A set of three linear actuators set atop a green with yellow grid cutting mat. The electric actuator on the top of the image is silver and has a squarish tube. It is slender compared to the other two. A black, hydraulic actuator sits in the middle and is the largest of the three. A silver pneumatic actuator at the bottom of the image is the middle sized unit.

Linear Actuators 101

Linear actuators are a great help when you’re moving something along a single axis, but with so many options, how do you decide? [Jeremy Fielding] walks us through some of the high level tradeoffs of using one type of actuator over another.

There are three main types of linear actuator available to the maker: hydraulic, pneumatic, and electric. Both the hydraulic and pneumatic types move a cylinder with an attached rod through a tube using pressure applied to either side of the cylinder. [Fielding] explains how the pushing force will be greater than the pulling force on these actuators since the rod reduces the available surface area on the cylinder when pulling the rod back into the actuator.

Electric actuators typically use an electric motor to drive a screw that moves the rod in and out. Unsurprisingly, the electric actuator is quieter and more precise than its fluid-driven counterparts. Pneumatic wins out when you want something fast and without a mess if a leak happens. Hydraulics can be driven to higher pressures and are typically best when power is the primary concern which is why we see them in construction equipment.

You can DIY your own linear actuators, we’ve seen tubular stepper motors, and even a linear actuator inspired by muscles.

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telescope mount

DIY Telescope Mount For Stellar Tracking

Pointing at stars may seem easy on the surface—just mount a telescope to a tripod and you’re done, right? As anyone who’s spent time with a telescope can tell you, it’s not that simple, given that the Earth is always spinning. [Sven] set out to make his own mount to compensate for the rotation of the Earth, which led to some pretty amazing results.

In this project, [Sven] designed a GoTo mount, which is a telescope equatorial mount capable of being pointed at specific parts of the sky and tracking them to allow for long-exposure photos with minimal blur due to the Earth’s movement. He first went down the path of finding the correct harmonic gearbox for the steppers used. A harmonic drive system would allow smooth, precise movement without backlash, and the 100:1 stepdown would provide for the slightest of adjustments.

The steppers are controlled by a custom PCB [Sven] designed around an ESP32-S3. The first PCB had a mistake in the power delivery circuit. After a small tweak, V2 boards arrived and work great. The PCB runs OnStepX, a great open-source project centered around pointing telescopes, cutting down a lot of the software workload on this project.

After all the work put in, you may be wondering how well it works. [Sven] was able to get a pointing accuracy of 1-2 arcseconds from his mount. To get an idea of how great that is, 1 arcsecond is about the same as pointing at a penny from 4 km (2.5 miles) away. Fantastic results, [Sven], and thank you for sending in this great project—be sure to head over to his site and read all the details of this impressive build. If you found this interesting, be sure to check out some of our other telescope-related projects.

A photo montage of scrap plastic being vacuumed up, processed in the main chamber, and bottled in gas tanks.

Solar Powered Pyrolysis Facility Converts Scrap Plastic Into Fuel

[naturejab] shows off his solar powered pyrolysis machine which can convert scrap plastic into fuel. According to the video, this is the world’s most complex hand-made pyrolysis reactor ever made. We will give him some wiggle room there around “complex” and “hand-made”, because whatever else you have to say about it this machine is incredibly cool!

As you may know pyrolysis is a process wherein heat is applied to organic material in an inert environment (such as a vacuum) which causes the separation of its covalent bonds thereby causing it to decompose. In this case we decompose scrap plastic into what it was made from: natural gas and petroleum.

His facility is one hundred percent solar powered. The battery is a 100 kWh Komodo commercial power tank. He has in the order of twenty solar power panels laying in the grass behind the facility giving him eight or nine kilowatts. The first step in using the machine, after turning it on, is to load scrap plastic into it; this is done by means of a vacuum pump attached to a large flexible tube. The plastic gets pumped through the top chamber into the bottom chamber, which contains blades that help move the plastic through it. The two chambers are isolated by a valve — operating it allows either chamber to be pumped down to vacuum independently.

Once the plastic is in the main vacuum chamber, the eight active magnetrons — the same type of device you’d find in your typical microwave oven — begin to break down the plastic. As there’s no air in the vacuum chamber, the plastic won’t catch fire when it gets hot. Instead it melts, returning to petroleum and natural gas vapor which it was made from. Eventually the resultant vapor flows through a dephlegmator cooling into crude oil and natural gas which are stored separately for later use and further processing.

If you’re interested in pyrolysis you might like to read Methane Pyrolysis: Producing Green Hydrogen Without Carbon Emissions.

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Close up of a DIY minimalist EDC multitool, a penny, and a paperclip

This Pocket Multitool Weighs Less Than A Penny

A multitool that weighs less than a penny? Yes, it exists. This video by [ToolTechGeek] shows his titanium flat-cut design tipping the scales at only 1.9 grams—lighter than the 2.5-gram copper penny jingling in your pocket. His reasoning: where most everyday carry (EDC) tools are bulky, overpriced, or simply too much, this hack flips the equation: reduce it to the absolute minimum, yet keep it useful.

