John Calhoun

Finished the portable (clamp downable) moxon vise. Made from beech, a $55 moxon vise kit, finished with a paste wax. (Still have to face the inside of one of the vise jaws with leather or similar.) (Banana, not going anywhere, for scale.) #woodworking #diy

Prototype of a mini-workbench w/ moxon vise I'm building for my daughter. This one is from construction lumber—the real one will be beech. Took a day and a half to throw together (and hours on YouTube beforehand doing the research). #woodworking #diy

I posted a 68K Macintosh "game shell" on Github if anyone wanted to dabble in writing a vintage Mac sprite-based game. github.com/EngineersNee... Included, a beta of "Flappy Toaster" (a game-shell demonstrator I threw together). #vintagemac #retro_gaming #vcfmw

Love the re-creation of Steve's garage at VCFMW. (Reminds me of Wonderfest 2026 recreating the Industrial Light & Magic model shop.) #VCFMW

Vibe-coded (donʼt hate me) an optical halftone web-app designed for screen printing. Free, your images never leave your device, no account—just enjoy it. (Send feedback if you find issues.) Here: engineersneedart.com/halftone/ #screenprinting #halftone

I'm enjoying diving into screen-printing. (White ink on a black sheet of French paper.) The Moon from the recent Artemis mission. Experimenting with exposure times, half-toning vs. dithering (vibe-coding custom Python algorithms and testing them). #screenprinting #silkscreen #nasa #artemis_art

Trying to get a screen-printing setup in the basement. First screen burned—test-strips at various exposure intervals to try to dial in my home-made, UV, LED jank-ass light. I'll pull a print tomorrow and see if I need to burn another test-strip with different intervals. #screenprinting #silkscreen

Probably the album that had the most profound effect on me (for some reason).

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

Happy Mother's Day, mom. Wish you were still here. 🥹

"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 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...

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...)

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

Any fans of John Foxx? Ultravox!?

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