Sometimes, it’s hard to stop picking up your phone every few minutes to check on notifications and scroll endlessly through the slop of the day. [PushpendraC2] has been working on a solution to this problem that would ideally discourage such behavior — a nifty little smartphone stand!
The concept is straightforward enough—the smartphone stand uses a simple tactile button to determine if your smartphone is sitting on the little 3D printed shelf, or not. However, the smarts inside do a bit more than that, too. An ESP32-S3 is charged with monitoring whether the smartphone is sitting in place, and starts counting “focus time” while it’s there. If the phone is picked up, the OLED display on the shelf starts ticking down a 5-second timer to encourage you to put it back. If you don’t, the focus time is reset and you lose your streak.
It’s also possible to tap a touch sensor on the device which sets a reminder timer, prompting you to put your phone back after a set period of time, between 2 to 30 minutes. A buzzer will then start going off to prompt you to put the phone down. If you want to track the devices impact, you merely need to log in to the web server hosted by the ESP32, which shows your current focus session time, along with a heatmap of your daily productivity.
It’s a simple idea, but one that uses a few neat psychological hooks to encourage compliance and behavioral change. We’ve featured similar projects in this vein before, No surprise, as phone addiction is a problem experienced by many.
Split-flap displays are a great, low-power way to display text to a wide audience. Compared to other display technologies like LCDs they only use energy when the characters change, but have fallen out of favor partially because of their greater mechanical complexity and also because LCD and LED technology has become so inexpensive. They still retain a loyal following though, and [Jason] is demonstrating his version which boasts high accuracy and can be 3D printed.
To get good results, one of the keys is getting the motor positioning just right. The motor sits in the center and spins the flaps around, so stopping at exactly the right point to display a certain character is critical. [Jason]’s system uses a 28BYJ stepper motor with a magnetic encoder to ensure that the correct flap is displayed. The flaps themselves are completely 3D printed, using a method which allows for two colors to be printed even if the printer is only designed for a single color. Once printed, the flaps are installed on the wheel which is the outer ring of a planetary gear set with the stepper motor sitting in the middle.
Each character in the display is housed in a printed enclosure, and for [Jason]’s project he only needs five characters, so to control the entire setup he’s using a Raspberry Pi Pico. For more characters he suggests that it is still possible to use a smaller microcontroller like the Pico but a multiplexer may be needed. Of course, displays like this are not limited to characters alone. Take a look at this display which has custom flaps to display the current weather conditions as well.
[Tony Goacher] has worked with a lot of cheap brushless DC motor controllers built in China. They can be very cost-effective, but sometimes limited in performance or capability, particularly when it comes to low-speed operation. Thus, he’s been working on a project to make cheap controllers more capable.
The prime problems [Tony] has faced are jerkiness, throttle deadspots, and inconsistent torque delivery at low speeds. This is especially the case when running brushless motors on heavier vehicles, where the greater inertia can compound any minor problems to the point things become undriveable. [Tony]’s solution has been to create a signal interceptor that lives in between a throttle and the cheap motor controller to change their overall behavior.
The demo vehicle for this build is TrakTrike, a sort of bicycle-half-track hybrid that [Tony] built for EMF Camp 2022. After blowing up some nicer controllers, [Tony] specced some cheaper parts from AliExpress. Only, the low-speed control was terrible, and the dual motor controllers didn’t respond identically to throttle and would cause the vehicle to steer or crab, making driving difficult. This was fixed by dropping in an Arduino Nano after the throttle, and before the two motor controllers. It allows calibrating the throttle output from the Arduino to eliminate dead spots, while also tuning the throttle output to left and right motors individually so they respond more similarly. There are also custom acceleration and deceleration curves that make the controllers respond more smoothly, and a precise crawling speed for consistent low-speed maneuvering.
Just by doing some fancy throttle smoothing and control, [Tony] was able to greatly improve the usability of these cheap controllers, for the price of an Arduino Nano and little more. Files are on GitHub for those eager to attempt the hack themselves. There are other ways to go about this of course, like diving into field-oriented control, if you’re so inclined. Alternatively, speculate on how you’d tackle this engineering challenge down in the comments.
The heart of the build is an ATmega328P microcontroller, running off of a 32.768 kHz crystal. This allows the chip’s counters to neatly divide down the frequency to get a steady 1 Hz pulse for accurate timekeeping. Time is displayed on a vacuum fluorescent display (VFD) harvested from an old calculator. These displays need rather high voltages to run, which in this case are produced by a HV5812 driver chip and supporting circuitry. The display itself is neatly cradled in a pair of copper pipe elbows for a stylish look, with some addressable RGB LEDs present to provide some charming underglow.
