When you’ve got time on your hands, doing something the hard way can be therapeutic. Not that the present situation and the abundance of free time that many are experiencing has anything to do with [Leo Fernekes] all-transistor digital clock build, which he started a year ago with his students. But if you’ve got time to burn, this might be a good way to do it.
[Leo] says one of his design goals with this clock was to do it with the technology commercially available in 1960, which means relying completely on discrete components. And he and his students managed to do just that, with the exception of the seven-segment displays, which were built from the LED filaments from some modern light bulbs. Everything else, though, is as old school as it gets, and really underscores all the complexity that gets abstracted away from timekeeping with modern chips. The video below covers each module in detail, from the Schmitt trigger that cleans up the 50-Hz line frequency to the ring counters and diode matrices used to drive the display. We found the analog stair step dividers used to bring the line frequency down to a more usable pulse train particularly interesting. That clever bit of engineering saved 10 transistors over what would be required for traditional flip-flop dividers.
There’s a lot to learn from this design, and the execution is great too – we’re suckers for Manhattan-style builds, of course. Hats off to [Leo] and his lucky students on a great build.
This Bluetooth speaker is full of delightful surprises. The outer shell is an antique radio cabinet, but its practically empty interior is a combination of Dead Bug circuitry and modern BT receiver.
[PJ Allen] found the BT receiver on Groupon and decided to whip up amplifier and threshold detector circuits using only parts he already had in order to make this vintage-looking Bluetooth speaker. The cabinet is from a Silvertone Model 1955 circa 1936. Don’t worry, no antiques were harmed in the making of this hack, the cabinet was empty when he bought it.
The amplifiers, one per speaker, began life as a circuit from TI’s LM4871 datasheet. Some of the departures came about because he didn’t have the exact component values, even paralleling capacitors to get in the right range. The finished board is a delightful mix of “Dead Bug” and quasi-Manhattan style construction, “quasi” because he carved up the ground plane instead of laying pads on top of it.
Look at the front of the cabinet and you’ll see a rectangular display. Watch the video below and you’ll see that it throbs in time to the music. To do that he came up with a threshold detector circuit which started out based on a circuit from a Sharp/Optonica cassette tape deck, but to which he made improvements.
Back in the 1980s I was a budding electronics geek working in a TV repair shop. I spent most of my time lugging TVs to and from customers, but I did get a little bench time in. By then new TVs were entirely solid-state and built on single PC boards, but every once in a while we’d get an old-timer in with a classic hand-wired tube chassis. I recall turning them over, seeing all the caps and resistors soldered between terminal strips bolted to the aluminum chassis and wondering how it could all possibly work. It all looked so chaotic and unkempt compared to the sleek traces and neat machine-inserted components on a spanking new 19″ Zenith with the System 3 chassis. In a word, the old chassis was just – ugly.
Looking back, I probably shouldn’t have been so judgmental. Despite the decades of progress in PCB design and the democratization of board production thanks to KiCad, OSH Park, and the like, it turns out there’s a lot to be said for ugly methods of circuit construction.
[Daniel] seems to have a lot of time on his hands for building clocks, and that’s fine by us. For his latest build, he used a vacuum fluorescent display (VFD) to display hours, minutes, and seconds using an MSP430 to drive it.
Like the analog meter clock he built recently, there is no RTC. Instead, [Daniel] used the 430’s watchdog timer to generate 1Hz interrupts from the 430’s 32KHz clock. [Daniel] wanted to try Manhattan-style board construction for this project, so he built each module on a punch-cut stripboard island and super glued them to a copper-clad board. We have to agree with [Daniel] that the bare-bones construction is a nice complement to the aesthetic of the VFD.
[Daniel] set out to avoid using a VFD display driver, but each of the segments require +50V. He ran through a couple of drawing board ideas, such as using 17 transistors to drive them all before eventually settling on the MAX6921 VFD driver. The +50V comes from an open-loop boost converter he built that steps up from 12V.
The time is set with two interrupt-triggering buttons that use the shift register example from TI as a jumping off point. All of the code is available on [Daniel]’s site. Stick around after the break for a quick demo of the clock.
The circuit is a weird mix of point to point and Manhattan style circuit construction; after modeling a printed plastic plate, [CarryTheWhat] added a few custom component holders to hold LEDs, batteries, and other tiny electronic bits.
To deliver power to each electronic bit, the components are tied off on blue pegs. These pegs are attached to each other by conductive thread much like wirewrap circuit construction.
Right now, the circuits are extremely simple, but they really remind us of a few vintage ham radio rigs. While this method is most likely too complex to print 3D printer electronics (a much desired and elusive goal), it’s very possible to replicate some of the simpler projects we see on Hackaday.
[CarryTheWhat] put the models and files up on GitHub if you’d like to try out a build of your own.
If you’ve never heard of “Manhattan Style” circuit construction, you’re not alone. Popular in ham radio circles, the process looks nicer than straight dead bug style circuit building, but not as involved as etching your own PCB – consider it a nice middle of the road solution.
This type of construction is often used to build circuits inside enclosures that are made of copper clad, which is a somewhat common practice among ham radio operators. Manhattan Style circuits are built using glued-on metal pads to which components are mounted. One might think that the large pads you see in the image above would limit you to through-hole components, but that’s definitely not the case. A wide array of SMD pads are available in common pin configurations as well, allowing you to use pretty much any type of component you prefer.
While it might not be appropriate for every project you work on, Manhattan Style circuits and copper clad boxes definitely add a nice touch to certain items, like the Wheatstone Bridge Regenerative Receiver you see above.