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Isolated AC/DC Power Supply and Testing Station for 230 V Devices

✇Hackaday
By: Maya Posch

When you’re testing or debugging some mains-powered gear, plugging it directly into the outlet can often be an exciting proposition. If such excitement is not really your thing, you can opt for an isolation transformer and other types of safeties. In the case of [Michał Słomkowski], he opted to take a few steps further by modding a vintage East-German isolating variac with a broken amp meter into an isolated AC/DC power supply and testing station.

The core is formed by the isolated variable transformer, to which a configurable DC output section, a current limiter and digital voltage and current read-outs were added. This enables a variable AC output of 0 – 330 VAC and 0 – 450 VDC on their respective terminals, with the incandescent light bulb providing an optional current limiter.

In its final configuration [Michał] has been using the device for the past four years now for a range of tasks, including the simulating of various undesirable mains power conditions, varying the speed of an old Soviet-era drill, powering vacuum tube devices, capacitor reforming and of course running 100-120 VAC devices from e.g. the US.

As far as feature set goes, we have to admit that it is an impressive device, indeed. Although some parts of it are clearly playing it fast and loose with best practices, with [Michał] admitting to not being an electrician, it was clearly engineered well enough to survive a few years of use, something which cannot be said for even professional laboratory equipment these days.

Driving A DAC Real Fast With A Microcontroller

✇Hackaday
By: Lewin Day

Normally, if you want to blast out samples to a DAC in a hurry, you’d rely on an FPGA, what with their penchant for doing things very quicky and in parallel. However, [Anabit] figured out a way to do the same thing with a microcontroller, thanks to the magic of the Raspberry Pi Pico 2.

The design in question is referred to as the PiWave 150 MS/s Bipolar DAC, and as the name suggests, it’s capable of delivering a full 150 million samples per second with 10, 12, or 14 bits of resolution. Achieving that with a microcontroller would normally be pretty difficult. In regular linear operation, it’s hard to clock bits out to GPIO pins at that sort of speed. However, the Raspberry Pi Pico 2 serves as a special case in this regard, thanks to its Programmable I/O (PIO) subsystem. It’s a state machine, able to be programmed to handle certain tasks entirely independently from the microcontroller’s main core itself, and can do simple parallel tasks very quickly. Since it can grab data from RAM and truck it out to a bank of GPIO pins in a single clock cycle, it’s perfect for trucking out data to a DAC in parallel at great speed. The Pi Pico 2’s clock rate tops out at 150 MHz, which delivers the impressive 150 MS/s sample rate.

The explainer video is a great primer on how this commodity microcontroller is set up to perform this feat in detail. If you’re trying for accuracy over speed, we’ve explored solutions for that as well. Video after the break.

A Guide To Using Triacs For Switching AC

✇Hackaday
By: Bryan Cockfield

For switching high-powered loads from a microcontroller, or for switching AC loads in general, most of us will reach into the parts bin and pull out a generic relay of some sort. Relays are fundamental, proven technologies to safely switch all kinds of loads. They do have their downsides, though, so if you need silent operation, precise timing, or the ability to operate orders of magnitude more times you might want to look at a triac instead. These solid state devices can switch AC loads unlike other transistor-based devices and [Ray] at OpenSprinkler is here to give us an overview on how to use them.

The key to switching an AC load is bi-directional conductivity. A normal transistor or diode can only conduct in one direction, so if you try to switch an AC load with one of these you’ll end up with what essentially amounts to a bad rectifier. Triacs do have a “gate” analogous to the base of a bipolar junction transistor, but the gate will trigger the triac when current flows in either direction as well. The amount of current needed to trigger the triac does depend on the state of the switched waveform, so it can be more complex to configure than a relay or transistor in some situations.

After going through some of the theory around these devices, [Ray] demonstrates how to use them with an irrigation system, which are almost always operating on a 24VAC system thanks to various historical quirks. This involves providing the triacs with a low voltage source to provide gate current as well as a few other steps. But with that out of the way, switching AC loads with triacs can become second nature. If you prefer a DC setup for your sprinklers, though, [vinthewrench] has demonstrated how to convert these sprinkler systems instead.

The eMac: Using Apple’s Forgotten Educational Mac in 2026

✇Hackaday
By: Maya Posch
Beauty truly is in the eye of the beholder. (Credit: MattKC, YouTube)
Beauty truly is in the eye of the beholder. (Credit: MattKC, YouTube)

What’s it like to use a 2002-era Apple eMac all-in-one in 2025? That’s what [MattKC] asked himself after obtaining one of these systems from a seller who ominously mentioned that it had been ‘left outside for years’.

The Apple iMac is a bit of a cult symbol, whether you’re talking about the iconic fruity iMac G3 or the desk lamp-like iMac G4, but few reminisce or actively collect the Apple eMac. Manufactured from 2002 to 2006, it featured the PowerPC 7450 (G4e) CPU with clock speeds ranging from 700 MHz to 1.42 GHz, as well as a 17″ CRT. In terms of design it was basically a bland iMac G3 that was firmly targeting the education markets to try and regain market share after Windows PCs had begun to eat its lunch there.

As for the model that [MattKC] purchased, it was this earliest model, featuring a 700 MHz PowerPC G4 CPU in addition to 640 MB SDRAM. Despite the seller’s description it seems to be in good nick with it firing right up, and even a glance inside after beating the challenge of 2.5 mm hex screws showed it to be in relatively good condition.

Unlike the iMac G3, you can play the Mac port of Halo on it, but the Minecraft port is very much not performant. With generally multimedia and gaming working well, it does show why the eMac was released, as it’s quite capable relative to an iMac G3 which would have struggled with the educational software of the era. We definitely hope that [MattKC] restores it to its full glory instead of ripping out its innards, as the neglected status of the eMac makes it much more likely to go extinct than PowerPC-based iMacs.

Download: iOS 26.3 Beta 2 Out Now Alongside Beta 2 Of iPadOS 26.3, macOS 26.3, tvOS 26.3, watchOS 26.3, visionOS 26.3

✇Redmond Pie
By: Oliver Haslam
iOS 26

Apple has just released for download iOS 26.3 beta 2 alongside the beta 2 versions of iPadOS 26.3, macOS 26.3, tvOS 26.3, watchOS 26.3, and visionOS 26.3 for compatible devices.

The post Download: iOS 26.3 Beta 2 Out Now Alongside Beta 2 Of iPadOS 26.3, macOS 26.3, tvOS 26.3, watchOS 26.3, visionOS 26.3 first appeared on Redmond Pie.

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