I've noted that really often, questions require the use of schematics, and answers too.

Since I've seen some online editors, why don't we also embed one, to encourage the use of proper schematics?


Thanks to the great work of the people at CircuitLab (special thanks to Yuan Wei, the developer who worked with me on this), this is now live.

For users with at least 11 reputation, everybody, there is a new button in the editor's toolbar:

screenshot of the editor with the new button

This button will launch the CircuitLab schematics editor / simulator. Clicking “Save and Insert” in the schematics editor closes it again and inserts the circuit's image into the post editor.

When editing an existing post that already contains a schematic, you can also click “edit the above schematic” which appears below the circuit image in the post editor's preview. This will open the corresponding circuit in the editor for further refinement.

If you're interested in some technical details and design decisions regarding the editor integration, you can read my announcement post on meta.ux (starting from “This was a somewhat…”). This was about the Balsamiq mockup editor, which was the first external editor that we integrated with a Stack Exchange site. The CircuitLab editor's integration is very similar; from a user's perspective it's almost identical.

CircuitLab officially only supports Firefox and Chrome. It seems to however work just fine in the other browsers that we support on Stack Exchange (IE9+, Safari, Opera). Nonetheless, when you launch the editor in a browser other than Firefox or Chrome, we'll warn you that the browser isn't officially supported by the editor (but we won't refuse to launch it – as I said, it generally works fine).

For detailed information about the CircuitLab editor, have a look at their documentation.

  • \$\begingroup\$ Awesome job! I accepted the answer right away, so it'll be more visible \$\endgroup\$ – clabacchio Feb 27 '13 at 14:43
  • \$\begingroup\$ Now for a button to be able to insert simulation output? I am unbelievably excited that you have the circuit editor embedded. \$\endgroup\$ – Kortuk Feb 27 '13 at 16:07
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    \$\begingroup\$ Could this be enabled on meta to allow questions and sandbox? \$\endgroup\$ – Kortuk Feb 27 '13 at 17:22
  • \$\begingroup\$ @Kortuk What would you need a sandbox for? And generally, what kind of Meta questions would required schematics? \$\endgroup\$ – balpha Feb 27 '13 at 17:32
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    \$\begingroup\$ @balpha Sorry to be a bother. Sandbox for people to play with the functionality of the plugin, just like latex. Asking questions about using the tool, that will happen often if latex is any measure, maybe more often as it is a more complicated tool. Just seemed like a good idea. \$\endgroup\$ – Kortuk Feb 27 '13 at 17:33
  • \$\begingroup\$ @Kortuk No worries; I'm happy to get feedback. But I'm trying to think whether it's really necessary. Playing with the editor doesn't require you to save anything, so you might as well do that on the main site (and FWIW, you could also just go to circuitlab.com), and question about using the editor may require things like screenshots, but not just plain circuit schematics I would think. \$\endgroup\$ – balpha Feb 27 '13 at 17:37
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    \$\begingroup\$ On behalf of the team at CircuitLab, thanks for your hard work, @balpha! \$\endgroup\$ – weiy Feb 27 '13 at 17:39
  • \$\begingroup\$ @weiy Thanks to you guys too for such a great product to use! Anyone in OKC gets a beer on me. \$\endgroup\$ – Kortuk Feb 27 '13 at 17:50
  • \$\begingroup\$ @balpha, okay, I was not sure if it was simple to do, and I feel there will be times where people are just going to want to ask about it and having the tool here would be simple, but it is just an idea. \$\endgroup\$ – Kortuk Feb 27 '13 at 17:55
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    \$\begingroup\$ Excellent news! @Kortuk - I think this deserves a Meta announcement \$\endgroup\$ – Chris Laplante Feb 27 '13 at 18:45

I'm one of the developers of the CircuitLab online schematic editor and circuit simulator, which we released publicly just a few weeks after this question was asked. You can draw and simulate a circuit, save it, click "Make public", and you've instantly got a circuit URL plus schematic images to share. It's also usable for "schematic only" (non-simulated) operation, where you just want to lay out ICs as blocks, etc. We have cross-tab copy+paste, so you can load someone else's circuit, select a bunch of components, hit Ctrl+C, switch to your clean schematic tab, and hit Ctrl+V and you're all set. 100% in-browser, no Flash/Java plugins required, fully Windows/Mac OS X/Linux compatible.

