Lenovo USB Keyboard

image I got this keyboard in spring 2010, thinking that it is comparable to my laptop’s keyboard, only as an external USB version. I like my laptop keyboard for its precision, stiffness and pressure point, so I bought it. The touch point is a neat extension, directly comparable to the Laptop’s integrated one. A touchpad would have been perfect, so that I could use it as scroll pad.

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Tektronix 2440

The Tektronix 2440 is an end-80s digitising oscilloscope (list price: 11,500$). It features 300 MHz equivalent-time or 200 MHz real-time sampling bandwidth and a rare analog peak value detector. It detects the signal minimum and maximum between two sampling points, making the display look a bit more like an analog scope with a filled area between both extremums – independent of the sampling rate. This peak detector simplifies the usage of the DSO, having only 500 Msps, by eliminating aliasing artifacts.

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Contact

Questions, improvements and critique are appreciated! Please contact me by e-mail: Romeo Alpha Uniform Charlie Hotel at hohlerde.org (all lowercase letters). Call me Dennis.

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Electronic Gas Meter

Background Our flat uses gas for heating. But since our gas supplier was unable to reduce our advance payment from over 100 Euro pro Month to a reasonable amount, we needed a convenient way to display our current gas consumption. Hardware finished installation Many gas counters have a reflective digit and/or a magnet which rotates with a specific digit. Main circuit The reflective area may be detected by a photo sensor, whose LED has to be constantly supplied with current.

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Dragon Isolator

Warning: This project is deprecated. Please invest in a USB isolator instead! This is one of my earlier project, it is only here for completeness. Take care, potential differences can kill you. Especially if you work with mains voltage! PCB Top USB port at the Dragon Target connector I own an AVR Dragon, which is a really cheap programmer and debugger for almost all of of Atmel’s AVR microcontrollers.

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