DIY Thermostat Keeps The Harsh Winter Cold At Bay

October 27, 2011 by Mike Nathan 13 Comments

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[Phil’s] parents grow their own organic food, but the harsh Ukraine winters make storing it a difficult proposition. Since it can drop to -30°C on occasion, they asked him to find a way to keep their storeroom at around 5-7°C above zero. He decided to construct his own programmable thermostat to keep things in check, and has been documenting the process as he goes along.

The thermostat uses a DS18B20 temperature sensor to monitor the room, and the logic is handled by an ATtiny2313. When the temperature dips low enough, the ATtiny triggers the room’s heater via a standard 240v relay. He can check the current temperature via a small 7-segment display mounted on the control board, which also contains three microswitches for controlling the heater.

It looks like a pretty solid build so far, and while he hasn’t finished coding the thermostat just yet, [Phil] says that those details are forthcoming. He has published a schematic however, so you can get a jump start on building your own if you’re looking to warm things up this winter.

Continue reading to see a video overview of the thermostat’s design.

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Simple Circuit Reminds You To Lock The Door As You Rush Out Of The House

October 11, 2011 by Mike Nathan 24 Comments

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It seems that [pppd] is always rushing out of his apartment to catch the bus, and he finds himself frequently questioning whether or not he remembered to lock the door. He often doubles back to check, and while he has never actually forgotten to lock the door, he would rather not deal with the worry.

Since he finally had some free time on his hands, he decided to put together a simple device that would help end his worry once and for all. Using an ATtiny13, [pppd] designed a circuit that would detect when his door has been unlocked and opened, beeping every few seconds until the lock is reengaged. The circuit relies on a reed switch installed inside the door frame, which is tripped by the magnet he glued to his door’s deadbolt.

He says that the system works well so far, though he does have a few improvements in mind already.

Hacking Your Car’s Multifunction Display

September 29, 2011 by Mike Nathan 27 Comments

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[Steve] has an older third generation VW Golf, and as those who have owned one surely know, the beloved VR6 engine is wonderful but finicky. He says that the VR6 is particularly picky when it comes to oil temperature, so his daily routine involves hitting the MFA switch five times upon starting his car to bring up the oil temp in the display. This obviously gets old after awhile, so he rigged up a small circuit to do the switching for him.

He pulled the gauge cluster from the dash and then located the pins that correspond to the MFA display switch. Using an ATtiny12, he put together a small circuit that toggles the switch for him automatically each time he starts the car. Since his solution uses so few parts, he was easily able to tuck his creation behind the gauge cluster before reinstalling it.

Now each time he gets in his car, he is quickly greeted with the engine’s oil temp without having to fuss with his display.

ATtiny Hacks: Stopwatch Turned Race Clock

September 25, 2011 by Kevin Dady 3 Comments

The folks over at blondihacks are gearing up for an event called “The 24 Hours Of LeMons” which is a form of low-budget endurance racing involving cheap cars, heroic repairs, wacky themes, and a lot of serious driving. The format of the race is pretty simple, the cars race around the track continuously for a set amount of time (usually 12 or 24 hours), and the goal is to complete as many laps as possible in that time.

In order to be racing that long each team has multiple drivers, and a in car timer would be especially helpful. While commercial models cost a pile of money, the team was able to source a dual clock / stopwatch with a nice big display, and hack it up with an Attiny13. The stopwatch is deactivated when the engine is off, and reactivated when the engine gets turned back on.

Now when one driver’s turn is up they come in for a pit stop where the engine is shut down for saftey reasons. When the new driver is ready to leave, the clock automaticly resets for them and they can get on with the race.

ATtiny Hacks: Robot Halloween Costume

September 24, 2011 by Brian Benchoff 7 Comments

When it comes to Halloween costumes, [Michael] doesn’t like buying expensive and poorly made bits of cloth and fabric that resembles [random Disney character]. Last year, his son decided to be a robot for Halloween and although gray spray paint and dryer vent hose make a very good costume, that only goes so far. The robot needed lights, so [Michael] spent a little time on this build that blinks a few LEDs in a random pattern.

The build is very simple; an ATtiny13 drives two 74HC595 shift registers. The code – all 30-odd lines of it – uses the random() function to shift high or low values to the shift registers. After pausing for a little bit, the cycle continues and a new patterns of LEDs light up.

The electronics of the robot costume could be easily transferred to another theme – astronauts need LEDs on their backpack, and of course aliens communicate with blinking lights. In any event, it would avoid last year’s fiasco with a dozen [Heath Ledger] Jokers. Check out the video of [Michael]’s intergalactic robot son after the break.

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ATtiny Hacks: Infrared Guidance And Navigation

September 23, 2011 by Brian Benchoff 3 Comments

After [trandi] got his hands on a cheap R/C helicopter he realized the difficulties in actually flying a remote control helicopter. Instead of giving up, he decided to reverse-engineer the infrared protocol and then build a decoder around an ATtiny that would send commands to another microcontroller using a serial connection.

The remote’s communications protocol was decoded with the help of a Freeduino and an IR remote analysis sketch [trandi] found on the Arduino website. After importing the data into Gnuplot, there was enough data to write a sketch in Processing to visualize the infrared pulses.

After figuring out the protocol of his remote control, [trandi] built a tiny circuit to decrypt the IR commands and send them over a serial link to another microcontroller. The ATtiny45-based build doesn’t take up very much space on the perfboard making it very easy to mount on any robot of his choosing. He ended up connecting it to a Lego NTX brick allowing him to use the helicopter remote with any Lego build he can dream up.

[trandi] invested a lot of work around a cheap remote control; if the remote broke, all would be for naught. This was remedied with an IR beacon that replicates the function of the remote. The beacon is based on an ATtiny13 and can serve as a stand-alone beacon for autonomous robots or can accept serial commands from a computer. Not a bad build if you ask us.

ATtiny Hacks: SerialCouple – A Standalone Thermocouple ADC Board With Serial Out

September 23, 2011 by Mike Nathan 8 Comments

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Since we are in the midst of featuring a wide assortment of ATtiny hacks, [Kenneth] wrote in to share a project he has been developing over the last few months, the SerialCouple.

Most all development platforms have the ability to function as an analog to digital converter, but you don’t always need a full-featured board when all you require is serial output for your computer. With his SerialCouple board, [Kenneth] is trying to take some complexity out of the process by building a standalone thermocouple ADC board. The SerialCouple is designed to take analog readings from a thermocouple, converting them to digital values that can be sent to any device over a serial connection. The grunt work is done by a Maxim MAX31855 chip, which converts the thermocouple’s analog data to digital temperature readings. The digital representation of the temperature is then retrieved by the on-board ATtiny2313, which sends the data out the serial port.

If a standalone thermocouple ADC board is something you’ve been looking for, be sure to swing by his site to take a look at his code and schematics.

Continue reading to see a short video demo that explains how the SerialCouple works.

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