For an example from a EE.SE question, see Diode reverse recovery time and the corresponding CircuitLab page and simulation:

diode reverse recovery time

We have a big to-do list of simulation and schematic capture features that we're working to add, so I'm not sure that we have the engineering resources to devote to making an "embedded" version of the editor at this time. However, I'm just curious to see if something similar is something the community might be interested in? Similar to how the User Experience stackexchange site embedded Balsamiq.

  • \$\begingroup\$ I tried to simulate this circuit, which is the same I've seen in a question; something went wrong, because I don't see the output charging. Also, I would like to see/put dots in intersection between wires, and a less tricky transient analysis. \$\endgroup\$ – clabacchio Mar 28 '12 at 13:00
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    \$\begingroup\$ Hi @clabacchio, I made two tiny changes to your circuit (see my description) and it works! Dots on intersections are definitely on the to-do list -- coming soon. "Less tricky" is vague but we think it's already pretty easy to use and have a few ideas in the pipeline. Thanks for giving it a try. \$\endgroup\$ – compumike Mar 28 '12 at 17:54
  • \$\begingroup\$ Thanks! I thought that since it was without supplies it would have worked...Anyway for quick simulations, I still find Falstad quicker, that's what I meant... \$\endgroup\$ – clabacchio Mar 28 '12 at 18:06
  • \$\begingroup\$ @clabacchio: Falstad's applet definitely provided some inspiration for what can be done in the browser! We think CircuitLab has some nice features in a number of areas: accurate SPICE-like component models and dynamic behavior, frequency domain simulation, parameter sweep simulations, multi-user save/share/edit workflow, hosted (and pretty) schematic images, support for "schematic only" (non-simulated) circuits with custom IC blocks... We haven't exposed this too publicly yet, but we've also got a growing repository of user-generated public circuits. \$\endgroup\$ – compumike Mar 28 '12 at 18:20
  • \$\begingroup\$ Indeed, it's awesome and I've already tried to use it for an answer :) \$\endgroup\$ – clabacchio Mar 28 '12 at 18:29
  • \$\begingroup\$ My thoughts are, go write yourself up an answer to this question and continue doing the awesome way of advertising (as I have told you before). If it starts to become an (informal) standard for the site then I would recommend pursuing a more tightly integrated connection at that point. \$\endgroup\$ – Kellenjb Mar 28 '12 at 20:54
  • \$\begingroup\$ Why can't I find a quick export to image? I see only pdf...it would be awesome an export function like the snipping tool, with an adequate resolution for this site like VGA or smaller \$\endgroup\$ – clabacchio Mar 29 '12 at 6:23
  • \$\begingroup\$ Occasionally people use your software to make make pictures to include in posts here. They generally look nice enough, except for that really annoying and distracting banner at the bottom. I know you want to promote your software, but getting in people's faces like that will have the opposite effect. Your images also have a lot of white space around them. they could be smaller or show more detail for the same size if the banner and the border white space was removed. I sometimes ding people here for posting images with all the trim left on. \$\endgroup\$ – Olin Lathrop Feb 27 '13 at 14:20
  • \$\begingroup\$ @OlinLathrop, we hated seeing the poorly cropped screenshots, too! :) So we made the new integrated tool automatically crop the circuit schematic correctly. \$\endgroup\$ – weiy Feb 27 '13 at 17:43
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    \$\begingroup\$ @OlinLathrop as you see, they do make a major point of helping with requests. Take your requests for their program here. \$\endgroup\$ – Kortuk Feb 27 '13 at 18:54

I suggested using Falstad simulator a while ago, which is free for such use and can be embedded in a page

two-inverter momentary toggle

Also has an option for a white background:

enter image description here

So most of it is implemented already, but it would be best if there were a way for the poster to edit the circuit and press Save instead of having to copy and paste the raw code into their post.

