Quartet of SMD Resistors Used to Sense Z-Axis Height

Here’s a neat trick for your next 3D-printer build or retrofit: a Z-axis sensor using a DIY strain gauge made from SMD resistors. We’re betting it could have plenty of other applications, too.

Conventional load cells, at least the ones you can pick up cheaply from the usual sources or harvest from old kitchen or bathroom scales, are usually way too big to be used on the extruder of a 3D-printer. [IvDm] wanted to build a touch sensor for his Hybercube printer, so he built his own load cell to do it. It consists of four 1000 ohm SMD resistors …read more

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Arduino-Powered Rocket Test Stand

If you’re into amateur rocketry, you pretty quickly outgrow the dinky little Estes motors that they sell in the toy stores. Many hobbyists move on to building their own homebrew solid rocket motors and experimenting with propellant mixtures, but it’s difficult to know if you’re on the right track unless you have a way to quantify the thrust you’re getting. [ElementalMaker] decided he’d finally hit the point where he needed to put together a low-cost test stand for his motors, and luckily for us decided to document the process and the results.

The heart of the stand is a common …read more

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Kinetic Sculpture Achieves Balance Through Machine Learning

We all know how important it is to achieve balance in life, or at least so the self-help industry tells us. How exactly to achieve balance is generally left as an exercise to the individual, however, with varying results. But what about our machines? Will there come a day when artificial intelligences and their robotic bodies become so stressed that they too will search for an elusive and ill-defined sense of balance?

We kid, but only a little; who knows what the future field of machine psychology will discover? Until then, this kinetic sculpture that achieves literal balance might hold …read more

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Never Go To The Office Breakroom Again

If you’re tired of having to make small talk with random people in the office break room every time you need a cup of coffee, or simply don’t have the time to get up to pour yourself some more, it would be nice if there was a way you could have your cup filled for you, right at your desk. With this new drink dispenser, you won’t have to get up or even pour your drinks yourself!

We’ve certainly seen plenty of automatic drink makers, but those are more suited to parties and complicated drink mixing. This beverage dispenser is …read more

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Assess Your Output with a Cheap DIY Urine Flowmeter

Some things about the human body are trivial to measure. Height, weight, blood pressure, pulse, temperature — these are all easily quantifiable with the simplest of instruments and can provide valuable insights into our state of health. Electrical activity in the heart and the brain can be captured with more complex instruments, too, and all manner of scopes can be inserted into various orifices to obtain actionable information about what’s going on.

But what about, err, going? Urine flow can be an important leading indicator for a host of diseases and conditions, but it generally relies on subjective reports from …read more

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Cocktail Machine Mixes Perfect Drinks Every Time

For many of us. the holiday season is coming up and that means hosting parties and mixing drinks, which can get tiresome. [GreatScott] has come up with a solution, what he calls a crude cocktail mixing machine. But don’t be fooled — it may look crude on the surface, and vibrate a bit while working, but the mechanism is plenty sound and functional.

The machine can mix three different liquids and does so using three peristaltic pumps. In typical [GreatScott] style, while he tears apart the pumps to replace the tubes, he gives us a good glimpse of just how …read more

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Instrument Packed Pedal Keeps Track of Cyclist’s Power

Exactly how much work is required to pedal a bike? There are plenty of ways to measure the power generated by a cyclist, but a lot of them such as heavily instrumented bottom brackets and crank arms, can be far too expensive for casual use. But for $30 in parts you can build this power-measuring bike pedal. and find out just how hard you’re stoking.

Of course it’s not just the parts but knowing what to do with them, and [rabbitcreek] has put a lot of thought and engineering into this power pedal. The main business of measuring the force …read more

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Load Cells Tell You to Lay Off the Donuts

Our old algebra teacher used to say, “You have to take what you know and use it to get what you don’t know.” That saying always reminds of us sensors that convert physical quantities into things our microcontrollers can measure. Sometimes the key to a project is knowing what kind of sensor will read the physical properties of the system you are interested in. If that physical property is weight, you can use what is known as a load cell. [DegrawSt] uses four 50 kg load cells to create a bathroom scale using an Arduino.

Load cells typically contain strain …read more

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Electronifying A Horror Fraught Hydraulic Press

[Josh] is replacing the springs in his car’s suspension. He wanted to know the travel rates of these springs, but apparently, this is a closely guarded trade secret in the industry. One company did manage to publish the spring rates, but they weren’t believable. Instead of taking this company’s word, [Josh] built a spring tester.

The theory behind a spring tester is pretty simple: apply a force to a spring, measure it, then measure how much the spring has traveled. Or compress a spring an inch or so, measure the force, and compress it some more. Either gets you the …read more

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Bandsaw Tension Gauge Uses Raspberry Pi And Load Cell

No matter what material you’re cutting, getting the blade tension right is one of the keys to quality cuts on the bandsaw. Unfortunately, most bandsaws come with only a rudimentary tension gauge, and while there are plenty of tricks for measuring blade tension indirectly, nothing beats a digital blade tension gauge for repeatable results.

Despite being an aftermarket accessory for his beefy Hitachi CB-75F bandsaw, [Stephen B. Kirby]’s Pi-based tension guide looks like an OEM product. Housed in a sturdy case and sporting a sealed membrane keypad and four-line LCD display, the interface electronics are pretty straightforward. The tricky bit …read more

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