A Pedal Powered Cinema

When the apocalypse hits and your power goes out, how are you going to keep yourself entertained? If you are lucky enough to be friends with [stopsendingmejunk], you can just hop on his pedal powered cinema and watch whatever movies you have stored on digital media.

This unit is built around an ordinary bicycle. A friction drive is used to generate the electricity via pedal power. In order to accomplish this, a custom steel stand was fabricated together in order to lift the rear wheel off the ground. A 24V 200W motor is used as the generator. [stopsendingmejunk] manufactured a custom spindle for the motor shaft. The spindle is made from a skateboard wheel. The motor is mounted in such a way that it can be lowered to rub the skateboard wheel against the bicycle wheel. This way when the rear bicycle wheel spins, it also rotates the motor. The motor can be lifted out of the way when cruising around if desired.

The power generated from the motor first runs through a regulator. This takes the variable voltage from the generator and smooths it out to a nice even power signal. This regulated power then charges two Goal Zero Sherpa 100 lithium batteries. The batteries allow for a buffer to allow the movie to continue playing while changing riders. The batteries then power the Optomo 750 projector as well as a set of speakers.

Automated Plant Watering System Uses Car Parts

[Shane] recently built an automated plant watering system for his home. We’ve seen several similar projects before, but none of them worked quite like this one. Shane’s system is not hooked into the house plumbing and it doesn’t use any off-the-shelf electronic valves.

Instead, [Shane’s] build revolves around a device that looks like it was intended to spray weed killer. The unit works sort of like a Super Soaker. The user fills the jug with water and then pumps a handle multiple times to build up some pressure inside the jug. Then a button can be pressed and the air pressure forces water out of the nozzle. [Shane] came up with a way to automate all of these mechanical motions.

First [Shane] had to find a way to pump up the bottle. He purchased a car door electronic lock actuator from eBay. It’s a pretty simple device. It’s just a DC motor with a gear box that turns the rotational motion of the motor into linear motion. This is mounted to a wooden jig and attached to the pump. A dsPIC microcontroller rotates the motor back and forth, which in turn pumps up the bottle.

The dsPic is also hooked up to a small servo. The servo is mounted to the same wooden jig as the car door actuator. A small arm is mounted to the servo so that when it rotates, the arm presses the pressure release button. This sends the water out of the bottles nozzle. [Pat] hooked up a small length of hose to the nozzle so he can direct the water into his plants. The video below demonstrates how the unit works. Continue reading “Automated Plant Watering System Uses Car Parts”

Electricity Usage Monitor is Linked to Google Spreadsheets

If you want to make your home more energy-efficient, chances are you will need a way to monitor your electricity usage over time. There are off-the-shelf solutions for this of course, but hackers like us tend to do things our own way. Take [Karl] for example. He recently built himself a solution with only a few smart components. We’ve seen similar projects in the past, but none quite like this.

[Karl’s] home has a power meter that blinks an LED to indicate the current amount of used electricity in Watt-hours. He knew all he needed was a way to electronically detect the blinking LED and he’d be able to accurately track his usage without modifying the meter.

The primary components used in this project were a CC3200 development kit and a photoresistor module. The dev kit contained a WiFi module built-in, which allows the system to upload data to Google spreadsheets as well as sync the built-in clock with an accurate time source. The photoresistor module is used to actually detect the blinking LED on the power meter. Everything else is done easily with code on the dev kit.

Solar Powered DIY Plant Watering System

Solar Powered Watering System

It’s great having fresh vegetables just a few steps away from the kitchen, but it takes work to keep those plants healthy. [Pierre] found this out the hard way after returning from vacation to find his tomato plant withering away. He decided to put an end to this problem by building his own solar-powered plant watering system (page in French, Google translation).

An Arduino serves as the brain of the system. It’s programmed to check a photo resistor every ten minutes. At 8:30PM, the Arduino will decide how much to water the plants based on the amount of sunlight it detected throughout the day. This allows the system to water the plants just the right amount. The watering is performed by triggering a 5V relay, which switches on a swimming pool pump.

[Pierre] obviously wanted a “green” green house, so he is powering the system using sunlight. A 55 watt solar panel recharges a 12V lead acid battery. The power from the battery is stepped down to the appropriate 5V required for the Arduino. Now [Pierre] can power his watering system from the very same energy source that his plants use to grow.

DIY 23mph+ electric skateboard

What’s the best way to get around NYC? If you asked [papo2110], he would probably suggest you build your own high-speed, long-range electric skateboard. You can’t cruise through any online maker community without tripping over a dozen e-vehicle projects these days. Nearly 18 months ago, even before the popular Boosted Boards Kickstarter, [papo2110] started piecing together a deck. His boards use a brushless outrunner motor, an RC car ESC (complete with brakes), and a chain drive to power him around Central Park at a top speed of 23mph.

The most impressive feat for this project, however, is the tireless revision through iterative design. The deck gets both an aluminum and a carbon fiber upgrade. Meaty 8S Headway LiFePo4’s replace a smaller 6S configuration. Even lights are added. As the build progresses, the board is pushing 27mph: with only one motor. Grab your helmet and motion-sickness pills and strap in for some videos after the break.

If four wheels are one too many and you want even more dangerous speeds, check out the E-trike build from a few months ago.

Continue reading “DIY 23mph+ electric skateboard”

Vitamin C used to detect the presence of Vanillin

[Markus Bindhammer] recently made a discovery while conduction chemistry experiments in his home lab. Ascorbic acid can be used to detect the presence of Vanillin. The reaction starts as a color change, from a clear liquid to a dark green. When he continued to heat the mixture he ended up with the surface crystallization seen above.

Vanillin is an organic compound which you will commonly find in vanilla extract, with the synthetic variety being used in imitation extract. Ascorbic acid is a type of vitamin C. When [Markus] first observed the color change he though it could be due to metallic contamination, but running the experiment again without the use of metal tools or probes, produced the same result.

You can see in the clip after the break that it doesn’t take long to turn green. The vanillin must be heated to 130 degrees C before adding the ascorbic acid or the color change will not occur. He believes this can be a reliable way to detect the presence of Vanillin in a substance.

Continue reading “Vitamin C used to detect the presence of Vanillin”

Get ready to play some wicked air harp

Who needs a tactile interface when you can wave your hands in the air to make music? Air String makes that possible and surprisingly it does so without the use of a Kinect sensor.

In the image above, you can see that two green marker caps are used as plectra to draw music out of the non-existent strings. Judiciously perched atop that Analysis and Design of Digital Systems with VHDL textbook is a camcorder recording an image of the player. This signal is processed by an FPGA (hence the textbook) in real-time, and shown on the monitor seen to the right. A set of guides are overlaid on the image, so the player knows where to pluck to get the notes she is expecting.

The program is designed to pick up on bright green colors as the inputs. It works like a charm as you can see in the video after the break. The team of Cornell students responsible for the project also mention a few possible improvements like adding a distance sensor (ultrasonic rangefinder?) so that depth can be used for the dynamics of the sound.

Continue reading “Get ready to play some wicked air harp”