Using an SMD capacitor as a clip for flash media on a circuit board.

SMD Capacitor Doubles As Cheap SD Card Latch

July 4, 2025 by John Elliot V 41 Comments

Here’s a clever hack. Simple, elegant, and eminently cost-effective: using an SMD capacitor to hold your flash media in place!

This is a hack that can pretty much be summed up with just the image at the top of the page — a carefully placed SMD capacitor soldered to a routed tab makes for an extremely cost effective locking mechanism for the nearby SD card slot. There’s just enough flexibility to easily move the capacitor when its time to insert or eject your media.

It’s worth noting that the capacitor in this example doesn’t even appear to be electrically connected to anything. But there’s also no reason you couldn’t position one of the capacitors in your existing bill of materials (BOM). This form of mechanical support will be much cheaper than special purpose clips or mounts. Not a big deal for low-volume projects, but if you’re going high-volume this is definitely something to keep in mind.

If you’re just getting started with SMD capacitors then one of the first things to learn is how to solder them. Also, if you’re hoping to salvage them then try to look for newer equipment which is more likely to have SMD components than through-hole. If you’re planning to use your capacitors for… “capacitance” (how quaint), you can start by learning the basics. And if you want to know everything you can learn about the history of capacitors, too.

Thanks to [JohnU] for writing in to let us know about this one. Have your own natty hacks? Let us know on the tipsline!

Behind RadioShack’s Cheapest Computer

June 30, 2025 by Bryan Cockfield 30 Comments

In the 1980s, there was a truly staggering amount of choice for a consumer looking to purchase a home computer. On the high end, something like an Apple Lisa, a business-class IBM PC, or a workstation from Sun Microsystems could easily range from $6,000 to $20,000 (not adjusted for inflation). For the time, these mind-blowing prices might have been worth the cost, but for those not willing to mortgage their homes for their computing needs, there were also some entry-level options. One of these was the Sinclair ZX-80, which was priced at an astounding $100, which caused RadioShack to have a bit of a panic and release this version of the TRS-80 computer to compete with it.

As [David] explains in his deep dive into this somewhat obscure machine, the TRS-80 MC-10 was a commercial failure, although not for want of features. It had a color display, a chicklet keyboard, and 4K of RAM, which were all things that the ZX-80 lacked.

Unfortunately, it also had a number of drawbacks compared to some of its other contemporaries that made consumers turn away. Other offerings by Commodore, Atari, Texas Instruments, and even RadioShack themselves were only marginally more expensive and had many more features, including larger memory and better storage and peripheral options, so most people chose these options instead.

The TRS-80 MC-10 is largely a relic of the saturated 80s home computer market. It’s drop in price to below $50, and the price competition between other PC manufacturers at the time was part of the reason for the video game crash of the 1980s, and even led to Steve Jobs getting fired from Apple. There’s not a huge retro scene for these machines either, although there is at least one game developer you can see in the video below from [Spriteworx]. If you want to experiment with some of the standard TRS-80 software, there are emulators that have everything you need.

Thanks to [Stephen] for the tip!

Audio Localization Gear Built On The Cheap

June 27, 2025 by Lewin Day 11 Comments

Most humans with two ears have a pretty good sense of directional hearing. However, you can build equipment to localize audio sources, too. That’s precisely what [Sam], [Ezra], and [Ari] did for their final project for the ECE4760 class at Cornell this past Spring. It’s an audio localizer!

The project is a real-time audio localizer built on a Raspberry Pi Pico. The Pico is hooked up to three MEMS microphones which are continuously sampled at a rate of 50 kHz thanks to the Pico’s nifty DMA features. Data from each microphone is streamed into a rolling buffer, with peaks triggering the software on the Pico to run correlations between channels to determine the time differences between the signal hitting each microphone. Based on this, it’s possible to estimate the location of the sound source relative to the three microphones.

The team goes into great deal on the project’s development, and does a grand job of explaining the mathematics and digital signal processing involved in this feat. Particularly nice is the heatmap output from the device which gives a clear visual indication of how the sound is being localized with the three microphones.

We’ve seen similar work before, too, like this project built to track down fireworks launches. Video after the break.

Continue reading “Audio Localization Gear Built On The Cheap” →

A Cheap Smart Plug To Block Distractions

June 27, 2025 by Jenny List 19 Comments

We have all suffered from this; the boss wants you to compile a report on the number of paper clips and you’re crawling up the wall with boredom, so naturally your mind strays to other things. You check social media, or maybe the news, and before you know it a while has been wasted. [Neil Chen] came up with a solution, to configure a cheap smart plug with a script to block his diversions of choice.

The idea is simple enough, the plug is in an outlet that requires getting up and walking a distance to access, so to flip that switch you’ve really got to want to do it. Behind it lives a Python script that can be found in a Git Hub repository, and that’s it! We like it for its simplicity and ingenuity, though we’d implore any of you to avoid using it to block Hackaday. Some sites are simply too important to avoid!

Of course, if distraction at work is your problem, perhaps you should simply run something without it.

