Arduino Tachometer Tutorial

August 30, 2012 by Mike Szczys 10 Comments

This tutorial will guide you through the process of building a tachometer around an Arduino. Tachometers are used to measure rotation rate in Revolutions Per Minute (RPM). You don’t need much in the way of hardware, this version uses an Infrared beam to measure fan speed. As with last year’s PIC-based tutorial, [Chris] is using a character LCD to output the reading. Wiring and driving the LCD ends up being the hardest part.

An IR transmitter/receiver pair are positioned on either side of the fan. When the blade passes in between then, the receiver shuts off a transistor connected to one of the Arduino’s external interrupt pins. He shows how to use this interrupt to measure the amount of time between the passing of each fan blade. If you divide for the number of blades, and average the reading for greater accuracy, you can easily calculate RPM.

Another alternative would have been to use a reflectance sensor which allows to for the transmitter and receiver to both be on the same side of the fan.

Use Your TV Remote As An HID Mouse

July 19, 2012 by Mike Szczys 17 Comments

[Vinod’s] latest project lets him use a TV remote control as a mouse. It may not sound like much, but he did it with a minimum of hardware and packed in the maximum when it comes to features.

He’s using an ATmega8 to read the remote control signals and provide USB connectivity. With the V-USB stack he enumerates the device as an HID mouse. One note of warning, he used the PID/VID pair from the USBasp programmer project. If you use that programmer you’ll need to uninstall the drivers to get this to work (we think this is only necessary on a Windows box).

The cursor can be moved in eight directions using the number pad on the remote. The numeral five falls in the center of the directional buttons so [Vinod] mapped that to the left click, with the zero key serving as right click. He even included the scroll wheel by using the volume buttons. The firmware supports cursor acceleration. If you hold one direction the cursor will move slowly at first,then pick up speed. Fine adjustments can be made by single clicking the button. Check out his demonstration embedded after the break.

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Cat Trainer Will Keep Them Off The Counters

July 12, 2012 by Mike Szczys 18 Comments

Our cats are not allowed on the kitchen counters, and [Iron Jungle] has the same rule. But he spotted some foot prints on the hood above his range and the addition of a security camera caught this picture of [Kelso] breaking the rules. Since he’s not always around to make the fur-ball behave he built an electronic cat trainer to do it for him.

The functionality needed isn’t very intricate. You need to monitor when the cat is where it shouldn’t be and then chase it away. For the latter he grabbed an infrared range finder. When the cat passes in front of the sensor it will trigger the second part of the system: a high-pitched buzzer that’s extremely loud. Any microcontroller will have no trouble driving the system. In this case it’s a PICAXE 28X1.

You can see the trainer in action after the break. It definitely works, because just playing the video chased our own sleeping kitty out of the room.

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Program Your Arduino Via IR Using The Arduino IDE

May 7, 2012 by Mike Szczys 13 Comments

Here’s a way to program an Arduino wirelessly while still using the stock IDE. It uses an alternative bootloader called SuperDuplex along with an IR receiver like the ones used for TV remotes.

As you can see, this does take two parts. There is the target device which has the IR receiver, as well as the transmitting unit which connects to the computer via USB. You can see a demonstration of the programming process after the break. It might be a bit slow, but nothing outrageous.

With hobby electronics we always thing that “what does it do?/what is it for?” is the wrong question. But in this case we there’s a very apparent use for it. If you’ve built a gadget for use in a harsh environment and want to keep the number of openings in the enclosure to a minimum (like for an underwater ROV) this is perfect. Just make sure there’s a window for the IR receiver and you’ll be able to program as much as you want. Of course it still looks like you need a method to manually reset the target chip, but you’ll think of something.

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A Flashlight For Any Occasion

April 27, 2012 by Mike Szczys 13 Comments

Whether you’re trying to light your path, build your own night vision, or do some tanning at home, this flashlight has you covered. [David Prutchi] designed the high power flashlight with three swappable heads.

He built the base unit out of aluminum pipe. It’s got plenty of room for the four 9V batteries that act as the power source. The driver circuit is just a bit smaller than one of those batteries, and to bring the whole thing together [David] and his helper added a potentiometer, toggle switch, and quick connector which makes head swaps a breeze. The heads themselves are all LED based, with one for visible light, another for infrared, and the final module outputs ultraviolet. We joke about tanning with it, but at 10 Watts you should be more worried about accidental damage to your vision.

The finished product is shown checking the security ink on some Canadian Currency. This would also make a nice secondary light source for your night vision monocle.

Simple Proximity Sensor

April 20, 2012 by Mike Szczys 18 Comments

[Dustin Andrews] built this add-on board which works as a proximity sensor. He wanted a standalone sensor for his Arduino projects which would use a single pin as a trigger. This lets him alert the Arduino when an object approaches the sensor without the need for polling or extra code on the Arduino side of things.

As you can see, a single chip on the board takes care of all the work. That’s an ATtiny13, they’re inexpensive and sometimes you can even salvage them from consumer electronics like this color changing light bulb. The microcontroller monitors the phototransistor which is wrapped in electrical tape to isolate it from the IR LED emitters on either side. This setup creates a reflective sensor. When an object nears the board, the infrared light from the emitters reflects off of it and onto the phototransistor. And since the Arduino works as an AVR programmer you don’t need special hardware to program the device.

IR Helicopter Controller Hacked Into A Linux Game Pad

April 14, 2012 by Mike Nathan 4 Comments

syma-linux-joystick

[Mike Kohn’s] Syma S107 helicopter wasn’t flying as well as it used to due to a broken gear, he figured he might as well find some use for the toy’s controller, since it was currently sitting around collecting dust. Having done a bunch of work with Syma IR protocols earlier this year, he decided it would be pretty easy to get the remote working as a game pad for his Linux desktop.

He patched an IR receiver into an MSP430 board, which decodes the incoming IR signals, sending them to his computer over a serial connection. [Mike] dug around in the Linux source for some good joystick driver code to borrow and found something that was close enough to work. After a bit of tweaking he loaded up his driver module and fired up Mame to give [Ms. Pacman] a try.

He says that the controller worked without much trouble, though as he discovered in previous projects, there are some quirks in the controller that make it somewhat less than convenient to use full time. Check out his site if you’re interested in taking a look at the code that he used to get things running.