The NanoVNA made network analyzers cheap enough for almost everyone. Now you can get a $49 spectrum analyzer to go with it. Is it worth it? Watch [IMSAI Guy]’s video after the break for his opinion. From the tinySA.org website:
Spectrum Analyzer with two inputs, high-quality MF/HF/VHF input for 0.1MHZ-350MHz, lesser quality UHF input for 240MHz-960MHz.
Switchable resolution bandpass filters for both ranges between 2.6kHz and 640kHz
Color display showing 290 scan points covering up to the full low or high-frequency range.
Input Step attenuator from 0dB to 31dB for the MF/HF/VHF input.
When not used as Spectrum Analyzer it can be used as Signal Generator, MF/HF/VHF sinus output between 0.1MHZ-350MHz, UHF square wave output between 240MHz-960MHz.
A built-in calibration signal generator that is used for automatic self-test and low input calibration.
Connected to a PC via USB it becomes a PC controlled Spectrum Analyzer
Rechargeable battery allowing a minimum of at least 2 hours portable use
A lot of cheap scopes and PC-based scopes can do spectrum analysis, too, of course, so this isn’t as exotic as a VNA. But at this price, having a dedicated instrument might be worth it to you, especially if you don’t care about frequency below 100 MHz.
[retrohax] has provided vintage computer guidance for years, and part of that guidance is this: sometimes using paint as part of restoration is simply unavoidable. But the days of tediously color-matching to vintage hardware are gone, thanks to [retrohax] offering custom-mixed spray paints in Amiga 500 Beige, C-64 Beige, and ATARI ST/SE Grey. (At the moment only delivery within Poland is available due to shipping restrictions, but [retrohax] is working on a better solution.)
It’s not every day we see someone mixing custom spray paint colors, but off the shelf options don’t always cut it. Another example of getting specialty materials made from the ground up is custom plywood specifically designed for laser-cutting puzzles, something done because the troubles that came with off-the-shelf options were just not worth the hassle.
As the pace of technology charges blindly forward, a lot of older tools or products get left in the dust, forgotten to most but those left with them. This doesn’t mean they’re useless, though. In fact, old technology that continues to survive in the present tends to be more robust and sturdy than most modern, cheap replacements. While this might be survivorship bias, this is certainly true in particular of oscilloscopes. Rugged CRTs in large metal housings with discrete through-hole components in simple layouts made them reliable, but they’re heavy, bulky, and lack features of modern instruments. With some modifications, though, you can give them a new home and keep their vintage aesthetic.
[BuildComics] had just such an oscilloscope on hand and set out to make it into something useful but aesthetically pleasing as well. With a small circuit board, formerly available as a kit from Sparkfun/Dutchtronix but now only available if you can build them yourself, the cathode ray tube can be modified to output not waveforms but rather a working clock face. The donor oscilloscope was a Heathkit IO-102 which was fine for its time but is now lacking, so the CRT was removed from its housing and placed in a custom-built enclosure with a 40s radio style that suits its new purpose well.
Seeing old hardware that is past its prime being put to work in a new way is great, both from a technical standpoint and also because that’s usable hardware that’s being kept out of the landfill. Oscilloscopes are popular for projects like these too since they are relatively easy to understand and modify. Besides being used as clocks, we’ve also seen them modified to play video games such as Pac-Man.
To be clear, of course there’s a blade. They aren’t magic, obviously. The fan is just small, and hidden inside the base. Air is pulled from the sides and bottom, and into the ring mounted to the top of the unit. When the air eventually exits the thin slit in the ring, it “sticks” to the sides due to the Coandă effect and produces a low pressure zone in the center. That’s all a fancy way of saying that the air flow you get from one of these gadgets is several times greater than what the little dinky fan would be capable of under normal circumstances. That’s the theory, anyway.
We can’t promise that all the physics are working as they should in this 3D printed version, but in the video after the break it certainly appears to be moving a considerable amount of air. It’s also quite loud, but that’s to be expected given it’s using a brushless hobby motor. To get it spinning, [Elite Worm] is using a Digispark ATtiny85 connected to a standard RC electronic speed control (ESC). The MCU reads a potentiometer mounted to the side of the fan and converts that to a PWM signal required by the ESC.
