When you’re debugging a board which has an ESP32, Raspberry Pi, or Arduino, it’s easy to slap on a small LCD display or connect via WiFi to see what’s wrong. At least, that’s what the kids are doing. But what if you’re old-school or you don’t have one of those pimped-out, steroid-filled boards? A resistor and an LED will often suffice. Powering the LED means one thing and not powering it means another. And with seven more LEDs you can even display 0-255 in binary.
[Miguel] is clearly in the latter camp. To make debugging-with-LEDs easy, he’s come up with an 8-LED board complete with resistors. He’s even included the Gerber files needed for you to make your own. One row of pins are all connected together and the other row are not. So whether you’re using common cathode or common anode depends on how you orient the LEDs when you solder them in place. You might perhaps have one board of each type at the ready.
But who are we kidding? This is just plain fun to have on a breadboard. Show your prototype doohickey to a friend and you know they’ll be drawn to the little binary counter in the corner pulsing 42 or counting down until it starts flashing 255.
What do you do when you want to add a new feature to some electronics but you can’t or don’t want to tear into the guts? You look for something external with which you can interface. We like these hacks because they take some thinking outside the box, literally and figuratively, and often involve an Aha! moment.
[Simon Aubury’s] big household load was electric heating and his ancient heaters didn’t provide any way to monitor their usage. His power meters weren’t smart meters and he didn’t want to open them up. But the power meters did have an external LED which blinked each time 1 Wh was consumed. Aha! He could monitor the blinks.
Doing so was simple enough. Just point photoresistors at the two meter’s LEDs and connect them and capacitors to a Raspberry Pi’s GPIO pins. Every time a pulse is detected, his Python code increments the LED’s counter and every fifteen minutes he writes the counters to an SQL database. Analysing his data he saw that nothing much happens before 5 AM and that the lowest daytime usage is around noon. The maximum recorded value was due to a heater accidentally being left on and the minimum is due to a mini holiday. Pretty good info given that all he had to go on was a blinking light.
The CatGenie is an amazing device to watch in action, basically a self-cleaning litter box for cats that even does away with the need to replace the litter. It’s comparable to what the indoor flush toilet is for humans compared to maintaining a composting toilet. However, there is a problem. It uses costly soap cartridges which have to be replaced because an RFID reader and a usage counter prevent you from simply refilling them yourself.
The RFID reader board communicates with the rest of the CatGenie using I2C and he needed to know what was being transmitted. To do that he learned how to use a cheap logic analyzer to read the signals on the I2C wires, which makes this an interesting story. You can see the logic analyser output on his blog and GitHub repository along with mention of a timing issue he ran into. From what he learned, he wrote up Arduino code which sends the same signals. He and his cat are now sitting pretty.
What he didn’t do is make a video. But the CatGenie really is amazing to watch in action as it goes through its rather complex 30-35 minute process so we found a video of it doing its thing, shown at 3.5x speed, and included that below. If you’re into that sort of thing.
We sometimes get our inspirations from art. When [kodera2t] saw some Japanese art of fish drawings embedded in clear epoxy he just had to make his own. But while skilled in electronics, he wasn’t skilled at drawing. We’d still call him an artist, though, after seeing what he came up with in his electronics embedded in crystal clear epoxy.
His first works of electronic art were a couple of transistors and some ICs, including an 80386, encased in epoxy. But then he realized that he wanted the electronics to do something interesting. However, once encased in epoxy, how do you keep the electronics powered forever?
He tried a solar cell charging a battery which then powered an LED but he didn’t like the idea of chemical batteries encased in epoxy for a long time.
He then switched to wireless power transmission with a receiving coil in the base of epoxy pyramids. For one of them, the coil powers a BLE board with an attached LED which he can control from his phone. And his latest contains an ESP32-PICO with an OLED display. The code allows him to upload new firmware over the air but on his Hackaday.io page, he shows the difference between code which can brick the ESP32 versus code which won’t. But don’t take our word for it. Check out the video below to see his artistry for yourself.
Your hands are filthy from working on your latest project and you need to run the water to wash them. But you don’t want to get the taps filthy too. Wouldn’t it be nice if you could just tell them to turn on hot, or cold? Or if the water’s too cold, you could tell them to make it warmer. [Vije Miller] did just that, he added servo motors to his kitchen tap and enlisted an AI to interpret his voice commands.
Look closely at the photo and you can guess that he started with a single-lever type of tap, the kind which can be worked with an elbow, so this project was probably just for fun and judging by his video below, he does have a sense of humor. But the idea is practical for dual taps with rotating knobs. He did realize, however, that in future versions he should move the servo motor openings from the top plate to the bottom instead, to avoid any water getting in. A NodeMCU ESP8266 ESP-12E board serves for communicating with the speech recognition side but other than the name, JacobAI, he’s keeping the speech part to himself. We secretly suspect that he has a friend named Jacob.
Here’s a DIY laser rifle which can explode a balloon at around 150 feet (45 meters) as well as some angry chemicals at a similar distance. Since there are plenty of videos of lasers doing that at around a meter, why shouldn’t doing so farther away be easy? Despite what many expect, laser beams don’t remain as straight lines forever. All light diverges over a distance. This makes it hard to create a laser which can do damage from more than around a meter and is why most demonstrations on YouTube are that distance or less.
[Styropyro’s] handheld, DIY laser rifle, or Laser Telescope Blaster as he calls it, works for long distances. His solution lies in some surprising physics: the larger the diameter of the beam, the more slowly it will diverge. So he used the opposite of a Galilean telescope to take the small beam of his 405-nanometer laser and increase its diameter. His best result was to explode a balloon at 150 feet (45 meters).
He did run into another issue first though. Anyone who’s tried to keep a camera aimed at a target through a telephoto lens while holding the camera in their hands knows that even a tiny movement will throw the camera off target. For a laser beam to sufficiently heat up the balloon in order to make it explode, the beam has to stay on it for a short period of time. But at a long distance, small movements of his rifle made the beam wander. Putting the rifle on a tripod fixed that. In the video below you can see him work through his design and these issues to finally get his big success.
We can guess what spurred on this interest in long-distance laser rifles. Back in July, a Chinese company made bold claims to building one which could do damage at 800 meters.
Sometimes a mix of old and new is better than either the old or new alone. That’s what [Brad Carter] learned when he was given an old 1990s sound board with a noisy SCSI drive in it. In case you don’t know what a sound board is, think of a bunch of buttons laid out in front of you, each of which plays a different sound effect. It’s one way that radio DJ’s and podcasters intersperse their patter with doorbells and car crash sounds.
Before getting the sound board, [Brad] used a modern touchscreen table but it wasn’t responsive enough to get a machine gun like repetition of the sound effect when pressing an icon in rapid succession. On the other hand, his 1990s sound board had very responsive physical buttons but the SCSI hard drive was too noisy. He needed the responsiveness of the 1990s physical buttons but the silence of modern solid state storage.
And so he replaced the sound board’s SCSI drive with an SD card using a SCSI2SD adaptor. Of course, there was configuration and formatting involved along with a little trial and error to get the virtual drive sizes right. To save anyone else the same difficulties, he details all his efforts on his webpage. And in the video below you can see and hear that the end result is an amazing difference. Pressing the physical buttons gives instant sound and in machine gun fashion when pressed in rapid succession, all with the silence of an SD card.