Bottle Filler Perfectly Tops Your Cup

February 26, 2021 by Mike Szczys 23 Comments

You know those bottle fillers at schools and airports? What if you had one of those at home?

We know what you’re going to say: “My fridge has one of those!” Well ours doesn’t, and even though [Chris Courses’] fridge did, his bottle of choice didn’t fit in the vertically-challenged water and ice hutch, nor did it fill autonomously. The solution was to build a dubiously placed, but nonetheless awesome custom bottle filler in his kitchen.

The plumbing for the project couldn’t be more straight-forward: a 5-year undersink water filter, electronically actuated valve, some tubing, and a T to splice into the existing water line going to the fridge. Where the rubber hits the road is making this look nice. [Chris] spends a lot of time printing face plates, pouring resin as a diffuser, and post processing. After failing on one formulation of resin, the second achieves a nice look, and the unit is heavily sanded, filled, painted, prayed over, and given the green light for installation.

For the electronics [Chris] went for a Raspberry Pi to monitor four buttons and dispense a precise allotment tailored to each of his favorite drinking vessels. While the dispenser is at work, three rows of LEDs play an animated pattern. Where we begin to scratch our heads is the demo below which shows there is no drain or drip tray below the dispenser — seems like an accident waiting to happen.

Our remaining questions are about automating the top-off process. At first blush you might wonder why a sensor wasn’t included to shut off the filler automatically. But how would that work? The dispenser needs to establish the height of the bottle and that’s a non-trivial task, perhaps best accomplished with computer vision or a CCD line sensor. How would you do it? Continue reading “Bottle Filler Perfectly Tops Your Cup” →

How To Design A Custom Generator Interlock Plate

February 22, 2021 by Tom Nardi 85 Comments

If you connect a generator to your home’s main electrical panel when the power goes out, you need to make sure the main breaker is shut off. Otherwise, when the power comes back on, you (or the linemen) are going to have a bad time. There are commercial interlock plates which physically prevent the generator and main breakers from being switched on at the same time, but since they tend to be expensive, [HowToLou] decided to make one himself.

The hardest part of this project is designing the template. It needs to be carefully shaped so its resting position prevents the generator’s breaker from being switched on under normal circumstances, but once the main is turned off and out of the way, you should be able to lift it up and have the clearance to flip the lower breaker. Spending some quality time at the breaker box with tape and a few pieces of cardboard is going to be the easiest way of finding the proper shape.

Continue reading “How To Design A Custom Generator Interlock Plate” →

Stray Cat Shelter Is Nicer Than Our First Apartment

February 14, 2021 by Kristina Panos 59 Comments

There are a lot of stray cats roaming around [Red Tie Projects’] neighborhood, and no one seems to care much about what happens to them. Fortunately for the cats, [Red Tie Projects] cares quite a lot, as evidenced by this colossal cat condo they built. The cats retain their freedom, but get food and a warm, sheltered bed whenever they decide to grace [Red Tie Projects] with their presence.

[Red Tie Projects] built this sturdy shelter from pallet wood and did a fine job of it, sealing all the seams and screws up with wood putty and waterproofing it with silicone. Inside there’s a heated pillow, a light, and a remote-controlled camera so RTP] can pan around and keep an eye on the cats. All the wires run out through a weatherproof junction box attached to the side and over to a control box made from an ATX power supply.

Most of the build is made from scrap, including the best part — an Arduino-driven motorized zip line for delivering food from the balcony to the cat porch. Details on the control box and the food delivery system are coming soon, as [Red Tie Projects] teases in the video after the break. We’re looking forward to seeing those. Oh, and don’t worry — there’s more than enough footage to cover the cat tax.

If [Red Tie Projects] ever takes any of those cats in, their demands will only increase. Maybe they can handle the sound of a motorized chair that follows the sun, since they’re tough street cats and all.

Continue reading “Stray Cat Shelter Is Nicer Than Our First Apartment” →

Spinach Photo Prints

February 13, 2021 by Brian McEvoy 14 Comments

Some people like spinach in their salads. Others would prefer it if it never gets near their fork. Still, other folks, like [Almudena Romero], use it for printing pictures, and they’re the folks we’ll focus on today.

Anthotypes are positive images made from plant dyes that fade from light exposure. Imagine you stain your shirt at a picnic and leave it in the sun with a fork covering part of the stain. When you come back, the stain not sheltered by cutlery is gone, but now you have a permanent fork shape logo made from aunt Bev’s BBQ sauce. The science behind this type of printmaking is beautifully covered in the video below the break. You see, some plant dyes are not suitable for light bleaching, and fewer still if you are not patient since stains like blueberry can take a month in the sun.

The video shows how to make your own plant dye, which has possibilities outside of anthotype printing. Since the dye fades in sunlight, it can be a temporary paint, or you could use samples all over your garden to find which parts get lots of sunlight since the most exposed swatches will be faded the most. Think of a low-tech UV meter with logging, but it runs on spinach.

If the science doesn’t intrigue you, the artistic possibilities are equally cool. All the pictures have a one-of-a-kind, wabi-sabi flare. You take your favorite photo, make it monochrome, print it on a transparent plastic sheet, and the ink will shield the dye and expose the rest. We just gave you a tip about finding the sunniest spot outdoors, so get staining.

