Mold-Making Masterclass In Minutes

August 5, 2020 by Kristina Panos 11 Comments

Making silicone molds seems easy, but there are a lot of missteps to be made along the way that can mean the difference between a great, reusable mold, and one that’s a sad waste of silicone. If you’re helpless to know the difference, then check out [Eric Strebel]’s 9-minute masterclass teaser video on making a two-part mold for resin casting, which is also embedded below.

Even if you already know how to do this, there’s probably a good tip in here somewhere. One of them being that you should always pour your silicone from one place and let it coat the piece being copied. Otherwise, there might be lines on the mold. Another tip is for DIY mold release made from petroleum jelly thinned with naphtha.

Our favorite tip has to do with the way [Eric] makes this a reusable two-part mold, which is more akin to injection molding. To pour silicone for the second part and get it to separately nicely, [Eric] uses sprues made out of resin rods that were cast inside of drinking straw molds. These he chamfers against a belt sander to minimize the contact with the cast part, which makes them a snap to break off. [Eric] says this is just the beginning, and there are more videos to come that will break down the steps.

There’s more than one way to make a mold, especially for casting in metal. We’ve seen everything from 3D-printed molds to kinetic sand.

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CBS Announces Functional Tricorder Replica For 2021

July 22, 2020 by Tom Nardi 61 Comments

It’s taken 54 years, but soon, you’ll finally be able to buy a fully-functional version of the tricorder from Star Trek. Announced on the official website for the legendary sci-fi franchise, the replica will be built by The Wand Company, who’ve previously produced a number of high-quality official Star Trek props as well as replicas for Doctor Who and the Fallout game series.

Admittedly, we’re not sure what a “fully-functional tricorder” actually is, mainly because the various on-screen functions of the device were largely driven by whatever bind Kirk and Spock managed to find themselves in that week. But the announcement mentions the ability to scan radio frequencies, pull in dynamic data from environmental sensors, and record audio. The teaser video after the break doesn’t give us any more concrete information than the announcement, but it does seem to confirm that we’ll be viewing said data on the device’s iconic flip-up display.

Now as the regular Hackaday reader knows, fans have been building extremely impressive “functional” tricorders for some time now. Unlike the sleek 24th century versions seen in Star Trek: The Next Generation, the original tricorder prop was rather clunky and offers plenty of internal volume for modern goodies. Cramming a Raspberry Pi, LCD, and a bunch of sensors into an inert replica is a relatively approachable project. So it will be interesting to see how the official version stacks up to what’s already been done by intrepid hackers and makers.

The official tricorder won’t be available until summer of 2021, but you can sign up to be notified when it’s your turn to beam one up. While the $250 USD sticker price might keep the more casual Trekkers at bay, it’s actually a bit cheaper than we would have assumed given the amount of time and money we’ve seen fans put into their own builds.

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Upgrading The RAM In A 25 Year Old Oscilloscope

July 19, 2020 by Tom Nardi 25 Comments

From reading his extensive write-ups on the subject, there’s one thing we know for sure: [Tom Verbeure] loves his Tektronix TDS 420A oscilloscope. While it might be older than some of the people reading this, it’s still an impressive piece of hardware with more than enough bells and whistles to keep the average hacker occupied. Especially if you’re willing to perform some hardware modifications.

Note the battery to retain calibration data.

[Tom] already knew how to tickle the scope into unlocking software features, a process not unlike what we’ve seen done on more modern scopes. But there’s only so far you can get by toggling software flags.

Some of the more advanced features that are turned off in the firmware actually need additional hardware to function. Simply bumping the sample points to 120,000 in software wasn’t enough, the scope actually needs the memory to hold them in.

Now logically, if there’s a software option to increase the number of samples, there must be a hardware upgrade that goes along with it. Sure enough, [Tom] found there were 6 open spots next to the scope’s existing M5M51008 static RAM ICs.

As luck would have it the chips are still available, albeit from a different manufacturer and a bit faster than the original parts. Digikey wouldn’t sell fewer than 100 of them, but UTSource was happy to sell him 10. In this case, the parts were cheaper than the shipping cost. Installation was about as straightforward as it gets, though [Tom] does note that he had to keep the board powered up during the operation or else the scope would have lost its calibration data.

Squeezing more features out of modern scopes like the Rigol DS2072A just takes a USB cable and some software. Sometimes it’s only a matter of tapping in a code. But we certainly appreciate [Tom] putting in a little extra effort to get the most out of this classic piece of hardware.

A Tin Can Modem, Just For Fun

July 18, 2020 by Dan Maloney 9 Comments

Anyone old enough to fondly recall the “bleep-burp-rattle” sequence of sounds of a modem negotiating a connection over a phone line probably also remembers the simple “tin-can telephone” experiment, where a taut string transmits sound vibrations from the bottom of one tin can to another. This tin can modem experiment puts both of those experiences together in a single project.

