John Calhoun
@engineersneedart.com
Old Macintosh shareware author. Making things I wish existed when I was a kid. engineersneedart.com github.com/EngineersNeedArt
Surfing YouTube and there's R.E.M. performing "Gardening at Night". Comments, some people talking about how that band changed them… Me too. And I'm trying to think why that was… @michaelstipe.bsky.social @remhq.bsky.social
R.E.M. - Gardening At Night | Live at The Capitol Theatre (1984)
YouTube video by Alt Vault
youtu.be
"Anna" I wrapped up (after more than 6 months?) my little #analogcomputer trainer (hobbyist machine—whatever). It's open—Github repo linked here. I made a few kits available (they were expensive to make though—but nice and with a nice manual!). #electronics github.com/EngineersNee...
Using a stereo digital camera (dated and not designed for low-light levels). Captured Letters to Cleo in Des Moines. (App to create stereogram from .MPO files is Stereographer.) #stereophotography #letterstocleo bsky.app/profile/kayh...
Islamic filigree created in Affinity Designer (a couple of hours), cut out of card-stock with a laser (about 5 minutes). So delicate… I was surprised it held together. (Beginning experiments in shadow puppetry.) #shadowpuppets
I hope to finally get this to Steam this time (and this summer).
Modular means I can add a breadboard to "Anna" if need be… This harmonograph program has not 2, but 4 pendulums! (2 pendulums for the X axis and 2 pendulums for the Y.) That's over 52 wires of code! (The longest program I have, um, written yet.) #analogcomputing #electronics
"Programmed" a simple harmonograph on the analog computer. One pendulum (displays red), a 2nd (yellow) and both mixed (green)—sometimes adding, sometimes subtracting. Switch to XY-oscilloscope mode for the Lissajous curve. (Next: double the program to 4 pendulums.) #analog_computer #electronics
(Little blurry…) "Anna" programmed for Lotka-Volterra (prey/predator) equation. 1st display mode: a strip chart with prey population red, predator orange. (Predator's population lags prey's.) 2nd display mode a kind of XY oscilloscope plotting pop. in "phase space". #analogcomputer #electronics
"Spring+Mass" is, I have heard, the "Hello World" of analog computing. "Anna's" pair of integrators connected in a circular arrangement give rise to oscillation. Pots control spring constant, dampening, mass… (ADCs & an ESP32 on "MAIN" give a visual representation.) #analogcomputing #electronics
I "programmed" (patched) Lunar Lander. A special "metering mode" on "Anna" reads analog voltages representing gravity, thrust, velocity, position—displays a small lunar module descending. (Breadboard is not for prototyping—it's how you program/wire-up the modules!) #analogcomputing #electronics
The final (1.0) boards/PCBs for my hobbyist analog computer (Anna) are finally rolling in from Asia. As I complete the manual, I'm playing with "programs" on it. I switch to "scope mode" and reset the integrators to display a "harmonigraph" simulation I wired up. #analogcomputing #electronics
Last for today: a scan of an ImageWriter printout of a screenshot of Glider 1.0.
Final "boss" in Glider: the cat that tried to obstruct your glider from escaping the house. An early sketch—the paw a separate bitmap could animate (the swat!). The cat "trick" was: move into pawRect & retreat quickly (swat misses). Then dive back in. (The cat waited a second or so between swats.)
Here's another early Glider sketch showing tables and candlesticks. For the tables, the bases were bitmaps, but the vertical support and table-top were rendered (allowing arbitrary heights/widths). The candle was a bitmap with a flickering bitmap flame. Just getting started here…
Very early Glider… Before I knew how to display an arbitrary PICT (picture, created with MacPaint, for example), I rendered icons instead (32 pixels by 32 pixels). Sketched on graph paper first… A very different glider on the left. The one on the right would win out (when I grew beyond 32 pixels).
Surprised I came across some sketches I did not know I had scanned/archived. This is an early Glider sketch when the paper airplane was the more common kind. It looks like electrical outlets might have given you "shots", not destroyed you. Ceiling ducts were bad too. I have a few more I can post.
I know, the timing is weird. Victor Franco ported my published sources for Glider 4.0 to the modern MacOS and, yes, we have another Glider game for the Mac. It's faithful to the original Glider 4.0 that came out in 1990. (And it's free.) apps.apple.com/us/app/glide...
Glider Retro App - App Store
Download Glider Retro by Victor Franco on the App Store. See screenshots, ratings and reviews, user tips, and more apps like Glider Retro.
apps.apple.com
Came across a book of nomograms & spent an hour recreating one (exported as SVG). Here it is. With just a ruler you can find the equivalent resistance for 2 resistors in parallel (see red dashed line as an example). Link (print it, try it): drive.google.com/file/d/1BeZ_... #electronics #nomogram
I re-made Glider some years back for MacOS/iOS. It broke at some point (perhaps an Apple change for Retina displays?) so I pulled it from the App Store. (Claude looked at the code—found some minor coordinate issues. Thanks!) Glider Classic for MacOS is back on. apps.apple.com/us/app/glide...
Glider App - App Store
Download Glider by Soft Dorothy LLC on the App Store. See screenshots, ratings and reviews, user tips, and more apps like Glider.
apps.apple.com
A friend who has been hand-making traditional medieval leather footwear for decades now wrote a book where he puts down his knowledge (for those wanting to learn): #sca #leatherworking #diy www.amazon.com/Process-Grid...
The Process and the Grid: How to make your own custom footwear
Buy The Process and the Grid: How to make your own custom footwear: Read Books Reviews - Amazon.com
amazon.com
I wrote a free, browser-based Moon simulator game. You're welcome to play. (I don't recommend trying it on mobile.) mooncraft2000.com (More info on developing it: engineersneedart.com/mooncraft200...)
So happy to find that Perry Bible Fellowship is on bsky.
PBF Comics@pbfcomics.bsky.social · 11mo ago
My hobbyist analog computer project coming along… The "strip chart" displays two voltages from the computer: an implementation of the Lotka–Volterra equation depicting prey population (red) & predator population (orange). (Red LED indicates overload.) #analogcomputing #analogcomputers #electronics
Ron McAdams & I chatted about my Mac game Pararena—published by Casady & Greene around 1992 (youtu.be/QpK6fYYr-6o). Was reminded that Michael (Greene) was not pleased with my proposed splash screen. (I had to move the figure down.) (He would have really disliked what AI did to it.) #MARCHintosh
This analog computer project is perhaps my longest ongoing electronic's project. From perfboard prototype to PCB, the Adder module is iterated upon… #electronics #analogcomputing #diy
Laying out a PCB is something I really hate—hurts my head. I wrestle with trying to keep it "elegant". I was explaining to my wife that every time I add a via, an angel in heaven cries. #electronics #pcb #kicad #angelscrytooeasily
