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....
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.
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 (http://www.fairchildsemi.com/ds/FQ/FQP47P06.pdf) 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
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.
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.
Click "Read more" for the Arduino code and details....
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:
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!
Here's some details of my radio spectrum analyzer hack at Maker Faire. But first, a quick video of the hack in action:
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