Broadcast Engineer at BellMedia, Computer history buff, compulsive deprecated, disparate hardware hoarder, R/C, robots, arduino, RF, and everything in between.
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Deal of the Day: 57% Off Star Wars Silicone Molds/Ice Tray (Set of 5) – $12.89

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Want to make ice cubes or chocolates shaped after your favorite Star Wars characters? This is of 5 silicone molds is just what you need! These are all made from 100% food grade pure silicone (no plastic fillers), are BPA free, and are non-toxic! Normally priced at $29.99, the mold are currently selling for just $12.89.

tray3

[Deal: 57% Star Wars Silicone Molds/Ice Tray (Set of 5) – $29.99 $12.89]

The post Deal of the Day: 57% Off Star Wars Silicone Molds/Ice Tray (Set of 5) – $12.89 appeared first on Geeks are Sexy Technology News.

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tekvax
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Cats in Famous Movie Scenes [Video]

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Cats make everything better as demonstrated by these felines that have been edited into famous movie scenes.

[PistolShrimps]

The post Cats in Famous Movie Scenes [Video] appeared first on Geeks are Sexy Technology News.

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Karaoke Night With The Muppets [Video]

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You’ve seen plenty of videos featuring the Muppets on the web, and they’re not all good, but this one is super entertaining! Check it out!

Ed Helms and The Muppets take on karaoke classics: the Spice Girls’ “Wannabe,” The B-52s’ “Love Shack,” The Sugarhill Gang’s “Rapper’s Delight,” Lisa Loeb’s “Stay,” Sonny and Cher’s “I Got You Babe,” Bette Midler’s “Wind Beneath My Wings,” and Journey’s “Don’t Stop Believin’.”

[ABC Television Network]

The post Karaoke Night With The Muppets [Video] appeared first on Geeks are Sexy Technology News.

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VCF East: A Retro Hackathon

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We got a banner.
We got a banner.

This weekend is the Vintage Computer Festival East in Wall, New Jersey. Every year is different, but there’s a general plan for each day. On Saturday and Sunday, the exhibits rule the con, the consignment shop is busy, and the keynotes bring down the house. Friday is a little different. This is the day for ‘in the trenches’ talks from the commodore crew, classes on recapping 30-year-old computers, and this year – for the first time – a retro hackathon. It’s basically the same format as any other hackathon, but instead of bringing MacBooks and building something cool, Apple IIs and Commodore 64s were provided. This is the report on the first retro hackathon we’ve ever been to.

The Apple II one-liner SIN graph
The Apple II one-liner SIN graph

First off, no one remembers how to program in BASIC. If you’re looking for a population that should remember the vagaries of the different dialects of BASIC, you would think it would be the people who came out to the middle of Jersey on Friday to talk about old CPUs. Apparently, this is not the case and several people were confused about single and double quotes in PRINT statements. Luckily, a few programming manuals for the C64 and Apple II were available, so everyone could still have fun with PEEKs and POKEs.

If you want to get people programming on some old machines, you need to give them some inspiration. The first half hour of the retro hackathon didn’t see any teams programming. Given this demographics proclivity to say, ‘I can do that better’, I typed a few BASIC one-liners in the C64 (random Truchet tiles in PETSCII) and Apple II (a SIN graph), and the people started pouring in. Yes, they could program something better than a single line of BASIC.

Truchet Hangman hangman2 Sound on an Apple IIc. lines3 lines hangman2 Hangman Truchet

What came of an impromptu retro hackathon? Hangman, in BASIC. No, it didn’t quite work, and there were only three or four possible words hardcoded into the program. Still, text mode graphics are a lost art. The Apple IIc was programmed to make fart noises. The original plan for this project was to program music. What would  have been the winning entry was a line-drawing program on the C64 that looked like the enemy in Qix. That guy wasn’t there during judging. The winner of a $50 credit to the consignment shop was a kid who programmed zero-player Pong on Apple II basic. He bought a Mac Portable (non-backlit) with that prize.

