iiinova — where your digital self keeps evolving

John Calhoun @engineersneedart.com · 15/09/2026

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

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John Calhoun @engineersneedart.com · 12/09/2026

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

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John Calhoun @engineersneedart.com · 09/09/2026

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

Screenshot of https://engineersneedart.com/halftone/

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John Calhoun @engineersneedart.com · 05/09/2026

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

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John Calhoun @engineersneedart.com · 28/08/2026

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

Silkscreen under a home-made UV LED light source.

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John Calhoun @engineersneedart.com · 19/08/2026

A professor Dr. Bernd Ulmann is the analog computer expert these days. After mailing my "Anna" analog computer kit to him he was able to "program" a Lorenz attractor. Schematic, layout (extra pots and an additional integrator were needed/added) and the scope. #electronics #analog #chaos

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John Calhoun @engineersneedart.com · 08/07/2026

"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...

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John Calhoun @engineersneedart.com · 01/07/2026

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...

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John Calhoun @engineersneedart.com · 30/06/2026

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

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John Calhoun @engineersneedart.com · 22/06/2026

Couldn't resist playing with Levels…

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John Calhoun @engineersneedart.com · 18/06/2026

I hope to finally get this to Steam this time (and this summer).

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John Calhoun @engineersneedart.com · 12/05/2026

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

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John Calhoun @engineersneedart.com · 10/05/2026

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

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John Calhoun @engineersneedart.com · 10/05/2026

"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

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John Calhoun @engineersneedart.com · 06/05/2026

(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

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John Calhoun @engineersneedart.com · 01/05/2026

"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

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John Calhoun @engineersneedart.com · 30/04/2026

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

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John Calhoun @engineersneedart.com · 30/04/2026

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

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John Calhoun @engineersneedart.com · 17/04/2026

Last for today: a scan of an ImageWriter printout of a screenshot of Glider 1.0.

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John Calhoun @engineersneedart.com · 17/04/2026

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.)

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John Calhoun @engineersneedart.com · 17/04/2026

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…

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John Calhoun @engineersneedart.com · 17/04/2026

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).

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John Calhoun @engineersneedart.com · 17/04/2026

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.

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John Calhoun @engineersneedart.com · 14/04/2026

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

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John Calhoun @engineersneedart.com · 06/04/2026

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...)

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John Calhoun @engineersneedart.com · 25/03/2026

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

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John Calhoun @engineersneedart.com · 25/03/2026

Any fans of John Foxx? Ultravox!?

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John Calhoun @engineersneedart.com · 02/03/2026

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

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John Calhoun @engineersneedart.com · 27/02/2026

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

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John Calhoun @engineersneedart.com · 21/02/2026

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

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John Calhoun @engineersneedart.com · 21/02/2026

When I began playing around with what would be the game, Pararena, I wrote a simple app to render a parabolic playfield. If a thing can be rendered with math, then math can also be used to simulate the physics of that surface (render players, a ball on it…) Screenshot I took (and later "painted").

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John Calhoun @engineersneedart.com · 21/02/2026

A sketch I put together in 1992. Back then I would have drawn it as line-art first and scanned it. Once digital color was added in Studio-8 or an early Photoshop. (Too risqué for Casady & Greene to put on the box for Pararena, so they hired someone to come up with truly atrocious box art.)

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John Calhoun @engineersneedart.com · 19/02/2026

I've been diving deep into analog computing—working on pieces of a kind of hobbyist-grade analog computer. (The way I like to learn a thing is to build a thing.) (If anyone is interested, I've begun documenting in this Google Group: groups.google.com/g/analog-com...) #analogcomputers #electronics

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John Calhoun @engineersneedart.com · 03/02/2026

Someone created a site including many of the games submitted to Hacker News (aka HN, news.ycombinator.com/active). (Look for my Mooncraft2000 among the games.) hnarcade.com/games/catego...

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John Calhoun @engineersneedart.com · 17/01/2026

I look back at the 3D-printing that I did in 2025, what I learned: engineersneedart.com/blog/3dprint...

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John Calhoun @engineersneedart.com · 16/12/2025

A power module for a breadboard analog computer. On left: prototype board, on right: 1st iteration from JLCPCB.

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John Calhoun @engineersneedart.com · 11/12/2025

Analog computer project in progress. Breadboard first. Circuits that are okay move to prototype boards… Parts get harvested along the way. IC's are easy because they are socketed. (I can't be bothered to harvest sockets). Switches, large caps… (I have a bunch of crap resistors I'm happy to lose.)

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John Calhoun @engineersneedart.com · 04/12/2025

Still prototyping analog computing modules. Moving stuff from breadboard to prototyping boards ("ElectroCookies"). (Red & blue "cookie" seen here.) An article from a 1970's hobbyist electronics magazine inspired the project. I've gone past that circuit now though. (Unsure where I'll land…)

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John Calhoun @engineersneedart.com · 26/11/2025

Playing with analog computing (but digital metering, so sue me). Last night (after several hours of hair pulling) I learned that a 1% 10 kΩ resistor color bands is indistinguishable from a 1% 120Ω resistor—that is flipped around. Breadboarding is messy. Will make up a PCB for part of it soon.

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John Calhoun @engineersneedart.com · 11/11/2025

A second analog (integrator) channel breadboarded (top). Both channels are tapped and displayed on the ESP32 "software meter" in the center (showing two needles at once). The new channel uses dual op-amps instead of singles. I may make another analog channel and have a go with a quad op-amp.

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John Calhoun @engineersneedart.com · 10/11/2025

From breadboard (left—wires can be bumped loose) to protoboard (right—wires soldered). One channel of an analog/digital hybrid computer experiment. An op-amp acts as an analog-computer integrator, 3 more op-amps scale, offset & invert the voltage so it is within 0.0-3.3V range for the ESP32 ADCs.

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John Calhoun @engineersneedart.com · 10/11/2025

Each year the wife hand-carves a multi-color X-mas card. A destructive process: inking/printing a color before carving for the next color. This year I suggested she make just one print at each stage (in black ink) for me to scan digitally—print on the Risograph. Seems to be going well.

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John Calhoun @engineersneedart.com · 02/11/2025

Mac Plus. I still have it (and it functions—needed recapping and reflowing the solder on the main connector on the mobo).

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John Calhoun @engineersneedart.com · 23/10/2025

Sweep meter is better. (Here it is responding to potentiometer acting as a voltage divider.)

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John Calhoun @engineersneedart.com · 23/10/2025

Working on an "analog" voltage meter for a project. (This slide-rule version will not make the cut.)

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