Low-Cost Electret Microphone Preamplifiers

October 16, 2023 by 8 Comments

Before the invention of microelectromechanical system (MEMS) microphones, almost all microphones in cell phones and other electronics were a type of condenser microphone called the electret microphone. The fact that this type of microphone is cheap and easy enough to place into consumer electronics doesn’t mean they’re all low quality, though. Electret microphones can have a number of qualities that make them desirable for use recording speech or music, so if you have a struggling artist friend like [fvfilippetti] has who needs an inexpensive way to bring one to life, take a look at this electret microphone pre-amp.

The main goal of the project is to enhance the performance of these microphones specifically in high sound pressure level (SPL) scenarios. In these situations issues of saturation and distortion often occur. The preampl design incorporates feedback loops and an AD797 opamp to reduce distortion, increase gain, and maintain low noise levels. It also includes an output voltage limiter using diodes to protect against input overload and can adjust gain. The circuit’s topology is designed to minimize distortion, particularly in these high SPL situations.

Real-world testing of the preamp confirms its ability to handle high SPL and deliver low distortion, making it a cost-effective solution for improving the performance of electret microphones like these. If you want to go even deeper into the weeds of designing and building electret microphones and their supporting circuitry, take a look at this build which discusses some other design considerations for these types of devices.

Bone-Shaking Haunted Mirror Uses Stable Diffusion

October 16, 2023 by 2 Comments

We once thought that the best houses on Halloween were the ones that gave out full-size candy bars. While that’s still true, these days we’d rather see a cool display of some kind on the porch. Although some might consider this a trick, gaze into [Tim]’s mirror and you’ll be treated to a spooky version of yourself.

Here’s how it works: At the heart of this build is a webcam, OpenCV, and a computer that’s running the Stable Diffusion AI image generator. The image is shown on a monitor that sits behind 2-way mirrored glass.

We really like the frame that [Tim] built for this. Unable to find something both suitable and affordable, they built one out of wood molding and aged it appropriately.

We also like the ping pong ball vanity globe lights and the lighting effect itself. Not only is it spooky, it lets the viewer know that something is happening in the background. All the code and the schematic are available if you’d like to give this a go.

There are many takes on the spooky mirror out there. Here’s one that uses a terrifying 3D print.

2023 Halloween Hackfest: A Spooky Muscle-Brain Interface

October 16, 2023 by 4 Comments

What could be better than a Halloween decoration? Something more perennial, or even something that could also be found in a classroom or lab. Something like [Markus Bindhammer]’s spooky muscle-brain interface. It was inspired by a series called “Tales From the Loop” in which a character’s muscle electrical activity is measured in preparation to adjust his prosthetic hand.

Essentially, it does what you think it does: attach the sensors to your muscles, move them around, and watch the brain light up. [Markus] started with a children’s learning kit that involves molding the brain and discs out of red rubbery goop, the vertebrae out of plaster, and then assembling the whole thing.

Instead, [Markus] molded the brain and vertebrae in two-part silicone for durability, and used two-component colored epoxy for the discs.

As the inspiring series is set in the 80s (we assume the brown, dingy 80s and not the fun, neon 80s), [Markus] gave the enclosure/stand an appropriate color scheme. Inside that box there’s an Arduino Pro Micro, a Grove EMG detector, and a mini step-up converter module. And of course, under the brain, there’s a NeoPixel ring. Don’t miss the build and demo video after the break.

There are a ton of things you can do with blinkenlights for Halloween. How about a light-up candy slide, or a bucket that seems them coming?

Continue reading “2023 Halloween Hackfest: A Spooky Muscle-Brain Interface” →

Illustrated Kristina with an IBM Model M keyboard floating between her hands.

Keebin’ With Kristina: The One With The Tile-Based Macropad

October 16, 2023 by 8 Comments

Prolific Hackaday.io member [Michael Gardi] has hit upon the biggest problem with making reprogrammable macro pads — the legend situation. What do you do when the whole point is that the keys can so easily be changed?

