Garage Monitor Has An Extra Arduino

December 14, 2010 by Devlin Thyne 57 Comments

[Jody] wanted to know when his garage door was open. He details his setup which uses a temperature sensor read by an Arduino to send over XBee radio to a computer running a Windows Service. We have seen this twice before, and is noteworthy as a lesson. The XBee radios have the ability to read analog data, relay digital signals, and a lot more. This means the Arduino is completely unnecessary. For example, the Tweet-a-Watt uses two of an XBee’s ADCs to measure voltage and current in a Kill-a-Watt power meter. Programming an XBee is really simple, with the help of tutorials from SparkFun and Adafruit. A bit of programming and soldering should get [Jody] back his Arduino. We hope this note will help you find more creative uses of XBees without microcontrollers.

[Via Make]

AVR HV Rescue Shield 2

December 14, 2010 by Mike Szczys 10 Comments

[Jeff Keyzer] has a new version of the HV Rescue Shield available. This tool allows you to use an Arduino to reset the fuse bits on AVR microcontrollers. This is necessary if you make a mistake and disable the reset pin, or choose the incorrect clock settings (this will probably happen to you at some point). In order to bring the chip back to life you’ll need to use High Voltage Programming. The last version of the shield only worked with High Voltage Parallel Programming (HVPP) but this rendition can also use High Voltage Serial Programming (HVSP) for 8-pin chips that don’t have enough inputs for parallel communications.

As we talked about in our AVR Programming Tutorials this is no replacement for a high-end programmer like the STK500 or an AVR Dragon, but if you already have an Arduino a kit will only cost you $20 (or you can etch and build it yourself). We would have liked to see a breakout header for the HVP signals for off-board use. The absence of a breakout header doesn’t preclude this, but since you need the on board boost converter for the 12V signals, and because this shield can’t be used with a breadboard due to pin spacing, it’s hard to patch into signals for non-DIP use. We also think some clever firmware hacking and this could be used for HV programming, like we needed for that LED light bulb.

Jacob’s Ladder Using EL Wire

December 12, 2010 by Mike Szczys 19 Comments

For Halloween [Paul] wanted to build a Jacob’s Ladder without the peril that working with high voltage might bring. He was inspired by a sequencer board for electroluminescent wire and decided to build a Jacob’s Ladder simulator using the glowing material. What he ended up with is quite convincing. Eight segments of EL wire have been mounted between two diverging towers. When a PIR sensor detects motion in the room, an Arduino switches on the simulation, playing a recording of the classic sizzling voltage sound while using the sequencer board to flicker the wires from bottom to top. See for yourself in the video after the break. We give [Paul] bonus points for constructing the base out of Lego.

But if you’re not one for being cautions, there’s always this real Jacob’s Ladder build. Or maybe you just want to make something glow with the EL wire.

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Using Analog Voltage References With Arduino

December 11, 2010 by Mike Szczys 31 Comments

Little Bird Electronics posted an article about using an analog voltage reference with Arduino. This is a tool available when using an analog-to-digital converter. By setting up either an internal or external AREF, you can better use the ADC considering its resolution limitations. For instance, if you are measuring a signal that you know will always be below 2V, an external circuit, such as a voltage divider or an adjustable regulator, can give you a reference voltage just above that upper limit; say 2.5V. This way the 1024 divisions of resolution will be spread across your signal’s range, rather than just the lower half of the ADC readings.

Analog references are common to microcontrollers that have ADCs. Even if you’re not working with an Arduino, read through the article and use what you learn with your uC of choice.

Skillet Reflow Controller

December 9, 2010 by Mike Szczys 21 Comments

Using an electric skillet to reflow surface mount circuit boards is a popular alternate use for those kitchen appliances. The real trick is monitoring and controlling the temperature. [Mechatronics Guy] built his own skillet temperature controller using a thermistor, a solid state relay, and an Arduino.

He was inspired by [Ladyada’s] work which used a servo to adjust the temperature dial on the skillet’s power supply. This started by attaching the thermistor to the bottom of the skillet using JB weld. since this area will be heating up he also attached a terminal block for connecting the feed wires as the heat would melt any solder joints. Those wires travel back to a control box housing the Arduino and solid state relay. To gain finer control over the heating element the relay is switched on and off, resulting in low-frequency Pulse Width Modulation, which should help maintain a consistent temperature better than just turning the temperature dial on the cord.

Pair this up with the vacuum tweezers hack and you’re on your way to a surface mount assembly line. If you want to see this process in action check out this post. It goes from stenciling, to populating, to reflowing in a toaster oven.

[Thanks Rob]

Knitting Machine Hack By Keypad Emulation

December 6, 2010 by Mike Szczys 3 Comments

[Travis Goodspeed] and Hackaday alum [Fabienne Serriere] joined forces to develop an alternative interface for a knitting machine. They’re working with the Brother KH-930E machine. We saw [Becky Stern] use the same model by manipulating data on an emulated floppy drive for the device. [Travis] and [Fabienne] went a different route, and are emulating the keypad using an Arduino and a set of transistors.

They started by reverse engineering the keypad matrix using a continuity tester. Once they worked out the column and row layout they connected each to an NPN transistor. The Arduino sketch simulates button presses to set knitting bits for each row, with just one reset button for user input. This can be used to send data from a PC, or as a standalone system. Either way, it’s not only a great way to add functionality to the kitting machine, but a good example of how to interface with the keypad on just about any device.

Arduino Electronic Speed Control Explained

November 26, 2010 by Mike Szczys 29 Comments

You can salvage some nice motors out of optical drives but they can be tricky to control. That’s because brushless DC motors require carefully timed signals used in a process called Electronic Speed Control (ESC). [Fileark] built and ESC using an Arduino and has a couple of posts explaining the concept and demonstrating how it works. His test circuit uses six 2N2222 transistors to protect the Arduino from excessive current. You can see six red LEDs above which are inline with the base of teach transistor. This gives visual feedback when a transistor is switched, a big help for troubleshooting your circuit.

Once you’ve seen the videos after the break you’ll probably come to the conclusion that this is an impractical way to use a brushless motor. But it is a wonderful way to learn about, and experiment with the concept of ESC. Chances are you can get your hands on an old optical drive for free, making this an inexpensive weekend project.

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