UptownMaker

Woot! had a neat WowWee RC vehicle on the other day, and I sent a link to a coworker thinking he might dig the locomotion system (he's a mechanical engineer, but an okay guy nonetheless). Five minutes later, he shows up at my desk with this: He'd bought it years before, for no particular reason. He dug a bit and found a website that sells it , $9 a pop. Yet another really cool item I'll never get to use in a project.

So, I have a stream of data from a FireWire device I need to interpret as an image. I'll not get into the how or why of this, but the problem is pretty simple: take a file which is 250,848 bytes long, with each byte representing the 8-bit grayscale intensity of a single pixel in a 536 x 458 pixel image, and reconstruct that image. Turns out, finding an app to do this is a non-trivial problem. Sure, I could write something to do it (in the past, I've written a Scilab script that plots it, but that takes a lot of memory, runs slowly, and generally gives me few or no tools to deal with the "image" resulting, besides my eyes), but I KNOW this is a solved problem (my favorite term of late) and anything I came up with would likely be a south-pointing chariot. In the end, I turned to my old friend, ImageJ . ImageJ is a powerful, free, Java-based image manipulation and analysis tool. It's no replacement for GIMP or Photoshop, but it provides a very simple interface to...

With apologies to Quentin Tarantino... For a 10-year-old problem, the capacitor plague has been bizarrely present in my life recently. It started a couple of weeks ago when a coworker offered me an LCD TV that was "flaky" as scrap (my scraphound predilections are by now legend among those who know me). Being the upstanding gent I am, I pointed out that it was probably bad caps, and I found and replaced the buggers for him. A friend in Iowa sent me an e-mail, asking for help debugging a dead plasma he'd been gifted. He hasn't found bad caps yet but I'm fairly confident he will. My PC was dead the other morning, when I got to work. Guess why? A couple of months ago, I found a dead 17" LCD in the trash bin at the office. By now you should know how I fixed it. A tweep I follow posted this article this morning. This is fascinating for me in that it hits a number of points that people fail to understand about electronics: They wear out, but certain component...

A friend was asking after a circuit for making pulses from a pushbutton on push and release. Two ways immediately suggest themselves- using a PIC and using a differentiator. The PIC is easy for me, at least- I have a small stock of 12F683s which are 8-pin devices. Add a bypass cap and you're in business- you could even reprogram it to change the delay, debounce the input, etc. Of course, not everyone has a PIC programmer, and I feel like it's a pretty trivial app for a PIC, so I'll not talk much more about it. The differentiator circuit is a little more involved. Apologies for the crappiness of the image- LTSpice doesn't generate great output images, for one, and this was part of a larger image (it started NPN based, and generated negative going pulses; that's where Q3, Q4, etc etc went). V3 is the switch- in the application, it should be a 100-ohm pull-up to 5V and a switch that yanks C2 to ground when it's closed. R4 pulls up the base of Q3 and Q4, keeping the...

For those in the electronics world, SPICE simulation can be a great way to answer the "will my circuit work as advertised" question without breadboarding. It's a great sanity check- if it don't work in SPICE, it won't* work on a breadboard. LTSpice is Linear Technologies' own incarnation of SPICE. It's a nice little product, and comes with models for many of Linear's products (power supplies, op-amps, etc) along with many supporting components from other manufacturers (diodes, transistors, capacitors, inductors, etc) and generic parts (555s, LEDs, etc). Obviously, they provide it expecting people to download it, sim up a solution involving Linear parts and then sell eleventy-billion a year, thus providing a nice income stream for Linear (and it works- LTSpice makes it much more likely that I'll reach for a Linear part for power supply design than another manufacturer's parts). But for the tinkerer, it means that there's a free, very po...

A few weeks ago, I purchased 10 Atmega328P's from Mouser , naively thinking it would be easy enough to get them working on a breadboard as an Arduino sans the fancy (expensive) board. I was planning to use an FTDI USB to TTL serial data cable to bootload (I bought a 5V one, then realized that the two 3.3V ones I already had would work fine- lesson one of this saga). I also bought a some 16MHz crystals and the appropriate capacitors. At this point, I want to extend my thanks to whomever it was that decided a 6-pin AVRISP compatible ICSP header would be a value-add to the Arduino. I know that 95% of the Arduino users out there will NEVER use it, but I am very grateful. So, first hurdle- I figure I'll take one of the 328s and upgrade my Arduino (it was one of the, what, six? Duemilanove's that shipped with a 168 from the factory). Supposedly, the Arduino IDE has the capability of loading the bootloader onto a blank chip through an AVRISP, but I'll be buggered if I co...

Quick and dirty math post- The media reports the balloon was about 20' x 5'. Modeled in SketchUp as a 20' diameter sphere, shmooshed to a disc with a 5' vertical, that yields ~1000 cu. ft. of helium, or ~28,300L. As we all know, helium can lift 1.113g/L, for a total of about 31.5 kg of lift for that volume of gas. A quick Google search tells me the average 6-year-old boy weighs 46.2 pounds, or 21kg. That leaves 10.5 kg for the mass of the craft itself- about 23 pounds, or slightly less than the weight of three gallons of milk. I guess it's plausible, but I'm skeptical. I think it will come out that he was never on board in the first place.