Measuring microamps & milliamps at 3 MHz bandwidth

Recently I needed to actually "see" a current waveform in the 100 uA to 5 mA range with at least a couple MHz bandwidth.  This extremely expensive probe would have been perfect, but instead I built something similar for about $30 using the amazing Analog Devices AD8428 amplifier.

Click "Read more" for details and a scope screenshot....

DorkbotPDX 0x0C

  • When: Monday August 26th, 2013 - 8pm
  • WhereInstrument (map)
  • Who: All ages -- open to the public
  • Cost: Free!

Zach Archer

The Hypnolamp

Using LEDs and an Arduino, Zach converted a simple lamp into a hypnotic work of art. Knobs and sensors were added to control the animation and colors. Zach will reveal the HypnoLamp's secrets, and discuss the creative process, interactivity, and the coming revolution in home lighting.
Zach is a developer who focuses on interactive media and installations. He lives in Portland.

Drew McIntyre

The Art of Breaking Video: Observations, Insights & Instabilities.

Why stop at Speak n' Spells and Nintendos?  Big Pauper employees an obscure arsenal of hand-modified electronics to sculpt multimedia installations, sound design & glitch visuals.  Glitch video production will be the matter at hand this evening as Pauper shares the methods & the madness behind modifying video equipment, personal computers and video gaming hardware.  Should be good fun!!

Big Pauper is a multimedia artist, producer & mad scientist of sorts living here in Portland, OR.  He works as part of the circuit bent sound-art collective Folktek.  He also breaks video gear for a living under the enterprise Big Pauper Modified Circuitry.  He also just released a multimedia EP you should hear/view:


An open-mic session for those looking to show off a project, ask a question, solicit help, or incite collaboration.  Please limit to 5 minutes.


Ideal diode circuit fixing

At the bi-weekly meeting tonight, as promised, I brought my non-working circuit, and as promised, Paul helped me get it working.  It is a circuit that allows current to flow through a p-channel mosfet ( from a power supply to a 12V sealed lead-acid battery and a load (which draws about 120 mA, normally), but that prevents current from flowing from the battery back into the power supply.  The idea is to use an op-amp to compare the voltages upstream and downstream of the mo

DMX Lighting Sequence Player

Portland CORE effigy at Burning Man will be using DMX controlled lighting this year.  At least that's the plan, but a low-cost and low-power way to automatically play the lighting sequence (without a PC) is needed.  Here's a little board I made for the purpose.

Click "Read more" for source code and other technical details.

USB Virtual Serial Benchmarks

Recently I've put a lot of work into improving USB virtual serial receive speed.  Here's a detailed article with complete source code for the benchmarks.

AD75019 Crosspoint Analog Switch

On my post about the regression test set, jeppius asked if I had sample Arduino code for these AD75019 chips.

Click "Read more" for the Arduino code and details....

Answer to David Turnbull's c-puzzle from April 6th

David's puzzle on April 6th was a lot of fun to work with.  If you want to see my answer, read the first few pages of:

The HypnoLamp Goes to Maker Faire

Portland Dorkbot had a booth at the Bay Area Maker Faire this year. Here's my first proper invention, the HypnoLamp, alongside the Editor's Choice award that we received:

HypnoLamp + Editor's Choice Award

Many factors helped birth the HypnoLamp: At Toorcamp 2012, I learned to program microcontrollers. Jeff of OlyMEGA blessed me with addressable LED strips, at the aforementioned event. Jeff was also at the Portland Mini Maker Faire, showcasing (among other things) glass Ikea lamps with LEDs inside. I decided to build my own version!

Radio Spectrum Analyzer at Maker Faire

[This post is originally from my blog. I'm bringing this spectrum analyzer to Darren Kitchen's Hak5 event at OMSI this Saturday (2013/05/25).]

Here's some details of my radio spectrum analyzer hack at Maker Faire. But first, a quick video of the hack in action:

Maker Faire 2013

The Dorkbot booth at Maker Faire worked out really well.  Here's a couple good photos Zach took:

This is the right-hand side, with my extremely bright OctoWS2811 Arduino library demo triggered by stomp pads.

This is the center with Tom's Bee counter, Zach's Hypnolamp, and Tara's soldering demo in the center, viewed over the top of Jared's VFD display spectrum analyzer (and FPGA Robotron not visisble in this photo).

Click "Read more" for more pictures, source code and other stuff

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