Falstad Math and Physics Simulations | Hacker News Reader

Falstad Math and Physics Simulations

falstad.com

83 pointspykello18 comments

He also made circuitjs, a very useful circuit simulator which I regularly use for prototyping. It lets you modify and probe elements in real time unlike spice simulators, so it is faster to modify a design in it.

I use spice simulators to check the final design since sometimes circuitjs can have instability issues in complex circuits involving stuff like the nonideal op amp.

https://www.falstad.com/circuit/circuitjs.html

I remeber using this when it was Java applet. Now he has converted everything to JavaScript for everyone to use. What a legend!

He also wrote zsh ( https://en.wikipedia.org/wiki/Z_shell ) as a sophomore in 1990, moved onto other things a few years later, and a couple decades later in 2019 it became the MacOS's default shell.

That's wild. I knew he was the circuitjs guy which is impressive on its own, and vaguely knew of the other simulations as well, but writing zsh as an undergrad... Wow

I use it rather often in professional projects, usually for figuring out power supply inrush transients, and I usually point anyone who wants to learn electronics to it.

Just be sure you set the simulation step size appropriately if there's high frequency stuff happening, or the results will not make any sense.

Reminds me of this [1] I made back in 2005 in Flash action script, thankfully bought back to life by Ruffle [2].

You can fix the ends of the string by pressing space. When both ends are fixed, you can you can drag the beads and release them.

No big deal, but hey I was quite happy with myself back then..

[1] https://www.newgrounds.com/portal/view/267616

[2] https://ruffle.rs/

Oh this is great. You ever play SodaPlay?

Thanks!

>You ever play SodaPlay?

Never heard until now. Looks interesting. Thanks for sharing, but is it available now?

I'll probably finally get around to cloning it sometime in the next decade.

This is pure gold, especially the rippld tank, 1d quantum mechanics, and the circuit simulator.

I cited it as one of the remarkable steps in the history of educational simulations, https://doi.org/10.1117/1.OE.61.8.081809, figure 2 (a broader overview in https://p.migdal.pl/blog/2024/05/science-games-explorable-ex...)

I really like this one, for some strange reason:

https://www.falstad.com/embox/

>"This java applet demonstrates standing electromagnetic waves in a 3-d rectangular box, or cavity resonator."

Maybe it's the idea that waves can carry slower frequency secondary waves, the idea that fields can carry slower frequency secondary fields, the idea that EM space itself can be stressed in a number of dimensions, and that these stresses, (depending on waveforms and modes of oscillations) could give rise to even smaller regions of stronger, localized (yet time/period/frequency dependent!) stress... much like waves in the ocean... to use a simple analogy... but this app really shows us what's possible...

Anyway, this page of apps is a must-have resource for any Physics or Engineering student... A+++++ !

This is a nice one to play with:

https://www.falstad.com/rendezvous/

Does anyone know what are Paul Falstad’s project right now?

(I haven’t seen any new. Not sure if perfect things do not need fixes, or some switch to another field, or a burnout, or he has ascended to godhood - out of a few options.)

Per his GitHub repo ( https://github.com/pfalstad ) last week he ported his electrostatics sim fro. GWT/Java to Typescript+Vite ...

I have fond memories of fiddling with the wave simulations on this website during high school!

I use there circuit.js for teaching. A realy usefull tool

Legendary

this is so cool, thanks for sharing!

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