Why bananas, you ask? Because [Marius Heier] uses them to demonstrate what we all intuitively know — that rubbing something over and over again tends to wear it away — but engineers seem to have forgotten. Wear such as this, with resistance material rather than fruits, is what causes the dreaded drift, a problem that the world collectively spends $20 billion a year dealing with, according to [Marius].
While numbers like that seem to be firmly in class-action lawsuit territory, sometimes it’s best to take matters into your own hands and not wait for the courts. The fix [Marius] shows here is to yank the potentiometers off a PS4 joystick and replace them with contactless Hall effect sensors. The end of the shaft for each axis gets a diametral neodymium magnet attached to it, while a 3D printed bracket holds a tiny custom PCB in close proximity. The PCB has an AS5600 Hall sensor, which translates the shaft angle to an analog voltage output. After programming the chip over its I2C bus, the sensor outputs a voltage proportional to the angle of each shaft, just like the original pots, but without all the wear and tear.
While [Marius] is selling these as drop-in replacements for PS4 controllers, he plans to release all the design files so you can build one yourself. He also has his sights set on replacements for PS5 and Xbox controllers, so watch for those. This isn’t his first foray into joystick hacking, having shared his 3D Hall effect and haptic feedback joysticks with us previously.
Knobs and switches can make or break the aesthetic and tactile appeal of a project. Fine hi-fi hardware goes hard on these details, while cheap knock-off guitar pedals often go the other way. If you’re looking for a unique, cheap, and compelling solution for potentiometer knobs, you might like to consider using converted brass hardware for the job.
The idea comes from [Kevin Jordan], who realized that some simple 3D printed parts would enable him to repurpose brass hardware for use with common split-shaft potentiometers. He grabbed a bunch of brass flare caps intended for use with gas piping, and got to work.
The result is the simple 3D printed cap converter. It has a threaded outer portion, which screws neatly inside a brass flare cap. Inside, it features a hole to mate to the potentiometer shaft. While this could be done with a spline, it also works with a simple hole since the plastic is soft enough to simply push the potentiometer shaft into.
The flare caps look great when pressed into service as knobs. [Kevin] uses them on a tennis racket guitar he built, and the brass knobs beautifully set off against the natural wood finishes of the build. If you’re looking for some unique adornments for your own projects, you might like to experiment with this concept yourself! Alternatively, you can try making your own knobs from scratch.
Sometimes the simplest hacks can be the most useful or ingenious, and such is the case with [Keri Szafir]’s method of ensuring that potentiometers used in audio devices are matched. If you consider a typical stereo amplifier for a moment, you’ll see two amplifiers in one box with a single volume control. Two channels, one knob? Volume knobs are ganged stereo potentiometers.
All potentiometers are not created equal, and particularly in the cheaper devices they may not have a consistently matched resistance across both pots and across their travel. This messes up the stereo balance, so naturally it’s worth selecting a part with good matching. [Keri] selects them not with his golden ears, but by wiring both pots together as a Wheatstone bridge. A meter between the two wipers would detect any current due to a mismatch.
As anyone who has ever owned a piece of older equipment that has a potentiometer in it can attest to, these mechanical components do need their regular cleaning ritual. Whether it’s volume knobs on a receiver or faders on a mixer, over time they get crackly, scratchy and generally imprecise due to the oxidation and gunk that tends to gather inside them.
In this blast from the past, [Keith Murray] shows a few ways in which fader-style potentiometers can be cleaned, and how well each cleaning method works by testing the smoothness of the transition over time with an oscilloscope. It’s enlightening to see just how terrible the performance of a grimed-up fader is, and how little a blast of compressed air helped. Contact cleaner works much better, but it’s essential to get all of the loosened bits of gunk out of the fader regardless.
In the end, a soak in isopropyl alcohol (IPA), as well as a full disassembly followed by manual cleaning were the only ones to get the fader performance back to that of a new one. Using contact cleaner followed by blasting the fader out with compressed air seems to be an acceptable trade-off to avoid disassembly, however.
What is your preferred way to clean potentiometers to keep that vintage (audio) gear in peak condition? Let us know in the comments below.
Many a gamer has found that after a few years of racing around the track or sending demons back from whence they came, the analog sticks on their trusty controller can start to drift around. Many times it’s a fairly minor problem, something you might only notice if you were really keeping an eye out for it, but it can definitely be annoying. Those handy with a soldering iron might just swap out the sticks for replacements once it gets to that point, but [Taylor Burley] wondered how difficult it would be to recalibrate the ailing sticks instead.
To be clear, [Taylor] acknowledges this approach is overkill. It would be cheaper and easier to just replace the drifting stick with a new one. Even if you take into account that new sticks might not be as high quality as the originals and could give up the ghost faster, this probably isn’t worth the effort. But that doesn’t mean it’s not an interesting hack.
In the video after the break, [Taylor] starts by explaining how stick drift occurs in the first place. Each axis of the stick is physically connected to the wiper of a potentiometer, so for 10K pots, the stick’s center point should correspond to a resistance of 5K. He then goes on to measure the resistance in a bad joystick, and sure enough, the center resistance is off by several hundred Ohms.
To fix this, he comes up with a simple circuit that places additional potentiometers between the wipers. With two joysticks and two adjustment pots per axis, that makes eight little adjustment wheels that need to be fiddled with to get the center points calibrated properly. In this case [Taylor] uses a controller diagnostic tool for the Xbox to quantify the impact his adjustments are making so he can dial it in perfectly, but the idea is the same no matter who’s logo is on the box.
Tape may not sound that great compared to vinyl, but cassette players can be tons of fun when it comes to making your own music. See for instance the Mellotron, or this relatively easy DIY alternative, [Rich Bernett]’s Cassettone cassette player synth.
The Cassettone works by substituting the trim pot that controls the speed of the tape player’s motor with a handful of potentiometers. These are each activated with momentary buttons located underneath the wooden keys. In the video after the break, [Rich] gives a complete and detailed guide to building your own. There’s also a polished Google doc that includes a schematic and the pattern pieces for making the cabinet.
Speaking of which, isn’t the case design nice? It’s built out of craft plywood but aged with varnish and Mod-Podged bits and bobs from vintage electronics magazines. This really looks like a fun little instrument to play.
Would you rather control your tape synth with a MIDI keyboard? Just add Arduino.
What’s the use of waiting around for something to break in order to hack into something else? As long as it’s just sitting around not being used, who cares? [OmniSaiRen] had a Behringer MIDI controller just taking up space. Instead of selling it, they decided to build it into something they would definitely use — a multi-volume controller with mute keys and other useful macros.
After gutting the case, [OmniSaiRen] gave it a couple coats of glossy white paint that looks really nice with the black keycaps and knobs. The plan was to use the original encoders, but [OmniSaiRen] replaced them with potentiometers when they couldn’t get the encoders working with the Arduino Nano. We are sad to report that Cherry Blues only made it to the build because they have all black housings and were also lying around taking up space, but maybe [OmniSaiRen] will grow to love them.