Gas station without pumps

2017 February 18

Digilent’s OpenScope

Filed under: Uncategorized — gasstationwithoutpumps @ 10:08
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Digilent, which makes the excellent Analog Discovery 2 USB oscilloscope, which I have praised in several previous post, is running a Kickstarter campaign for a lower-cost oscilloscope: OpenScope: Instrumentation for Everyone by Digilent — Kickstarter.

I’m a little confused about this design, though, as is it is a much lower-quality instrument without a much lower price tag (they’re looking at $100 instead of the $180 or $280 price of the Analog Discovery 2, so it is cheaper, but the specs are much, much worse). The OpenScope looks like a hobbyist attempt at an oscilloscope, unlike the very professional work of the Analog Discovery 2—it is a real step backwards for Digilent.

Hardware Limitations:

  • only a 2MHz bandwidth and 6.25MHz sampling rate (much lower than the 30MHz bandwidth and 100MHz sampling of the Analog Discovery 2)
  • 2 analog channels with shared ground (instead of differential channels)
  • 12-bit resolution (instead of 14-bit)
  • 1 function generator with 1MHz bandwidth and 10MHz sampling (instead of 2 channels 14MHz bandwidth, 100MHz sampling)
  • ±4V programmable power supply up to 50mA (instead of ±5V up to 700mA)
  • no case (you have to 3D print one, or buy one separately)

On the plus side, it looks like they’ll be basing their interface on the Waveforms software that they use for their real USB oscilloscope, which is a decent user interface (unlike many other USB oscilloscopes).  They’ll be doing it all in web browsers though, which makes cross-platform compatibility easier, at the expense of really messy programming and possibly difficulty in handling files well.  The capabilities they list for the software are much more limited than Waveforms 2015, so this may be a somewhat crippled interface.

I would certainly recommend to students and educators that the $180 for the Analog Discovery 2 is a much, much better investment than the rather limited capabilities of the OpenScope.  For a hobbyist who can’t get the academic discount, $280 for the Analog Discovery 2 is probably still a better deal than $100 for the OpenScope. The Analog Discovery 2 and a laptop can replace most of an electronics bench for audio and low-frequency RF work, but the OpenScope is much less capable.

The only hobbyist advantage I can see for the OpenScope (other than the slightly lower price) is that they are opening up the software and firmware, so that hobbyists can hack it.  The hardware is so much more limited, though, that this is not as enticing as it might be.

Some people might be attracted by the WiFi capability, but since power has to be supplied by either USB or a wall wart, I don’t see this as being a huge win.  I suppose there are some battery-powered applications for which not being tethered could make a difference (an oscilloscope built into a mobile robot, for example).

Going from a high-quality professional USB scope to a merely adequate hobbyist scope for not much less money makes no sense to me. It would have made more sense to me if they had come out with OpenScope 5 years ago, and later developed the Analog Discovery 2 as a greatly improved upgrade.

2017 February 6

Every second counts

Filed under: Uncategorized — gasstationwithoutpumps @ 21:03

I’ve been enjoying the videos at http://everysecondcounts.eu/, which were started by a Netherlands comedy show in response to Trump’s America First speech.  They made a fake tourism video, with an excellent Trump voice impersonator, arguing for making the Netherlands second.

Other comedy shows soon took up the challenge creating their own mock tourism videos (I particularly liked Denmark’s entry and Germany’s).

There are now nine videos, with more undoubtedly in the pipeline.

2017 January 8

Applying for Mini Maker Faire 2017

Filed under: Uncategorized — gasstationwithoutpumps @ 17:41
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I’m submitting an application for the Santa Cruz Mini Maker Faire 2017 (2017 April 29), since last year’s Mini-Maker Faire went well (see Santa Cruz Mini Maker Faire went well).  This year I’m getting my application in early, rather than dithering about it for months as I did last year.  I have less free time to prepare the display this year, but I have a better notion what I want to do, so it should not take long to get ready.

Last year's banner, which I can reuse this year. I might also make a shorter one that will fit on the front of the table.

Last year’s banner, which I can reuse this year. I might also make a shorter one that will fit on the front of the table.

The “non-public” description of my display is straightforward:

I’ll bring a tabletop full of electronics projects, as last year (see https://gasstationwithoutpumps.wordpress.com/2016/04/16/santa-cruz-mini-maker-faire-went-well/ ).

Laptops demonstrating free software to turn cheap microprocessor boards into data-acquisition systems suitable for home labs and science-fair projects.
Homemade LED desk lamp and stroboscope.

Several of the projects will be interactive (an optical pulse-rate monitor, oscillators that can be adjusted to change Lissajous figures on an oscilloscope, …).

A few changes from last year: a more reliable pulse-monitor design and a new USB oscilloscope.

The public blurb is similar to last year’s:

See your pulse on a home-made optical pulse monitor!
Record air pressure waveforms using free PteroDAQ data acquisition software!
Play with a bright custom-design LED stroboscope!
Control fancy Lissajous patterns on an oscilloscope!

I removed mention of an EKG, because I decided that it was too much trouble to tether myself with EKG leads all day.

My “Maker bio” is a bit boring, :

Kevin Karplus has been an engineering faculty member at UCSC since 1986, but has done hobbyist electronics on-and-off since the 1960s. For the past few years he has been working on a low-cost textbook to make hands-on analog electronics accessible to a wider range of students.  Several of the projects on display are from the textbook.

2016 December 31

Twentieth weight progress report

Filed under: Uncategorized — gasstationwithoutpumps @ 09:52
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This post is yet another weight progress report, continuing the previous one, this being the 20th since I started in January 2015.  This has not been a good year for maintaining my weight:

My weight has trended up by over 5 lbs this year, and it is currently 5 lbs above the top of my self-imposed "ideal" range.

My weight has trended up by over 5 lbs this year, and it is currently 5 lbs above the top of my self-imposed “ideal” range.

My weight only stayed in my desired range for about 6 months at the end of my diet.

My weight only stayed in my desired range for about 6 months at the end of my diet.

Because of the problems with my bicycle seat plus a week-long trip to Boulder to visit my Dad, I don’t have good records of exercise for the past few months—I think it was less than normal, because fall quarter I only went to campus 3 days a week.  I’ll be back to daily commuting for the next few months, though. I’ll have to find some more reliable form of exercise during summer and fall of 2017, as the beginning of summer seems to have been when my weight jumped the most.

My goal for this quarter is to get my weight back down to 158, an 8-pound loss that will take me most of the quarter to achieve, assuming I can stick to the strict diet as I did two years ago.

2016 December 25

Banana slug Christmas

Filed under: Uncategorized — gasstationwithoutpumps @ 16:50
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When my wife was decorating our Christmas tree last night (a Christmas Eve tradition for us), she was regretting that we did not have a good tree topper.  She did not want to repeat last year’s Christmas tree topper.

Today, we received from her sister a banana slug mask, which immediately became this year’s topper:

The mask as tree topper.

The mask as tree topper.

The whole tree—I think this is the 4th year we've used this live tree, getting it up the front steps using the hand truck visible in the background.  Note also the tiny Festivus pole in front of the tree.

The whole tree—I think this is the 4th year we’ve used this live tree, getting it up the front steps using the hand truck visible in the background. Note also the tiny Festivus pole in front of the tree.

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