Recent Blog Posts

6 Nov 2015 wedesoft   » (Master)

Arduino hello world

Making an LED blink with the Arduino micro controller board

Syndicated 2015-11-06 00:00:00 from Jan Wedekind

26 Oct 2015 steve   » (Master)

Triumph of the Fail Whale

Fail Whale by Matthias Töpfer (CC-BY-NC)

Early social networks had status fields; little boxes where you posted a short status line about your current emotional state (“I’m bored”) and maybe an emoticon. As social networks proliferated, Twitter came along, based on the useful idea that you could enter your status one time and have it automatically sync to anywhere else you wanted. I adopted Twitter relatively early on and it was a great time saver.

It was also easy to generate tweets from programs. When I published a new blog post, like this one, WordPress generated a tweet; the tweet then appeared as my status on Facebook, Google Plus, LinkedIn, on my personal websites (even on Myspace back in the day). Flickr and other sites could generate tweets to reflect current activity and I often wrote programs for websites I developed that generated tweets. For example, I wrote a bot for that tabulated the number wiki edits each week and posted it as a tweet. Twitter was the universal plumbing of the social media universe.

Gradually, Twitter has stopped talking to most sites. One of the earliest ones I remember this happening with was LinkedIn. One day my tweets stopped appearing on my LinkedIn profile status. LinkedIn claimed Twitter had changed their policy and no longer allowed LinkedIn to display tweets. Twitter claimed LinkedIn changed their policy. Sometime later, Google Plus started blocking Twitter. Then Twitter dropped their RSS feeds and created a new system that allowed them to block usage on personal websites unless you gave them your mobile phone number for tracking and demographics purposes. The final straw for me is that Facebook, while still allowing me to sync my Facebook status from Twitter, considers tweets as second class posts. If I post a status update via Twitter maybe 1% of my Facebook followers will ever see it. If post directly or from other, non-Twitter services such as Instagram, a much larger percentage of my followers see it.

For me, the sole purpose of Twitter is syncing my status with other social networks, so Twitter is now next to useless. I recently turned off my Facebook to Twitter sync. I think it’s not just me. Twitter seems to be largely a wasteland of lost status postings these days; an endless stream of status messages flying into a vacuum with no humans left to read them. I’ll probably keep posting there out of habit for a while longer but I think Twitter’s 15 minutes of fame are winding down.

Syndicated 2015-10-26 21:39:54 from Steevithak of the Internet

20 Oct 2015 Flanneltron   » (Journeyer)

2014: Postmortem

Oh no! I forgot to post a personal postmortem 1 for the year 2014 like I did for the previous year! Oh well, here it is ten months late. What Went Right Started a new day job at a biotech company called GnuBIO, now the skunkworks division of Bio-Rad. Essentially I write robotics code for […]

Syndicated 2015-10-20 20:04:53 from SynapticNulship

22 Sep 2015 shimniok   » (Journeyer)

Fixing Flaky LCD Monitor with ESR Meter

My Dell E2210H LCD monitor was really wonky.

Powering up from sleep, it would only occasionally come back to life, usually after resetting itself several times.

More often, it would power off or go into power saving mode, leaving the front panel buttons inoperative.

Occasionally it would reset or power off while operating normally.

Here's how I fixed it, using my DIY ESR test harness to find a bad capacitor without desoldering.

You can find disassembly videos and tutorials out on the web specific to your monitor. Remember, safety is your responsibility so please learn how to safely deal with dangerous high voltages, how to safely discharge capacitors, etc.

Low voltage drop; low ESR.
Meanwhile, after disassembling, I used my
Equivalent Series Resistance (ESR) Test Harness to identify bad aluminum electrolytic power supply capacitors.

The device sends a 1.0 Vp-p, 1kHz - 250kHz square wave through a capacitor on the board while the oscilloscope displays voltage drop across the capacitor.

You turn on the ESR harness, connect Channel 1 to the Probe BNC and Channel 2 to the Trigger BNC.

Then touch the red/black probes to the positive/negative capacitor terminals while they are on the board. Which is nice; you don't have to desolder every cap.

High voltage drop; high ESR.
The harness incorporates a voltage divider, so you can compute ESR based on voltage drop and the harness' series resistance.

But usually it's really obvious when you find a bad capacitor.

What you should see is a very low voltage drop across the capacitor as pictured above right.

A capacitor with overly high ESR will drop far less voltage as shown below right.

And that is just what I found on one of the 100uF supply capacitors on the main driver board for the LCD. The rest of the capacitors tested ok.

The bad cap looked fine but tested bad.
The test harness I built uses a 6.8 ohm series resistor so the ESR is computed as:

Normal ESR for good capacitors of similar size are orders of magnitude less than that.

With such a high ESR, the capacitor was slowly charging and discharging, likely confusing whatever circuit or MCU was controlling the main power.

After replacing the capacitor with a good one, the monitor works normally, as expected. All with a minimum of work and the very low cost of a capacitor.

Admittedly, I somehow missed the bad capacitor the first time I tested so I ended up buying a power supply board. Now I have a spare. Oops.

Syndicated 2015-09-22 00:00:00 (Updated 2015-09-22 00:00:07) from Michael Shimniok

10 Sep 2015 svo   » (Master)

Flexible LED filaments driver

A driver for flexible white LEDs

Драйвер гибких белых светодиодов

Driver para los LED blancos flexibles

Syndicated 2015-09-10 21:27:21 from svo's interactive persuasion vehicle

9 Aug 2015 Petar.Kormushev   » (Master)

Online Regeneration of Bipedal Walking Gait Optimizing Footstep Placement and Timing

The video presents experiments during which a humanoid robot is subjected to external pushes and recovers stability by changing the step placement and duration.

It starts from showing effectiveness of the feedback controller during stepping in place. Then it continues to present how the developed algorithm regenerates the step placement and duration to regain stability after lateral pushes. It concludes with showing how the algorithm works during forward locomotion.