We’ve gone to hackathons, we’ve waded through the sea of MacBooks, and had a Red Bull drip installed. This retro hackathon was completely different, but somehow familiar. No, no one is going to create something new – everything that can be done on these machines in a few hours of BASIC programming has already been done. That’s not the point, though. It’s a geek pride of proving your mettle, putting your money where your mouth is, and doing it in a casual environment where everyone is friendly. This is the first retro hackathon we’ve gone to, and it won’t be the last. We’re going to do this again, once we get an Apple IIc+, a few Commodores, a Speccy, and a few good monitors. We already have the banner, anyway.


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Pillaging the Wealth of Information in a Datasheet

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It’s a fair assumption that the majority of Hackaday readers will be used to working with electronic components, they are the life blood of so many of the projects featured here. In a lot of cases those projects will feature very common components, those which have become commoditized through appearing across an enormous breadth of applications. We become familiar with those components through repeated use, and we build on that familiarity when we create our own circuits using them.

All manufacturers of electronic components will publish a datasheet for those components. A document containing all the pertinent information for a designer, including numerical parameters, graphs showing their characteristics, physical and thermal parameters, and some application information where needed. Back in the day they would be published as big thick books containing for example the sheets for all the components of a particular type from a manufacturer, but now they are available very conveniently online in PDF format from manufacturer or wholesaler websites.

A 2N3904 in a TO92 through-hole package
A 2N3904 in a TO92 through-hole package

Datasheets are a mine of information on the components they describe, but sometimes they can be rather impenetrable. There is a lot of information to be presented, indeed when the device in question is a highly integrated component such as a DSP or microprocessor the datasheet can resemble a medium-sized book. We’re sure that a lot of our readers will be completely at home in the pages of a datasheet, but equally it’s a concern that a section of the Hackaday audience will not be so familiar with them and will not receive their full benefit. Thus we’re going to examine and explain a datasheet in detail, and hopefully shed some light on what it contains.

The device whose datasheet we’ve chosen to put under the microscope is a transistor. The most basic building block of active semiconductor circuits, and the particular one we’ve chosen is a ubiquitous NPN signal transistor, the 2N3904. It’s been around for a very long time, having been introduced by Motorola in the 1960s, and has become the go-to device for a myriad circuits. You can buy 2N3904s made by a variety of manufacturers all of whom publish their own data sheets, but for the purposes of this article we’ll be using the PDF 2N3904 data sheet from ON Semiconductor, the spun-off former Motorola semiconductor division. You might find it worth your while opening this document in another window  or printing it out for reference alongside the rest of this article.

Let’s take a look at all the knowledge enshrined in this datasheet, and the engineering eye you sometimes need to assign meaning to those numbers, diagrams, and formulas.

The front page of the ON Semiconductor 2N3904 datasheet.
The front page of the ON Semiconductor 2N3904 datasheet.

Give it to Me Straight

The front page of a data sheet will have the information the manufacturer considers to be most important. This should include the basic electrical properties of a device, a succinct description of what it does, and assuming it is not a device with a myriad pins, information about its external connections. Unfortunately some manufacturers seem more driven by marketing considerations than technical ones, so from time to time you will find data sheets whose front pages feel more like sales brochures, leaving you to have to hunt through the pages for the most basic of information. Happily the folks at ON Semiconductor seem to have a good understanding of what an engineer really wants from the front page of a data sheet, so straight away you have a table of the 2N3904’s maximum electrical ratings and an identification of its external connections.

In the case of a transistor, that table of maximum ratings is probably the single most important set of information for the designer in the whole sheet. You may have special requirements for which you need to know more about the device, but these are the most fundamental parameters that tell you a lot about what the transistor is suitable for, and those that (should you ignore them) can result in it releasing its inner store of magic smoke and costing you the price of another transistor. These are the voltage, current, and power dissipation figures you will have in front of you when you calculate the DC bias circuit for your application, in order to ensure that you’re operating the device within its electrical capabilities.

