Automatic Coin Sorter Brings Order To Your Coin Jar

Few things hold as much promise as the old coin jar. Unfortunately, what’s generally promised is tedium, as one faces the prospect of manually sorting, counting, and rolling the accumulated change of cash transactions past. Unless, of course, you’ve got a fancy automatic coin sorter like this one.

True, many banks have automatic coin sorters, but you generally have to be a paying customer to use one. And there’s always Coinstar and similar kiosks, but they always find a way to extract a fee, one way or another. [Fraens] decided not to fall for either of those traps and roll his own machine, largely from 3D-printed parts. The basic mechanism is similar to that used in commercial coin counters, with an angled bowl rotating over an array of holes sized to fit various coins. Holes in the bottom of the feed bowl accept coins fed from a hopper and transport them up to the coin holes. The smallest coins fall out of the bowl first, followed by the bigger coins; each coin drops into a separate bin after passing through an optical sensor to count the number of each on an Arduino. Subtotals and a grand total of the haul are displayed on a small LCD screen. The video below shows the build and the sorter in operation.

[Fraens] built this sorter specifically for Euro coins, but it should be easy enough to modify the sorting slots for different currencies. It’s not the first coin sorter we’ve seen, of course, and while we applaud its design simplicity and efficient operation, it can’t hold a candle to the style of this decidedly less practical approach.

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To Turn An ATtiny817 Into A 150MHz Counter, First Throw Out The Spec Sheet

One generally reads a data sheet in one of two ways. The first is to take every spec at face value, figuring that the engineers have taken everything into account and presented each number as the absolute limit that will prevent the Magic Smoke from escaping. The other way is to throw out the data sheet and just try whatever you want, figuring that the engineers played it as safely as possible.

The latter case seems to have been the motivation behind pushing an ATtiny way, WAY beyond what the spec sheet says is possible. According to [SM6VFZ], the specs on the ATtiny817 show that the 12-bit timer/counter D (TCD) should be limited to a measly 32 MHz maximum frequency, above which one is supposed to employ the counter’s internal prescaler. But by using a 10-MHz precision frequency generator as an external clock, [SM6VFZ] found that inputs up to slightly above 151 MHz were countable with 1-Hz precision. Above that point, things started to drift, but that’s still pretty great performance from something cobbled together on an eval board in a decidedly suboptimal way.

We’d imagine this result could lead to some interesting projects, since the undocumented limit for this timer puts it well within range of multiple amateur radio allocations. Even if it doesn’t prove useful, that’s OK — just seeing how far things can be pushed is cool too. And it’s not like this is the first time we’ve caught [SM6VFZ] persuading an ATtiny to do unusual things, either.

Empty Spools Make Useful Tools, Like Counters

What’s the deal with getting things done? There’s a Seinfeld anecdote that boils down to this: get a calendar, do a thing, and make a big X on each day that you do the thing. Pretty soon, you’ll thirst for chains of Xs, then you’ll want to black out the month. It’s solid advice.

[3D Printy] likes streaks as well, and made several resolutions at the beginning of 2022. As the first of 30 videos to be made throughout the year, they featured this giant 3D printed counting mechanism (video, embedded below) that uses empty filament spools, some 3D prints, and not much else. These are all Hatchbox spools, and it won’t work for every type, but the design should scale up and down to fit other flavors.

This isn’t [3D Printy]’s first counter rodeo — he’s made several more normal-sized ones and perfected a clever carryover mechanism in the process, which is of course open-source. So each spool represents a single digit, and there are printed parts in the core that make the count carry over to the next spool. Whereas the early counters used threaded rod, this giant version rides on 2.5 mm smooth rod, so the spools can slide apart easily. But how does everything stay together? A giant elastic band made of TPU filament, of course — because the answer is always in the room.

Check out the video after the break, and stay for the 900%-sped-up assembly at the end.

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Rŏ̽ta: Counting, With Style

Rǒta counts things. That’s it, really — what a cheap little mechanical counter does with a thumb press, or what you can do by counting on your fingers and toes, that’s pretty much all that Rǒta does. But it does it with style.

OK, that’s being a bit unfair to [Kevin Santo Cappuccio] — Rǒta has a few more tricks up its sleeve than simple counting. But really, those functions are just icing on the cake of how this little gadget looks. Rǒta was built around the unbeatable combination of a rotary telephone dial mechanism and a trio of Nixie tubes. The dial looks like it might have come from an old pay phone, all shiny and chrome and super robust looking. The Nixies sit atop the dial on a custom PCB, and everything, including the high-voltage supply for the tubes, is enclosed in a 3D printed case with a little bit of a Fallout vibe.

