FM stereo radio receiver with RDS

Dilshan Jayakody has published a new build:

This tuner circuit is a quick prototype which I build to test the RDA5807M FM radio tuner IC. RDA5807M is a single-chip tuner IC with RDS and MPX decoder, and it equipped with I2C interface for control.
This receiver builds around Atmel’s ATmega16A 8-bit MCU. The output stage of this design consists of AN7147N, 2×5.3W audio power amplifier.

See the full post on his blog.

App note: Paralleling eFuses

ON Semiconductors guide to cover much higher current capacity from eFuses. Link here (PDF)

The standard 12 V, 5 V and 3.3 V electronic fuses from ON Semiconductor provide overcurrent and overvoltage protection and come in different current limit configurations. As an example, the 5 V NIS5452 eFuse has a recommended operational 5 A current limit. Sometimes the operating current for the user system might be much higher than the maximum allowed current limit provided by the eFuse.

App note: How to prevent thermal issues with high output current DC to DC converters in portable applications

Tips and tricks from ON Semiconductors on how to optimize high output current switching regulators thermal dissipation. Link here (PDF)

As power demand in portable designs is more and more important, designers must optimize full system efficiency in order to save battery life and reduce power dissipation. Energy losses study allows knowing thermal stakes. Due to integration and miniaturization, junction temperature can increase significantly which could lead to bad application behaviors or in worst case to reduce components reliability.

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.