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Oscilloscopes For Modern Engineers?

John Miles Re: Price (337 comments)

Are you sure you're not talking about an 8000-series scope, rather than a 6000-series one? My MSO6054A was about $8500 on eBay, new in box but about half normal retail, and Agilent was running a special where they'd enable the maximum memory (8M points, which is actually just a software option) for free.

There's definitely no way to get 256M points on this particular scope, or to pay $100,000 for one.

But yeah, firmware support from Agilent has been outstanding. The DSO/MSO6000 line is rather 'mature' at this point, and they have released updates that enable a lot of features for free (8M, waveform statistics, RS-232 lister, and tracking cursors).

more than 4 years ago
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Oscilloscopes For Modern Engineers?

John Miles Re:An old Tektronix is fine for a modern engineer (337 comments)

I like the Tek 2430/2432/2440 scopes a lot, and used one for years in conjunction with a 2467, for those cases where analog-scope performance was needed. Apart from a few considerations like record length, this combination could easily stand up to any DSO costing less than several thousand dollars.

With the 2430-series scopes, the key points to watch out for are 1) make sure it passes its power-up self tests, as the CCD chips used for acquisition are no longer available; 2) avoid the original 2430s with no GPIB port if you think you will ever want to record screenshots from it; and 3) always use an external fan to cool the chips on the main board when servicing it. These scopes seriously stretched the performance envelope available at the time, and those custom chips can be replaced only by buying a parts mule.

Of course, if good ones are going for $200 with probes, it's probably a good idea to just go ahead and spend another $50-$100 on a parts unit to go with it...

more than 4 years ago
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White House Panel Seeks Input On Spaceflight Plans

John Miles Re:How about "Robots Only" (224 comments)

You don't want random nut to fly to Mars just to go bat shit insane and wreck perfectly good experiment.

Why not? The movie rights alone would pay for the mission.

more than 5 years ago
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White House Panel Seeks Input On Spaceflight Plans

John Miles Re:How about "Robots Only" (224 comments)

Which is clearly not the case based on experiences with the mars rovers and similar devices.

Ridiculous. Think of one of the most interesting discoveries made by the Phoenix lander -- the frozen condensate that formed on one of the landing struts. A human would have noticed that immediately and been able to analyze it in detail. Conversely, a robotic probe can do only what it's programmed to do. All we can do is stroke our beards and say "Hmm, wonder what that is?"

When you're not only expecting the unexpected, but hoping for it, you want human boots on the ground. One human mission is easily worth twenty robotic missions.

Hell, NASA should consider offering one-way trips. They'd have enough volunteers to crash their Web server. Most people aren't doing anything that important or interesting with the rest of their lives, are they? Send one old guy with a shovel, a microscope, and a carbon-monoxide canister, and we'll learn more than we would from the next hundred years' worth of robots.

more than 5 years ago
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Suggestions For Learning FPGA Development At Home?

John Miles Re:I like the Digilent Nexys2 (185 comments)

Of course, the problem is that I don't know of anyone who can comfortably solder BGA chips.

People have been doing it with toaster ovens (http://www.instructables.com/id/Toaster-Oven-Reflow-Soldering-BGA/ and http://www.sparkfun.com/commerce/tutorial_info.php?tutorials_id=60&page=). I haven't tried that yet. I have soldered QFNs by laying down some solder paste and blasting the other side of the board with a heat gun, but it's a high-pucker-factor operation. I plan to try the toaster oven hack the next time I need to do that.

more than 5 years ago
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Suggestions For Learning FPGA Development At Home?

John Miles Re:I like the Digilent Nexys2 (185 comments)

True, but I was not able to get the FX2's pipe to operate reliably on every edge of IFCLK. This might have to do with the fact that my data transfer FPGA logic is clocked off IFCLK as well, but might be a limitation of the FX2 or board design.

Clocking the FPGA from the 48 MHz IFCLK is the right thing to do IMHO. That's how my setup's working. Email me offline if you want a code dump; no guarantees that it's optimal or even "correct", but I've run it for several days at a time without any problems.

You aren't trying to use asynchronous writes, are you? Those can't be pushed beyond about 6 MB/sec from what I could tell.

Also, what USB driver are you using? CyUSB? If so, make sure you use overlapped reads or you'll miss tons of data.