As [Mike Kohn] notes, this project was harder than it would seem that it should be. He actually had a much harder time getting the tin can phone part of the project optimized than getting the electronics sorted out, resulting in multiple tries with everything from the canonical tin cans to paper coffee cups before eventually settling on a pair of cardboard nut cans, the kinds with the metal bottoms. Linked together with a length of kite string — dental floss didn’t work — [Mike] added a transmitter on one end and a receiver on the other.

The transmitter used an ATtiny 2313 and everyone’s favorite audio amplifier, the LM386, while the receiver sported an electret mike preamp board, an LM566 tone decoder, and an MSP430 microcontroller. The modulation scheme was as simple as possible — a 400 Hz tone whose length varies whether it’s a one or a zero, or a stop or start bit. Connected to a pair of terminal programs, [Mike] was able to send his name over the ~~wire~~ string at what he calculates to be six or seven baud.

This project has all the hallmarks of lockdown boredom, but we don’t care because it’s good fun and a great learning opportunity, particularly for the young ones. There’s plenty of room for optimization, too — maybe it could even get fast enough for the Hackaday Retro 300-baud challenge.

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Reverse Engineering Teaches An Old Scope New Tricks

July 18, 2020 by Adil Malik 8 Comments

[PMercier] clearly loves his old Tektronix TDS3014 scope, which did however lack essentially modern connectivity such as an Ethernet port for control and a USB port for a convenient way to capture screenshots. So he decided to do some in-depth reverse engineering and design his own expansion card for it. The scope already has an expansion port and an expansion card, but given this model was first released in 1998, purchasing an OEM part was not going to be an option.

They don’t make ’em like they used to. Test equipment is today is built to last a decade — but usually lives on much longer. This is certainly true for the previous generations of kit. It’s no surprise that for most of us, hand-me-downs from universities, shrewd eBay purchasing, and even fruitful dumpster dives are a very viable way to attain useful and relevant test equipment. Now, while these acquisitions are more than adequate for the needs of a hobbyist lab, they are admittedly outdated and more to the point, inaccessible from a connectivity and communication standpoint. A modern lab has a very high degree of automated data acquisition and control over ethernet. Capturing screen dumps on a USB is a standard feature. These modern luxuries don’t exist on aging equipment conceived in the age of floppy disks and GPIB.

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Take Pottery For A Spin With A Pocket-Sized Wheel

July 14, 2020 by Kristina Panos 23 Comments

If 2020 can be remembered in any positive light, it would be that this has been the year of the hobby tryouts. Why not pottery? Sure, throwing pots won’t fill your belly like homemade bread. But we would bet you can see the value in having a bunch of expendable objects that are easily (and quite satisfyingly) smashed to smithereens. The best part is that between the workbench, junk box, and recycle bin, you can probably build [Jadem52]’s pottery wheel for ants with stuff you already have. Bonus!

Pottery wheels aren’t that complicated. They’re honestly kind of expensive for what they are — a motor and a belt driving a rotating platter. It’s like a record player, but less fussy. Where they really get you on expense is the kiln to heat-treat those pots into sturdy vessels. But you could always use air-dry clay, especially if you’re making these things just to smash them whenever you need to let off some steam.

So anyway, you don’t need much more than a motor, a jar lid for a wheel to throw on, and a bearing to make it spin smoothly. Store-bought pottery wheels have a foot feed to control the motor speed, but this pocket version is either spinning on nine volts or it isn’t. The great thing about a project like this is that once you have the general principle down and use the thing, you can iterate and upgrade to your heart’s content. Take it for a little spin after the break.

If you want to hack together a more conventionally-sized wheel, an old ceiling fan motor should be more than sufficient.

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Build An Everlasting Continuity Tester

July 13, 2020 by Kristina Panos 34 Comments

When you need a continuity tester at the bench, what do you reach for? Probably your multimeter, right? It may surprise you to know that the continuity tester in the meter isn’t all that sensitive, even if it’s the yellow expensive kind. [Leo]’s will beep even if there is 50Ω of resistance in the line.

Disgusted by modern commercial testers, [Leo] set out to make the ideal continuity tester in the spirit of old school tools that do one thing and do it really well. It had to be simple to use, always ready to go, and capable of measuring continuity at 5Ω or less resistance (video, embedded below).

There’s no power switch or even labels, because it doesn’t need any. Just put the probes where you want ’em, and it either beeps and lights the LED or it doesn’t. It looks simple, but inside that blast-resistant enclosure are lots of cool features that certainly make it seem like the ideal tester to us.

Our favorite has to be the transient blocking unit that works like a little circuit breaker. They’re used to protect circuits from lighting and electrostatic discharge by way of depletion-mode MOSFETs and switches to protected mode in under a microsecond. Watch [Leo] build this workbench necessity and then abuse test it with mains power after the break.

Making your own tools, however simple or complex is a great experience. If you want to up your speedy prototyping game, [Leo]’s got you covered there with a special scratching tool for hand-scribing copper PCBs. Continue reading “Build An Everlasting Continuity Tester” →