Turn A Parking Sensor Into An Anemometer

October 28, 2021 by Danie Conradie 10 Comments

To measure wind speed and direction, most people turn the traditional cup anemometer and wind vane. Another less-known method is to use an array of ultrasonic transducers, which doesn’t need any moving parts. [Andy] demonstrates building an ultrasonic anemometer using a cheap after-market parking distance sensor kit and an Arduino. Demo video after the break.

Aside from the price, these kits have the added advantage of including waterproof ultrasonic transducers, perfect for an outdoor weather station, and all the required circuitry to drive them. Some circuit surgery is required to remove the existing 8-pin microcontroller and wire in an Arduino Pro Micro and a few passives to take control of the pulse outputs and processing of the received signal to calculate direction and velocity. The ultrasonic transducers are mounted in a circular baseplate pointing up to an “echo plate” mounted on a carbon fiber rod. [Andy]’s latest version also added an ESP8266 Wi-Fi module for connectivity.

One of the challenges of DIY environmental sensors is calibrating them to output reliable absolute values, and this is especially the case for wind speed. You need another anemometer that is known to be accurate or a wind source of a known velocity. A while back we covered [Jianjia Ma]’s ultrasonic anemometer build, where he mounted it on top of his car and went for his drive, but still couldn’t quite get consistent results.

While the lack of moving parts are nice, ultrasonic anemometers are significantly more complex on the software and electronics side, and a DIY cup and vane anemometer is still a viable alternative.

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Speaker ‘Stun Gun’ Aims To Combat China’s Dancing Grannies

October 28, 2021 by Lewin Day 74 Comments

One of the more popular social activities in China is group dancing in public squares. Often the pastime of many middle-aged and older women, participants are colloquially referred to as “dancing grannies.” While the activity is relatively wholesome, some dancers have begun to draw the ire of their neighbourhoods with their loud music and attempts to dominate the use of public parks and recreational areas.

Naturally, a technological solution sprung up promising to solve the problem. The South China Morning Post has reported on a “stun gun” device which claims to neutralise speakers from a distance, in an effort to shut down dance gatherings. The device created a huge stir on social media, as well as many questions about how it could work. It’s simpler, and a bit less cool, than you think. Continue reading “Speaker ‘Stun Gun’ Aims To Combat China’s Dancing Grannies” →

A troublesome Triple-Z80 arcade board requires negative voltage for audio output

Vintage Arcade Used Negative Voltage To Turn Volume Up To 11

October 27, 2021 by Ryan Flowers 50 Comments

When [Nicole Express] got her hands on the logic board for the 1986 SNK arcade game Athena, she ran into a rather thorny problem: The board expected to be fed negative five volts! [Nicole]’s analysis of the problem and a brilliant solution are outlined in her well written blog post.

[Nicole]’s first task was to find out which devices need negative voltage. She found that the negative five volts was being fed through a capacitor to the ground pins on the Mitsubishi M151516L, an obscure 12 W audio amplifier. After finding the data sheet, she realized something strange: the amp didn’t call for negative voltage at all! A mystery was afoot.

To fully understand the problem, she considered a mid-1980’s arcade and its cacophony of sounds. How would a manufacturer make their arcade game stand out? By making it louder, obviously! And how did they make their game louder than the rest?

The answer lays in the requirement for negative five volts. The amplifier is still powered with a standard 12 V supply on its VCC pin. But with ground put at -5 V, the voltage potential is increased from 12 V to 17 V without overpowering the chip. The result is a louder game to draw more players and their fresh stacks of quarters.

How was [Nicole Express] to solve the problem? ATX PSU’s stopped providing -5 V after the ISA slot disappeared from PC’s, so that wouldn’t work. She could have purchased an expensive arcade style PSU, but that’s not her style. Instead, she employed a wonderful little hack: a charge pump circuit. A charge pump works by applying positive voltage to a capacitor. Then the capacitor is quickly disconnected from power, and the input and ground are flipped, an equal but negative voltage is found on its opposite plate. If this is done with a high enough frequency, a steady -5 V voltage can be had from a +5 V input. [Nicole Express] found a voltage inverter IC (ICL7660) made just for the purpose and put it to work.

The IC doesn’t supply enough power to get 12 W out of the amplifier, and so the resulting signal is fed into an external amplifier. Now [Nicole]’s arcade game has sound and she can play Athena from the original arcade board, 1986 style!

Arcades are few and far between these days, but that doesn’t mean you can’t introduce your young ones to the joys of dropping a quarter or two, or build a gorgeous oak Super Mario Bros cabinet complete with pixel art inlays. Do you have a favorite hack to share? Be sure let us know via the Tip Line!

Simple Electronic Hacks Inspire Doing More With Less

October 26, 2021 by Ryan Flowers 18 Comments

It’s late at night. The solder smoke keeps getting in your tired eyes, but your project is nearly done. The main circuit is powered by your 13.8 V bench supply, but part of the circuit needs 9 V. You dig into your stash to find your last LM7809 voltage regulator, but all you have is a bunch of LM7805’s. Are you done for the night? Not if you’ve watched [0033mer]’s Simple Electronic Circuit Hacks video! You know just what to do. The ground pin of a LM7805 connects to the cathode of a TL431 programmable Zener diode pulled from an old scrapped TV. The diode is referenced to a voltage divider, and voila! Your LM7805 is now putting out a steady 9 V.

