8 ms·

Math, Physics, and Engineering Applets

133 points by timokoesters 3y ago

yeknoda 3y ago
Retro Ciechanowski
TrackerFF 3y ago
Falstad circuit simulator, the app(let) that carried thousands of EE students through college, when they should have been writing Spice. (I'm guilty as charged) I have no idea who this Paul Falstad fella is, but I do owe a big thank you to him!
- JohnKemeny 3y ago
  Well, he's the author of Zsh, for one ...
  - kragen 3y ago
    holy shit, i had no idea
  - TrackerFF 3y ago
    Must be one of them fabled 10x engineers.
    - kragen 3y ago
      you'd be amazed what you can achieve if you release your software under a free license
robblbobbl 3y ago
cool
bytesmith 3y ago
Looks like he used swingjs[0] to port the applets to javascript since it hasn't been possible to run Java applets in a Chrome since v45 circa 2015. Always nice to see web 1 code live on. [0] https://chemapps.stolaf.edu/swingjs/site/swingjs/examples/ https://chemapps.stolaf.edu/swingjs/site/swingjs/examples/
- giantrobot 3y ago
  I loaded one of the pages up for fun expecting an error message. My mind was blown when I saw a loading screen and then the applet load. Pretty awesome. I've got to try swingjs with some applets I wrote decades ago.
- bbor 3y ago
  Was hoping someone would comment on that -- he said it so casually, like he just had to the add the "-script"! So glad that you closed the loop. I was looking at what it would look like to setup an AI pipeline to port them to modern responsive typescript + three.js code, but now that I look, it appears that these aren't open source...?
  - kragen 3y ago
    at least the circuit simulator applet is licensed under the gnu gpl
r_klancer 3y ago
Fun! This is the kind of thing I got back into programming for around 2010. Just to toot my own (and my former employer's) horn, I worked on a bunch of the underlying models behind the Concord Consortium activities here: https://learn.concord.org/ https://learn.concord.org/ They're aimed more at middle and high school, are "curriculum aligned" and developed into classroom-ready form by professional educators, and then Concord researches how well they work in actual classrooms. We had been using a Java app (and applet) called Molecular Workbench for some of these, but in 2012 we got a Google.org grant to reimplement the same concept but natively running in browsers.
- kragen 3y ago
  what do the models do, and how are they similar to or different from falstad's applets?
torcete 3y ago
It's very cool. But also, I am surprised that java applets are still working nowadays. I am using safari and I didn't have to install anything. I honestly thought that java applets was something from the past. I was also surprised by their responsiveness. It's been a while since I saw one running, and I remember them as something clunky and slow.
- deleted 3y ago
  [deleted]
- danans 3y ago
  FTA: > These are some educational applets I wrote to help visualize various concepts in math, physics, and engineering. They were originally written in Java, but they've mostly been converted to Javascript, so you should be able to view them without a Java-capable browser.
kragen 3y ago
i've been doing a lot of small circuit simulations in paul falstad's circuit.js lately i've learned a lot of interesting things: - it's free software under the gnu gpl - you can download the repo and run the javascript locally when you're offline. for this purpose the 'export as text' file menu option is useful; it gives you a textual representation of the circuit you can copy and paste, so you aren't dependent on tinyurl.com to get your circuit back. like spice, it ignores leading whitespace, which is super convenient if you keep your notes in markdown - you can set the background to white (under options) - the list of available devices isn't extensive but it does include a tl431 - the svg export (file menu) is great for including in a web page, but it only includes 'undocked' scopes, and the data that's plotted in them may not be the same as what you see - the simulations are generally in good agreement with the ngspice simulations i've done, but you have to use a smaller timestep than spice usually chooses (i guess because of the lower order of integration), and unless it's much smaller, it can still have some numerical stability problems - they run slower than spice, but often the faster feedback loop for interactivity makes up for it - you can simulate an avr in it at the instruction level with avr8js: https://hackaday.com/2021/06/11/circuit-vr-arduino-virtually-meets-analog/ https://hackaday.com/2021/06/11/circuit-vr-arduino-virtually... which i don't know how to do in ngspice or any other spice — ⁂ — i have some questions, maybe someone knows the answers: - is there a way to convert spice netlists into circuit.js designs? because that would be pretty useful, especially if i could, say, import a spice model of a 7805 as a subcircuit - is there a way to convert circuit.js designs into spice netlists? because i feel like the schematic view is a lot clearer than the textual netlist - is there a way to import and/or export to kicad? - is there a way to do monte carlo simulation in circuit.js? or at least sensitivity analysis? — ⁂ — here are some circuits i've put together in circuit.js this week: http://tinyurl.com/27m6usjw http://tinyurl.com/27m6usjw http://tinyurl.com/23u2y4w8 http://tinyurl.com/23u2y4w8 http://tinyurl.com/2cf5kgxc http://tinyurl.com/2cf5kgxc http://tinyurl.com/23qvuylw http://tinyurl.com/23qvuylw http://tinyurl.com/27agyg4q http://tinyurl.com/27agyg4q http://tinyurl.com/2bssxwjq http://tinyurl.com/2bssxwjq and last week: http://tinyurl.com/2889h6o8 http://tinyurl.com/2889h6o8 http://tinyurl.com/2a8by2mq http://tinyurl.com/2a8by2mq (happy to explain any of these if anyone is curious)
- bgoated01 3y ago
  It has apparently been longer since I was a TA for an electronics class in college than I realized. I appear to have lost most of that knowledge. I would love a one-sentence explanation of what each of these circuits you put together are meant to demonstrate, if you're up for it.
lxe 3y ago
I didn't expect this to "just work", but it does for me. I don't remember getting java installed. I'm running firefox nightly on windows.
- 01HNNWZ0MV43FF 3y ago
  Seems to be a Java -> JS compat layer, like Ruffle.js is for Flash I guess: https://news.ycombinator.com/item?id=39470724 https://news.ycombinator.com/item?id=39470724
  - lxe 3y ago
    Looking at it closer, many (all?) of these are GWT apps, not applets. GWT was "The React" of 2006.
- SJC_Hacker 3y ago
  The 2D Vector fields one crashed on me