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    \$\begingroup\$ I'll vote for using the Falstad simulator, been using it for a few weeks now and I think it's pretty good. It does lack certain things, such as simulating enhancement mode MOSFETs, but it would certainly be useful for most applications. You can even download it and run it offline, which is nice. \$\endgroup\$ – Jim Feb 6 '12 at 12:01
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    \$\begingroup\$ @Jim: I asked the author for URL export, and he implemented it within the day. He's open to adding more parts, but doesn't have time. Since it's open source and we have permission to modify it, we can add them, too. \$\endgroup\$ – endolith Feb 6 '12 at 14:21
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    \$\begingroup\$ Yucc. If schematics look like above, then this Falstad thing should not only not be implemented but outright banned! Even if the stupid yellow turds are optional, you have proven it's possible to export a image with them turned on, and provided one existance of someone being too lazy to turn off private features before exporting the schematic for others to see. If you posted a question with such a mess, I'd probably downvote it. \$\endgroup\$ – Olin Lathrop Feb 6 '12 at 16:57
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    \$\begingroup\$ @OlinLathrop: This is an interactive applet, not a static image. The speed of the yellow dots illustrates the flow of current through the circuit, and should definitely be on by default. See electronics.stackexchange.com/a/13753/142 for an example of them helping someone. \$\endgroup\$ – endolith Feb 6 '12 at 19:28
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    \$\begingroup\$ @endolith: No, I just want to see the circuit someone is asking about. Those yellow turds are annoying and cause confusion. I shouldn't have to, and certainly don't want to spend the time to, know how to use yet another tool like that. I want people to simply show me nice, neat, readable, well labled, uncluttered, static schematics of the circuits they are asking about. \$\endgroup\$ – Olin Lathrop Feb 6 '12 at 22:02
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    \$\begingroup\$ @OlinLathrop: You don't have to use it if you don't want to. \$\endgroup\$ – endolith Feb 6 '12 at 22:43
  • \$\begingroup\$ @endolith: Yes, but we'll all be having to look at the resulting messes. It's best to not invite them in the first place, especially since this is such a solved problem already. \$\endgroup\$ – Olin Lathrop Feb 7 '12 at 14:29
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    \$\begingroup\$ @OlinLathrop: It's a solved problem? What do you mean? What's the solution? \$\endgroup\$ – endolith Feb 7 '12 at 15:53
  • \$\begingroup\$ @endolith - The current solution is to design the circuit in our capable schematic capture programs on the PC, and upload an image. \$\endgroup\$ – Kevin Vermeer Feb 9 '12 at 9:27
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    \$\begingroup\$ @KevinVermeer: You'll still be able to do that if you want, but that's certainly not a "solution". \$\endgroup\$ – endolith Feb 9 '12 at 15:49
  • \$\begingroup\$ Since Falstad runs as an external applet from the browser, it should be possible to include a link to it in the "Question" or "Answer" box, since the author is so open... \$\endgroup\$ – clabacchio Feb 27 '12 at 19:50
  • \$\begingroup\$ @clabacchio: The author gives permission to make copies and modify the applet, so it could be hosted on stack exchange servers with our own modifications. \$\endgroup\$ – endolith Feb 28 '12 at 0:36
  • \$\begingroup\$ That's basically what I mean : (removed the previous comments) \$\endgroup\$ – clabacchio Feb 28 '12 at 7:07
  • \$\begingroup\$ I'll also point out that Falstad is a Java applet, which is a clunky and old-fashioned solution. I'd much prefer something better looking and more modern like the CircuitLab page. \$\endgroup\$ – Kevin Vermeer Mar 28 '12 at 20:39

Maybe a collaboration with Upverter? Though their circuits are very... blocky. They have PNG export, though.

