USB mini media keyboard


Sven Krasser built a small USB keyboard input device for media control and wrote a post on his blog detailing its assembly:

The project is based on a Pro Micro, an Arduino-compatible ATmega 32u4 board (the 32u4 allowing to easily create USB devices). For iteration 1, I added a couple of buttons and a rotary encoder to a breadboard alongside the Pro Micro to see how I can get media controls over USB to work. Turns out, Nico Hood’s HID library makes that quite simple.

Control the bicycle traffic signal with a Particle Photon


Glen has been working on a Wi-Fi enabled bicycle traffic signal project:

In the first post in this series, we built a miniature LED bicycle traffic signal using 3D printing, laser cutting, a sticker, and an Adafruit Neopixel Jewel. In this post, we’ll look at bringing the signal to life using a Particle Photon. We’ll start with basic code to blink the traffic signal green, yellow, and red then add code to control the color over the web using the Particle Cloud or locally using an iPad and the Art-Net protocol.

More details on Photons, Electrons, and Dirt blog.

1750Hz tone generator


Dilshan Jayakody published a new build:

The 1750Hz tone bursts are often used to trigger repeaters. There are several methods to build 1750Hz tone generators which including TC5082 divider, using MCUs, etc.
In this post, I present another 1750Hz tone generator which I built using 74HC4060 high-speed 14-stage binary ripple counter and 7.168MHz crystal. In this design, 74HC4060 is used to drive the crystal and divide its output by 4096. By using 7.168MHz crystal, this circuit produces 1750.0Hz square wave output with a 50% duty cycle.

See the full post on his blog.

App note: Magnetometer placement in mobile devices


App note from Kionix about magnetometer integration challenges from the mobile equipment point of view, and gives guidelines for the mounting position of the magnetic sensor. Link here (PDF)

Electronic devices contain many parts which can affect a magnetic sensor. When deciding the mounting position, it is necessary to consider the types of materials and the amount of current carried in proximity of the magnetic sensor. Accuracy of an electronic compass depends upon getting clean geomagnetic data from the magnetic sensor output without errors caused by other magnetic elements. These errors need to be canceled by calibration or correction.

App note: Using two tri-axis accelerometers for rotational measurements


App note from Kionix on utilizing 2 linear accelerometers to determine angular rotational rates. Link here (PDF)

In many applications, customers would like to measure rotational motions (angular velocity, angular acceleration) in addition to linear motions. Most often, gyroscopes are added to their end product to obtain the rotational information. In some instances, customers already have a system that contains two or more accelerometers. With some understanding of fundamental physics, they can extract more than just linear acceleration data from their system.

Decap a Chinese chip at home: Clone or not?


Sjaak writes, “It has been a while before I posted something useful. On my search for obscure chips, I came around another interesting Chinese chip (which I don’t reveal yet). The chip was advertised as a cheap drop-in replacement for a American IC so I suspected it would be a clone. I wanted to look inside the chip to check if that is true.”

More details at

Teardown of a Marconi 2305 modulation meter


Kerry Wong did a teardown of a Marconi 2305 modulation meter:

I picked up a Marconi 2305 modulation meter off eBay the other day. As the name indicated, a modulation meter is used to measure the modulation characteristics of a source signal. The Marconi 2305 is capable of measuring amplitude/frequency and phase modulated signals from a few hundred kHz all the way up to 2 GHz.
The Marconi 2305 was built sometime between the late 70’s and 80’s. It is a pity that the iconic British Marconi Instruments went under in 1998 and had since changed hands a couple of times.

See the full post on his blog.

Check out the video after the break.

DIY inline refractometer


DIY inline refractometer project from Anfractuosity:

The idea of this project is to image the refractometer output, then convert the position of the blue line, to a digital reading, using image processing. The idea is to measure the brix of wort during mash and sparging, so that sparging can be stopped around 1.010 SG, to avoid tannins.

More details on Anfractuosity blog.

Check out the video after the break.

App note: Light quality – White light parameters


App note from OSRAM on consistency of colors specifically white lights. Link here (PDF)

White light is not the same as white light. When different light sources are used, color differences may become visible. To understand why this can happen, it is necessary to understand how people perceive color and light. Nevertheless, it is possible to reduce the color shifts by choosing suitable white LEDs combined with an appropriate system setup. This application note provides basic information on optical quantities, color spaces and CIE chromaticity diagrams. Furthermore, it describes how color consistency for white light applications can be achieved.