There are a couple of options: blank keycaps and memorization, re-legendable keycaps, and little screens instead of keycaps. Surely there has to be another way, and [Michael] has discovered one: a tile-based system of descriptors.

As you can see, the labels are removable 3D-printed tiles that swap out with ease thanks to tiny magnets. But these aren’t just tidy labels. Inserting a new label automatically changes the macro! Each tile holds a “simple numeric value” which maps it to a macro when inserted and detected by a Hall effect sensor. I can’t wait to hear these tiles click in action during a demo video, which I can only hope is forthcoming.

Continue reading “Keebin’ With Kristina: The One With The Tile-Based Macropad” →

Satellite Hunting Hack Chat

October 16, 2023 by 3 Comments

Rescheduled — note new date!

Join us on Wednesday, October 18 at noon Pacific for the Satellite Hunting Hack Chat with Scott Tilley!

From the very first beeps of Sputnik, space has primarily been the domain of nations. It makes sense — for the most part, it takes the resources of a nation to get anything of appreciable size up out of the gravity well we all live in, but more importantly, space is the highest of high ground, and the high ground has always been a place of advantage to occupy. And so a lot of the hardware we’ve sent upstairs in the last 70 years has been in the national interest of this or that country.

join-hack-chatA lot of these satellites are — or were, at least — top secret stuff, with classified payloads, poorly characterized orbits, and unknown communications protocols. This can make tracking them from the ground a challenge, but one that’s worth undertaking. Scott Tilley has been hunting for satellites for years, writing about his exploits on the Riddles in the Sky blog and sometimes being featured on Hackaday. After recently putting his skills to work listening in on a solar observation satellite as its orbit takes it close to Earth again, we asked him to stop by the Hack Chat to share what he’s learned about hunting for satellites, both long-lost and intentionally hidden. Join us as we take a virtual trip into orbit to find out just what’s going on up there.

Our Hack Chats are live community events in the Hackaday.io Hack Chat group messaging. This week we’ll be sitting down on Wednesday, October 18 at 12:00 PM Pacific time. If time zones have you tied up, we have a handy time zone converter.

A 6502-based single-board computer with a ROMulator attached

Debug Your Senile Computers With The ROMulator

October 16, 2023 by 6 Comments

Some of you may have heard of the ROMulator, a device that can emulate RAM and ROM on 6502-based computers. But how does it work? How do you use it? What computers is it compatible with? [Jeff Tranter] covers that and more in his review of the ROMulator 6502.

The ROMulator is an FPGA-based board that slots between the 6502 and its socket on whatever computer it came from. It can emulate, but not intercept, accesses to RAM and ROM, which can be used to e.g. replace a ROM that you’re swapping very often or expand the RAM available to the CPU.

In his review, [Jeff] shows the ROMulator in action many computers, notably his custom 6502-based computer, a replica of an Apple 1 and two different replicas of the SUPERBOARD 2. He shows how the ROMulator can be configured, tested, used to debug the computers and even expand their RAM. Overall, [Jeff] thinks it’s a useful 6502 debugger that would have saved him lots of time in the past and we definitely agree.

Continue reading “Debug Your Senile Computers With The ROMulator” →

Why The RP1 Is The Most Important Product Raspberry Pi Have Ever Made

October 16, 2023 by 92 Comments

We’ve had about a week to digest the pending arrival of the Raspberry Pi 5, and it’s safe to say that the new board from Cambridge has produced quite some excitement with its enhanced specifications and a few new capabilities not seen in its predecessors. When it goes on general sale we expect that it will power a slew of impressive projects in these pages, and we look forward with keen anticipation to its companion Compute Module 5, and we sincerely hope eventually a Raspberry Pi 500 all-in-one. It’s the latest in a line of incrementally-upgraded single board computers from the company, but we think it conceals something of much greater importance than the improvements that marked previous generations. Where do we think the secret sauce lies in the Pi 5? In the RP1 all-in-one PCIe peripheral chip of course, the chip which provides most of the interfacing on the new board. Continue reading “Why The RP1 Is The Most Important Product Raspberry Pi Have Ever Made” →