Power for the device comes from a single AA battery, using a transformer-based low voltage converter. Alternatively, it can run off a USB 5 V power supply, which also charges the NiMH AA cell while available with the aid of an LM2576-ADJ buck converter.
The idea to pursue this came from off-the-shelf panel displays commonly used for power supply builds and other such equipment. These come in relatively standard sizes and are designed from the outset to slot neatly into a panel with a bezel that covers any ugly edges or awkward gaps.
The build began with a 48 x 29 mm enclosure grabbed from an off-the-shelf power panel meter. There are two PCBs—one holding the regulator and other equipment to run the display, the other carrying a set of screw terminals that make it easy to wire up the display to a piece of equipment. The SSD1306-compatible OLED screen itself connects to the first board with a flat flex cable, as is the norm.
If you find yourself often wanting to pop a small display into a piece of custom test equipment, this might be relevant to your interests. Files are on GitHub for the curious.
This design (shown in this simple box as an example) makes a very close-fitting hinge point.
This design prints half the hinge as a separate piece — the u-shaped one in the picture to the side — that must be glued into the target object after printing. It’s a bit of extra work, but doing it this way has a couple advantages.
One is that printing some of the hinge elements separately means one no longer needs to choose between a print orientation that best suits the object, and a print orientation that works best for the hinge. Also, the length of 1.75 mm filament used as a hinge pin is held captive after assembly so there’s no need to glue the hinge pin itself.
[Alex] helpfully provides the parts in STEP format, which makes CAD tweaks and adjustments easy. While incorporating the design should be doable even if one is just using .stl or .3mf files because boolean subtraction and merging is all that’s needed, having the model in STEP format is so much better.
Should you need some pointers on incorporating either into FreeCAD, we have you covered.
First introduced in 1979 by Signetics, the NE5532 was a pretty spiffy dual op-amp for the time with low noise and low distortion. Over the years it has become a standard part that showed up in countless audio products, and has become a so-called jellybean generic component with Texas Instruments (TI) being one of countless manufacturers.
It being such a standard, multi-sourced part makes it thus even more puzzling that TI has now decided to completely overhaul this IC in a way that makes it incompatible with even the original Signetics NE5532. These changes are covered in detail by [Dave] of EEVblog as his mind is pretty much blown at such an incomprehensible change.
The changes entail an entirely different manufacturing process and a big change in specifications, while making no change to the part number. In revision K of the TI datasheet these changes are first seen, with some specifications changed for the better, like a higher unity gain bandwidth by 2 MHz, but a much slower slew rate.
Texas Instruments SA5532A variant of the 5532 op-amp. (Credit: Raimond Spekking, Wikimedia)
Although the 5532 op-amps are multi-sourced, there are good reasons to just stick with manufacturers like TI, as that means receiving a product change notification (PCN) when anything changes. In the PCN related to this op-amp a change to process node is noted, along with other changes, but no reasoning.
Among the other big changes are a reduction in the supply voltage from 22 V to 18 V, and a halving of the ESD protection from 2 kV to 1 kV. Although it might be slightly more efficient on the new process node this way, it clearly comes with a lot of trade-offs that make it an overall worse op-amp, while also being incompatible with the same op-amp from other manufacturers.
In the video [Dave] goes through the datasheets of this jellybean part of other manufacturers, showing that they still have the original 1980s specifications. Only one exception here was the NE5532DR from Shenzhen HuaXuanYang Electronics, whose supply rail voltage is also 18 V for some reason, along with a similar internal transistor configuration that reduces the ESD resistance.
In addition to the NE5532 op-amp, it seems that TI also took an axe to the OPA134 op-amp, by removing its offset trim feature and listing the pins as ‘NC’, with a warning to not connect these pins and also worsening other specifications. This makes these similar jellybean parts incompatible, with no change to the part number. Worse is that it continues with the LMH6518, whose changes [Dave] argues might even kill oscilloscopes as they are commonly found in those.
Meanwhile the LM317M also got an overhaul, but here TI opted to give it a new part name, calling it the LM317MQ with at first glance no major degradations in the specifications, but instead some actual improvements. This makes it even more puzzling why TI didn’t give the other ICs a new part number to differentiate them from the jellybean part.
Until there’s some clarification from the side of TI, it might be a good idea to source these parts from a manufacturer that is not TI, especially when replacing these ICs in older devices.
