The Mohmmeter: A Steampunk Multimeter

April 24, 2025 by Matt Varian 12 Comments

[Agatha] sent us this stunning multimeter she built as a gift for her mom. Dubbed the Mohmmeter — a playful nod to its ohmmeter function and her mom — this project combines technical ingenuity with heartfelt craftsmanship.

At its core, a Raspberry Pi Pico microcontroller reads the selector knob, controls relays, and lights up LEDs on the front panel to show the meter’s active range. The Mohmmeter offers two main measurement modes, each with two sub-ranges for greater precision across a wide spectrum.

She also included circuitry protections against reverse polarity and over-voltage, ensuring durability. There was also a great deal of effort put into ensuring it was accurate, as the device was put though its paces using a calibrated meter as reference to ensure the final product was as useful as it was beautiful.

The enclosure is a work of art, crafted from colorful wooden panels meticulously jointed together. Stamped brass plates label the meter’s ranges and functions, adding a steampunk flair. This thoughtful design reflects her dedication to creating something truly special.

Want to build a meter for mom, but she’s more of the goth type? The blacked-out Hydameter might be more here style.

Virtual Nodes, Real Waves: A Colpitts Walkthrough

April 22, 2025 by Heidi Ulrich 14 Comments

If you’ve ever fumbled through circuit simulation and ended up with a flatline instead of a sine wave, this video from [saisri] might just be the fix. In this walkthrough she demonstrates simulating a Colpitts oscillator using NI Multisim 14.3 – a deceptively simple analog circuit known for generating stable sine waves. Her video not only shows how to place and wire components, but it demonstrates why precision matters, even in virtual space.

You’ll notice the emphasis on wiring accuracy at multi-node junctions, something many tutorials skim over. [saisri] points out that a single misconnected node in Multisim can cause the circuit to output zilch. She guides viewers step-by-step, starting with component selection via the “Place > Components” dialog, through to running the simulation and interpreting the sine wave output on Channel A. The manual included at the end of the video is a neat bonus, bundling theory, waveform visuals, and circuit diagrams into one handy PDF.

If you’re into precision hacking, retro analogue joy, or just love watching a sine wave bloom onscreen, this is worth your time. You can watch the original video here.

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Game Boy PCB Assembled With Low-Cost Tools

April 22, 2025 by Bryan Cockfield 13 Comments

As computers have gotten smaller and less expensive over the years, so have their components. While many of us got our start in the age of through-hole PCBs, this size reduction has led to more and more projects that need the use of surface-mount components and their unique set of tools. These tools tend to be more elaborate than what would be needed for through-hole construction but [Tobi] has a new project that goes into some details about how to build surface-mount projects without breaking the bank.

The project here is interesting in its own right, too: a display module upgrade for the classic Game Boy based on an RP2350B microprocessor. To get all of the components onto a PCB that actually fits into the original case, though, surface-mount is required. For that [Tobi] is using a small USB-powered hotplate to reflow the solder, a Pinecil, and a healthy amount of flux. The hotplate is good enough for a small PCB like this, and any solder bridges can be quickly cleaned up with some extra flux and a quick pass with a soldering iron.

The build goes into a lot of detail about how a process like this works, so if you’ve been hesitant to start working with surface mount components this might be a good introduction. Not only that, but we also appreciate the restoration of the retro video game handheld complete with some new features that doesn’t disturb the original look of the console. One of the other benefits of using the RP2350 for this build is that it’s a lot simpler than using an FPGA, but there are perks to taking the more complicated route as well.

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Low Cost Oscilloscope Gets Low Cost Upgrades

April 20, 2025 by Bryan Cockfield 51 Comments

Entry-level oscilloscopes are a great way to get some low-cost instrumentation on a test bench, whether it’s for a garage lab or a schoolroom. But the cheapest ones are often cheap for a reason, and even though they work well for the price they won’t stand up to more advanced equipment. But missing features don’t have to stay missing forever, as it’s possible to augment them to get some of these features. [Tommy’s] project shows you one way to make a silk purse from a sow’s ear, at least as it relates to oscilloscopes.

Most of the problem with these lower-cost tools is their low precision due to fewer bits of analog-digital conversion. They also tend to be quite noisy, further lowering the quality of the oscilloscope. [Tommy] is focusing his efforts on the DSO138-mini, an oscilloscope with a bandwidth of 100 kHz and an effective resolution of 10 bits. The first step is to add an anti-aliasing filter to the input, which is essentially a low-pass filter that removes high frequency components of the signal, which could cause a problem due to the lower resolution of the device. After that, digital post-processing is done on the output, which removes noise caused by the system’s power supply, among other things, and essentially acts as a second low-pass filter.

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Frankenflair 58: Manual Roots, Advanced Brew

April 19, 2025 by Matt Varian 2 Comments

The user interface of things we deal with often makes or breaks our enjoyment of using a device. [Janne] thinks so, he has an espresso machine he enjoys but the default controls were not what he was looking for and so in true hacker fashion he took what was and made it his own.

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A Blacksmith Shows Us How To Choose An Anvil

April 17, 2025 by Jenny List 16 Comments

No doubt many readers have at times wished to try their hand at blacksmithing, but it’s fair to say that acquiring an anvil represents quite the hurdle. For anyone not knowing where to turn there’s a video from [Black Bear Forge], in which he takes us through a range of budget options.

He starts with a sledgehammer, the simplest anvil of all, which we would agree makes a very accessible means to do simple forge work. He shows us a rail anvil and a couple of broken old anvils, before spending some time on a cheap Vevor anvil and going on to some much nicer more professional ones. It’s probably the Vevor which is the most interesting of the ones on show though, not because it is particularly good but because it’s a chance to see up close one of these very cheap anvils.

Are they worth taking the chance? The one he’s got has plenty of rough parts and casting flaws, an oddly-sited pritchel and a hardy hole that’s too small. These anvils are sometimes referred to as “Anvil shaped objects”, and while this one could make a reasonable starter it’s not difficult to see why it might not be the best purchase. It’s a subject we have touched on before in our blacksmithing series, so we’re particularly interested to see his take on it.

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A broken bolt is removed by welding on a hut and then using a wrench to unscrew.

Using A MIG Welder, Acetylene Torch, And Air Hammer To Remove A Broken Bolt

April 16, 2025 by John Elliot V 13 Comments

If your shop comes complete with a MIG welder, an acetylene torch, and an air hammer, then you have more options than most when it comes to removing broken bolts.

In this short video [Jim’s Automotive Machine Shop, Inc] takes us through the process of removing a broken manifold bolt: use a MIG welder to attach a washer, then attach a suitably sized nut and weld that onto the washer, heat the assembly with the acetylene torch, loosen up any corrosion on the threads by tapping with a hammer, then simply unscrew with your wrench! Everything is easy when you know how!

Of course if your shop doesn’t come complete with a MIG welder and acetylene torch you will have to get by with the old Easy Out screw extractor like the rest of us. And if you are faced with a nasty bolt situation keep in mind that lubrication can help.

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