enter image description here

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    \$\begingroup\$ awesome!!! however, I'm appreciating also Falstad simulator! \$\endgroup\$ – clabacchio Feb 6 '12 at 14:46
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    \$\begingroup\$ That's way better looking than the mess from the Falstad simulator. I don't like how the text is vertical for all vertical components though. I'd be embarassed showing that to a customer and really don't want to see a lot of that here either. \$\endgroup\$ – Olin Lathrop Feb 6 '12 at 17:00
  • \$\begingroup\$ The wires are all auto-routed, which would be good if it always worked perfectly, but it doesn't, so it isn't. \$\endgroup\$ – endolith Feb 6 '12 at 19:41
  • \$\begingroup\$ @endolith: Use whatever your favorite schematic capture software is, export image (they can all do that as far as I know), and post that. \$\endgroup\$ – Olin Lathrop Feb 7 '12 at 17:08
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    \$\begingroup\$ @OlinLathrop: That's not a solution; that's the problem we're trying to solve. \$\endgroup\$ – endolith Feb 7 '12 at 17:20
  • \$\begingroup\$ It's pretty hard to read some of the text on this one, if it was a link to a larger resolution image that would be helpful \$\endgroup\$ – Jim Feb 11 '12 at 14:26
  • \$\begingroup\$ Just done a view image and have seen that it is a larger resolution than image shown, doh! \$\endgroup\$ – Jim Feb 11 '12 at 14:30

Before we ask the time-strapped devs to embed some online schematic editor, let's look at the problem and determine what we need.

What do we have now?

We all have schematic capture programs on our PCs. They're high-quality pieces of software that we're intimately familiar with and that we may have paid a lot of money for. Additionally, the designs that we're talking about are usually already in that format, we've just got to grab the screenshot. We've mastered the learning curve, and can use them efficiently. Furthermore, they're linked into a toolchain that can generate PCBs and possibly simulations, and if not, we've got programs for that too. Why are these programs inadequate?

Why is this inadequate?

I can see two arguments against the continued use of desktop-only editors.

It's not in-browser

First, the desktop-only editors require you to launch an app outside of your browser. My response to this is that if it increases the effort requirement and removes some low-quality answers, then that's a pro and not a con. It's not that onerous to alt-tab out of the browser and into your schematic editor.

It's not editable

Second, the desktop-only editors don't allow editing the schematic when it's uploaded as an image. You might draw parallels to Stack Overflow users posting screenshots of code - Sure, they've all got text editors, but there's value in making the content easy to copy/paste and edit.


I'd love to see an online, editable schematic capture program that we all knew and with which we could edit schematics. I simply don't think the benefits are worth the sacrifices.

  • \$\begingroup\$ Yup, +1. I've posted a bunch of schematic snippets here and never really considered it a problem. \$\endgroup\$ – Olin Lathrop Feb 9 '12 at 16:04

I think this is an excellent idea. I would certainly love to be able to edit schematics directly in the questions and answers. Maybe it's just me, but my workflow for adding a schematic to an answer goes something like this.

  1. Launch Altium - wait
  2. New schematic - wait
  3. Search through several libraries to find the components I want
  4. Draw schematic
  5. Carefully edit each component designator, otherwise Altium puts red error wiggles everywhere
  6. Screen cap
  7. Launch paint program - wait
  8. remove all the grey grid if I can be bothered (tedious)
  9. Crop image
  10. reduce colours to 256
  11. save as PNG
  12. back to browser
  13. upload image
  14. realise I made a mistake in the schematic
  15. delete the image from the answer
  16. back to Altium
  17. Goto step 4

I sometimes find myself going round this loop several times at the expense of about half an hour.

I think that certain people are objecting to an in-browser because it's something they don't yet have. I expect that if we already had one, and clabacchio suggested getting rid of it, then those same people would be up in arms, explaining in detail why this was a bad idea.


I've just come across http://www.diagram.ly/ which might be helpful as an online editor, as it does have electrical symbols.

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    \$\begingroup\$ It seems nice, but it's not for schematics, it's just a diagram editor... \$\endgroup\$ – clabacchio Apr 19 '12 at 20:32

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