Anthotype printing shares some similarities with etch-resist in circuit board printing processes, but maybe someone can remix spinach prints with laser exposure!

Continue reading “Spinach Photo Prints” →

Teardown: Bug Zapper Bulb

February 9, 2021 by Tom Nardi 17 Comments

Up here in the Northern Hemisphere, mosquitoes and other flying pests are the last thing on anyone’s mind right now. The only bug that’s hindering gatherings at the moment goes by the name of COVID-19, but even if we weren’t social distancing, insects simply aren’t a concern at this time of year. So it’s little surprise that these months are often the best time to find a great deal on gadgets designed to deter or outright obliterate airborne insects.

Case in point, I was able to pick up this “Bug Zapper LED Bulb” at the big-box hardware store for just a few bucks. This one is sold by PIC Corporation, though some press release surfing shows the company merely took over distribution of the device in 2017. Before then it was known as the Zapplight, and was the sort of thing you might see advertised on TV if you were still awake at 3 AM. It appears there are several exceptionally similar products on the market as well, which are likely to be the same internally.

In all fairness, it’s a pretty clever idea. Traditional zappers are fairly large, and need to be hoisted up somewhere next to an electrical outlet. But if you could shrink one down to the size of a light bulb, you could easily dot them around the porch using the existing sockets and wiring. Extra points if you can also figure out a way to make it work as a real bulb when the bugs aren’t out. Obviously the resulting chimera won’t excel at either task, but there’s certainly something to be said for the convenience of it.

Let’s take a look inside one of these electrifying illuminators and see how they’ve managed to squeeze two very different devices into one socket-friendly package.

Continue reading “Teardown: Bug Zapper Bulb” →

An ESP Will Read Your Meter For You

February 7, 2021 by Jenny List 17 Comments

As home automation starts to live up to its glossy sci-fi promise there remains a deficiency when it comes to interfacing between the newer computerised components and legacy items from a previous age. A frequent example that appears in projects on Hackaday is the reading of utility meters, and in that arena [jomjol] has a very neat solution involving an ESP32 camera module and a software neural network to identify meter readings directly.

The ESP and camera sit at the top of a 3D-printed housing that fits over the meter. The clever trick comes as each photo’s orientation is determined, and not only is OCR used to read digits but also figures are derived from small dial meters and other indicators on the meter face. It’s a very well-thought-out system, with a web-based configuration tool that allows full customisation of the readable zones and how they should be treated.

This project makes full use of the ESP32’s capabilities, and the attention to detail that has gone into making it usable is particularly impressive. It certainly raises the bar against previous OCR meter reading projects.

[Thanks for the tip Sascha]

Open-Source Thermostat Won’t Anger Your Landlord

February 6, 2021 by Anool Mahidharia 51 Comments

[Nathan Petersen] built a Hackable Open-Source Thermostat to smooth out temperature fluctuations caused by the large hysteresis of the bimetallic strip thermostat in his apartment. While it may be tempting to adjust the “anticipator” to take care of the problem or even replace the bimetallic thermostat with an electronic version, building your own thermostat from scratch is a good way to add to your project portfolio while making your way through college. Plus, he got to hone his hardware and software design chops.

The hardware is designed around the STM32, using a cheap, minimal variant since the device just needs to sense temperature and control the furnace in on-off mode. The TMP117 high-accuracy, low-power, temperature sensor was selected for temperature measurement since accuracy was an essential feature of the project. Dry-contact output for the furnace is via a normally-open solid state relay (opto-isolator). For the user interface, instead of going the easy-route and using an I²C/SPI OLED or LCD display, [Nathan] used three 7-segment LED displays, each driven by an 8-channel constant current driver. The advantage is that the display can be viewed from across the room, and it’s brightness adjusted via PWM. Temperature set-point adjustment is via a simple slide potentiometer, whose analog voltage is read by the micro-controller ADC. To remind about battery replacement, a second ADC channel on the micro-controller monitors the battery voltage via a voltage divider. The PCB components are mostly surface mount, but the packages selected are easy enough to hand solder.

[Nathan]’s Github repo provides the hardware and firmware source files. The board is designed in Altium, but folks using KiCad can use either the awesome Altium2KiCad converter or the online service for conversion. (The results, with some minor errors that can be easily fixed, are quite usable.) Serendipitously, his PCB layout worked like a charm the first time around, without requiring any rework or bodge wires.

The firmware is a few hundred lines of custom bare-metal C code, consisting of drivers to interface with the hardware peripherals, a UI section to handle the user interface, and the control section with the algorithm for running the furnace. [Nathan] walks us through his code, digging into some control theory and filtering basics. After making a few code tweaks and running the thermostat for some time, [Nathan] concludes that it is able to achieve +0.1°F / -0.5°F temperature regulation with furnace cycles lasting about 10-15 minutes (i.e. 4-6 cycles per hour). Obviously, his well insulated apartment and a decent furnace are also major contributing factors. Moving on, for the next version, [Nathan] wants to add data collection capabilities by adding some memory and SD card storage, and use an RTC to allow seasonal adjustments or time-based set-points.

This is his first attempt at a “functional’ useful project, but he does love to build the occasional toy, such as this POV Top.