You needs these when you are selecting a device, for example if you are building an audio amplifier you might be interested in the device power dissipation for an idea of how much power it might be capable of delivering to a loudspeaker. In the case of a 2N3904 you’ll see that after allowing for the heat dissipation inherent to a transistor operating in a linear mode it can only yield a few hundred milliwatts, so a more powerful transistor might be a better choice as an audio power amplifier.

I Want All the Data

datasheet-3904-characteristicsTurning the page, on page 2 of the datasheet we find a much more comprehensive table of parameters for the 2N3904. Off characteristics, on characteristics, small-signal characteristics, and switching characteristics.

The off characteristics relate to the device in the off state, which is to say when the voltage between base and emitter is below the roughly 0.7 volts required to start current flowing between collector and emitter. The breakdown voltages are the same ones that were in the table of maximum ratings on the previous page, they are the maximum voltages a 2N3904 can take before it is damaged. The cutoff currents though are different, they release no magic smoke, instead they are the tiny currents that still flow even when the transistor is turned off. You’ll notice they are measured in nA, nano-amperes, a very tiny figure indeed.

What is an ‘h’ Parameter?

The h parameter model. User Rohitbd [GFDL or CC-BY-SA-3.0 ], via Wikimedia Commons
The h parameter model. User Rohitbd [GFDL or CC-BY-SA-3.0 ], via Wikimedia Commons
Moving to the on characteristic table, we encounter our first h parameter, the current gain hFE. The h parameter model is a mathematical model for describing the operation of a transistor. It’s something first-year electronic engineering students agonize at length over, but fortunately to use the figures it generates you do not need to know it in detail. In the case of hFE, this figure is the current gain of a transistor, or the ratio between the base current and the collector current it generates for a constant collector-emitter voltage. You will often see the hFE figure simply referred to as the transistor’s gain. In the case of the 2N3904 this has a maximum value of 300, so in a transistor with that hFE value if you put 1mA into the base you will be able to measure 300mA flowing into the collector if the collector-emitter voltage is 1 volt. It’s a slightly artificial figure in the way mathematical models sometimes can be, but it gives a straightforward idea of how good an amplifier this transistor is likely to be.

The collector-emitter and base-emitter saturation voltages are the voltages at which those connections are at maximum forward bias and will go no further in terms of voltage. The base-emitter path, and the collector-emitter path when the transistor is in the on state can both be considered as though they were forward biased diodes. One of the properties of a forward biased diode is that the voltage across it remains nearly constant no matter the value of the current flowing through it, and it is that constant voltage which is being referred to for the two paths through the transistor. If you think a constant voltage might cause the transistor to cease amplifying though, think again. The bipolar transistor is a current amplifying device, so once the junctions are at their saturation voltages the current flowing in the collector will still be hFE times that flowing in the base and amplification will still occur.

3904-datasheet-small-signalThe small-signal characteristics relate to how the transistor performs as an AC amplifier. First up is the gain-bandwidth product, fT. It might be tempting to think that since the fT of a 2N3904 is 300MHz that the device might be usable up to that frequency, but this is a misleading figure. In fact it refers to the frequency at which the gain drops to 1, so the likely maximum frequency at which the device is useful will be considerably lower. In the case of a 2N3904 you would find it to be useful somewhere beyond 100MHz, for example.

Below the fT figure are the capacitances of the different parts of the transistor which will probably be of little importance in the majority of applications, followed by the rest of the h parameters. Again these are likely to be of little interest unless you are putting a 2N3904 into a modelling package. You will notice hfe, the small-signal AC counterpart of the DC hFE we mentioned earlier.

And finally in this section we have the noise figure. This is not a figure that will trouble you in the majority of applications but it is worth taking a moment to consider. If you are working in an environment in which noise considerations are important – perhaps a radio receiver or a demanding audio application – you will need to pay close attention to ensuring that this number is as low as you can make it in particular in the early stages of amplification. In this case the 2N3904 with a 5dB noise figure is not a particularly low-noise transistor, but then again it’s a general purpose workhorse rather than a high-performance thoroughbred.

How Well Does It Switch?