But what does this thing do? Actually, quite a lot. It’ll count up and down, using whatever number you dial into it. You can either increment from zero, or enter any three-digit number as the starting count. It keeps track of the score of your golf game, if that’s your thing, and it’s also got a stopwatch function. You can even dial up a display of the current battery voltage. It takes some ingenuity to use just the dial for all these functions, but that’s as easy as dialing the operator used to be — dialing 0 puts it in menu mode, allowing you to access any of the functions printed on the card in the center of the dial. It’s pretty clever — check out the video below.

Is it particularly useful? Perhaps not. But when has that ever been a measure of the worth of a project? Something like this rotary cellphone might be more useful, but sometimes looking great is good enough.

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Nixie clock from a frequency counter

A Nixie Clock, The Hard Way

Notice: no vintage Hewlett Packard test equipment was harmed in the making of this overly complicated Nixie clock. In fact, if anything, the HP 5245L electronic counter came out better off than it went into the project.

HP 5245 hand-wired backplane
Beautiful hand-wired backplane in the HP 5245 counter.

We mention the fate of this instrument mainly because we’ve seen our fair share of cool-looking-old-thing-gutted-and-filled-with-Arduinos projects before, and while they can be interesting, there’s something deeply disturbing about losing another bit of our shared electronic heritage. To gut this device, which hails from the early 1960s and features some of the most beautiful point-to-point backplane wiring we’ve ever seen, would have been a tragedy, one that [Shahriar] wisely avoided.

After a bit of recapping and some power supply troubleshooting, the video below treats us to a tour of the Nixie-based beauty. It’s a wonderful piece, and still quite accurate after all these decades, although it did need a bit of calibration. Turning it into a clock non-destructively required adding a little bit of gear, though. Internally, [Shahriar] added a divide-by-ten card to allow the counter to use an external 10-MHz reference. Externally, an ERASynth++ programmable signal generator was used to send a signal to the counter from 0 Hz to 23,595.9 kHz, ramping up by 100 Hz every second.

The end result is the world’s most complicated 24-hour clock, which honestly wasn’t even the point of the build at all. It was to show off the glorious insides of the counter, introduce us to some cool new RF tools, and as always with [Shahriar]’s videos, to educate and inform. We’ve always enjoyed his wizardry, from his look into automotive radars to a million-dollar scope teardown, and this was another great project.

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Homebrew ROM Reader Saves Data From A Vintage Minicomputer

Have you ever heard of a Centurion minicomputer? If not, don’t feel bad — we hadn’t either, until [David Lovett] stumbled upon a semi-complete version of the 1980-ish mini in all its wood-trimmed, dust-encased glory. And what does a hacker do with such an acquisition but attempt to get it going again?

Of course, getting a machine from the Reagan administration running is not without its risks, including the chance of losing whatever is on the machine’s many ROM chips forever. When finding a commercial ROM reader supporting the various chips proved difficult, [David] decided to build his own. The work was eased considerably by the fact that he had managed to read one chip in a commercial reader, giving him a baseline to compare his circuit against. The hardware is straightforward — a 12-bit counter built from a trio of cascaded 74LS161s to step through addresses, plus an Arduino Nano to provide clock pulses and to read the data out to the serial port.

The circuit gave the same results as the known good read, meaning results would be valid for the rest of the chips. The breadboard setup made supporting multiple ROM pinouts easy, even for the chips that take -9 volts. What exactly the data on the ROMs mean, if anything, remains a mystery, but at least it’s backed up now.

Before anyone notes the obvious, yes, [David] could have used a 555 to clock the reader — perhaps even this one. We’d actually have loved that, but we get it — sometimes you just need to throw an Arduino at a job and be done with it.

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Telco Curio Hacked Into Simple Counter

The tikkenteller was a device used to measure the duration of telephone use. 70 Volts were sent down the telephone line at 50Hz to run an electromechanical counter, and the devices were often used in communal areas where several users shared a single phone. [Charles Babbadge] decided to repurpose the stout 1950s hardware into a simple counter.

The build uses an ATtiny13 to generate pulses for the original hardware, when receiving inputs from the tikkenteller’s buttons. A solid state relay is triggered by the microcontroller, which connects the original solenoid to mains power to jog the counter. An HLK-PM01 5V power supply is used to run the micro, allowing the entire project to run off a single mains supply.

It’s a big, heavy, beautiful hunk of metal, built in a style that we simply don’t see anymore. It’s in no way the cheapest or most efficient counter you could build, but it’s got a charm you can’t find on more modern hardware. You could use such a device to track your Youtube subs, that is… if the API hadn’t broken that for everyone. Video after the break.

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