Temperature Sensing Mug Means Never Burning Your Mouth Again

April 12, 2011 by Mike Nathan 14 Comments

temp_sensing_mug

Some people tend to get awfully attached to their favorite mug. Like an old friend, the mug holds a special place in their hearts, and there’s a weird sadness when it finally gives up the ghost. Through the winter months [Ben’s] girlfriend is never without hers, and when it broke, he decided to give her a new one with some added functionality.

He built her a temperature sensing mug that uses a rather novel way of determining how hot or cold the contents are. Instead of using a thermistor to determine the drink’s temperature, he opted to use a simple diode since it is well known that a diode’s forward voltage varies with temperature. After determining the diode’s voltage range using hot and cold beverages, he hooked it up to the ADC of a PIC12F615 micro controller. The temperature is displayed via 10 LEDs, which are driven through a pair of 8-bit shift registers and buffers since his PIC did not have enough pins to control them on its own.

He had some PCBs made, and after a handful of setbacks got everything put together. He says the mug works pretty well, though the display changes a bit more slowly than he would like. He also mentions that if he builds a second version, he will be sure to select a different PIC that has enough I/O pins to do the job, as well as use a thermistor instead of a simple diode for sensing the temperature.

Continue reading to see a brief demo video [Ben] put together.

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Giant Scale Printer

April 11, 2011 by Jason Komp 16 Comments

Giant Printer Print Head

This giant printer was originally constructed by [Komponent/LAB] in 2006 to print some large-format banners for a festival, but has recently been pulled out of storage and updated for the Venture Cup competition. The system received a few mechanical and software updates and was also mounted on tripods in order to make it fully portable.

Instead of using stepper motors and encoders to directly control the print head as in a typical printer, the entire print axis is turned vertically and the relative lengths of two belts are varied (along with the constant downward pull of gravity) to precisely control movement across the plane. The software uses HPGL plotter files and is able to scale them to fit the available printing area.

Although there are some issues with the print head wobbling due to the rapid accelerations, any printed imperfections appear to be difficult to notice from more than a few feet away. Precision could be further increased by tweaking the software to compensate for such unwanted movements.

Although we can imagine many different applications for such a printer such as architectural or street art, some fine tuning would definitely be required at very large scales and to compensate for wind, etc if done outdoors.

Here are some pictures of the build and there is a short video of it in action after the jump.

[via GeekPhysical]

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Print Your Own Header Shrouds

April 11, 2011 by Mike Szczys 10 Comments

Don’t get us wrong, printable whistles are cool and all, but these printable header shrouds make us think that filament printers like the Makerbot and RepRap might just be worth their salt. This utilitarian purpose is a departure from the souvenirs, toys, and art that we’re used to seeing from the expensive development ~~toys~~ tools.

The six and ten pin header shrouds are designed for a snug fit that makes it easy to glue them onto the plastic spacers of male pin headers. We use IDC plugs and ribbon cable all the time in our projects, but never seem to order shrouded connectors; this is perfect for us. It makes us wonder what other PCB-friendly printable designs we’ve been missing out on? Surely someone’s been printing stand-offs with threaded inserts, right? If you know of something useful that we can share with the rest of the readers, don’t hesitate to send in a tip.

[via Dangerous Prototypes]

PIC-based Temperature Logger With Onboard Storage

April 10, 2011 by Mike Nathan 5 Comments

pic_temp_logger

Last summer, [Rajendra Bhatt] built himself a simple PIC-based temperature monitor with data logging abilities and recently got around to sharing it on his site. The sensor is based on a PIC12F683 micro controller and measures the ambient temperature on a set interval, storing the values on the MCU’s internal EEPROM.

He used a Maxim DS18B20 temperature sensor, which communicates with the PIC over a 1-wire bus. The sensor is read based upon the interval chosen by the user, and can be configured to measure the temperature every second, every minute, or every 10 minutes. The data is stored on the aforementioned EEPROM and can be uploaded to a computer via a serial connection. The PIC has the ability to store 254 readings before the data must be cleared from the device.

It’s a great beginner project, and has plenty of room for improvement. As [Rajendra] points out, an external EEPROM could be added to expand the recording capacity, and it would be nice to have a real-time clock on hand for accurate time stamping. If we were to build one ourselves, a means of wireless data transfer would be first on our list of potential enhancements.

Hackaday Reader Throwdown: Electronic Dice

April 10, 2011 by Mike Nathan 5 Comments

electronic_dice

Hackaday reader [Daid] posted in our forums showing off a set of electronic dice he recently constructed. Back in January, we featured a similar set of electronic dice built with an Arduino that was way overpowered as far as [Daid] was concerned. Not satisfied with simply saying it could be done better, he put his money where his mouth is – something we would love to see more of.

He used an ATTiny2313 to provide the device’s logic, outputting the dice values on a set of four 7 segment displays. The whole setup is controlled by a single push button that serves triple duty rolling the dice, configuring how many sides the dice have, as well as selecting how many dice are being thrown.

He admits that the wiring job is a bit of a mess, but he was going for function over form, and it works just fine. He also says that he would have finished it far sooner if it hadn’t been for ~~those meddling kids~~ some broken 7 segment displays.

We think he did quite a nice job, though we’re all ears if you think you can do it better.

Bolt Action Pneumatic Spud Gun

April 9, 2011 by Jesse Congdon 44 Comments

No one should ever make a potato cannon. They are wildly unsafe, powerful, and can easily shatter your neighbor’s gaudy bay window, you know the neighbor with the mean dog.

That said, [Jeremy Cook] made a minature bolt action spud gun! Using a custom machined Delrin bolt, a fitted Delrin reducer, and some PVC, the spud gun is capable of quickly loading custom shaved potatoes with the greatest of ease. Pushing the bolt (literally a bolt) forward forces the spud through the reduction coupling and into the barrel. Lock the bolt to the side, pull the trigger (an air blower) and two expansion chambers toss compressed air behind your starchy projectile. The design is reminiscent of a common bolt action rifle, but all that Delrin reminds us of paintball markers.

[Jeremy] is writing up the project in multiple posts, so check his blog for info. We are also no strangers to the strange, dangerous and wonderful world of potato launching tech.

Stick around for a video of the launcher in action!

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Light-sensing Circuit For Power Saving Applications

April 8, 2011 by Mike Nathan 6 Comments

light_sensing_circuit

Instructables user [MacDynamo] was thinking about home security systems and wondered how much electricity is being wasted while such systems are powered on, but not activated. He pondered it awhile, then designed a circuit that could be used to turn a security system on or off depending on the time of day, but without using any sort of clock.

His system relies on a 555 timer configured as a Schmitt trigger, with a photoresistor wired to the reset pin. When the ambient light levels drop far enough, the resistance on the reset pin increases, and the 555 timer breaks out of its reset loop. This causes the circuit to power on whatever is connected to it. When the sun rises, the resistance on the reset pin drops and the 555 timer continually resets until it gets dark again. He notes that this behavior can be easily reversed if you were to put the photoresistor on the trigger pin rather than the reset pin.

We like the idea, though we are a bit wary about using this for any sort of real security system. An errant insect or debris could cause the system to be turned on, and we’d feel pretty foolish if someone disabled our alarm with a flashlight. That said, this sort of circuit still has plenty of practical, power-saving applications outside the realm of home security.