Cordless Water Pump!

A water pump is one of those items that are uncommonly used, but invaluable when needed. Rarer still are cordless versions that can be deployed at speed. Enter [DIY King 00], who has shared his build of a cordless water pump!

The pump uses an 18 volt brushed motor and is powered by an AEG 18V LiPo battery. That’s the same battery as the rest of [DIY King]’s power tools, making it convenient to use. UPVC pipe was used for the impeller — with a pipe end cap for a housing. A window of plexiglass to view the pump in motion adds a nice touch.

A bit of woodworking resulted in the mount for the pump and battery pack, while a notch on the underside allows the battery to lock into place. Some simple alligator clips on the battery contacts and the motor connected through a switch are all one needs to get this thing running.

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Tiny Electric Motor Runs on Power from an LED

If you were not aware, LEDs can also work in reverse: they deliver tiny amounts of current, in the microamp range, when illuminated. If you look on YouTube you can find several videos of solar panels built with arrays of LEDs, but powering an electric motor with a single 3 mm LED is something that we’ve never seen before. [Slider2732] built a small electric motor that happily runs from a green LED in sunlight.

The motor uses four coils of 1,000 ohms each. Using coils with many turns of very fine wire helps to draw less current while keeping an appropriate magnetic field for the motor to run. To keep friction at a minimum, the rotor uses a needle that hangs from a magnet. Four neodymium magnets around the rotor are periodically pushed by the coils, generating rotation. A simple two-transistor circuit takes care of the synchronization and yes, the motor does run on the four microamps provided by the LED, and runs pretty well.

Building motors is definitely an enjoyable activity, these small pulse motors can be built in just a couple of hours. You can use coils with just a few tens of turns which are much more easy to make but of course you will need something more than four microamps! The nice part of making an ultralow current motor like this is that it can run for a very long time on a tiny battery or even a capacitor, we invite you to try building one.

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Turn Your New Years Resolution Into a Belt Grinder

We’re just over a month into the new year, and some people’s resolve on those exercise plans are already dwindling. There’s some good news though. That treadmill can be hacked into a nice belt grinder for your shop.

[Bob]’s treadmill belt grinder is based on a 2.5 horsepower motor he salvaged from a broken, donated treadmill. This motor needs 130 VDC to run, which is a bit of a challenge to generate. Fortunately, lots of treadmills seem to use the same MC-60 motor controller, which is compatible with this motor. Due to the widespread use of this controller, they can be found on eBay for about $30.

With the motor spinning, [Bob] built up a frame for the grinder, added rollers to hold the belt, and a spring based belt tensioner. The motor’s speed set point is controlled by a potentiometer, and the controller varies the power to keep a constant speed. Since the motor is capable of some serious RPM, a tachometer was added for feedback to prevent high-speed belt shredding.

The final result is a very professional looking tool for under $200. What would a grinder like this be used for? Knives of course! 2″ belt grinders are perfect for shaping and grinding knives and swords. In fact, you can see one in use in this sword hack.

Check out a video of the build after the break.

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Use A Brushless Motor As A Rotary Encoder

The electric motor is the fundamental building block of almost all robotic projects but, without some form of feedback, it lacks the precise positional control required for the task. Small servos from the modelling world will often use a potentiometer to sense where they are on their travel, while more accomplished motors will employ some form of shaft encoder.

Commercial shaft encoders use magnets and Hall-effect sensors, or optical sensors and encoder discs. But these can be quite expensive, so [Hello1024] hacked together an alternative in an afternoon. It uses another motor as the encoder, taking advantage of the minute changes in inductance as the magnet passes each of its coils. It’s a technique that works better with cheaper motors, as their magnets are more imperfect than those on their expensive cousins.

The sensing is rather clever in its economy, sending a pulse to the motor through an off the shelf motor controller and measuring the time it takes to decay through the body diode of the driving MOSFET. It requires a calibration procedure before first use, and it is stressed that the whole thing is very much still in beta, but it’s a very impressive hack nevertheless. He’s posted a video demonstration which you can see below the break.

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Baby’s First Hands-Free Stroller

So you’ve had your first child. Congratulations; your life will never be the same again. [Dusan] was noticing how the introduction of his children into his life altered it by giving him less time for his hobbies in his home laboratory, and decided to incorporate his children into his hacks. The first one to roll out of his lab is a remote-controlled baby stroller.

After some engineering-style measurements (lots of rounding and estimating), [Dusan] found two motors to drive each of the back wheels on a custom stroller frame. He created a set of wooden gears to transfer power from the specialized motors to the wheels. After some batteries and an Arduino were installed, the stroller was ready to get on the road. At this point, though, [Dusan] had a problem. He had failed to consider the fact that children grow, and the added weight of the child was now too much for his stroller. After some adjustments were made (using a lighter stroller frame), the stroller was eventually able to push his kid around without any problems.

This is an interesting hack that we’re not sure has much utility other than the enjoyment that came from creating it. Although [Dusan]’s kid certainly seems to enjoy cruising around in it within a close distance to its operator. Be sure to check out the video of it in operation below, and don’t forget that babies are a great way to persuade your significant other that you need more tools in your work bench, like a CNC machine for example.

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Scratch-Built EV From Hoverboards

Electric vehicles are everywhere now. Even though battery technology hasn’t had the breakthrough that we need to get everyone out driving an electric car, the price for batteries has dropped enough that almost anything else is possible. The hoverboard was proof of this: an inexpensive electric vehicle of sorts that anyone who was anyone in 2015 had. Taking his cue from there, [Harris] used off-the-shelf parts normally used for hoverboards to build his own battery-powered trike.

The trike is homemade from the ground up, too. The H-frame was bolted together using steel and lots and lots of bolts. Propulsion comes from a set of hub motors that are integrated into the wheels like a hoverboard or electric bicycle would have. Commonly available plug-and-play lithium batteries make up the power unit and are notably small. In fact, the entire build looks like little more than a frame and a seat, thanks to the inconspicuous batteries and hub motors.

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DIY Electric Pennyboard Can Hit 40Km/h!!

Home-made transportation is a thriving area for makers to flex their skills. Looking to shorten their university commute, [doublecloverleaf] modded his penny board by adding a motor that can have him zipping along at 40 Km/h!

The electric motor is mounted to the rear truck and delivers power to the wheel gear using a HTD 5 m pulley belt. Finding the deck too flexible to mount the battery pack under, [doublecloverleaf] strengthened it with a pair of carbon-fiber tubes bracketed on the underside. A few custom PCB boards connect ten 5 Ah LiPo battery cells in series to create two, five-cell packs which are kept safe by a thick housing mounted between the board’s trucks. [doublecloverleaf] calculates that they could make up to a 15 km trip on a single charge.

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