POLF: Retro 3D Game Uses Only A Character Display

Got a retrocomputing itch? So does [David Given], and luckily for us all he indulged it by writing POLF: a first-person 3D game for the Commodore PET that uses only the system’s 40×25 text mode character display for visuals. It’s a fantastic achievement, considering that the 80s-era computer boasts 32 kB of memory and doesn’t even have a graphical display.

Each level has an 8×8 layout.

Each level in POLF is a small, maze-like room in which one’s goal is to play a sort of cross between billiards and golf, aiming to move the round “ball” object into the square “hole” object. The 3D view is rendered using raycasting, which is a way of efficiently drawing a workable 3D perspective using limited resources. Raycasting can only do so much, but as a method it works fantastically within its limitations, and there are useful tutorials out there that lay the process bare.

The GitHub repository for the project is here, and it should run on any 40-column screen PET with at least 16 kB of RAM. Watch it in action in the video, embedded below. (Hint: the little bar graphs under the compass headings at the bottom of the screen represent the player’s proximity to the ball and hole objects. )

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A Microwave Frequency Doubler

It is an age-old problem. You have a 2.5 GHz source and you want it at 5 GHz. You need a frequency doubler. [All Electronics Channel] has an interesting video that talks not only about the theory of such a device but shows a practical one made with copper strips on a blank PCB substrate.

A fun thing about microwaves is that even little strips of copper are circuit elements since the wavelength at 2.5 GHz is only 12cm. That means a quarter-wave stub is only 3 cm — just over an inch.

The construction technique used is simple and, as he points out, experimenting with a real circuit will give you much more feel for how these circuits work than just reading and working out the math.

The multiplier drives an amplifier into nonlinearity which, of course, generates harmonics. Then a bandpass filter selects the second harmonic. If you haven’t dealt with stub circuits before, you might want to read up on how a piece of copper connected at one end can act like an inductor, a capacitor, or even a tuned circuit.

If you want more detail on the copper tape technique, we can help. If you don’t want to double frequency, maybe you would prefer to try voltage.

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A game board with five LEDs and a hand shining a laser pointer at it

Laser Pointer And Arduino Make A Minimalistic Shooting Game

Video games are great and all, but sometimes you just want the thrill of manipulating actual objects in addition to watching action on a screen. This must have been the reason why Nintendo’s Duck Hunt became so popular despite the simplicity of its gameplay. Prolific hacker [mircemk] similarly made a computer-plus-physical game called “Laser Shooter“, which somehow reminds us of the good old NES game.

The game is based on an Arduino Nano, to which five LEDs as well as five photoresistors (LDRs) are connected. When the game is started, the LEDs light up at random and the player has a limited time to “shoot” the corresponding LDR with a laser pointer. This time limit is decreased as the game progresses, and the game is over once the player fails to hit the target on time. The “Game Over” message is accompanied by a sad tune, but luckily no giggling dog.

Complete schematics and code are available for anyone willing to try their hand at replicating or improving this game. And no, you can’t simply sweep your laser across the five LDRs all the time, because you lose if you shoot at the wrong target. For more laser pointer-based games, try this Laser Command clone or this laser tag badge system.

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Build A Dog Ball Launcher That Kinda Looks Like A Dog

The average garden dog will play fetch long beyond the average human’s endurance. If you want to keep your dog exercised without hurting your pitching arm, [brankly’s] automatic dog ball launcher might just be what you need.

The design is straightforward. The 3D printed housing features a large funnel into which a ball can be dropped. A servo then holds the ball while a pair of rollers are spun up by brushed DC motors. After two seconds, the servo releases the ball towards the rollers which launch the ball out of the machine. A Raspberry Pi Pico runs the show, controlling the timing of the ball launch and varying the motor speed to change the distance the ball is launched on each firing.

Files are available on Thingiverse for those eager to build their own. If you’re good, you might even be able to train your dog to drop the ball in themselves. We’ve seen similar builds before, too! Video after the break.

