[Dave Jones] got his hands on a really wide, 2-row Vacuum Fluorescent Display. We’ve come across these units in old equipment before and you can get them from the usual sources, both new and used, but you need to know how to drive them. This recent installment of the EEVblog reverse engineers this VFD.
The function of these displays is pretty easy to understand, and [Dave] covers that early in the video after the break. There is a cathode wire and phosphorescent coated anodes. When current is applied the anodes glow. To add control of which anodes are glowing a mesh grid is placed between the anodes and the cathode wire. Applying negative potential to the grid prevents the electrons from traveling to the anode so that area will not be lit.
Now driving this low-level stuff is not easy, but rest assured that most VFDs you find are going to have a driver attached to them. The reverse engineering is to figure out the protocol used to control that driver. On this board there is a 2-pin connector with a big electrolytic filtering cap which is a dead giveaway for power rails. Looking at the on-board processor which connects directly he ascertains that the input will be 5V regulated since this is what that chip will expect. Connecting his bench supply yields a blinking cursor! [Dave] goes on to pump parallel data and test out the control pins all using an Arduino. He finds success, sharing many great reverse engineering tips along the way.
We often call this type of thing a dark art, but that’s really just because there aren’t a lot of people who feel totally comfortable giving it a try. We think that needs to change, so follow this example and also go look at [Ben Heckendorn’s] recent LCD reverse engineering, then grab some equipment and give it a try for yourself. We want to hear about your accomplishments!
Continue reading “Reverse Engineer a VFD after Exploring How They Work”
[Dave Jones] shows us just how bad audio equipment can get with his white van speaker scam teardown (YouTube link). Hackaday Prize judge [Dave] has some great educational videos on his EEVblog YouTube channel, but we can’t get enough of his rants – especially when he’s ranting about cheap electronics. Check out his world’s “cheapest” camcorder teardown for a classic example
This week [Dave] is tearing down some white van speaker scam A/V equipment. The White Van Speaker Scam (WVSS) is an international hustle which has been around for decades. A pair of guys in a white van stop you in a parking lot, gas station, or other public area. They tell you they’ve got some brand new A/V equipment in the back of their van that they’ll give you for a “great deal”. The speakers are always in fancy packaging, and have a name that sounds like it could be some sort of high-end audiophile brand worth thousands.
Needless to say anyone who buys this equipment finds they’ve been duped and are now the proud owner of some equipment which only sounds good when hitting the bottom of a dumpster. Coincidentally, a dumpster is exactly where [Dave] found his WVSS equipment.
The case of his “Marc Vincent” surround sound system turned out to be nothing more than thin chipboard hot glued together. The electronics were of such shoddy quality that few words describe them – though [Dave] is always ready to improvise. From the ultra cheap subwoofer driver to the 1990’s era vacuum fluorescent display, everything was built down to the lowest cost while still looking nice from the outside. Even the ground wire was just tack soldered to the frame. We especially liked the three vacuum tubes that weren’t even soldered in. The leads were bent over to hold them onto a PCB, while a blue LED lit the tube from below.
Click past the break to see what [Dave] found inside his “3D Optics” projector.
Continue reading “EEVblog Tears into the White Van Speaker Scam”
For the last few years, very well-informed people have been able to tell if an alkaline battery is good or not simply by dropping them. When dropped from an inch or two above a hard surface, a good battery won’t bounce, and will sometimes land standing up. A dead battery, on the other hand, will bounce. Thanks to [Lee] and a few of his friends, we now know why this happens.
While hanging out with a few of his buddies, [Lee] was able to condense all the arguments on why dead batteries bounce to two theories. The first theory, the ‘bounce theory’ said dead batteries had an increase in outgassing in the battery, increasing the pressure in the battery, which increases the spring constant of the battery itself. The second theory, the ‘anti-bounce theory’, said the gel-like properties of the electrolyte worked as a sort of mass damper.
[Lee] designed an experiment to test the outgassing ‘bounce theory’ of bouncing batteries. Instead of dropping a battery, an object – in this case a brass slug – was dropped onto both good and bad batteries. There was no difference. Even after holes were drilled to vent any gasses inside the battery, the brass slug bounced off both good and bad batteries the same way.
This means the reason dead alkaline batteries bounce is due to the electrolyte. [Lee] cut open a few AA cells and found the electrolyte in a good battery was a mushy mess of chemicals. In the dead battery, this same electrolyte hardened into a solid mass. [Lee] compares this to an anti-bounce hammer.
