nickajeglin

This site is a huge collection of simulation applets for analog circuit, filters, acoustics, general harmonic stuff, quantum mechanics, thermodynamics, linear algebra, and so on.

The analog circuit simulator in particular is very feature rich. I have used it to design some synth circuits in lieu of/addition to breadboarding.

Also try the acoustics ones, especially the ripple tank. The examples drop down has a bunch of cool setups like speaker designs, mirrors, lenses, mechanical filters(!), and can even simulate temperature (impedance) gradients.

This one is Ray Wilson's DIY synthesizer website.

I first saw him on youtube, screwing around with an echo rockit noise box. I was hypnotized.

I found his site and was hooked. I spent the next couple years making synthesizer modules at a manic pace.

The magical thing about Ray's site is is his teaching style. He gives the circuit schematics, but also explanations of how/why they work in language that is pretty easy to understand. He really approaches electronics from a practical standpoint rather than what you'd get in an intro class somewhere. This website was my introduction to electronics, and it can get you far when it comes to understanding analog design and signal processing.

You can really get a feel for Ray's personality from his writing on the site. He died in 2016, and I weirdly get a little choked up when I look at that echo rockit page. His website was a right-time-right-place thing for me, and it helped change the trajectory of my life in a very real way.

Anyways. Check out Music From Outer Space, and like Ray would say, Good learning...

This is the website of Gene Slover (now deceased). He was a firecontrolman in the navy back in the day. Now I don't care about the navy, nor do I really care about Gene. What I do care about is mechanical computers.

Firecontrolman in this context is the dude who operated the Mk 1 fire control computer on navy ships. Gene's website is significant to me because it has a massive amount of information on the design and operation of that computer.

It's wild to me that information this detailed is out there, cataloged by someone who actually operated the system.

Here's a short writeup that I posted elsewhere to explain why I think the computer is so cool:

The mark 1 fire control computer is an entirely mechanical computer that reads in the speed of the ship in water, the wind direction and speed, the pitch and roll from waves, the ballistic characteristics of the guns all the way down to how worn in the barrels were, and so on. Then a gun director feeds it the bearing, elevation, and distance to a target, and it does that rapidly so the computer can establish a vector.

So at one end you have a guy with a telescope/rangefinder that he points at the incoming plane, and that's all mechanically connected through a calculating machine that aims the guns the right direction, sets the fuzes to the right distance, and applies "corrections for gravity, relative wind, the magnus effect of the spinning projectile, and parallax" so that the shells explore right on a plane that zooming by.

They did all that with levers, cams, gears, mechanical integrators, etc. And they made that super complex machine reliable enough that it was used in a loss-of-life application. That's some pretty badass engineering imo

Here is a much more in depth page about it than the Wikipedia entry: https://eugeneleeslover.com/USNAVY/CHAPTER-25-C.html

And his page has a flow diagram that shows all of the inputs, intermediate quantities and outputs of the thing. I wish I could actually read them :( https://eugeneleeslover.com/USN-GUNS-AND-RANGE-TABLES/FLOW-SCHEMATIC-COMPUTER-MK-1MOD-7.html

I mean check this shit out. They had an adjustable integration step size so that you could manually adjust to balance between firing solution speed and accuracy:

The rate control system of Computer Mark 1A includes sensitivity units which control the time required by the computer to reduce errors in generated rates to the point where the corrected rates are sufficiently accurate to compute adequate gun orders. Sensitivity may be thought of as the speed with which the errors are corrected by the rate control mechanism. If the errors are corrected within a relatively short time interval, the sensitivity is considered to be high, and if the errors are corrected within a relatively long time interval, the sensitivity is considered to be low.

Blows my mind.

This section of the Project Rho site is one that I have actually used for real projects in the past. The section gives guidelines for creating nomograms, or alignment charts.

Nomograms are graphical representations of a math equation. For a basic 3 variable equation, given 2 of the variables, you simply lay a straight edge across the chart to read the answer from the 3rd scale.

The specific page I linked is a cheatsheet of "standard forms". If you can manipulate your equation into one of these forms, then making it into a nomogram is trivial.

This page is one of very few resources online that will take you step by step through building a nomogram. The intended purpose of the page is to be a resource for board game designers, but I have found it useful in creating time/distance/speed nomograms, various engineering calculations, and calculators for film photography and darkroom printing.

Even if you aren't a math nerd, I hope you find the idea of a graphical representation of an equation as fascinating as I do. It doesn't tell you the answer to 1 question, it tells you the answer to all the questions that an equation can answer simultaneously.

I have a large terrarium where I grow various types of moss. I keep springtails in there to handle any mold that pops up, but some creature (fungus gnat larvae?) was killing off the springtails. So I captured a jumping spider, thinking it would gobble up the fruit flies/larvae. The fungus gnats have disappeared, so it seems like the spider might have done the job, but now I'm worried about it getting hungry.

I gave it a mayfly a couple days ago, and that evening it was sitting in the corner of the terrarium like a toddler with a juice box, so it obviously likes those. Are there any specific things that are good to feed it, or can I give it anything that I catch that isn't predatory? For example, would a "regular" sized moth be dangerous? It'd be like 2-3x the size of the spider.