App note: High-power emitters for illumination applications

App note from OSRAM on High-power LEDs and their special requirements. Link here (PDF)

In general high power emitters can be driven with DC currents in the range of 1 Ampere whereas most low power products like 5 mm Radials are limited to 100 mA.

As the light output increases with driving current the optical power is raised by a factor of ten compared to standard devices. At the same time much less board space is occupied as fewer devices are needed. On the other hand a careful thermal management is absolutely mandatory because the thermal power dissipation is increasing in the same way as the optical output power. To keep the junction temperature of the chip as low as possible a low thermal resistance is needed and the standard FR4-PCB has to be replaced by a metal core PCB. By this a high optical efficiency of the IRED can be achieved.

Low cost high accuracy STM32 FFT LCR meter

Adil Malik made a low cost FFT LCR meter with an STM32 MCU:

The approach I took was a mixed signal one where a capable analog front end would be paired up with a beefy DSP processor to compute the Impedance. Most importantly, in this scheme, the DSP is responsible for discriminating the phase between the sampled voltage and current waveforms; this approach is preferred because it leads to good accuracy and calibration stability.

See the full post on his blog.

Mechpen drawbot


Alexander Weber has a nice build log on his drawbot called Mechpen, that is available on GitHub:

This is Mechpen, my newest drawbot.
The idea was to have a robot arm that could sketch on a rather large surface.
It is a SCARA (Selective Compliance Assembly Robot Arm) robot arm, meaning the robot has a shoulder and an elbow joint and a hand. Mechpen has a reach of 140 cm which means it could sketch up to A0 format.

You can see the full build on Weber’s Tinkerlog site.

Check out the video after the break.

App note: Analog switch lowers relay power consumption


Clever way of starting-up relays discussed in this app note from Maxim Integrated. Link here

Relays are often used as electrically controlled switches. Unlike transistors, their switch contacts are electrically isolated from the control input. On the other hand, the power dissipation in a relay coil may be unattractive for battery-operated applications. You can lower this dissipation by adding an analog switch that allows the relay to operate at a lower voltage.

USB Morse keyer


Dilshan Jayakody writes about a new open source project, the PIC16F886 based CW auto key controller with USB support:

USB Morse Keyer is a microcontroller-based auto keyer project with following features:
*USB / straight key / iambic key inputs
*Support for both standalone and USB operating modes
*64-character USB typeahead buffer and 6-character Morse key typeahead buffer
*Support 5, 10, 15 WPM.
*6-page message memory
*1W Audio output
*Audio and PTT output interfaces
*32 character display

More details on Dilshan Jayakody’s blog and the GitHub repository here.

App note: Thermal mass flow sensors for gas and liquid applications


White paper from Integrated Device Technology on the emergence of MEMS thermal mass flow sensors. Link here (PDF)

Flow meters represent the instrumentation of flow sensors and are used to measure the amount of flow that passes through them. There are in principal five different flow meter types: velocity flow, positive displacement flow, differential pressure flow, open channel flow, and mass flow. Mass flow meters are one of the dominant types in the market due to their faster response and better accuracy than other flow meters. They can also be effectively miniaturized and manufactured on silicon wafers. The emergence of MEMS has already revolutionized the consumer electronics market for motion, pressure, and other sensors, and similar micro-machining processes are now being adapted to fabricate flow sensors. Flow sensing applications are typically high-mix and low-to-medium volume compared, for example, to motion sensors that have become ubiquitous in hundreds of millions of smartphones. This paper will focus on the emergence of thermally-based MEMS mass flow sensors and how they match up with existing and more traditional flow sensor technologies.

App note: Ferrite bead demystified


App note from Analog Devices hinting for proper selection of ferrite bead for you applications. Link here (PDF)

An effective method for filtering high frequency power supply noise and cleanly sharing similar supply rails is the use of ferrite beads. A ferrite bead is a passive device that filters high frequency noise energy over a broad frequency range. It becomes resistive over its intended frequency range and dissipates the noise energy in the form of heat. The ferrite bead is connected in series with the power supply rail and is often combined with capacitors to ground on either side of the bead. This forms a low-pass filter network, further reducing the high frequency power supply noise.

Building and Flashing ESP32 applications with Eclipse


Erich Styger shared the steps how to use Eclipse with CMake:

The current Espressif documentation integrating with Eclipse are kind of broken and did not work for me (they are changing from make files to use CMake).  The good news is that I have found a way to easily integrate the IDF with Eclipse which is documented below. Because I’m using the ESP32 in combination with the NXP Kinetis and SDK, it makes sense to have everything in the MCUXpresso IDE (I’m using the Version 11.0.0).

See the full post on MCU on Eclipse blog.

The Script


Peter Scargill’s Script:

Regular readers will know about the script that Aidan Ruff and I originally developed to put Node-Red and several other packages onto the Raspberry Pi for our own home control purposes. This has been developed with help from several people and in particular my friend Antonio “Mr Shark”.
WELL – here is the script which is intended to help set-up certain Raspbian, Debian or similarly-based SBCs which now includes logging and handling Raspbian Buster (tested on Raspberry Pi 2, 3, 3B+, 4 with Stretch, 3B+ and 4 with Buster). As well as it’s original purpose of setting up a Raspberry Pi, the script also runs well with several other boards. See right hand side of the above image for what the script does, given a basic operating system install. We currently suggest NOT using this with DIET PI, original Pi or the Raspberry Pi Zero as we are no longer testing either and the latter pair are just TOO SLOW.

See the full post on Scargill’s Tech Blog.

Check out the video after the break.