Kerry Wong writes:
As I mentioned in my previous posting, there was an issue with my Wavetek 907 microwave frequency generator. While everything was fine during my initial testing, the frequency display is now stuck with an out-of-range display and the adjustable frequency range is limited to between around 6.9 Ghz to 7.9 Ghz (instead of all the way up to 11 Ghz). My initial suspicion was that the PTC heater inside the YIG-Gunn oscillator was malfunctioning. But as it turned out, it was something else.
Since initially my gut feeling told me that the YIG oscillator might be at fault, I thought I would at least try taking it apart to see if it was something trivial to fix. And even if it is beyond economical repair, it would at least be a pretty interesting teardown of the YIG oscillator itself.
Wavetek 907 repair, YIG oscillator teardown - [Link]
App note(PDF) on schottky rectifiers from Microsemi.
Schottky rectifiers have been used for over 25 years in the power supply industry. The primary advantages are very low forward voltage drop and switching speed that approach zero time making them ideal for output stages. This latter feature has also stimulated their additional use in very high frequency applications including very low power involving signal and switching diode requirements of less than 100 picoseconds.
App note: Introduction to schottky rectifiers - [Link]
PyroElectro.com proudly presents their new contest:
View the Pyro Propeller Clock POV Project to learn more about the concept Persistence of Vision (POV) – a phenomenon where an afterimage persists for roughly one twenty-fifth of a second on the retina after the stimulus that produced it is removed.
Build an original electronic device demonstrating POV and photograph in action in a darkened environment. You may use any electronic parts desired as long as the POV signals are driven by either an FPGA or CPLD.
Submit your entry to firstname.lastname@example.org with the subject line “PyroElectro POV Contest.” Your entry must contain two photos of the device – one of its components in a well-lit environment and one of it in action in a darkened environment – as well as a circuit diagram and the VHDL code to run the device.
Who Can Build The Best P-O-V Contest - [Link]
Imagine specifying the types of components needed for an electronics project and letting an algorithm take care of the component selection and pin matching. Well, eda_solver makes this idea a reality.
I just launched a site called edasolver.com where users translate their project requirements into a JSON format and let the algorithm take care of finding components and pin connections that support each other. For example, it can be used to find the cheapest Arduino model that supports 10 servo motors and match the pins in such a way that the I2C ports are still preserved. It can be thought of a project requirements to schematic generator.
edasolver.com – A functional EDA - [Link]
by limpkin @ limpkin.fr:
During the month of July I was visiting Beijing and had an extra 10 days to spare. What to do? Well it took me less than a few minutes to decide to go the wonderful city that is Shenzhen…
Video Series – Touring Factories in Shenzhen - [Link]
by Russell Barnes @ www.raspi.today
The Director of Hardware at the Raspberry Pi Foundation, James Adams, walks us through the making of the new and improved Model B+ and more…
While he was a chip designer at Broadcom, James Adams ran the design team that created the 3D graphics engine that went on to feature in the Raspberry Pi, arguably the Pi’s strongest asset.
Later he moved to a tech startup called Argon Design that was created by the same man behind the original company that Broadcom bought many years ago for its multimedia technology. The 4th generation of that very chip also features in the Raspberry Pi, so Adams was already well versed with its capabilities long before joining the Foundation in February 2013.
The making of the Raspberry Pi Model B+ - [Link]
by dreded @ dredx.com:
In my home I have a fairly long hallway that has light switches at either end but 99% of the time we enter the hallway from the middle where there is no switch. So I decided I needed to do something about this as walking down a dark hallway all the time was annoying.
I have seen a fair number of people use an arduino or even a standalone ATTiny85 with a El cheapo HC-SR501 which can be found on ebay for about $1.25 each and I find these things work fantastic, they have an excellent range and detection spread.
Motion activated lighting without a Micro-Controller - [Link]
Did you know you can use your frequency counter to detect gravity? You’ve likely done it before and you didn’t even know it!
Dave demonstrates the phenomenon of 2g-tipover on quartz crystal oscillators in an Agilent 53131A frequency counter.
EEVblog #646 – Gravity Detection Using A Frequency Counter! - [Link]
Most of the work that I have done in the past with vacuum tube and solid state electronics has been repair. So, I have ventured into the realm building. This is actually my second build (I’m still getting the bugs out of the first attempt) but I have applied all that I learned from mistakes to this build. Building from scratch is nothing like repairing. It takes time, a lot of thought and reasoning go into a build no matter how simple it may look.
6v6 Stereo Amplifier - [Link]
Analysis of the bipolar transistor amplifier at low-frequency is relatively easy, and several calculators exist online that do a good job. For high-frequency operation, there are fewer references available. For my projects, I like to build a reference spreadhseet where everything is in one place. This allows me more flexibility in optimizing the circuit, and is much faster than simulating with LTSpice or similar package. Furthermore, constructing such a tool is a great way of gaining more insight into how the circuit works, and how each of the parameters affects performance.
Common-Emitter and Common-Collector Transistor Amplifier Calculator for High-frequency Operation - [Link]