Comparing 12 VDC Air Fryers With Regular 240 VAC Ones

April 16, 2026 by Maya Posch 11 Comments

That boiling water is a contentious topic of discussion is clear, but what about hot air? When you take a 12 VDC, 280 Watt-rated air fryer and pit it against a bog-standard 240 VAC, 1400 Watt unit, which one would you want to use when you’re doing some camping or other exciting off-the-grid opportunities? Unlike with boiling water the physics aren’t as clear-cut here, so [Cahn] did some testing to figure out exactly what the efficiency numbers look like

Since air fryers rely on the transfer of thermal energy from the resistive heating element into the food, any thermal energy that’s not immediately transferred is effectively wasted. This, combined with the relatively low power rating and thus much higher time demand of the low-voltage air fryer is enough to set one’s expectations pretty low.

As scientific test samples chicken nuggets were used with the test, following a preheating period for the 12 VDC unit. Both units managed to hit a safe temperature inside the nuggets after 20 minutes, thus successfully staving off food poisoning, but the browning with the 240 VAC air fryer was much better.

As for the efficiency, the 12 VDC unit required 150 Wh for 20 minutes plus the 10 minutes of preheating, with 45 minutes total at 225 Watt to get proper browning. Meanwhile the 240 VAC unit burned through 250 Wh in 20 minutes, with no pre-heating, though only 230 Wh with no inverter losses included. As a final test, the 12 VDC unit was run at 400 Watt using 14.6 VDC input, which did indeed get it up to temperature much faster.

Thus both are equivalent, just with the caveat that the low-voltage unit will take considerably more time to get the same result. This mirrors the results with boiling water, where most options mostly vary in how much time they require to get water up to a boiling temperature.

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Comparing The Power Usage Of 12 VDC And 240 VAC Kettles

March 26, 2026 by Maya Posch 40 Comments

If you have a 12 VDC power system, like the battery of a PV solar system or car, would it be more efficient to boil water for that cup of tea with that 12V straight from the battery, or use a 240 VAC mains kettle via a ~90% efficient inverter instead? That’s the question that [Cahn] decided to answer experimentally, using a bulky 3 kW inverter and a collection of electric kettles.

Although the used amount of 500 mL of water is boiled much faster in the 2,200 Watt mains kettle than in the 150 and 350 Watt low-voltage kettles, this obvious difference is somewhat irrelevant if you’re only concerned with efficiency. To measure the power used a Victron smart shunt was used with each run, keeping in mind that a perfect efficiency for heating 500 mL from room temperature to boiling is around 43-44 Wh.

With two runs per kettle, the 240 VAC kettle used 65-70 Wh. The first ‘150 Watt’ kettle pulled nearly 200 Watt to boil the water after about 20 minutes, using 62-64 Wh. The second ‘150 Watt’ kettle pulled around 180 Watt, took 23-25 minutes and used 68-74 Wh. Finally, the ‘350 Watt’ kettle drew over 420 Watt and used 50-56 Wh in just over 8 minutes.

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Rewinding A Car Alternator For 240 Volt

February 3, 2026 by Maya Posch 22 Comments

Two phases installed on the stator. (Credit: FarmCraft101, YouTube)

As part of his quest to find the best affordable generator for his DIY hydroelectric power system, [FarmCraft101] is trying out a range of off-the-shelf and DIY solutions, with in his most recent video trying his hands at the very relaxing activity of rewiring the stator of an alternator.

Normally car alternators output 12VDC after internal rectification, but due to the hundreds of meters from the turbine to the shed, he’d like a higher voltage to curb transmission losses. The easiest way to get a higher voltage out of a car alternator is to change up the wiring on the stator, which is definitely one of those highly educational tasks.

Disassembling an alternator is easy enough, but removing the copper windings from the stator is quite an ordeal, as they were not designed to ever move even a fraction of a millimeter after assembly.

With that arduous task finished, the rewinding was done using 22 AWG copper enamel wire, compared to the original 16 AWG wire, and increasing the loops per coil from 8 to 30. This rewinding isn’t too complicated if you know what you’re doing, with each coil on each of the three windings placed in an alternating fashion, matching the alternating South/North poles on the rotor.