Passive Saturation Box Is A Cheap Way To Distort Your Sound

June 4, 2025 by Lewin Day 10 Comments

Distortion pedals and overdrive effects usually have a bunch of lovely transistors or op-amps inside and lots of knobs and dials to tweak the sound to your personal taste. However, it’s possible to get some crunchiness in your audio signal without all that fuss, as [Simon Hutchinson] demonstrates with his $2 “analog saturation box”.

The effect is achieved quite simply by installing a pair of diodes in opposite orientations, connected from the signal path to ground. This configuration is also known as wiring diodes in “anti-parallel.” When the signal increases in amplitude beyond the diode’s forward voltage, the diode conducts and the signal’s peak is clipped off, which creates a distorted tone. Since there are two diodes, one in each orientation, both the tops and bottoms of the AC audio signal are clipped in this manner.

The amount of clipping is highly dependent on the diodes chosen and the strength of the signal you’re working with. Silicon diodes clip around 0.7 V, while germanium diodes clip at about 0.3 V, but that doesn’t give you much flexibility. You can work with this to some degree, though. You can up the minimum clipping level by stacking more diodes in series in each direction, or you can put in a potentiometer to vary your signal’s level before it hits the diodes. Really, though, this hard voltage limit is why more commonly, we use active distortion or overdrive effects that have more options for gain and level and such.

[Simon Hutchinson] does an able job of explaining the effect and demonstrates its use with some simple beats. As a passive device, it’s pretty one note—there’s no EQs to mess with the frequency response, and no ability to change anything else about the sound, either. Still, it’s interesting to hear the effect it does have on a signal, and you might just find this is all the distortion you need. If you’d rather go into full-fat distortion though, we’ve covered that too.

Continue reading “Passive Saturation Box Is A Cheap Way To Distort Your Sound” →

The Cost Of A Cheap UPS Is 10 Hours And A Replacement PCB

May 29, 2025 by Maya Posch 26 Comments

Recently [Florin] was in the market for a basic uninterruptible power supply (UPS) to provide some peace of mind for the smart home equipment he had stashed around. Unfortunately, the cheap Serioux LD600LI unit he picked up left a bit to be desired, and required a bit of retrofitting.

To be fair, the issues that [Florin] ended up dealing with were less about the UPS’ capability to deal with these power issues, and more with the USB interface on the UPS. Initially the UPS seemed to communicate happily with HomeAssistant (HA) via Network UPS Tools over a generic USB protocol, after figuring out what device profile matched this re-branded generic UPS. That’s when HA began to constantly lose the connection with the UPS, risking its integration in the smart home setup.

The old and new USB-serial boards side by side. (Credit: VoltLog, YouTube)

After tearing down the UPS to see what was going on, [Florin] found that it used a fairly generic USB-serial adapter featuring the common Cypress CY7C63310 family of low-speed USB controller. Apparently the firmware on this controller was simply not up to the task or poorly implemented, so a replacement was needed.

The process and implementation is covered in detail in the video. It’s quite straightforward, taking the 9600 baud serial link from the UPS’ main board and using a Silabs CP2102N USB-to-UART controller to create a virtual serial port on the USB side. These conversion boards have to be fully isolated, of course, which is where the HopeRF CMT8120 dual-channel digital isolator comes into play.

After assembly it almost fully worked, except that a Sonoff Zigbee controller in the smart home setup used the same Silabs controller, with thus the same USB PID/VID combo. Fortunately in Silabs AN721 it’s described how you can use an alternate PID (0xEA63) which fixed this issue until the next device with a CP2102N is installed

As it turns out, the cost of a $40 UPS is actually 10 hours of work and $61 in parts, although one cannot put a value on all the lessons learned here.

Continue reading “The Cost Of A Cheap UPS Is 10 Hours And A Replacement PCB” →

Automated Blinds Opener On The Cheap

May 27, 2025 by Matt Varian 7 Comments

We love seeing hacks that involve salvaging parts from what you have on hand to make a new project work, and this project is a great example of that. [Simon], in a quick weekend build, created an automated blinds opener using parts he had available.

The project began with the desire to have his blinds open slowly and silently, gradually letting in more light. To accomplish this, a few key components were needed, including a motor with a gearbox to provide the torque required to actuate the blinds and a magnetic encoder to track their progress. To isolate vibrations and keep the system silent, the motor is mounted using a silicone motor mount that he salvaged from a broken water flosser.

The printed holder for the magnetic encoder is a nice touch.

To mount the motor to the wall near the window, he used some 3D printed parts. A clever combination of surgical silicone tubing and silicone tape attaches the motor to the window blind shaft while limiting vibration transfer, keeping things quiet. [Simon] advises against using magnetic encoders as he did, noting that while he had them on hand and made them work, the magnetic shaft’s misalignment with the encoders makes it a less-than-ideal approach. Nevertheless, he got it working.

Automating blinds is a fairly common project around these parts, made all the more accessible with clever 3D printed mechanisms. We’ve even seen variations that can be used in rentals, dorms, and other places were permanent modifications need to be avoided.