Nice.

One of the challenges of working with a project like this that uses “exotic displays” such as Vacuum Fluorescent or Nixie Tubes is that these displays are very fickle with the way they are driven. VFDs typically need about 20-80 volts to light up the anode/grid segments of the display, and because they are vacuum tubes, they also need a filament to be heated up with about 1-5 volts.

There are a variety of ways to get the higher voltages. If the tubes you are using are not too picky you might get away with 12-24 volts, but if you want to support a variety of displays, and if you want to be able to drive the displays with multiplexing (i.e. flashing the segments+digits one at a time, in rapid succession), then you will need up yo 80v.

I have very little knowledge of analog circuitry and switch-mode power supplies, so I wanted to change that, and researched various ways to get the voltages I would need, and settled on a switch-mode PSU based on the MAX1771 step-up converter. After some trial and error with procuring the right components, I settled on a design based on this switch-mode power supply. This circuit was designed for nixies, which need up to 250 volts. It’s overkill for my current requirements but I want to support a variety of displays, and may use nixies at some point.

It took me a long time to get this working and I smoked a few mosfets and 1771s along the way, so it was pure joy when I saw the voltmeter jump up to 50v. After playing with some resistor values I soon had it cranking out 250v from a 5v supply. I added a trimpot to make it adjustable from about 25-100v.

I then got out one of the russian IV-18 tubes from my collection and hooked it into a breadboard, and ran 5v into a trimpot and then to the filament, and ran the HV power to the anodes/grid. After some trial and error I finally got it to light up. It seems to like about 60v.

The IV-18 tubes more than are worthy of a close-up. I am quite enamoured with them.

I’m making a few minor updates to the clock design, specifically for the prototype. I’m not as fond of this shape, it’s now 3″ high instead of 2″, not as sleek, but this initial prototype is more about getting everything functional, and will allow more room for error when fitting all the electronics in. Once we have all the components in there, we can see about shrinking it down.

There are now two knobs instead of one. The one on the top will be for alarm functions, and the one on the back will be for time functions. In many hardware interface designs we see instances where many controls can be accessed from a single point, in this case a knob. The downfall in that approach is that you end up lumping together the more commonly-used functions with the less commonly-used. So for example, if most of the time people just want to adjust the alarm time, but they end up paging through the current time, date, etc…, it becomes more cumbersome than it needs to be.

With a single rotary encoder, there is no “back” button, so the user cannot page back if they accidentally skip over the function they want, so they have to click several times to come back to the page they meant to be on. So by having one knob for the alarm, and one for the time, the user will have to do less paging, and they will be less likely to make any mistakes, such as changing the current time.

Make: television Preview – Music Machines from make magazine on Vimeo.

This is me when I retire.

The “What is a switch?” project is a Tellart classic.

It takes the form of a workshop or a longer course, and, by using low-cost materials and familiar design tools, is meant to demystify electronics for design students and artists – expanding their conception of what it means to design with embedded electronics.

via What is a Switch? – Tellart [stream].

This is the first prototype of the Alarm Clock Project. It is currently hooked up to a doorbell chime. This demos the user interaction style with the rotary encoder. The 5-digit number on the top line is for debugging – it represents the time of day expressed in total seconds elapsed since midnight.

I think I fried my programmer. I knew something bad happened when I shorted 24v into the voltage regulator. So I must have killed the programmer along with it. Now it shorts out my circuits every time I connect it. I doubt there is anything I can do now.  I have AVRStudio running on WindowsXP, running on Parallels, runnong on my iMac, and this little programmer worked through it all without any complaints. I’ll miss this little guy. It might be time to move on to the Arduino platform, considering I can get a USB development board for about $40, and a new programmer will run be about $150.

CHRIS SORENSEN

BUSINESS REPORTER

As many as 129,000 cellphones made by Korean conglomerate LG are being recalled across Canada because they may not meet federal guidelines for radio frequency exposure.

The voluntary recall was issued after tests found the LG 150, a black flip phone, did not meet Industry Canada specifications for radio frequency emissions, resulting in the device being decertified.

via TheStar.com | Business | Company recalls LG 150 cellphones

It’s one thing for a company to release a product that doesn’t meet the needs or  expectations of their users, it is a whole other thing when they release a product that is a potential health hazard. The LG 150 may be one of hundreds of canary corpses in the mobility coalmine.

Does it even matter when health warnings on mobile phones are substantiated? People keep using them anyway, just like people continue to eat junk food and drink and drive. For better or worse, cell phones have replaced the cigarette as the ubiquitous vice accessory. And just like tobacco, governments are in no hurry to act on the warnings from the scientific community.

With its most important numbers rendered in supersized Helvetica—9 a.m. arrival, lunch at noon, out the door by 5—Swedish firm BVD’s new Klocka clock for Askul looks like it’s for a 1950s businessman, which actually makes sense. The Tokyo-based company—whose name means “delivery following day and in Japan is a strange mix of Amazon.com and FedEx, is known mainly for its office products; BVD’s other recent designs for the Japanese giant include candy-colored packaging for USB sticks and a series of Muji-like pens. www.bvd.se

via I.D. – I.D. Magazine – New + Notable Product Designs.

I could use a few of these around the house.