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Restoring A 1924 Frigidaire B-9 Refrigerator Back To Working Condition

January 26, 2026 by Maya Posch 14 Comments

Before the refrigerator became a normal part of any kitchen, those with enough money to throw around could get an icebox, which used melting ice to cool food and drinks in a second compartment. As refrigerators became available for sale in the 1920s, this created somewhat awkward transition models, like the 1924 Frigidaire B-9 that [David Allen] recently got offered for a restoration. This was part of the restoration of a 1926 house, which foresaw putting this venerable unit back into operation.

As [David] explains, this refrigerator was still in use until about 1970 when it broke down, and repairs proved tricky. Clearly, the fault wasn’t that severe as [David] got it working again after a number of small repairs and a lot of maintenance. The running unit with its basic elements can be seen purring away in the completion video, with the journey to get there covered in a video series starting with the first episode.

What’s fascinating is that during this aforementioned transition period, the vapor compression electric cooling system was an optional extra, meaning that the basic layout is still that of an icebox. Correspondingly, instead of ice in the ice compartment, you find the low-side float evaporator, with the basement section containing the condensing unit, motor, and compressor. The temperature sensor is also a miracle of simplicity, using bellows that respond to the temperature and thus volume of the evaporator coolant, which trigger a switch that turns on the compressor.

Despite a hundred years having passed since this refrigerator was constructed, at its core it works exactly the same as the unit we have in our kitchens today, albeit with higher efficiency, more electronics, and with the sulfur dioxide refrigerant replaced with something less toxic to us humans.

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Drive 1024×600 Pixels Via I2C With An ATtiny85

January 8, 2026 by Tyler August 10 Comments

If you need to drive a big screen for a project, it’s fair to say your first thought isn’t going to be to use the ATtiny85. With just 512 bytes of RAM and 8 kilobytes of flash memory, the 8-bit micro seems a little cramped to drive, say, a 10″ screen. Yet that’s exactly what [ToSStudio] is doing with TinyTFT_LT7683: 1024 x 600 pixels of TFT goodness, over I2C no less.

With the right TFT controller, this little micro-controller can do magic.

The name kind of gives away the secret: it won’t work on just any TFT display. It’s using properties of the LT7683 display driver, though if you don’t have one of those, the RA8875 is also compatible. Those drivers can take more than just a pixel stream– a good thing, since you’d be hard pressed to get that many pixels streaming from an ATtiny. These are character/graphic display drivers, which means you can get them to draw both characters and graphics on the screen if you speak the lingo.

It’s still not blazing fast; the documentation suggests “static or moderately dynamic UIs” as the suggested use case, and a clock is of the pre-programmed examples. From that, we can surmise that you can get 1 FPS or better with this code. You’re limited both by the simple micro-controller and the bandwidth of the I2C bus, but within those limits this seems like a very powerful technique.

This isn’t the first ATtiny graphics library to blow our minds, but if you really want an impressive graphics demo from the little micro that could, you really need to race the beam.

Thanks to [Thomas Scherer] for the tip!

Electronic Wizard in his lab wearing his wizards hat

How To Use The AT24C32 EEPROM For 4KB External Memory For Microcontrollers

September 8, 2025 by John Elliot V 27 Comments

Over on YouTube [Electronic Wizard] explains how to use the AT24C32 EEPROM for external memory for microcontrollers.

He begins by explaining that you don’t want to try modifying your microcontroller flash memory for storing settings, you want to use a separate EEPROM for that. Sometimes your microcontroller will have EEPROM memory attached, but you might still find yourself needing to attach more. The AT24C32 EEPROM is a 4KB non-volatile memory chip. It’s available in various 8-pin packages and two voltage levels, either 2.7 to 5.5 volts or 1.8 to 5.5 volts, and it’s programmed using the I2C protocol.

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Hackaday Links: August 24, 2025

August 24, 2025 by Dan Maloney 9 Comments

“Emergency Law Enforcement Officer Hologram program activated. Please state the nature of your criminal or civil emergency.” Taking a cue from Star Trek: Voyager, the Seoul Metropolitan Police Agency is testing a holographic police officer, with surprisingly — dare we say, suspiciously? — positive results. The virtual officer makes an appearance every two minutes in the evening hours in a public park, presumably one with a history of criminal activity. The projection is accompanied by a stern warning that the area is being monitored with cameras, and that should anything untoward transpire, meat-based officers, presumably wearing something other than the dapper but impractical full-dress uniform the hologram sports, will be dispatched to deal with the issue.

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