Finally, more than a year after most of us learned about bouncing dead batteries thanks to [Dave Jones]’ video, we have an answer. It’s a chemical change in the electrolyte that turns it from a goo to a solid that makes dead batteries bounce.
Continue reading “The Reason Dead Batteries Bounce”
This week’s Judge Spotlight features [Dave Jones] who posted a video reponse to our slate of questions. If you’ve spent much time around here chances are you know of [Dave] quite well. He is the man behind the EEVblog and also hosts The Amp Hour podcast along with [Chris Gammell].
It’s great to pick [Dave’s] brain a bit. He’s seen a lot during his career, with insights on professional engineering from the point of view of job seeker, employer, job interviewer, and more. His time with the EEVblog and Amp Hour have furthered his experience with looks inside of all manner of equipment, adventures in crowd funding, and interactions with a multitude of hardware start-ups. Check out his video, as well as a list of the questions with timestamps, after the jump.
We’re sure you know by now, he’s judging The Hackaday Prize which will award a trip to space and hundreds of other prizes for showing off your connected device built using Open Design.
Continue reading “Judge Spotlight: Dave Jones”
It looks like [Dave Jones] got himself on a US government watch list. We don’t mean [Dave L. Jones], awesomesauce electronic wizard and host of eevblog, though. Some three-letter agency is just looking at someone named [David Jones]. Is this going to screw over our Aussie friend? You betcha.
[Dave] bought a few things through Element 14 that he would later pick up at their Sydney warehouse. When he got there, he discovered the parts were ‘on hold’. Out of curiosity, he asked what the holdup was and discovered his name was flagged on a US government watch list.
If you’re keeping score, this is an Australian citizen buying stuff from an Australian subsidiary of a UK company, and being told ‘no’ by the US government.
The folks behind the counter at the Element 14 warehouse were extremely helpful, clearing the hold and getting [Dave]’s parts in just a few minutes. This has, apparently, been going on for a while; [Dave] recalled a few times when orders showed up a few days late with the Farnell/Element 14 people apologizing with the word ‘hold’ in there somewhere.
Of course this means it’s possible for someone working at the Element 14 warehouse to clear one of these US government holds, and even if they don’t the order will still go through in a day or two. Government efficiency at its best.
At the time of this writing, [David Bowie], the singer for The Monkees, the creator of Grand Theft Auto, and the British author famous for perpetual motion machines were unavailable for comment. -ed.
Have you ever seen hard drive platters this big before? Of course you haven’t, the cost of this unit is way beyond your pay grade. But now that it’s decades old we get a chance to post around inside this beast. [Dave Jones] — who we haven’t seen around these parts in far too long — takes a look inside this $250,000 storage device.
In this episode of the EEVblog [Dave] is tearing down a late 1980’s IBM hard drive. This an IBM 3390. It stores either 1.78GB or 3.78GB. These days we’d never use a mechanical drive for that little storage as flash memory is so much cheaper. But this was cutting edge for servers of the day. And that’s why you’d pay a quarter of a million dollars for the thing.
[Dave] does what he’s known for in the video after the break. He energetically pours over every aspect of the hardware discussing function and design choices as he goes.
Continue reading “$250,000 hard drive teardown”
Have you ever wanted to see what it’s like inside of a PCB assembly factory? Have you ever wondered how digital storage oscilloscopes work? If so, be sure to check out the EEVblog podcast. The Electronics Engineering video blog podcast, hosted by [Dave Jones], was created for anyone interested in learning more about electrical engineering. While some knowledge of electronics definitely helps, [Dave]’s thorough explanations and firsthand knowledge in the field of electrical engineering make the video blog easily accessible to beginners in the field. The EEVblog covers a wide range of electronics related topics, offering everything from multimeter reviews to GSM mobile phone audio design advice. In the latest episode (shown above), [Dave] discusses and demonstrates how to solve the infinite resistor problem, involving measuring the resistance at different points of an infinite grid of resistors that all have the same resistance. In addition to giving a detailed explanation, [Dave] created a 14 x 14 grid of 420 10ohm resistors to demonstrate how to solve the problem. While we’ve only mentioned a few episodes here, be sure to check out all 25 episodes of the EEVblog podcast and subscribe to the RSS feed so you’ll never miss an episode.