Shop Exhaust Fan Salvaged From Broken Microwave

May 20, 2021 by Tom Nardi 7 Comments

You don’t have to look hard to find a broken microwave. These ubiquitous kitchen appliances are so cheap that getting them repaired doesn’t make economical sense for most consumers, making them a common sight on trash day. But is it worth picking one of them up?

The [DuctTape Mechanic] certainly thinks so. In his latest video, he shows how the exhaust fan from a dead microwave can easily and cheaply be adapted to blow smoke and fumes out of your workshop. While it’s obviously not going to move as much air as some of the massive shop fans we’ve covered over the years, if you’re working in a small space like he is, it’s certainly enough to keep the nasty stuff moving in the right direction. Plus as an added bonus, it’s relatively quiet.

Now as you might expect the exact internal components of microwave ovens vary wildly, so there’s no guarantee your curbside score is going to have the same fan as this one. But the [DuctTape Mechanic] tries to give a relatively high-level overview of how to liberate the fan, interpret the circuit diagram on the label, and wire it up so you can plug it into the wall and control it with a simple switch. Similarly, how you actually mount the fan in your shop is probably going to be different, though we did particularly like how he attached his to the window using a pair of alligator clips cut from a frayed jumper cable.

Got a donor microwave but not in the market for a impromptu shop fan? No worries. We recently saw a dud microwave reborn as a professional looking UV curing chamber that would be the perfect partner for your resin 3D printer. Or perhaps you’d rather turn it into a desktop furnace capable of melting aluminum, copper, or bronze.

Continue reading “Shop Exhaust Fan Salvaged From Broken Microwave” →

A Standing Desk On The Cheap

May 17, 2021 by Chris Lott 23 Comments

A programmer forced to work from home during the pandemic, [MrAkpla] was having back pains from sitting in front of the computer all day. He considered buying a standing desk, but all the various options didn’t fit with either his desk or his budget. Not to be deterred, he devised one of the simplest standing desk implementations that we’ve seen. It clearly works for him, because he’s been using it for one year now with great success. [MrAkpla] espouses three main benefits of his approach:

Cheap as heck
Five minute set up time
Uses your existing desk

These goals were accomplished. You can see in the video below that transition from sitting to standing is indeed as quick as he claims, is clearly inexpensive, and indeed it doesn’t require any modifications to his desk or furniture.

This design centers on a having an 80 cm long monitor arm, which is quite a range of adjustment. He’s using a monitor arm pole mount from UK manufacturer Duronic. Although they are having delivery problems these days because of Brexit issues, [MrAkpla] was able to get one delivered from existing inventory outside of the UK.

Admittedly, this is a crude design — in effect two trash bins and a board. But even if this doesn’t fit well with your office decor, its a great way to try out the concept of a standing desk without the up-front investment. By the way, [MrAkpla] is on the lookout for similar monitor mounting poles from non-UK manufacturers. If you have any recommendations, put them in the comments below. If you’re interested in a DIY standing desk that is on the opposite side of the complexity spectrum, check out this beauty that we covered back in the pre-pandemic era.

Continue reading “A Standing Desk On The Cheap” →

Using Ikea Guts To Add Sonos Compatibility To A Vintage Speaker

May 15, 2021 by Jenny List 8 Comments

We’re in a fortunate position when it comes to audio gear, because advances in amplifier and signal processing technology have delivered us budget devices that produce a sound that’s excellent in comparison to those of a few years ago. That said, a decent quality device is good whichever decade it was manufactured in, and a speaker from the 1960s can be coaxed into life and sound excellent with a modern amplifier. It’s something [Sebastius] has explored, as he picked up an attractive-looking set of Swedish speakers from the 1960s. Wanting to bring them into the 21st century, he’s upgraded them for Sonos compatibility by hacking in the guts of an IKEA Symfonisk bookshelf speaker.

The speakers themselves looked good enough, but on closer examination they proved to bear the scars of many decades. After testing new wiring and drivers they still had a good sound to them. Their passive crossover meant that hooking them up to a single amplifier is as straightforward as it was decades ago, but a Symfonisk has an active crossover and two amplifiers. Fortunately there’s a neat hack by which those two amplifiers can be combined as one, and this is what he’s done with the resulting Symfonisk electronic package mounted on the reverse of the speaker.

The fate of the original speaker’s broken mid-range and tweeter drivers was a common enough one back in the day as speakers were ill-matched to amplifiers. Too small an amp would need turning up in volume to get a good sound resulting in distortion that would burn out the top end drivers, while too much power would result in the bass drivers being overloaded and failing. It’s unclear whether the drivers in a vintage speaker would be well-matched to an amplifier such as the Symfonisk, but we’re guessing they are safe while run at sensible volumes. Perhaps of more interest is whatever on-board DSP a Symfonisk contains, because while vintage speakers were designed for as flat a response as possible, modern compact speakers use DSP to equalise the frequency and phase responses of otherwise not-very-good-sounding enclosures. If the Symfonisk does this then those adjustments will appear as distortion in the sound of a different cabinet, but the question remains whether that distortion will be significant enough to be detectable by ear.

