Dilshan R Jayakody’s Web Log

TDA7052A is an audio power amplifier designed for use in low voltage battery-powered equipment. Compare with the popular LM386, TDA7052A is not so popular among DIY electronic enthusiasts.  Final view of the finished amplifier with speaker.   Using the Bridge Tied Load principal, this IC delivers an output power of 1.2W into an 8Ω load with, 6V power supply.   The most striking feature of this amplifier is the minimum external component count. This IC only needs two external capacitors to build a functional audio amplifier.   The gain of the amplifier is fixed internally at 40dB. The amplifier got, short-circuit protection, requires no external heatsinks, and not producing any switch on/off click sound(s).    Although this is an old amplifier IC, it is still available to purchase in many local and online stores. Compare with the other low-power AF power amplifier ICs, TDA7052 is a little expensive in the local market. Although it is costly, I use this IC ...

This 12V uninterruptible power supply initially designs to drive my fiber optic modem/router. The key reason to build this power supply is to get continuous internet and phone connection during power failures. Core components of this power supply are a constant voltage charger, 12V DC power supply, AC line monitoring unit, and 12V high capacity sealed lead-acid battery. The entire system designs using locally available components. Prototype version of 12V UPS system The charging circuit of this system builds around using the popular LM350 voltage regulator. This regulator calibrates to provide both 14.4V fast charging and 13.6V trickle charging. Based on the condition of the battery, the MCU will determine the appropriate charging mode. At the online state, the LM2576-12 switching regulator provides 12V output to the driving system. (in my arrangement, a fiber optic router). Block diagram of the 12V UPS system The PIC16F688 MCU monitors the AC line and battery to controls the output...

Programmable timer lite is a miniature, USB programmable timer module. This module can handle more than 100 alarm configurations and trigger the output channel based on the programmed conditions. The timer module can program using SRIKit 's Timer Controller software. All the timer configurations are store in the EEPROM to prevent the loss of data during power failures. Programmable timer module. We design this module around the STM8S001J3M microcontroller and DS3231 real-time clock. AMS1117-3.3 regulator in this module can handle a maximum of 9V DC input without installing an external heatsink. Bottom side of the timer module These programmable timer modules were specifically developed to handle long-duration alarm configurations which span up to years. Firmware of this timer module develops using SDCC version 3.9. Programming utility is a GUI application and develops using Lazarus and FPC toolchain. Both these projects are built and tested on a 64-bit Linux environment. Th...

OpenFAT is an open-source FAT file system implementation for embedded systems. The original library is well written and documented. We recently came across this library while looking for a LibOpenCM3 support SD/MMC FAT file system library. At the initial review, we notice that this library does not maintain for the last ten years. Also, it does not provide support to the latest SD card types. After review the latest SD card specifications , we add SD card support to this library and release it with the same license. The updated library is available at the github.com/dilshan/sdfatlib . The testing of this library is carry on a popular STM32F103C8T6 blue pill development board. The suggested wiring layout is given, below. Wiring layout for the test setup. For the above test layout, we use a standard SD card adapter module (which comes without a built-in level-shifter and voltage regulator). Due to the 3.3V support of the STM32F103C8T6 , the wiring layout is straightforward. The CH34...

This project introduces an open-source, ATmega328 based, configurable NTP clock with a 2.3-inch, 7-segment display driver. This clock automatically obtains time from the configured NTP server and updates the date and time of the built-in RTC (real-time clock). If the connection to the NTP server is lost, the clock continues to run using its built-in RTC. Finished NTP clock driver PCB. All the parameters of this clock can configure using its USB base serial terminal. The firmware of this clock supports both static and DHCP addressing modes. Apart from that, parameters such as NTP server address, time-offset, and clock display formats can change through the menu-driven configuration terminal. This clock is designed to drive large common-anode, 7-segment displays. The prototype version is assembled using four individual segments of 7.2V, 2.3-inch, red color displays ( FJS23101BH ). To archive, the necessary high output voltage and the current, the 7-segment display output stage of this ...

This is an RDA5807M based FM stereo radio module. This module is designed to replace old, low-voltage, analog FM stereo radio receiver modules. Like many digital receivers, this module also got auto scanning, station memory, and digital volume control. This module can driver using 5V to 9V DC power source. FM stereo receiver module with seven-segment display unit. The frequency range of the receiver is 88MHz to 108MHz. The auto scanner of this module can tune the receiver with 25kHz increments in up and down directions. The memory manager available with the current firmware can hold up to 10 stations in MCU EEPROM. Bottom side of the receiver module The dimensions of this module are 72.85mm × 32.0mm. With the seven-segment display, the depth of the assembled module is 37.5mm. AF output power of this module is not sufficient to handle the pair of speakers. To drive speakers, this module needs to pair with a stereo AF power amplifier kit/module .  This is an open-source hardware pro...

I 2 C is a popular data bus to communicate with inter-board peripherals. Today I 2 C based chips and modules are widely available in many categories, including data storage, ADC/DAC, I/O Expanders, sensors, etc. The I 2 C master mode emulator allows communication with I 2 C devices by sending or receiving data to/from the I 2 C bus. To issue the I 2 C commands, the emulator should connect to a PC over the USB port. After initializing the emulator, the PC and directly control the I 2 C slave chip/module. Finished prototype of the I 2 C Terminal This emulator is base on ATmega16A MCU. The USB communication channel is develop using the V-USB firmware. Initially, we develop this emulator to work with 5V I 2 C devices, but later it has extended to work with 3.3V I 2 C devices. The 3.3V design is still under testing, and at the prototyping stage, we found a couple of issues in 3.3V mode.  In 3.3V mode, the required output level is available only if the emulator is in a "ready" sta...