Review: DSLogic Logic Analyzer

Logic analyzers historically have been the heavy artillery in an engineer’s arsenal. For many of us, the name invokes mental images of large HP and Tektronix iron with real CRT screens. Logic connections were made through pods, with hundreds of leads weaving their way back to the test equipment. The logic analyzer came out when all else failed, when even a four channel scope wasn’t enough to figure out your problems. Setting them up was a pain – if you were lucky, the analyzer had a PC keyboard interface. If not, you were stuck typing your signal names into the front panel keyboard. Once setup though, logic analyzers were great at finding bugs. You can see things you’d never see with another tool – like a data bus slowly settling out after the read or write strobe.

There have been a number of USB based logic analyzers introduced in recent years, but they didn’t really catch on until Saleae released their “Logic” line of devices. Low cost, high-speed, and easy to use – these devices were perfect. They also inspired an army of clone devices based upon the same Cypress Semiconductor parts. DSLogic designed by DreamSource Labs, can be thought of as an open source evolution of the original Saleae device.

DSLogic appeared in 2013 as a Kickstarter campaign for an open source logic analyzer with an optional oscilloscope extension. I think it’s safe to say that they did well, raising $111,497 USD, more than 10 times their initial goal of $10,000 USD. These days both the DSLogic and the oscilloscope extension are available at The Hackaday Store. In this review we’re focusing on the logic analyzer portion of the tool. 

Click past the break for the full story!

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Review: Transistor Tester

Amazon has been getting creepier and creepier lately with their recommendations.  Every time I log in, I’m presented with a list of new Blinky LEDs, Raspberry Pi accessories, Arduino shields, and the like. It’s as if they know me. Their customer database paid off when it recommended a $22 transistor / component tester. I’ve been seeing those testers around quite a bit lately. Curiosity got the better of me and my mouse found its way to the “Buy it now with one click” button. Two days later I had a “SainSmart Mega328 Transistor Tester Diode Triode Capacitance ESR Meter MOS/PNP/NPN L/C/R” in my hands.

I’m going to get the obvious out of the way. This thing is built cheap – as cheap as the factories can make it. My particular unit arrived with the LCD flapping in the breeze, hanging on by its flex cable. Fitting the LCD back into the acrylic backlight frame revealed a slightly worrisome twist in that same flex. Thankfully nothing was actually damaged, though I do want to give the flex cable some protection in the future. More on that later. The circuitry was open for all the world to see on the bottom of the tester. The heart of the unit is an ATmega328. Supporting it are a few transistors and a handful of passives.

I didn’t have huge expectations for the tester, but I hoped it would at least power up.  Hooking up a 9 volt battery and pressing the magic button brought the tester to life. Since I didn’t have anything in the socket, it quickly lit up and displayed its maker information – “91make.taobao.com”, and “By Efan & HaoQixin”, then it informed me that I had “No, unknown, or damaged part”.

I had a few resistors lying around the bench (doesn’t everyone?) so I put one in. The tester read it as 9881 ohms. Sure enough, it was a 10K 5% resistor.  Capacitors – ceramic disc, electrolytic, and surface mount all worked as well. The tester even provided ESR values. The real test would be a transistor. I pulled an old  2N2222 in a TO-18 metal can, and popped it in the tester. The damn thing worked – it showed the schematic symbol for an NPN transistor with Collector, Base, and Emitter connected to Pins 1,2,and 3 respectively. Flipping the pins around and re-testing worked as well. The tester showed hFe as 216, and forward voltage as 692 mV, both reasonable numbers for a 2N2222.

triacThe tester worked surprisingly well – it was able to correctly identify BJTs, FETs, even esoteric parts. The only thing it balked on was a linear voltage regulator, which showed up as two diodes. Regulators are a bit more than a simple device though, so I can’t blame the tester there.  The values returned were all reasonable as well. While I don’t have a calibrated lab to check against, the numbers lined up with my Fluke meter.

So what exactly is driving this little tester? There are about 20 versions of it on the market, all of them from China. 91make is a seller on taobao.com, often referred to as “China’s ebay.” 91make’s front page features no less than 7 versions of the transistor tester, with various cases and LCDs. Some digging turned up the history on this device. It turns out the transistor tester is an open source hardware project (translated) originally created by [Markus Frejek], and built upon by [Karl-Heinz Kubbeler] and a number of others. The Subversion repository  for the project shows it is quite active, with the most recent check-in only a few hours ago. The project is also well documented. The English PDF is 103 pages, explaining theory of operation, the circuit itself, and the software. The document even explains some of the shortcomings of the Chinese versions of the tester, including using a zener diode where the original schematic calls for a precision 2.5V reference. Yes, it will work, but it won’t be as accurate as the original.

The devs also don’t officially support the clones which I can understand, considering the quality and changes in design each manufacturer is baking in to their own version. There is  a huge thread on the EEVblog forum covering these testers. Some can be modified to be closer to the official version. In fact, with an ISP tool the intrepid hacker can update the firmware to the current rev from [Karl-Heinz’s] repository.

So the final verdict on this tester is that it is a thumbs up with a small caveat. These testers are built down to a cost (and that cost is as close to zero as possible). They’re great for sorting parts, but they’re no substitute for a higher quality measuring device. I’d also love to see a version that supports the original developers.

