Hackaday Links: March 12, 2013

Thankfully saved from steampunkers


[Chris] found a really cool pocket watch-style multimeter in a box of junk that was passed down from father to son. There aren’t any markings on it, so he’s looking for any information he can get on it. It’s a cool piece of vintage tech in any occasion; check out the pics he sent in below:

Here’s a fix for your illegal stuff


[Don] ‘acquired’ one of those China-only Raspberry Pis, but after plugging it in, only the power light would stay on. The fix, apparently, is putting these three files in the /boot folder of a Red Pi SD card.

Not a pocket watch


[Tom] picked up an old DC volt meter in an antiques shop. He quickly gutted it to make an analog meter display for his Raspberry Pi. There’s  a few status lights to remind [Tom] of something he hasn’t figured out yet. Bonus points for a cheap buck boost converter, though.

Smashing monitors? Really?

NESIT Hackerspace

The Meriden, CT hackerspace, the New England Society of Information and Technology, was vandalized last week. They’re dealing with some real punks here; their computers weren’t stolen, they were just smashed. NESIT is looking for donations (both money and equipment), so if you have a few monitors or old boxxen and live around there, consider donating them.

Help a guy out here.


[Jonathan] is a real cool dude that’s working on his master’s thesis on ways to build a sustainable company through the development of open source hardware. He wants you to take a survey. How do we know he’s cool? He had something posted on HaD back when we had the old black and white and scotch tape images.

Volt meter clock also displays the temperature

[IronJungle] got around to putting together every tinkerers favorite project: a clock with a strange way of displaying the time. For his clock, [Jungle] took a trio of voltmeters and turned them into a clock that displays the current hour, minute, and second on custom paper dials.

[IronJungle] connected a PIC 14M2 microcontroller to a DS1307 real time clock to keep track of the current time. As for display, [Jungle] took a trio of volt meters and wired them in to the PWM outputs on his PIC. With this, he was able to precisely control the position of the needle in the meter, and thus display the time.

In addition to displaying the time, [IronJungle] added a small temperature sensor to his build. By pressing a button below the seconds display, the clock is able to display the current temperature in Fahrenheit, Celsius, and Kelvin.

After the break you can check out a time-lapse video of [IronJungle]‘s voltmeter clock going through the hours.

[Read more...]

Millivolt meter Nixie clock

Surprisingly, up until a year ago, [Jimmy] hadn’t seen a Nixie tube. Awful we know, but he has come around to the beauty of glowing numbers in a tube. He recently found an old millivolt meter in a junk pile that used Nixie tubes. The wondrous orange glow beckoned him, so [Jimmy] decided to build a clock.

Just about all of the Nixie clocks we’ve seen (including non-clock builds) rely on building a controller for the Nixie tubes. The controllers range from Nixie Arduino shields to the good ‘ol 74141 IC. [Jimmy] realized he didn’t need to bother with controlling the tubes in an already functional millivolt meter – he only needed to send the right voltage.

For his clock build, [Jimmy] used an Arduino to output a voltage through a bunch of resistor dividers. For example, if the time is 12:30, the output voltage will be 12.30mV. Using this technique, the values for the needed resistors don’t exist, so a little bit of PWM means the Arduino keeps fairly good time.

There’s one added bonus of [Jimmy]‘s clock – because the voltage varies around 0.01mV, the finished project acts like a digital version of Lord Vetinari’s clock. It may not be perfect, but at least a nice piece of equipment was saved from the trash.