Join Hackaday Editor-in-Chief Elliot Williams and Managing Editor Tom Nardi as they look back on the best hacks and stories of the previous week. There’s plenty in the news to talk about, though between faulty altimeters and the ongoing conflict in Ukraine, it isn’t exactly of the positive variety. But things brighten up quickly as discussion moves on to 3D printed car wheels, a fantastically complex drum machine from 1958, a unique take on the seven-segment flip display, and a meticulously designed (and documented) coffee machine upgrade. Somewhere in there a guy also recreates a rare German anti-air rocket launcher from WWII, but it’s all in the name of history. We’ll also tackle two very different forms of electric propulsion, from the massive wheeled batteries popping up in garages and driveways all over the world to high-efficiency thrusters for deep space missions.
Earlier this year, we featured an unusual radio receiver that took the very traditional superhetrodyne design and implemented it in an unexpected fashion without any inductors, using instead a combination of 74HC logic chips and op-amps. Its designer [acidbourbon] remarks that the circuit bears a striking resemblance to a ring modulator,so has taken it down that path by producing a 74HC based ring modulator guitar pedal.
In both circuits, a 74HC4046 phase-locked loop chip serves as an oscillator, driving a 74HC4051 analogue switch chip that performs the mixer task. The extra-op-amp filter and demodulator circuitry from the radio is omitted, and the oscillator frequency moved down to the audio range. The result can be heard in the video, and we probably agree with him that it’s not quite the same as a classic ring modulator. This lies in the type of mixer, the diodes used in a traditional circuit have a forward voltage to overcome before they start or end conducting, while the CMOS switch chip does so immediately on command.
The 4000 series CMOS and their descendants are a fascinating family with many unexpected properties that our colleague Elliot Williams has gone into detail with for his Logic Noise series. Meanwhile take a look at our coverage of the original radio.
In a world with software-defined radios and single-chip receivers, a superheterodyne shortwave radio might not exactly score high on the pizzazz scale. After all, people have been mixing, filtering, and demodulating RF signals for more than a century now, and the circuits that do the job best are pretty well characterized. But building the same receiver using none of the traditional superhet trappings? Now that’s something new.
In what [Micha] half-jokingly calls a “74xx-Defined Radio”, easily obtained discrete logic chips, along with some op-amps and a handful of simple components, take the place of the tuned LC circuits and ganged variable capacitors that grace a typical superhet receiver. [Micha] started by building an RF mixer out of a 74HC4051 analog multiplexer, which with the help of a 2N3904 phase splitter forms a switching mixer. The local oscillator relies on the voltage-controlled oscillator (VCO) in a 74HC4046 PLL, a chip that we’ve seen before in [Elliot Williams]’ excellent “Logic Noise” series. The IF filter is a simple op-amp bandpass filter; the demodulator features an op-amp too, set up as an active half-wave rectifier. No coils to wind, no capacitors to tune, no diodes with mysterious properties — and judging by the video below, it works pretty well.
It may not be the most conventional way to tune in the shortwave bands, but we always love the results of projects that are artificially constrained like this one. Hats off to [Micha] for the interesting trip down the design road less travelled.
Hackaday editors Mike Szczys and Elliot Williams recap a week of great hacks. You won’t want to miss the dynamometer Leo Fernekes built to measure the power output of his Sterling engine, which is also DIY. In this age of lithium-powered multirotors, it’s nice to step back and appreciate a hand-built rubberband-powered ornithopter.
We have a surprising amount to say about Python’s addition of the match statement (not be be confused with switch statements). And when it comes to electromechanical synth gear, it’s hard to beat a spinning tape-head sequencer.
Take a look at the links below if you want to follow along, and as always, tell us what you think about this episode in the comments!
Hackaday editors Mike Szczys and Elliot Williams discuss the many great hacks of the past week. Just in case you missed the fact that we’re living in the cyberpunk future, you can now pop off your prosthetic hand and jack directly into a synthesizer. The robot headed for Mars has a flying drone in its belly. Now they’re putting foaming agent in filament to make it light and flexible. And did you ever wonder why those pinouts were so jumbled?
Take a look at the links below if you want to follow along, and as always tell us what you think about this episode in the comments!
Take a look at the links below if you want to follow along, and as always, tell us what you think about this episode in the comments!
Hackaday’s premiere European hardware conference returns for the third time on May 9th, 2020, bringing together talks, workshops, hardware hacking, food and drink, entertainment, and of course the best gathering of hardware geeks you’ll find anywhere. It’s awesome, because you’re awesome — and I do mean you. Whether you’re submitting a talk proposal or just grabbing a ticket to make this the first conference you’ve ever been to, we can’t do it without you.
Hackaday’s Home in Serbia
We’ll be at Dom Omladine again this year. The venue has feels like a home for Hackaday with a large space for talks, a workshop area, and a huge open area for lobby-con where you’ll find Belgrade’s finest baristas, a great spread of food, and a beer tap to keep the day rolling. Bring along your hardware projects to hack alongside the conference’s custom hardware badge designed by Voja Antonic as we open up the bar and get the live IDM sets started.
Flooding into Hackaday Belgrade
Breakfast spread as the doors open
What is better than hacking to live music?
It’s still early in our planning (these are Early Bird tickets after all) but it’s very likely we’ll have a meetup the night before the conference. Friends old and new often get together on Sunday to keep the fun going. On Saturday, doors for the conference will open around 9 am and the fun will continue well beyond the 2 am “official” end. We recommend you make travel plans to include the full weekend.
Elliot Williams demos Logic Noise live on stage
Don’t just ask for Friday off of work, bring your friends and co-workers along with you. If you’re most comfortable digging through datasheets while a hot soldering iron idles on your bench and a 3D-printer whirs away in the corner, Hackaday Belgrade is calling you. I encourage those who were at the first two events in 2016 and 2018 to share their stories below.
Don’t miss this one, it only comes around in even-numbered years and tickets will sell out.
Hackaday Belgrade 2020 Posters by Aleksandar Bradic (click for full size download link):
A while back, [lonesoulsurfer] stumbled upon a mind-blowing little DIY synth on YouTube and had to make one of his own. We don’t blame him one bit for that, ’cause we’ve been down that cavernous rabbit hole ourselves. You might want to build one too, after you hear the deliciously fat and guttural sounds waiting inside those chips and passives. Don’t say we didn’t warn you.
The main synth is built on five LM358 op-amps that route PWM through a pair of light-dependent resistors installed near the top. There are two more oscillators courtesy of a 40106 hex inverting Schmitt trigger, which leaves four more oscillators to play with should you take the plunge and build your own.
He didn’t just copy the guy’s schematic and call it good. He added [a 555-based arpeggiator that’s controlled with two homebrew optocouplers. These sound fancy and expensive, but can be bred easily at home by sealing an LED and an LDR inside a piece of black heat shrink tubing and applying a bit of PWM. With the flick of a toggle, he can bypass the momentary buttons and use the yellow knob at the top to sweep through the pitch range with a single input.
Although he doesn’t hold your hand through the build, [lonesoulsurfer] has plenty of nice, clear pictures of the process that nearly give a step-by-step guide. That plus the video demo and walk-through should get you well on your way to DIY synthville.
If this all seems very cool, but you’d really like to understand what’s happening as you descend into the rabbit hole, our own [Elliot Williams]’s Logic Noise series is an excellent start.
