After seeing our Larson Scanner kit, Martin shared this LED metronome project with us. Martin says:
It was designed as a “Visual Metronome” So a learning music student could help see the timing by watching the green light. There was to be an optional clicking sound by using a small solenoid for the ticking – I chose that in place of a speaker for a more authentic sound.
The timing is a standard 555 timer which is fed to 7442 BCD to DECIMAL counter. Next chip is a 74193 UP/DOWN counter. When the count hits the last number, it sends a pulse to reverse the count or start over – depending on the toggle switch on the side.
There is also a pot on the 555 to control the speed. All this was made in one night while I was working the graveyard shift.
The entire LED display was hand wired using a manual wire-wrap tool.
The chip pin labels on the back of the perf board are a particularly awesome relic of a different era of electronics assembly. Thanks for sharing your project photos and video with us!
Last year, I wrote about a case of 3D printed parts being used for a vintage car. This year, another fine example of modern manufacturing and prototyping techniques being used for a vintage vehicle showed up on my doorstep when my parents stopped by during a road trip in my dad’s 1934 Dodge Brothers pickup
Passenger side mirrors on cars and trucks used to be a luxury, add-on, or aftermarket item— if they were even available at all. My dad’s truck never had one. In the intervening years, many states have made side mirrors a requirement, and having them makes safely driving a vintage vehicle much easier. So how did he get the matching one you see in the picture above?
He did what pretty much anyone can do these days: he had the driver side one 3D scanned, had a CAD model made up from the scan and then mirrored it. The model was then 3D printed and sand cast in aluminum. After some finishing work and paint, it looks fantastic.
However, geometry reared its head: it turns out that because the driver sits on one side of the car, a perfectly mirrored mirror mount doesn’t put the mirror in quite the right place. As a temporary fix, he added a standoff to correct the position of the mirror. After returning from the road trip, he’ll adjust the CAD model and have a new one printed and cast. Since the world of vintage cars is a close-knit one, he has already had requests for additional units from friends in the community, and making more will be straightforward from the digital master.
He’s had a few other components made using scanning and digital manufacturing techniques, including a laser cut insulation board for between the engine compartment and the cab. These techniques are a perfect fit for a community with low-volume needs for custom, unavailable, or never before made parts.
If you solder, you’ve likely come across an “untinned” tip at some point— that’s when the tip of your soldering iron loses its shine, and doesn’t easily wet to solder any more.
Once your tip gets this way, it doesn’t make nearly as good of a thermal contact to whatever you are trying to solder, and it simply doesn’t work well. Soldering can take 2-10 times as long, and that isn’t good for your circuit board, components, or mental health.
You can sometimes re-tin the tip by melting fresh solder onto it, but that can be challenging, because the whole problem is that the tip isn’t melting solder. It’s particularly hard to keep tips tinned with modern lead-free solder, because it needs to get even hotter to begin melting. If you get to this point, you might think about even replacing the tip.
But before you throw that tip away, instead consider using one of the “old standard” solutions, which is to refurbish the tip with a tip-tinning compound. And we came across the most classic of them in one of the most unexpected locations. Continue reading Soldering Tip Tinning with Sal Ammoniac
Last fall, we built an oversized Digi-Comp II for MIT, which we’ll be posting about in the near future. Today, MIT computer science professor Scott Aaronson published a short “paperlet” about the computational capabilities of the Digi-Comp II on his blog, Shtetl-Optimized:
…it’s amazing that such a simple contraption of balls and toggles could already take us over the threshold of universality. Universality would immediately explain why the Digi-Comp is capable of multiplication, division, sorting, and so on. If, on the other hand, we don’t have universality, that too is extremely interesting—for we’d then face the challenge of explaining how the Digi-Comp can do so many things without being universal.
Once upon a time, cameras did not come with LED illumination or even xenon strobes, but rather with a socket that could fire a one-time-use flashbulb.
An advance from this was the “flip flash” cartridge which held 8 or 10 flash bulbs, ganged up so that you could take one photo after another, without pausing to swap bulbs. Each time that you took a picture (exposing actual film!), the next flashbulb in the cartridge would fire.
But you might ask a tricky question here: How does it know which bulb to fire next?
Today we’re introducing version 2.0 of our “Three Fives” Discrete 555 timer kit. Version 2.0 has a number of little tweaks and improvements, with a cleaner design and — coolest of all — an all-new set of smooth anodized aluminum legs.
The Three Fives kit is a faithful and functional transistor-scale replica of the famous 555 timer integrated circuit — one of the most popular and well-loved chips of all time. (An original NE555 IC is shown above for scale.)
We are also releasing the first version of our educational supplement for the Three Fives kit: A detailed description of how the 555 circuit actually works, with plenty of opportunities for further exploration. You can find it on the downloads section of the product page or on our documentation wiki.
Hey look! It’s the fossilized remains of a possible evolutionary ancestor of the EggBot!
Okay, it’s pre-USB but technically it’s not a fossil. Like many of us, the decoregger dates from the mid-1970’s. It’s a simple function gadget that mounts an egg so that you can spin it, with arm second arm that holds tiny felt-tip pens. Curiously, there are also some contemporary machines bearing the same name that lack the separate arm.
In the upper-left photo, you can see that the pen holder has a separate “paddle” that you hold, to manually move the pen in the arc across the egg surface. Lacking the proper felt-tip pens, we found that a uni-ball micro pen was about the right diameter to fit in the holder.
One surprising thing: To model this thing, we used regular “large AA” (not extra large, and not jumbo) size eggs from the grocery store. And it was only barely possible to squeeze the egg into the holders. From the picture on the box, it looks like there’s plenty of room for even the largest egg. Possible explanation #1: Plastic shrinks over time. Possible explanation #2: The egg pictured on the box is from the advertising land of freaky micro-children.
But in any case, the decoregger is a cute little machine, and it looks like it might be fun to play with. The actual play is a matter of turning knob 1 and knob 2, so it feels a lot like an Etch-a-Sketch in spherical coordinates. Now if only there were some way to strap a couple of motors to it and perform a CNC conversion….
Speaking of which, it really is a lot smaller than the EggBot. Heck, you could probably fit the whole thing inside the EggBot.
Wait — am I doing this right?
Special thanks to Michelle Hlubinka for finding this artifact and sending it to us!
They don’t make — or package — them like they used to. This is a vintage radio crystal from the Bliley Electric Company. Bliley is still around, making modern oscillators and even space flight hardware, but this vintage unit is a beauty.
Introduced in the 1930’s, the Bliley LD2 was a popular frequency standard for amateur radio operators. A 1935 advertisement in QST magazine claimed efficiency and extremely low drift (<8 ppm/°C), guaranteed operation, an improved holder, and a cost of only $4.80, or $82.79 in 2014 dollars. This particular unit is calibrated at 3.9895 MHz (“3989.5 KC”), for a radio wavelength of about 75.2 m.
Unlike most modern crystals, this type comes apart easily. Inside, two rectangular steel plates sandwich a thin slice of quartz crystal, all held pressed together with a simple spring.
If you’re interested to learn more, there’s a wealth of additional information about vintage crystals and the Bliley company available online, here.