Below the small-signal characteristics is a table of the switching characteristics. If you imagine a perfect square wave, you might imagine it would appear on your oscilloscope screen as a sequence of sharp right angles. Every transition should be instantaneous from low to high voltage. In practice of course it doesn’t work that way. it takes a short time to traverse the gap. These are the parameters that give you those timings, and ultimately that tell you what the fastest logic signals a 2N3904 can handle are. You’d play close attention to these if you were designing fast logic circuitry, but for simple DC or analogue use they would not be something you’d need to know.

Rise and fall time test circuits for the 2N3904
Rise and fall time test circuits for the 2N3904

On page 3 of the 2N3904 datasheet you’re into the really irrelevant stuff for most Hackaday readers. Surprisingly, in many sheets this page would be further towards the back of the bundle. Ordering information, something that will interest you if you are buying ten million 2N3904s from ON Semiconductor, but since you are likely to get your transistors from a stockholder like RS, Farnell, Mouser, or DigiKey this section has little relevance. Below that are the circuits used to measure the switching characteristics, yet again something of great interest to a designer using the device in fast logic circuitry but not so gripping for others.

The next three pages have all the transistor’s parameters expressed as graphs. Now you might think that this would be the main event of a datasheet, and in some sheets you’d be right, but in the case of a transistor sheet it’s all very interesting in an Art of Electronics kind of way but you don’t need to bury yourself in them. You already know the pertinent information surrounding a 2N3904 from the first couple of pages, these graphs fill in the edge cases and tell you in more detail about how the device behaves. Fascinating if you are learning about how transistors work, but in most cases of straightforward transistor design you will not gain much from studying them.

And finally at the back of the datasheet, the package information. You’d expect the ordering information to be here too, but for some reason ON Semiconductor put that on page 3. Package information is something you might not consider important, however if you are creating a PCB you may find yourself spending a lot of time in this part of a datasheet. If your PCB CAD package doesn’t already have the device in its library you may have to create it. Even if there is a CAD footprint you had better ensure the dimensions match the part you are sourcing. It is the dimensions on this page that will ensure you get it right. If your device is surface-mount you will usually find a recommended area for its PCB lands with full dimensions, something that can save you a lot of trouble with wrongly-dimensioned boards.

Beyond this Datasheet

We hope this piece has helped demystify the manufacturer datasheet for you if you were intimidated by them. It’s a shame we only have a Hackaday article in which to cover this topic, for if we had looked at all the graphs in detail this would have made a decent sized book chapter. The 2N3904 is hardly an accomplished device, but with luck you’ll now know a little bit more about this most basic electronic building block.

Since we feel that the information contained in electronic component data sheets is often buried and not always fully understood, we’d like to feature more articles like this one. The example here is a transistor, but there is no reason why any of the other devices we use every day could not also be explored in depth, analog ICs, digital ICs, even passive components. Which devices would you like to see given this treatment? What are some of your favorite quirks and tidbits from other datasheets? Let us know in the comments below, and send in a tip for future articles.


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Belgrade Experience: MikroElektronika, Museums, and FPGA Computing

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I recently had the chance to visit Belgrade and take part in the Hackaday | Belgrade conference. Whenever I travel, I like to make some extra field trips to explore the area. This Serbian trip included a tour of electronics manufacturing, some excellent museums, and a startup that is weaving FPGAs into servers and PCIe cards.

MikroElektronika

After the second world war Serbia was part of Yugoslavia and the region was a manufacturing hub for the entire Soviet bloc. In particular, a lot of electronic components (resistors, capacitors, etc.) were manufactured here. Those types of components may no longer be made here, but there is still a strong electronics manufacturing hub and a good example is MikroElektronika, a company built in the footprints of some of the old factories. The building and business are anything but old, and they have been so successful they are planning a second large building to increase their manufacturing capacity. Sophi Kravitz and I were greeted by the CEO, Nebojsa Matić in the picture at the top of this post.

