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I'm using a touch-screen device (a smartphone or a tablet) to access this site.

Hence, the built-in circuit lab won't work for me. What do I do to add a schematic to my question?

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  • \$\begingroup\$ NB: this is a reference Q&A! Competing answers (like: use this app, use this website, shake your phone rigorously until circuit lab works) are most welcome! \$\endgroup\$ – Marcus Müller Jun 16 at 9:05
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    \$\begingroup\$ Obligatory XKCD reference: #730 - Circuit Diagram \$\endgroup\$ – pipe Jun 18 at 16:19
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We take any kind of schematic, as long as it's clean.

Get a piece of paper, a ruler, a pen and get drawing and draw a clean schematic:

  • Make sure you use the right schematic symbols
    • don't use any "fancy" symbols because you feel like it
    • don't draw resistors as little round components with colors, but use the normal US-American or IEC symbols (e.g. resistors are either "zick-zack lines" or "white boxes", nothing else).
  • connections are vertical or horizontal. There's about two exceptions to that that also use 45° angles.
    • Exception 1: Wheatstone bridges
    • Exception 2: Bridge rectifiers
  • Make sure you adhere to good schematic structure practices
    • Signal always flows from left to right.
    • Ground symbols always point down.
  • It's mandatory components have names (e.g. R1, R2, C14, …), not just values (100 Ω, 2 kΩ, 100 nF), so that we can refer to them by name when discussing them.
  • use a dot ⏺ to mark junctions between traces, and if it helps clarity, use an arch ∩ to mark a crossing that isn't a junction (i.e. where the two traces are not connected.

Then, take a good photo.

Hints for taking good photos:

  • use much light from around, so that there's no shadows or bright spot
    • using the flash is usually not a good idea, since that will overexpose some of the paper, but underexpose the rest
  • Take a photo that isn't at an angle, but straight.
  • Make sure the whole drawing is in focus – being sharp is better than being blurry but larger.
    • Check that the picture is sharp!
    • Your camera won't be able to focus on the paper if you're up too close. If you zoom in and the lines aren't crisp, try moving away from the paper.
  • Rotate your image so that it's upright
    • (feels a bit stupid to say that, but reality is it's often missed) a 90° or 180° rotation is not acceptable
  • Crop your picture to the relevant part.
  • Most importantly, really check the image is OK before uploading it. Zoom in, and scroll around in it.

All that can be done with any modern smart phone or tablet.


Couple of examples. Even the "this is good enough" example isn't perfect, on purpose. Neither is the way the schematic has been drawn. This all goes to show that with

OK

OK, could be brighter and slightly more evenly lit, better white balance. This works, however.


shadow

A shadow obscuring parts of the image. Sometimes hard to avoid when not having a lot of ambient light.


Flashed

Used flash: image overexposed in the center, underexposed elsewhere. Also, upside down, unsharp.


uncropped

Needs cropping. The relevant part only takes up a small fraction of the image area.


rotated

Needs to be upright.


out of focus

Picture above is out of focus. Camera was too close to paper.


slightly out of focus

Still out of focus, though not as badly, but still too close. Having more pixels of your schematic doesn't help if they're blurry!


slanted
slanted2

Pictures taken at an angle. A very common mistake, because one rarely looks at a piece of paper from straight above. However, one typically looks at a screen in a very straight way, so this isn't great.
Notice how due to the difference in distance, some parts are out of focus.


overcompressed and underenjoyed

Overcompressed; rarely happens these days, but when using image compression apps, make sure you avoid having such visible JPEG artifacts.

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  • \$\begingroup\$ I have to say that all of those images are better than no image at all. \$\endgroup\$ – Solar Mike Jun 23 at 9:11
  • \$\begingroup\$ @SolarMike indeed, they are! \$\endgroup\$ – Marcus Müller Jun 23 at 9:20
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    \$\begingroup\$ I will use this to suggest to posters when they don't include a diagram. \$\endgroup\$ – Solar Mike Jun 23 at 9:23
  • \$\begingroup\$ that was exactly the intention \$\endgroup\$ – Marcus Müller Jun 23 at 9:41
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    \$\begingroup\$ the fact that it's a bit on the overly helpful side with regards to photography is exactly to make it useful to both: the people that don't include a schematic at all because "thick thumb-operated devices can't run the circuit lab schematic editor" and these that "here's a photo, lit by burning lard in the next room, shot at an artistically interesting angle of 117.23°, with the camera focusing on the alps, which happen to be 12,812 km away". Reading that, this describes a lot of "identify this component" photos, too. \$\endgroup\$ – Marcus Müller Jun 23 at 9:42
  • \$\begingroup\$ Related: Rules and guidelines for drawing good schematics \$\endgroup\$ – Lundin yesterday
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I once had a boss with lots of experience and a PhD but did not know how to use a computer, but he knew the power of a pencil.

Meaning: you don't need computer skills or even a schematic editor to be a great engineer.

This was filtered from @MarcusMüller 's last photo.

enter image description here

But you need some computer skills to make a readable photo.

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