloud/online based services going belly-up, or just simply discontinued. Don't count on them. You don't want your work to be at the mercy of a 3rd party.

CAD is good only after the draft design, and in parallel with paper sketches. Jumping straight to CAD is a mistake IMO.

Take a look at the background paper in the attached pic, it would be a mess to sketch all those pencil scribbles in a CAD.

[bd139]

pilot g2 + silvine 5mm squared A4 exercise books. You don't need to rub stuff out. Don't use a pencil - they're evil; low contrast, unreliable, need sharpening or maintenance.

1. Write small circuit fragments and ideas at a time and give the parts labels like RH, RL in a divider for example.
2. Write experimental values underneath. Means you don't have to relabel the diagram.
3. If the idea is a write off. mark it up as a write off. don't scribble it out. Start a new diagram below for that fragment and explain in writing why you did it.
4. When you have a working "system", draw the block diagram then the schematic on a new sheet.
5. Keep 25mm or so of the right hand side clear as a margin for annotations and cross references.

[frog_jr]

I typically start by drawing a schematic, taking the time to create those components that are not already in the library.
I then print it out and scribble any changes, notes or new devices on that schematic. When the notes become too dense to continue, I incorporate the valid changes and notes into the schematic, re-print and continue. ALL of the schematics and notes are then filed with the project upon completion.

[Wimberleytech]

Visio studio from Microsoft is very good for sketches, it's very easy to create and manipulate custom components.  It's more like a graphical editor but has a fairly large selection of circuit and engineering components.  I use it for drawing cable and wiring diagrams with non common plugs and connectors.

Visio is a great tool which I use for this purpose as well.  I built a nice library of generic components which save in a stencil.  Have done this for many years!

[james_s]

I use a good old fashioned pencil and a pad of paper, no need to over-complicate things in the very early stages. Move to CAD once you have a rough idea of what the circuit is going to look like.

[vk6zgo]

Whiteboard & erasable marker pen.

[bson]

Pencil. With rubber pencil eraser. B2 works well.

Same here, I use a cartridge pencil and a graphing grid lab notebook.  Same book I jot down notes like measurements, dimensions, and other notes, in case I want to revisit them later.  It's good to have all ideas, even the bad ones, in one place.

[bson]

pilot g2 + silvine 5mm squared A4 exercise books. You don't need to rub stuff out. Don't use a pencil - they're evil; low contrast, unreliable, need sharpening or maintenance.

Consider a mechanical pencil...
https://www.amazon.com/gp/product/B00AZWYUA4

And:
https://www.amazon.com/Rotring-Tikky-Mechanical-Pencil-0-5mm/dp/B01B0JSCOU

[BravoV]

At the more expensive's side though  , and powerful enough to run LTSpice.

Sorry, can't help it as I just watched it while ago. 

https://youtu.be/4bLdrCEjVbA

[thermistor-guy]

...
However, often while "thinking up" a circuit, you need to quickly be able to visualize a schematic (or at least I do). I still prefer old-skool paper and pen for this - if I have to do them in CAD, I always feel like I'm wasting a good bit of time drawing the pinouts/schematic symbols for parts I might not even use. But at the same time, with paper it gets really messy really quickly and even more so when you start "replacing" or "inserting" stuff into your schematic. (examples of this would be "oh hey I think we are going to need a compensation capacitance here" or "perhaps we can use a voltage divider here so we can use a different reference voltage there" etc).
...

One option: draw your circuit freehand, using a drawing program, like Gimp or FireAlpaca. My son uses FireAlpaca and a Monoprice graphics tablet every day, for visual arts homework and just playing around. The speed with which he goes from rough sketch to finished artwork, using just the tablet, is amazing.