Repairing and Reviewing a 1976 PONG Clone

Hackaday alum [Todd] has been searching for an old PONG clone for the last two years. This variant is called, “The Name of the Game”. [Todd] has fond memories of playing this game with his sister when they were young. Unfortunately, being the hacker that he is, [Todd] tore the game apart when he was just 14 to build his own Commodore 64 peripherals. He’s been wanting to make it up to his sister ever since, and he finally found a copy of this game to give to his sister last Christmas.

After opening up the box, [Todd] quickly noticed something strange with the power connector. It looked a bit charred and was wiggling inside of the enclosure. This is indicative of a bad solder joint. [Todd] decided he’d better open it up and have a look before applying power to the device.

It was a good thing he did, because the power connector was barely connected at all. A simple soldering job fixed the problem. While the case was still opened, [Todd] did some sleuthing and noticed that someone else had likely made repairs to several other solder joints. He also looked for any possible short circuits, but everything else looked fine. The system ended up working perfectly the first time it was started.

The end of the video shows that even after all this time, simple games like this can still capture our attention and be fun to play for hours at a time. [Todd] is working on part 2 of this series, where he’ll do a much more in-depth review of the system. You can watch part 1 below. Continue reading “Repairing and Reviewing a 1976 PONG Clone”

Kick off the Christmas decorating with a review of 3 types of LED strings

[Todd Harrison] has been on a quest to replace his incandescent Christmas lights with less power hungry LED lights. There are plenty of options out there, but so far he hasn’t found any have the appearance he’s looking for. Since last year he bought three different kinds to try out and has posted a review of each.

Check out the strand of Brite Star Symphony Lights he’s showing off above. There is a white ‘Try Me’ button that lights up the string while still in the package! This offers fifteen bulbs each twelve inches apart. The strand draws 8.4 Watts when in use, you can connect up to 30 strands in series, and they are RGB lights with several different blinking patterns. He spends nearly an hour on this strand in his video review.

Next on his list is a set of Brite Star Classic Style C7 lights. They are single color and are meant to look like traditional large-bulb incandescent strands. At 2.4 Watts per strand you can string together 87 sets of them. This video is much more concise at around twenty-five minutes.

Finally he looks at the Brite Star 50 Mini LED strings. These are the traditional white Christmas tree lights, except in LED. One bulb every four inches on the string adds up to a 2.4 Watt power draw. You can string 58 sets together for a 1000 foot long string. [Todd] spends less than eight minutes reviewing this set.

You can see an intro video after the break but the full reviews are linked in his article. He really liked the Symphony Lights but the other strands have some issues. He discusses what he sees as design flaws in those strands and has decided they’re not really usable because of flickering.

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Parts: ChronoDot RTC Module (DS3231)

ChronoDot

Macetech’s ChronoDot is a Real Time Clock module for projects requiring highly accurate time keeping and measurement. The ChronoDot uses the DS3231 chip, which features a TCXO to compensate for variations in temperature which affect normal oscillators, like the ones in most microcontrollers. The DS3231 uses simple I2C commands and registers for storing and retrieving time, but also features a variable output that goes all the way down to 1.000 hz for low power, interrupt style timekeeping applications. With the provided watch battery, the ChronoDot can keep time in idle mode for up to 8 years.

Normally the ChronoDot comes mostly assembled, requiring you to only solder on the watch battery. However, due to a manufacturing mistake, Macetech is selling a version with the header pins on the wrong side they call the ChronoDoh. This module is currently nearly half off the regular price of $14.99, which makes it a great low cost addition to a project. Macetech has sent us a couple of these modules to demonstrate how functional they still are.

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DSO nano oscilloscope reviewed

dsonano

We’ve been eyeing Seeed Studio’s DSO nano digital storage oscilloscope with a mix of intrigue and skepticism. A pocket-sized $89 storage ’scope? This is a joke, right? Hack a Day reader [Blair Thomson] has written a thorough review based on his experience with one of the beta test units, and it might be a winner after all.

[Blair] feels the unit compares favorably to buying a similarly-priced secondhand analog oscilloscope. The DSO nano wins major points for ease of use, a good range of functionality, and of course the whole portability thing (the enclosure is a repurposed portable media player). Can’t say we’re entirely convinced though. As a single-trace ’scope with 1 MHz bandwidth, the DSO nano may be extremely limiting for anything but basic hobbyist use…which, to be fair, is exactly how they’re marketing it. We can see a place for this the same way there’s a place for $10 multimeters — an inexpensive, toss-in-the-toolbag second ’scope to quickly test for vital signs, something that might complement but not replace a good bench unit.

Pocket multimeter review

three_pocket_multimeters

Reader [Mikey Sklar] told us about a review he wrote covering 3 different models of pocket multimeters. We’re sure that you’ve had the same experiences we have being the go-to-guy or got-to-gal  for all things electrical. For our sort, having a multimeter on hand at all times has become an expectation.

[Mikey] looks at a model from ebay, Harbor Freight, and Radio Shack. Not surprisingly, the ebay offering doesn’t rate too well but does get the job done. We were surprised to read that he picked up the Cen-Tech model for about $10 at Harbor Freight. Although it may no longer be sold there (we haven’t checked) [Mikey] seems pretty happy with it so we’ll be on the lookout during our next tool-buying trip. We’re unfamiliar with the tiny Radio Shack 22-820 but we’ve always been happy with our larger 22-811. The 22-820 allows the probes to be folded up inside of the case cover for a truly pocketable package.

You can never have too many meters at your disposal and we’ll have to keep this article in mind the next time we’re shopping for another. Never used a multimeter before? Take a look at the tutorial [Mikey] linked to over at ladyada.