Beyond the electronics, essentially every piece of this project has been printed on a standard desktop 3D printer. An impressive accomplishment, though we probably would have gone with a commercially available propeller for safety’s sake. On the other hand, the base of the fan should nicely contain the shrapnel created should it explode at several thousand RPM. Probably.
Some of us have computer mice with more buttons than we have fingers, resolution tracking finer than a naked eye can discern, and forced-air vents. All these features presuppose one thing; the user has a functioning hand. [Federico Runco] knows that amyotrophic lateral sclerosis, ALS, or Lou Gehrig’s disease, will rob a person of their ability to use standard computer inputs, or the joystick on a motorized wheelchair. He is building EyesDrive for the 2020 Hackaday Prize, to restore that mobility to ALS patients. There are already some solutions, but this one focuses on a short bill of materials.
Existing systems are expensive and often track pupil location, which returns precise data, but EyesDrive only discerns, left, right, and resting. For these, we need three non-invasive electrodes, a custom circuit board with amplifiers, signal processing circuits, and a microcontroller. He includes a Bluetooth socket on the custom PCBs, which is the primary communication method. In the video below he steers a virtual kart around a knotty course to prove that his system is up to the task of an urban wheelchair.
It was with considerable interest last month that I set out to track down where in the world there are still factories making tubes. My research found them in Slovakia, Russia, and China, and it’s fairly certain I didn’t find all the manufacturers by any means. There appeared to be a whole class of mundane tubes still in production that weren’t to be found on their glossy websites. A glance at any outlet through which Chinese modules can be bought will find this type of tube in small audio amplifier projects, and some of them can be astoundingly cheap. When faced with cheap electronics of course I’m tempted to buy some, so I parted with about £10 ($12.50) and bought myself a kit for a two-tube device described as a stereo preamplifier and headphone amplifier.
An Unusual Tube Choice For Audio
What I received for my tenner was a press-seal bag with a PCB and a pile of components, and not much else. No instructions, which would have been worrisome were the board not clearly marked with the value of each component. The circuit was on the vendor’s website and is so commonly used for these sort of kits that it can be found all over the web — a very conventional twin common-cathode amplifier using a pair of 6J1 miniature pentodes, and powered through a +25 V and -25 V supply derived from a 12 VAC input via a voltage multiplier and regulator circuit. It has a volume potentiometer, two sets of phono sockets for input and output, and the slightly naff addition of a blue LED beneath each tube socket to impart a blue glow. I think I’ll pass on that component.
The 6J1 seems to be ubiquitous throughout the Chinese kits, which is surprising when you understand that it’s not an audio tube at all. Instead it’s a small-signal VHF amplifier, a rough equivalent of the European EF95, and would be much more at home in an FM radio receiver or turret TV tuner from the 1950s. I can only assume that somewhere in China there’s a tube factory tooled up for radio tube production that is targeting this market, because another tube you will see in audio power amplifier kits is the FU32 or QQV03-20 in European parlance, a large power beam tetrode that might have been found in a 1950s military radio transmitter. Still just as if you were to use an RF transistor in an audio circuit it would give good account of itself, so it is with an RF tube. There is no reason a 6J1 won’t do an acceptable job in a circuit such as this one.
In case you needed more confirmation that we’re living in the future, a flight on approach to Los Angeles International Airport on Sunday night reported “a guy in a jet pack” flying within about 300 yards of them. A second pilot confirmed the sighting. It’s worth watching the video after the break just to hear the recordings of the conversation between air traffic control and the pilots.
The sighting was reported at about 3,000 feet which is an incredible height for any of the jet packs powerful enough to carry humans we’ve seen. The current state of the art limits jet pack tech to very short flight times and it’s hard to image doing anything more than getting to that altitude and back to the ground safely. Without further evidence it’s impossible to say, which has been an ongoing problem with sightings of unidentified flying objects near airports.
While superheros (or idiots pretending to be superheros) flying at altitude over the skies of LA sounds far fetched, the RC super hero hack we saw nine years ago now comes to mind. At 300 yards, that human-shaped drone might pass for an actual person rather than a dummy. This is of course pure speculation and we don’t want to give the responsible members for the RC aircraft community a bad name. It could have just as easily been trash, balloons, aliens, or Mothra. Or perhaps the pilot was correct and it was “some guy” flying past at 3,000 feet. That’s not impossible.
We anxiously await the results of the FAA’s investigation on this one.