How many times has this one happened to you? Just coming home from work, you walk in from the garage, settle down, and pick up the newspaper. But wait, did you remember to shut the garage door?
Presenting the open garage door indicator. [xjc2010] chose the simplest circuit possible, using only a switch to turn on and off the setup, an LED acting as the signal, and a transformer/resistor combo to drop the voltage to an acceptable LED friendly 2.8 volts. We don’t like how he strung wire all over his house to place the beacon, and would have…
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Open garage door indicator
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AVR Dragon wiring alternative
We love our AVR Dragon programmer. It is a small board with a lot of functionality: in-circuit serial programming, JTAG, debug wire, and high voltage serial programming. Unfortunately, out of the box it is not quite ready for action. The Dragon ships with an unpopulated prototyping area and missing a pin header for the HVSP. For most people this means soldering on pin headers and a ZIF socket then jumpering between the various programming headers and the header for the socket. Tired of working with jumper wires, [Jussi] designed a small PCB to make the connections (original link in…
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Hacking USB serial port adapters
The folks at Openschemes.com have written up an article on how to convert a USB serial port adapter to a low voltage serial interface for interfacing with microcontrollers. Though you can always just buy one, this is a fairly quick and cheap solution, especially if you are in a pinch or don’t have access to a retailer. The specific models you should watch for, are the ones with two chips, a microcontroller and a line translater.They go through the process of finding exactly where to patch in to add an extra interface. It only takes a couple wires and…
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Laptop running on a sealed lead acid battery
[Viktor's] laptop needed a new battery; he had the trade off between carrying around a cheap but heavy sealed lead acid (SLA) battery, or buying an expensive but light Li-Ion battery. Figuring his old laptop was pretty heavy already, and having an unused SLA available, re-purposing it for his laptop wouldn’t be too much of a hassle. Using a boost converter he built out of a custom dip MAX668, he is able to output the necessary 5 amps required. An MC 34161 voltage monitor chip is planned for future revisions, but he’s currently running it just fine. Check out…
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Dual voltage power supply
[Melanie] had some time this weekend so she whipped up a dual voltage power supply from parts on hand. This design plugs right into a breadboard and, unlike the last breadboard power supply we saw, provides two voltages at one time. 5v is delivered to one power bus while 3.3v goes to the other. Her design uses two linear low voltage drop regulators from the LF00 family (PDF datasheet) to accomplish this. Nice work!
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Cellphone-controlled home
[Tixlegeek] used a Motorola 68HC705J1 development board to remotely control his home through his cellphone. The video above, as well as [Tixlegeek]’s website, is in French, though the video has been captioned. The development board (called the ERMES125) is controlled by a PIC externally. It has an array of LEDs, and apperantly a few high voltage relays. The PIC is connected to a laptop through a serial interface. The laptop is running a small web server, which uses CGI to control the PIC from a webpage. This system allows [Tixlegeek] to log onto the webpage from his web enabled phone, click a few…
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Hacking the smart tweezers
These Smart Tweezers are pretty cool tools for anyone doing SMD components. We tried them out and found them very pleasant well made. They are able to identify components and take readings easily with one hand. One thing they are missing, however, is the ability to measure voltage. The people over at Openschemes decided to see if there was a way around that. As it turns out, the chip used in the unit already has the capability to measure voltage. They take us through the process of modding the unit to be able to take advantage of this un…
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Open-Frame digital clock
Here’s an interesting project from several years ago. The clock design itself isn’t too noteworthy, but the construction is definitely inspired. You’ll notice that there is no breadboard or PCB, the frame actually is the circuit. The tubes he’s using are Numitron tubes, which aren’t as high voltage as Nixies or even VFDs. This means that there is only 12V maximum going through the exposed rails. He discusses some possible future upgrades such as LED or Nixie or VFD, but since this project is a few years old, who knows if he is still working with it.
[thanks Agent420]…
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Learn from the Ice Tube Clock
Looks like they’re at it again over at Adafruit. This time they’ve produced a clock that looks more like it should be attached to a munition rather than cruising bedside. But, geek-cred aside, there’s a lot to be learned from their design. Like we’ve grown to expect, they’ve put together some good documentation on their choice of components.
Start off by taking a peek at their 5v power regulator. There is an extra diode on the output side that prevents reverse current from the 3v backup battery. The AVR ATmega168 that controls the clock is used to detect loss…
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Regulated breadboard PSU
SparkFun has released a breadboard power suppy that can provide regulated 3.3v or 5v. Unlike the supply we saw from adafruit industries earlier this summer, this one is based on an lm317. This small device features on/off switch, voltage selection swith, and appropriately spaced pin headers to plug into both the top and bottom rails of a standard breadboard. Rather build it yourself? Take a look at the schematic provided (PDF).
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Serial hacking with an ATtiny2313
[Sprite_tm] automated a portion of serial hacking by sniffing out the baud rate using an ATtiny2313 and FT232 breakout board. The firmware assumes 8 data bits, no parity, and 1 stop bit (8N1). This is pretty much defacto among serial ports so it should work well, though some devices do use different settings. The auto detection routine can sniff rates as low as 110 baud and supports non standard rates. Released under GPLv3, the software is also supplied in hex format. [Sprite_tm] has provided great project in past such as Working with VFDs, Controllable bristlebot, and AVR boost converter. Additional information regarding serial…
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Lazy man’s USB RFID reader
[Don] had some Serial RFID readers that he needed to work and be powered by USB. He went out and purchased a simple serial to USB converter, but was left with the problem of the operating voltage. He supplies the schematics on his site for his solution. Basically he gutted the converter and integrated it all with the appropriate voltage broken out. The final project is nice, using the serial to USB convert as the project box and even including a nice LED to show when an RFID tag has been read.
