Older people often have troubles opening plastic bottles. Also, people with gout or other disabilities lack the required strength to turn the small caps independently. The reason is the small diameter of the caps, which requires a strong grip with just two fingers.
There exist a variety of helper tools, assisting this task by increasing the leverage. A common problem with these tools is the static design. So if the manufacturer changes the size of the bottle cap, they do not grip properly anymore.
[Ken] stepped up, and at first glance, it was obvious that most of the chip is unused, and there appeared to be four copies of the same circuit. After identifying resistors and the different transistor types, [Ken] found differential pairs.
Differential pairs form the heart of most op-amps, and by chaining them together, you can get a strong enough signal to treat it as a logic signal. Based on the design and materials, [Ken] estimates the chip is from the 1970s. Given that it appears to be ECL (Emitter-Coupled Logic), it could just be four comparators. But there are still a few things that don’t add up as two comparators have additional inverted outputs. Searching the part number offered few if any clues, so this will remain somewhat a mystery.
Inductors are not the most common component these days and variable ones seem even less common. However, with a ferrite rod and some 3D printing, [drjaynes] shows how to make your own variable inductor. You can see him show the device off in the video below.
The coil itself is just some wire, but the trick is moving the ferrite core in and out of the core. The first version used some very thick wire and produced an inductor that varied from 6 to 22 microhenrys. Switching to 22 gauge wire allowed more wire on the form. That pushed the value range to 2 to 12 millihenrys.
What can you do with an inductor? For this type of inductor, you are usually interested in resonating a capacitor either for an oscillator or a filter of some kind. You see big roller variable inductors in antenna matching circuits, but it is doubtful that these inductors would be suitable for transmitting unless it was with very low power.
Next week, Dmitry Nedospasov and I are giving a 4-day live-streamed course on Intro to Hardware Hacking and Reverse Engineering. In this video, I just quickly overview the Spearf1sh platform we built which is the basis for the class and hopefully for further hardware hacking fun.
BioAmp EXG Pill is a small (2.54 X 1.00 cm) and elegant Analog Front End (AFE) board for BioPotential signal acquisition that you can use with any 5v Micro Controller Unit (MCU) with an ADC. It is capable of recording publication-quality BioPotential signals like ECG, EMG, EOG, and EEG without the inclusion of any dedicated Hardware/Software filter.
OpenSCAD is a fantastic free tool for 3D modeling, but it’s far less intuitive to use for non-programmers than mouse-driven programs such as Tinkercad. Powerful as it may be, the learning curve is pretty steep. OpenSCAD’s own clickable cheat sheet and manual comes in handy all the time, but those are really more of a reference than anything else. Never fear, because [Jochen Kerdels] had quite the productive lockdown and wrote a free comprehensive guide to mastering OpenSCAD.
[Jochen]’s book opens with a nice introduction to OpenSCAD and it’s user environment and quickly moves into 10 useful projects of increasing complexity that start with simple stuff like wall anchors and shelf brackets and ends with recursive trees.
There are plenty of printing tips along the way to help realize these projects with minimum frustration, and the book wraps up by covering extra functions not expressly used in the projects.
The Data Fitness Connector (DFC) data broadcaster is a Bluetooth device that allows Peloton bikes to communicate with fitness watches, head units, and apps—a feature that’s not available on stock Peloton bikes. It reads power and cadence data in realtime, through a cable connected to your bike, and broadcasts them to nearby devices, including those built around non-Peloton platforms like Zwift and Garmin. This allows you to enjoy the built-in functionality of your bike while simultaneously utilizing features and services that depend on third-party platforms.
Who Wants to Ride a Bike in Walled Garden?
Interested in the fitness data you produce? Want more control over who else has access to those data? Prefer not to be locked into a particular platform? If you have a Peloton bike, then DFC is for you.
We like to pretend that our circuit elements are perfect because, honestly, it makes life easier and it often doesn’t matter much in practice. For a normal design, the fact that a foot of wire has a tiny bit of resistance or that our capacitor value might be off by 10% doesn’t make much difference. One place that we really bury our heads in the sand, though, is when we use bipolar transistors as switches. A perfect switch would have 0 volts across it when it is actuated. A real switch won’t quite get there, but it will be doggone close. But a bipolar transistor in saturation won’t be really all the way on. [The Offset Volt] looks at how a bipolar transistor switches and why the voltage across it at saturation is a few tenths of a volt. You can see the video below.