So many mikroBUS click boards! STM32 Development Board

MikroElektronika is well known for their mikroBUS click boards. These are standardized modules that host every sensor, display, input method, and communication scheme under the sun. Want a joystick? Yes. Bluetooth LE, ZigBee, WiFi, LoRa RF? All big yes. The image above shows the click boards that the customer support department had laid out for recent testing and this is far from all that are available.

MikroBUS is a standard for attaching peripherals which we’ve seen in many boards like the Microchip Curiosity. But of course MikroElektronika makes their own dev boards that use the form factor. Above is one of many development boards — this is for STM32 development but you name it an they probably have it — which includes a pair of mikroBUS slots in the upper right. The boards remind me of the 300-in-one electronics projects I did as a kid. Just add “embedded” to that title and we’re living in a brand new age.

Getting solder paste machine ready Solder paste stencil Aleksandar Nikolić explains equipment to Sophi Kravitz and me Selective soldering machine Huge pick-and-place machine Reels!

Once we had a look at the finished product it was off to see how everything is made. They have two sets of lines to populate all of their boards. Currently they do not make their own printed circuit boards but are hoping to change that with the new building. Once they get the PCBs from their fabricator, everything else is done on site.

Above you can see one of the technicians preparing the solder paste machine to apply paste to boards. From there it’s into a huge and impressive pick-and-place machine. Just seeing the reels feeding the machine is beautiful. They have reflow ovens for the surface mount components, and in another room (not pictured) there is wave soldering. For me, the coolest machine in the place was the selective soldering machine. It has an upturned pipe underneath the board that has overflowing molten solder coming out of it. The board moves over this wand to solder through-hole components. Here is a random video of a selective soldering machine to give you an idea of what’s going on here.

Museums

I was excited to get to the Museum of Science and Technology along with Mike Harrison and Chris Gammel. They have a huge exhibit of computer technologies and we dove right into the analog computers.

Pace patch board for programming Pace analog computer Analog calculator uses stylus for set up

This huge PACE computer is impressive to behold. You get a real sense of where we come from when taking a picture of it with the $200 smart phone that you carry around in your pocket. A big part of the programming is the patch board which harkens back to telephone operators patching calls between lines. There were a number of other analog computing devices on display as well, I enjoyed this handheld analog calculator which uses a stylus to set up the calculation.

Galaksija computer designed by Voja Antonic IMG_20160410_190046

I should have realized that this computer would be on display, but it was a happy shock to see the Galaksija computer. This was a build-it-yourself personal computer developed by Voja Antonić. In 1983 when personal computers were getting going in Silicon Valley, the chips being used were unavailable in Yugoslavia because of embargo. Voja figured out a way around all of those problems and about 8,000 kits were purchased to so that people for the first time could have their own computer. Of course we know Voja Antonić well, he has been writing amazing articles for Hackaday and designed the Hackaday | Belgrade badge. His conference talk on the hardware will be published soon.

Maxeler

Finally we visited the Belgrade office of Maxeler. They are a high-speed computing company who have created an FPGA-based platform that can be used as a power-house for certain types of algorithms. Offloading software loops to the highly-parallel hardware can bring huge speed increases.

PCIE fpga module 1U server contians up to 8 FPGA computing modules

The hardware comes in two form-factors. Shown on the left is a $5,000 PCIe card that you can load into a desktop computer. The company has been making these available to University programs to aid in research and get their platform out to programmers as they learn their craft. On the right is a 1U server blade which can be loaded with up to eight of the FPGA modules.

The hardware alone is one small part of the puzzle. The rest depends on customizing the software so it knows when to call in the big iron. Maxeler has a Java-like programming environmentto help with this, and a large part of their business is customizing client code to work with the hardware. One of the main use cases for Maxeler is financial analysis.

serbian-dinar-tesla

This is far from all we did in Belgrade, and there is much we didn’t get to. The city, the people, and the history is amazing. You will feel welcomed and wanting to return.

I didn’t make it to the Tesla museum this time around, but hopefully there will be another opportunity. Nikola Tesla, the famous inventor and forward thinker is from Serbia. I’ll leave you with this image of 100 Serbian Dinar note that bears his image (and now adorns my office bulletin board). But what about that equation?


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