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The HP3458A: King Of Multimeters For Three Decades

[Marco] looks at a lot of meters. However, he considers the HP3458A the best even though they were introduced more than 30 years earlier in 1989. Someone donated one to [Marco] but it presented some error messages on startup and exhibited erratic behavior, so he had some repairs to do.

The error codes hinted there were issues with the multislope analog to digital converter and that’s what sets the meter apart, according to [Marco]. The meter has 8.5 digits, so a normal conversion stage won’t cut it.

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They Milk Cows, Don’t They?

You’ve no doubt heard of the many alternatives to cow’s milk that are available these days. Perhaps you’ve even tried a few of them in your quest to avoid lactose. Some coffeehouses have already moved on from soy milk, offering only oat or almond milk instead of 2% and whole. Their reasoning is that soy milk is a highly processed product that can’t be traced back to a single source, which stands in stark contrast to all those bags of single-origin coffee beans.

These nut-based alternatives kicked off what is known as the milk wars — the dairy industry’s fight against labeling plant-based dairy alternatives as ‘milk’ and so on. Well, now it’s getting even more interesting. A company called Perfect Day is making milk using microorganisms that secrete milk proteins. It may sound kind of gross, but it’s essentially microbial fermentation, which is the normal process by which bread, cheese, yogurt, wine, and beer are made.

To be fair, what Perfect Day and other companies are doing is precision fermentation using genetically engineered microorganisms in a bioreactor, so it’s a bit more involved than what you could probably pull off in the basement. Precision fermentation lies somewhere between two modern extremes — plant-based meat and cultured meat. The latter is actual animal tissue grown from stem cells, and is only available at high-end restaurants for exorbitant prices.

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Making Your Projects Move: Jeremy Fielding To Deliver Remoticon Keynote

We’re really excited to announce that Jeremy Fielding will give a keynote address at Hackaday Remoticon in November! Get your free ticket now!

The projects we in this community choose to tackle often take a lot to see to completion. Parts, tools, expertise, time; all are critical to getting projects from concept to reality. But how deep your parts bin is or how well-equipped your shop may be matters not a whit unless you’ve got the one thing that makes it all go: passion. Passion is what keeps a project rolling ahead paste the inevitable roadblocks and diversions; it’s what keeps us going back to the bench to try something new when we think we’ve tried it all.

Jeremy Fielding showing off his robot arm back in April

The passion to understand, to create, to innovate, is something that Jeremy Fielding clearly has. Anyone who has watched even a few of his YouTube videos knows how much he loves to make things move. His current project is a seven-axis industrial robot arm, and it’s a seriously impressive build that could easily be mistaken for a commercial product. What’s perhaps most impressive about this is that many of the skills needed to pull it off, like welding aluminum and machining, are skills that Jeremy has been teaching himself on the fly. Talk about passion!

For his keynote, Jeremy is going to focus on building hardware that moves. Most of us are reasonably good at putting together projects that flash a few lights or perhaps move a few small steppers or servos. But scaling that up, as Jeremy has done for his robot arm as well as other projects, introduces new challenges: what type of electric motor do I choose? How do I figure out the trade-offs between torque and speed? Do I even want to use electric motors — maybe pneumatics will be better? What are my control options? These questions can be just as daunting to the old hands as they are to beginners, and Jeremy is going to focus on how to handle these and other mechatronic challenges that crop up in our projects.

Aside from the (literal) nuts and bolts of mechanical engineering, there’s another place where Jeremy’s passion shines through: his passion for communicating what he has learned. His presentation style and enthusiasm are infectious, and we’re sure that’s going to come across in his keynote. Jeremy fancies himself a “contraption engineer,” which is both an apt and engaging way to look at what he does. Fellow contraption builders take note — you’re going to want to make sure you don’t miss this one!

Call for Proposals is Still Open!

We’re still on the hunt for great talks about hardware creation, so the Call for Proposals has been extended to October 20. And remember, get your tickets early — knowing how many people to expect really helps us with infrastructure planning so we can give everyone a quality experience.