133 points by timokoesters 3y ago

Retro Ciechanowski

Falstad circuit simulator, the app(let) that carried thousands of EE students through college, when they should have been writing Spice. (I'm guilty as charged) I have no idea who this Paul Falstad fella is, but I do owe a big thank you to him!

JohnKemeny 3y ago
Well, he's the author of Zsh, for one ...
- kragen 3y ago
  holy shit, i had no idea
- TrackerFF 3y ago
  Must be one of them fabled 10x engineers.
  - kragen 3y ago
    you'd be amazed what you can achieve if you release your software under a free license

robblbobbl 3y ago

cool

bytesmith 3y ago

Looks like he used swingjs[0] to port the applets to javascript since it hasn't been possible to run Java applets in a Chrome since v45 circa 2015. Always nice to see web 1 code live on. [0] https://chemapps.stolaf.edu/swingjs/site/swingjs/examples/ https://chemapps.stolaf.edu/swingjs/site/swingjs/examples/

giantrobot 3y ago
I loaded one of the pages up for fun expecting an error message. My mind was blown when I saw a loading screen and then the applet load. Pretty awesome. I've got to try swingjs with some applets I wrote decades ago.
bbor 3y ago
Was hoping someone would comment on that -- he said it so casually, like he just had to the add the "-script"! So glad that you closed the loop. I was looking at what it would look like to setup an AI pipeline to port them to modern responsive typescript + three.js code, but now that I look, it appears that these aren't open source...?
- kragen 3y ago
  at least the circuit simulator applet is licensed under the gnu gpl

r_klancer 3y ago

Fun! This is the kind of thing I got back into programming for around 2010. Just to toot my own (and my former employer's) horn, I worked on a bunch of the underlying models behind the Concord Consortium activities here: https://learn.concord.org/ https://learn.concord.org/ They're aimed more at middle and high school, are "curriculum aligned" and developed into classroom-ready form by professional educators, and then Concord researches how well they work in actual classrooms. We had been using a Java app (and applet) called Molecular Workbench for some of these, but in 2012 we got a Google.org grant to reimplement the same concept but natively running in browsers.