How did [0033mer] become adept at doing more with less? As he explains in the video below, his primary source of parts in The Time Before The Internet was old TV’s that were beyond repair. Using N-Channel MOSFETs to switch AC, sensing temperature changes with signal diodes, and even replacing a 555 with a blinking LED are just a few of the hacks covered in the video below the break.

We especially appreciated the simple, to-the-point presentation that inspires us to keep on hacking in the truest sense: Doing more with less! If you enjoy a good diode hack like we do, you will likely appreciate learning Diode Basics by W2AEW, or a Diode Based Radiation Detector.

Thank you [DSM] for the tip! Be sure to submit your the cool things you come across to our Tips Line!

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Refining The Greatest Joystick Of The 1980s

October 20, 2021 by Tom Nardi 24 Comments

The Competition Pro joystick is often considered to be the pinnacle of input devices, at least as far as the 1980s gaming goes. But the design isn’t perfect, and time hasn’t been kind to certain aspects of its mechanism. For example, the large rubber disc used to keep the stick centered on early generations of the hardware will invariably be hardened up on any surviving specimens. Looking to return these classic controllers to their former glory, and then some, [mageb] has released a number of 3D printed modifications for the Competition Pro that should be of great interest to the vintage gamer.

First and foremost is the deletion of the original rubber disc for a new spring mechanism. Even if this is the only modification you do, [mageb] says you’ll already have a better and longer-lasting joystick to show for it. But if you want to continue with the full rebuild, be aware that there’s no going back to stock. Once you start cutting the original parts, you’re committed to taking it all the way.

Assuming you’re not afraid to get your hands dirty, the next step is cutting the metal contacts from the bottom of the face buttons so they’ll work with the new microswitch array he’s designed. Each button gets its switch, and four handle movement of the joystick. You can try out different switches to adjust the feel of the joystick, but [mageb] assures us that he’s already done the research and put the best quality switches in the bill of materials.

The end result is a Competition Pro joystick that looks more or less the same from the outside, but is considerably improved internally. That’s always a win in our books, though we’re sure somebody out there is going to get mad that the brittle old rubber disc wasn’t sent to the Smithsonian.

A homebrew telephone connects home and workshop.

The Calls Are Coming From Inside The House (or Workshop)

October 19, 2021 by Kristina Panos 16 Comments

Hot on the heels of their carbon microphone build a few years ago, [Simplifier] strung up a two-phone network between the house and the workshop. Both telephones are completely DIY except for the pair of switches on the front. Each side has a bell, a microphone, and an audio transformer. Listening is done through a pair of headphones, and both users speak through a homebrew carbon microphone.

We particularly love the bell, which is made from fence post caps. Sitting between the bells and ready to strike is a ball bearing mounted on a really thick piece of wire that’s driven by an electromagnet. To make a call, you use both switches — the one on the left pulls either the bell or the microphone to ground, while the switch on the ~~left~~ right is used momentarily to send 6 V from the lantern battery down the 50 ft. line to the other phone to ring it. You’ll see what we mean in the demo video after the break. Check out the sound of those fence post caps!

[Simplifier] wound an audio transformer that provides the necessary impedance matching to use regular headphones as receivers. Since the homebrew microphones only need 1.5 V, [Simplifier] split the voltage across two carbon contacts placed in series. That’s still more than necessary, but [Simplifier] was able to make it work.

More recently, [Simplifier] has built a beautiful and even better carbon microphone and even hosted a back-to-basics Hack Chat.

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ESP32 Clock Pushes Outrun Graphics Over Composite

October 19, 2021 by Tom Nardi 24 Comments

We’ve covered plenty of clocks powered by the ESP32, but this one from [Marcio Teixeira] is really something special. Rather than driving a traditional physical display, the microcontroller is instead generating a composite video signal of an animated digital clock. This could be fed into whatever device you wish, but given the 80’s synthwave style it’s pumping out, you’ll probably want to find a suitably retro CRT to do it justice.

Specifically this is a variant of the “Dali” clock, where each digit seems to melt and morph into its successor. Though his version doesn’t necessarily share code with all the previous iterations, [Marcio] does credit the developers who have pulled off similar visual tricks going all the way back to 1979. Given the vintage of this particular animation, the neon skyline and infinite scrolling grid certainly feel like a perfect fit.

Want to add a little vaporwave vibe to your own workbench? Assuming you’ve already got a 80s style CRT, all you need is an ESP32 and two wires stuck into the composite video port. One goes to ground, and the other goes to the chip’s analog pin. Once everything is powered up, you’ll be able to configure the clock with a web-based interface. It doesn’t get much easier than that.

In the documentation, [Marcio] calls out a few open source projects which were instrumental to getting his clock off the ground. The pioneering work [bitluni] did to get video out of the ESP32 is something of a given, but he also sends a hat tip to [rossumur] for his collection of 8-bit game console emulators written for the microcontroller. Projects like this are a fantastic example of what’s possible when a community works together to truly push the envelope.

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