You might have seen this before. This second attempt is done by laser-cutting titanium instead of stainless steel. Thinner, tougher, and rust-proof, titanium slashes the weight dramatically, while still keeping edges functional without sharpening. Despite the size, this tool manages to pack in a Phillips and flathead screwdriver, a makeshift saw, a paint-lid opener, a wire bender (yes, tested on a paperclip), and even a 1/4″ wrench doubling as a bit driver. High-torque screwdriving by using the long edges is a clever exploit, and yes—it scrapes wood, snaps zip ties, and even forces a bottle cap open, albeit a bit roughly.

It’s not about replacing your Leatherman; it’s about carrying something instead of nothing. Ultra-minimalist, featherlight, pocket-slip friendly—bet you can’t find a reason not to just have it in your pocket.

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Pinout of 74HC595

Using The 74HC595 Shift Register To Drive 7-Segment Displays

In a recent video our hacker [Electronic Wizard] introduces the 74HC595 shift register and explains how to use it to drive 7-segment displays.

[Electronic Wizard] explains that understanding how to apply the 74HC595 can increase the quality of your projects and also help keep the demands on the number of pins from your microcontroller to manageable levels. If you’re interested in the gory details you can find a PDF datasheet for the 74HC595 such as this one from Texas Instruments.

[Electronic Wizard] explains further that a shift register is like a small one byte memory where its data is directly available on its eight output pins, no input address required. When you pulse the clock pin (CLK) each bit in the eight bit memory shifts right one bit, making room for a new bit on the left. The bits that fall off the right hand side can daisy chain into another 74HC595 going out on pin 9 and coming in on pin 14.

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A photo for a motor and a meter on a bench.

Let’s Brief You On Recent Developments For Electrostatic Motors

Over on his YouTube channel [Ryan Inis] has a video about how electrostatic motors are breaking all the rules.

He explains that these days most motors are electromagnetic but suggests that may be changing as the age-old principles of electrostatics are being explored again, particularly due to the limited supply of rare-earth magnets and other materials (such as copper and steel) which are used in many electromagnetic motors.

[Ryan] says that new electrostatic motors could be the answer for highly efficient and economical motors. Conventional electromagnetic motors pass current through copper windings which create magnetic fields which are forces which can turn a rotor. The rotor generally has permanent magnets attached which are moved by the changing magnetic forces. These electromagnetic motors typically use low voltage and high current.

Electrostatic alternatives are actually an older design, dating back to the 1740s with the work of Benjamin Franklin and Andrew Gordon. These electrostatic motors generate motion through the attraction and repulsion of high voltage electric charges and demand lower current than electromagnetic motors. The high voltages involved create practical problems for engineers who need to harness this energy safely without leading to shocks or sparks or such.

[Ryan] goes on to discuss particular electrostatic motor designs and how they can deliver higher torque with lower energy losses due to friction and heat making them desirable for various applications, particularly industrial applications which demand low speed and high torque. He explains the function of the rotor and stator and says that these types of motors use 90% less copper than their electromagnetic alternatives, also no electrical steel and no permanent magnets.

For more coverage on electrostatic motors check out Electrostatic Motors Are Making A Comeback.

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door spring

Compliant Contacts: Hacking Door Locks With Pen Springs

As you may have guessed given our name, we do love hacks around here, and this one is a great example of making some common, everyday things work in uncommon ways. [Nathan] sent in his hack to detect the door lock position in his basement.

Having a house that dates back to the 1890s, much of it was not very conducive to using off-the-shelf home automation devices. [Nathan] wanted a way to check the status of the basement deadbolt. He went about putting together a custom sensor using some spare parts, including a spare BeagleBone Black. Going full MacGyver, [Nathan] used springs from a ballpoint pen to craft a compliant contact for his sensor.

The pair of springs sat in the door frame and came in contact with the deadbolt; given they are springs, the exact position of the sensor was not very sensitive, as if too close it would just compress the springs slightly more. The springs were wired to the BeagleBone Black’s GPIO, acting as a switch to sense when there was conductivity between the springs through the deadbolt.

This wasn’t just a plug-it-in-and-it-works type of project, mind you; the BeagleBone Black was over 15 ft away from the sensors, lending plenty of opportunity for noise to be introduced into the lines. To combat this, [Nathan] created an RC filter to filter out all the high-frequency noise picked up by his sensor. Following the RC filter, he added in some code to handle the debounce of the sensor, as the springs have some inherent noise in them. Thanks [Nathan] for sending in your resourceful hack; we love seeing the resourcefulness of reusing things already on hand for other purposes. Be sure to check out some of the other repurposed components we’ve featured.