kragen 3y ago
what do the models do, and how are they similar to or different from falstad's applets?

torcete 3y ago

It's very cool. But also, I am surprised that java applets are still working nowadays. I am using safari and I didn't have to install anything. I honestly thought that java applets was something from the past. I was also surprised by their responsiveness. It's been a while since I saw one running, and I remember them as something clunky and slow.

deleted 3y ago
[deleted]
danans 3y ago
FTA: > These are some educational applets I wrote to help visualize various concepts in math, physics, and engineering. They were originally written in Java, but they've mostly been converted to Javascript, so you should be able to view them without a Java-capable browser.

kragen 3y ago

i've been doing a lot of small circuit simulations in paul falstad's circuit.js lately i've learned a lot of interesting things: - it's free software under the gnu gpl - you can download the repo and run the javascript locally when you're offline. for this purpose the 'export as text' file menu option is useful; it gives you a textual representation of the circuit you can copy and paste, so you aren't dependent on tinyurl.com to get your circuit back. like spice, it ignores leading whitespace, which is super convenient if you keep your notes in markdown - you can set the background to white (under options) - the list of available devices isn't extensive but it does include a tl431 - the svg export (file menu) is great for including in a web page, but it only includes 'undocked' scopes, and the data that's plotted in them may not be the same as what you see - the simulations are generally in good agreement with the ngspice simulations i've done, but you have to use a smaller timestep than spice usually chooses (i guess because of the lower order of integration), and unless it's much smaller, it can still have some numerical stability problems - they run slower than spice, but often the faster feedback loop for interactivity makes up for it - you can simulate an avr in it at the instruction level with avr8js: https://hackaday.com/2021/06/11/circuit-vr-arduino-virtually-meets-analog/ https://hackaday.com/2021/06/11/circuit-vr-arduino-virtually... which i don't know how to do in ngspice or any other spice — ⁂ — i have some questions, maybe someone knows the answers: - is there a way to convert spice netlists into circuit.js designs? because that would be pretty useful, especially if i could, say, import a spice model of a 7805 as a subcircuit - is there a way to convert circuit.js designs into spice netlists? because i feel like the schematic view is a lot clearer than the textual netlist - is there a way to import and/or export to kicad? - is there a way to do monte carlo simulation in circuit.js? or at least sensitivity analysis? — ⁂ — here are some circuits i've put together in circuit.js this week: http://tinyurl.com/27m6usjw http://tinyurl.com/27m6usjw http://tinyurl.com/23u2y4w8 http://tinyurl.com/23u2y4w8 http://tinyurl.com/2cf5kgxc http://tinyurl.com/2cf5kgxc http://tinyurl.com/23qvuylw http://tinyurl.com/23qvuylw http://tinyurl.com/27agyg4q http://tinyurl.com/27agyg4q http://tinyurl.com/2bssxwjq http://tinyurl.com/2bssxwjq and last week: http://tinyurl.com/2889h6o8 http://tinyurl.com/2889h6o8 http://tinyurl.com/2a8by2mq http://tinyurl.com/2a8by2mq (happy to explain any of these if anyone is curious)

bgoated01 3y ago
It has apparently been longer since I was a TA for an electronics class in college than I realized. I appear to have lost most of that knowledge. I would love a one-sentence explanation of what each of these circuits you put together are meant to demonstrate, if you're up for it.

lxe 3y ago

I didn't expect this to "just work", but it does for me. I don't remember getting java installed. I'm running firefox nightly on windows.

01HNNWZ0MV43FF 3y ago
Seems to be a Java -> JS compat layer, like Ruffle.js is for Flash I guess: https://news.ycombinator.com/item?id=39470724 https://news.ycombinator.com/item?id=39470724
- lxe 3y ago
  Looking at it closer, many (all?) of these are GWT apps, not applets. GWT was "The React" of 2006.
SJC_Hacker 3y ago
The 2D Vector fields one crashed on me