I agree that Gigabit (or 10G) is the way to go, but do you know of any convenient boards (like Nexys) for that ? Thank you !

Unfortunately, no... it seems there are numerous boards with 10/100 Ethernet interfaces but I haven't seen any GigE or better, except for the expensive Virtex-based ones like the NetFPGA board. Digilent had something called the FX12 for awhile that had a Webpack-supported Virtex chip and a GigE port, but it's been discontinued.

more than 5 years ago
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A History of Early Text Adventure Games

John Miles Re:Proof Graphics != Good Game (130 comments)

I really want to see some level of text based gaming come back.

Text gaming didn't leave, it just went indie. Some of the best works since the Infocom days have appeared in the annual rec.arts.int-fiction competition, the 15th of which is in progress now.

Someone below mentioned Photopia, and that's a good place to start (it took first place in the IF competition nine or ten years ago).

more than 5 years ago
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Suggestions For Learning FPGA Development At Home?

John Miles Re:I like the Digilent Nexys2 (185 comments)

I don't think the 8-bit path between the CY68013 and FPGA is a bottleneck, really. With an IFCLK of 48 MHz, you'd have to be able to shove 48 MBytes/sec through the endpoint to be bus-width limited, and that just isn't going to happen over USB 2.0. You'll have to spin on FIFO-full either way.

In practice about 32 MBytes/sec is about the best you can count on achieving, although I understand that the GNU Radio guys are pushing 40 MB/sec with some 8051 bus-mastering hacks.

Seems that most of the speed-constrained designs are moving to Gigabit Ethernet these days, avoiding the problem entirely.

more than 5 years ago
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Suggestions For Learning FPGA Development At Home?

John Miles Re:Try these modules (185 comments)

Opal Kelly modules are clean, well-documented designs, but because of their relatively high cost they're better thought of as embeddable modules rather than as learning platforms. For education and basic home tinkering, you want a cheap well-documented board with lots of peripherals to play with.

I think the best overall learning platform right now is the Nexys2. You can teach yourself everything from USB interfacing to VHDL/Verilog design for $129, and it's got a lot of switches, lights, ports, and outboard RAM to play with.

There are also a couple of reasonably priced books written especially for novices learning logic design with the Digilent platforms. $200 will get you both the basic- and advanced-level books from LBE and a Nexys2 to do the exercises. Very hard to beat that combination IMHO. (You can use the Nexys2 with the first book, even though it was written for the lower-end Basys board.)

more than 5 years ago
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Suggestions For Learning FPGA Development At Home?

John Miles Re:Don't buy a board and CtoVerilog.com (185 comments)

For a newbie, CtoVerilog.com is the mother of all bad ideas. Verilog is not isomorphic to C. Being able to represent a few trivial C loops as Verilog code will not help you learn what's going on under the hood, and it will not help you get the fundamental aspects of your design up and running.

Also, much of what's done in HDL is gluing other chips together. If you try to use CtoVerilog to make a high-speed USB chip talk to an ADC, the results will be amusing at best. If you find yourself wanting to use C in an HDL design, consider either falling back to a conventional microcontroller or using a software core to run it.

more than 5 years ago
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I'd rather measure my days by means of ...

John Miles Re:What, no atomic decomposition? (534 comments)

At the least, they're more accurate than atomic clocks - when someone first tried measuring how accurate quasars are by comparing them to an atomic clock, they found that ALL quasars were drifting at the same amount relative to the atomic clock - the drift was the clock, not the quasars.

Do you have a cite for this?

more than 5 years ago
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History of the LED — the Movie

John Miles Re:YouTube Illumination (106 comments)

Very few electronic parts will fail to produce light, if biased properly.

more than 5 years ago
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Good Deep-Knowledge Analog Design Books?

John Miles Re:Some Good PDF Op-Amp References (65 comments)

I agree, it'd be a good idea to have all of those app notes in one place. You might zip them up into one archive file and upload it to the "Manuals" link at http://www.ko4bb.com/ . (Various people have been stashing EPROM images, useful emails, spreadsheets, and other resources in that directory, not just manuals.)

more than 5 years ago
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Australia Developing Massive Electric Vehicle Grid

John Miles Re:Where are they getting the power? (260 comments)

Those aren't rolling blackouts. Those electrons were used to create child pornography.

What -- do you support child pornography, or something?

about 6 years ago

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