If the Symfonisk catches your attention, we’ve covered a teardown of it in the past.

South Australia Vs. Too Much Home Solar

May 10, 2021 by Lewin Day 209 Comments

Once upon a time, the consensus was that renewable energy was too expensive and in too sparse supply to be a viable power source to run our proud, electrified societies on. Since then, prices of solar panels have tanked, becoming more efficient along the way, and homeowners have been installing them on their rooftops in droves.

Where once it was thought we’d never have enough solar energy, in some cities, it’s becoming all too much. In South Australia, where solar output can be huge on a sunny day, electricity authorities are facing problems with grid stability, and are taking measures to limit solar output to the grid.

Isn’t More Usually Better?

The problem faced by South Australian utilities is one of how to properly control an electrical grid with many thousands of distributed power sources. Typically, in conventional modern power grids, voltage and frequency is controlled within set limits by carefully matching the supply from major power plants with the demand from users. Fast-response plants can be brought online to meet shortfalls, and switched off when demand drops, and everything hums along nicely.

Unfortunately, solar power isn’t so easy to throttle, and even less so when it’s coming from thousands of separate households each with their own rooftop install and an inverter to feed back into the grid. This has led to authorities contemplating measures such as charging homeowners to export energy to the grid in peak periods in an effort to slow the huge uptake of home solar systems. Export limits have also been proposed for suburbs with the highest concentration of home solar, as substations in certain residential areas struggle to cope under the huge inflows of energy. Continue reading “South Australia Vs. Too Much Home Solar” →

Adding MQTT To A Solar Powered PIR Light

May 6, 2021 by Danie Conradie 10 Comments

The size and price of the ESP wifi modules have quickly made them into one of the preferred building blocks for IoT devices. Unfortunately they are not particularly well suited for very low power applications. [LittlePetieWheat] wanted to add MQTT to a cheap PIR solar light, so he paired an ESP with an Attiny85 to hold it to a strict power budget.

Most of these lights contain some sort of no-name microcontroller that monitors the analog PIR sensor, and turns on the LEDs as required. [LittlePetieWheat] replaced the PIR sensor with one that gives a digital output for simpler interfacing. The Attiny serves as the low power brains of the project. Its tasks include reading the solar panel and battery voltages, and PIR output. When movement is detected by the sensor, it activates a clever little latching power circuit to power on the ESP01 just long enough to send a MQTT message. The LEDs are only turned on if there is no power coming from the solar panel. The solar power is stored in a 18650 battery.

The Attiny85 might not be a powerhouse, but it is perfect for simple, low power applications like this. We’ve also seen it pushed to its limits by running tiny machine learning models, or receiving software updates over I2C. Continue reading “Adding MQTT To A Solar Powered PIR Light” →

Pool Temperature Monitor Mollifies Fortunate But Frustrated Children

May 2, 2021 by Kristina Panos 25 Comments

Who needs the city pool when you can party in the private pool over at Grandma and Grandpa’s house? No need to wait until Memorial Day weekend when it hits 90° F in the first week of May. But how can you placate grandchildren who want to know each and every day if it’s finally time to go swimming, and the pool itself is miles away? Although grandparents probably love to hear from you more often there’s no need to bother them with hourly phone calls. You just have to build a floating, remote pool temperature monitor which broadcasts every 30 minutes to an Adafruit MagTag sitting at kid’s eye level on the refrigerator.

Between the cost of commercial pool temperature monitors and all the reviews that mention iffy Wi-Fi connections, it sounds like [Blake] is better off rolling his own solution. Inside the floating part is an ESP32, a DS18B temperature sensor, and a 18650 cell. Most of the body is PVC, except for the 3D-printed torus that holds some foam for buoyancy. A handful of BBs in the bottom keep the thing pointed upright. For now, it shows the water temperature, but [Blake]’s ultimate goal is to show the air temperature as well.

Maybe it’s still too cold to swim, but the sun shines brightly most days. Why not harness its energy to heat up the water?

This Bunny Reminds Toddlers That It’s Night Time

May 1, 2021 by Jenny List 14 Comments

It’s easy to spot recent parents, they are the people who look as though they haven’t slept in months. Sometimes the little bundle of joy responsible isn’t even a babe in arms but a toddler; old enough to wake up and find their parents for some solace but not old enough to understand that not everyone is up for being woken at 3 am. [Eyal] approached this problem in some style, by modifying a rabbit night light to indicate the time by changing colour, reminding the youngster when it’s a bit early to be rousing the grown-ups.

The bunny in question is a plastic moulding, sold with a white LED providing illumination, This was removed, and replaced with a rather nice custom PCB sporting a ring of addressable LEDs surrounding a Wemos ESP8266 board. In the darkest hours of the night, it is lit as a soft red to indicate sleep time. When an appropriate wake-up point is reached it bursts into a vibrant light show of many colours. Thus the recalcitrant early-riser can be taught to give Mum & Dad a little rest through the medium of light and colour.

This isn’t the first kids night light we’ve seen, indeed some of them have been rather elegant.