Wireless Speaker Made Using Arduinos And 2.4 GHz Tranceivers

November 23, 2012 by 22 Comments

[Texane] picked up a 2.4 GHz transmitter/receiver pair for transmitting sensor data wirelessly. After using them in a project he wanted to try pushing them a bit to see what the limits are when it comes to higher bandwidths. He ended up building a wireless speaker that transmits audio at about 90 KB/s. That link leads to a subfolder of his git repository. The code for this project is in the RX and TX folders, with images and video in the DOC folder.

The radio hardware that he’s using is a Nordic nRF24L01P chip which is available on a breakout board from Sparkfun. [Texane] mentioned to us that the chip includes error checking, packet ACK, and automatic retransmission. But these add overhead that can slow things down. The chip does offer the option to disable these features to get lower level access to the hardware. That’s exactly what he did and he mentions that the example code he wrote for the transmitter and receiver make every cycle count. This makes us wonder if it’s the speed of the ATmega328 chip that is the bottleneck, or the transceivers themselves?

Quick And Easy Personal Evaporative Cooler

November 23, 2012 by 17 Comments

This quick and easy evaporative cooler might be just the thing the next time the air conditioning goes on the fritz. [Stephen] saw an eBay listing for a personal air conditioner that used a moist sponge and fan to send some cool relief your way. But he wanted to run his own test to see if it really did anything before laying down the cash.

The idea is to run air past a moisture source. Some of the heat energy in the air is reduced through evaporation resulting in the exhaust air feeling a bit cooler. It’s the same concept used in swamp coolers (an evaporative type of air conditioning). To build his device [Stephen] grabbed a refrigerator deodorizer which uses a hinged plastic cage to hold a packet of baking soda. He attached a small PC fan to the cage, then inserted a damp sponge. This is so easy to put together you could hit the dollar store on your lunch break and have some relief for the second half of the work day.

If you’re looking for a technique that cools just a bit better consider leveraging a beer fridge as a personal cooler.

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Arduino Data Logger Maps Out The Potholes On Your Morning Commute

November 23, 2012 by 27 Comments

Now you can prove that you have the bumpiest commute in the office by measuring how rough your ride actually is. [Techbitar] calls the project the Bump-O-Meter. It uses an Arduino, GPS, and accelerometer to map out rough roads.

The hardware was built on a breadboard and [Techbitar] goes into detail about connecting and communicating with each module used. Once it’s running, the logger will read up to six sensors and record them to an SD card. In the video after the break he shows the method used to dump and graph the data. He starts by looking at the data in a spreadsheet. There are many fields included in the file but only three of them are needed to graph what is seen above. After narrowing down the number of columns he heads over to GPS Visualizer and uploads the data set which is then automatically plotted on the map.

In a Utopian society all city owned vehicles would have a system like this and the bad sections of road would automatically appear on the road crew’s repair list.

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MonoPong: A CMOS 1-D Pong

November 23, 2012 by 6 Comments

We’ve seen a few 1-D pong games recently, and they’ve all be controlled using microcontrollers. Inspired by some of these hacks, [mischka] built the monoPong using a handful of logic chips.

The monoPong has four major components. A 555 timer in astable mode provides a clock source which is fed into a 4510 decade counter, which connects to a 4028 BCD to decimal decoder to drive the LEDs. Finally, a 4011 NAND gate IC is used to deal with the button presses. Two of the NAND gates form a RS flip-flop, and the other two NAND each player’s button with the last LED on the player’s side of the strip. If the player hits the button when their LED is on, the RS flip-flop toggles and changes the decade counter from count up to count down mode. This makes the ball bounce back.

[mischka] finished the project off by putting it in a wooden box and drilling holes for the LEDs, buttons, and a power switch. The final product looks pretty good, and is a great example of how you can use a couple logic chips instead of a microcontroller.

After the break, watch a quick game of monoPong.

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A Suitcase Full Of Tunes

November 22, 2012 by 12 Comments

Take the party with you by building your own boomcase. It’s an amplifier and set of speakers built into luggage. It uses an audio jack to connect to your favorite music player, and with a bit of  added protection — like grills for those speakers — it could still be gently used to transport your wardrobe.

A 1960’s suitcase was mutilated for this build. [Jay] must have already had it on hand because combined with some used parts he claims to have only spent $50 total. After trying out a few different speaker orientations on a piece of cardboard he covered the outside of the case in blue painter’s tape and started cutting holes. The amp he chose has a nice face plate which happens to  fit nicely on the top side of the case. For now he’s powering it with a 10,000 mAh (ie: 10 Ah) portable device recharging battery. But as you can hear in the demo after the break this seems to have no problem supplying the system with enough power.

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Bilbio-mat Is An Awesome Yet Simple Used Book Vending Machine

November 22, 2012 by 9 Comments

You’ll find this used book vending machine at The Monkey’s Paw in Toronto, Canada. For two Loonies you can buy a random book from the machine’s hopper. Silly? Absolutely. But as you can see from the video after the break, the act of buying a book this way is a lot of fun, and we always like to see the insides of a machine like this.

[Craig Small’s] creation looks vintage, and the chugga-chugga and mechanical bell that accompany each sale go along well with that appearance. Of course the machine is new. A trio of hoppers behind the façade hold stacks of books at a forty-five degree angle. Each stack is raised one at a time by a winch and pulley. Once the top book on the stack is high enough to slide into the dispenser chute the winch stops and the bell rings. A simple solution to dispensing something that is not a standard size.

Because the Biblio-Mat is meant to clear out the discount books, slight damage caused by falling down the chute won’t even be noticed. And if you end up really loving the book you can digitize it by running it through one of these.

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Beefing Up A Smoke Alarm System With Video, Temperature, And Connectivity

November 22, 2012 by 5 Comments

Here’s a little smoke detector hack which [Ivan] has been working on. He wanted to extend the functionality of a standard detector and we’re happy to see that he’s doing it with as little alteration to the original equipment as possible (this is a life-saving device after all). He sent all the build images for the project to our tips line. You’ll find the assembly photos and schematic in the gallery after the break.

As you can see his entry point is the piezo element which generates the shrill sound when smoke as been detected. He connected this to his own hardware using an optoisolator. This allows him to monitor the state of the smoke alarm on his server. It then takes over, providing a webpage that display’s the board’s temperature sensor value and streams video from an infrared camera.

Of course this is of limited value. We’ve always made sure that our home was equipped with smoke detectors but the only time they’ve ever gone off was from normal cooking smoke or after an extremely steamy shower. But still, it’s a fun project to learn from and we’ve actually got several of the older 9V battery type of detectors sitting in our junk bin.

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