We don’t think [VK4FFAB] did himself a favor by calling his seven-part LTSpice tutorial LTSpice for Radio Amateurs. Sure, the posts do focus on radio frequency analysis, but these days lots of people are involved in radio work that aren’t necessarily hams.
Either way, if you are interested in simulating RF amplifiers and filters, you ought to check these posts out. Of course, the first few cover simple things like voltage dividers just to get your feet wet. The final part even covers a double-balanced mixer with some transformers, so there’s quite a range of material.
Continue reading “LTSpice for Radio Amateurs (and Others)”
After getting a power supply and a multimeter, the next piece of gear a hacker would want to add to their bench is the oscilloscope. Nowadays, even the cheapest ones cost a few hundred dollars yet pack in the features. At the other end of the scale, if you can pony up close to a million dollars, you can help yourself to an oscilloscope capable of 100 GHz bandwidth and 240 GS/s sampling rate. With that perspective, it becomes interesting to take a look at this video (embedded below), where [Jack Ganssle] shows us the Philco 7019 Junior Scope which was introduced way back in 1946. It seems the Philco 7019 model was an identical re-badged version of the Waterman Model S-10-A PocketScope.
[Jack] is familiar to all of us as an embedded systems engineer, but in this video he does a teardown of this vintage analog model. He starts off by walking us through the various controls, of which there are not a lot, in this “portable” instrument. At around the 3:40 mark in the video, he’ll make you wince as he uses a screwdriver and hammer combo to smash another ’40’s vintage CRT just so he can show us it’s innards — the electron beam source and the horizontal and vertical deflection plates. The circuit is about as bare-bones as it can get. Besides the CRT, there are just three vacuum tubes. One is the rectifier for the power supply, a second one is used for the vertical amplifier while the third one is the free running horizontal sweep oscillator. There is no triggering option — you just adjust the sweep frequency via a potentiometer as best you can. It does have internal, external and line frequency function selection, but it still requires manual adjustment of the sweep oscillator. There’s no blanking signal either, so the return sweep is always clearly visible. This is evident from the horizontal burn mark on the phosphor of the CRT after decades of use. It’s amusing to see that the vertical position could be adjusted by moving a magnet attached to the side cover.
The Oscilloscope Museum website hosts the Instruction Manual for this model, as well as a sales brochure which makes for very interesting reading after viewing [Jack]’s video.
Thanks, [Itay], for the tip.
Continue reading “Taking Apart a Vintage Oscilloscope”
We’ve seen a lot of interest in LSM (LASER Scanning Microscopes) lately. [Stoppi71] uses an Arduino, a CD drive, and–of all things–two speakers in his build. The speakers are used to move the sample by very small amounts.
The speakers create motion in the X and Y axis depending on the voltage fed to them via a digital analog converter. [Stoppi71] claims this technique can produce motion in the micron range. His results seem to prove that out. You can see a video about the device, below.
Continue reading “Speakers Make a LASER Scanning Microscope”
Way back in the before years when there were still interesting concepts for reality TV, Nate Seidle blew up a power supply in his dorm room. Instead of finding replacement parts, Nate decided to start a company. For the last decade and a half, SparkFun has grown immensely, been an incredible resource for makers and engineers alike, and shipped out hundreds of thousands of their iconic red boxes.
Being the CEO of a company means you need to do CEO stuff, and a few summers ago Nate the CEO became Nate the Engineer once again. SparkFun is still doing great, but now we know what Nate has been up to these last months. He’s getting back to SparkFun’s roots with SparkX. This is the newest stuff SparkFun has to offer, there is zero documentation or support, and they’re only developing products because Nate wants to.
In a series of blog posts on the SparkFun blog, Nate goes over what is involved in building a new brand for the latest and greatest SparkFun can produce. This involves setting up the SparkX lab, getting the OtherMills pumping out circuit boards, and inevitably the occasional containment failure of the blue smoke.
The first product in the SparkX lineup, Product 0, is a breakout board for the MLX90393 magnetometer. This is a pretty nifty magnetometer that Ted Yapo over on hackaday.io has used to characterize magnets. Really, though, the SparkX Product 0 is exactly what it says on the tin: a breakout board that is just an experiment, comes with no guarantees or support. It is the heart of what Sparkfun set out to do twenty years ago.
Address Space Layout Randomization or ASLR is an important defense mechanism that can mitigate known and, most importantly, unknown security flaws. ASLR makes it harder for a malicious program to compromise a system by, as the name implies, randomizing the process addresses when the main program is launched. This means that it is unlikely to reliably jump to a particular exploited function in memory or some piece of shellcode planted by an attacker.
ASLR have been broken before in some particular scenarios but this new attack highlights a more profound problem. Since it exploits the way that the memory management unit (MMU) of modern processors uses the cache hierarchy of the processor in order to improve the performance of page table walks, this means that the flaw is in the hardware itself, not the software that is running. There are some steps that the software vendors can take to try to mitigate this issue but a full and proper fix will mean replacing or upgrading hardware itself.
In their paper, researchers reached a dramatic conclusion:
Continue reading “ASLR^CACHE Attack Defeats Address Space Layout Randomization”
Whenever I end up with a new vehicle I ultimately end up sticking in a new GPS/Receiver combination for better sound quality and a better GPS.
I am quite at home tearing into a dashboard as I was licensed to install CB radios in my teens as well as being the local go-to guy for 8-track stereo upgrades in the 70’s. I have spent a portion of my life laying upside down in a puddle on the car floor peering up into the mess of wires and brackets trying to keep things from dropping on my face. If you remember my post on my Datsun 280ZXT, I laid in that same position while welding in a clutch pedal bracket while getting very little welding slag on my face. I did make a note that the next time I convert a car from an automatic to a manual to do so while things are still disassembled.
Swapping out a factory radio usually involves choosing whether to hack into the existing factory wiring wire-by-wire, or my preference, getting a cable harness that mates with the factory plug and making an adapter out of it by splicing it to the connector that comes with the new radio.
Usually I still have to hunt down a few signals such as reverse indicator, parking brake indicator, vehicle speed sensor and the like. In my last vehicle the Vehicle Speed Sensor (VSS) wire was supposed to be in the factory harness, but driving experience showed it must not be as the GPS would show me driving 30 feet to the right of the highway. That and the calibration screen on the GPS verified that it was not receiving speed pulses.
Continue reading “Bil Herd Asks OBD “How Fast am I Going?””
[Max K] has been testing the battery life of his self-designed watch under real-world conditions. Six months later, the nominally 3 V, 160 mAh CR2025 cell is reading 2.85 V, so the end is near, but that’s quite a feat for a home-engineered smart watch.
We’ve tipped our hats to the Chronio before in this Hacklet, but now that the code is available, as well as the sweet 3D-printed case files, it’s time to make your own. Why? It looks sweet, it plays a limited version of Flappy Bird (embedded below), and six month’s on a button cell is a pretty great accomplishment, considering that it’s driving a 96×96 pixel LCD display.
The Chronio is more than inspired by the Pebble watch — he based his 3D model directly on theirs — so that’s bound to draw comparisons. The Pebble is color, and has Bluetooth and everything else under the sun. But after a few weeks away from a power socket, ask a Pebble wearer what time it is. Bazinga!
Continue reading “Chronio DIY Watch: Slick and Low Power”