Dilshan R Jayakody’s Web Log

This project is about a wireless musical call bell, which I designed to meet some of my friend's requirements. This circuit design uses only the 4000 series CMOS logical ICs, NE555 , UM66 , and TDA7233 audio amplifier IC. For the remote control, we use a 433MHz 4-channel remote control module . This circuit is designed to work continuously with a low-power external 5V power supply. Prototype version of wireless call bell. The PCB in this call bell is designed as a single-sided PCB. The dimension of the PCB is 82mm × 50mm.  All the components in this circuit are commonly available through-hole-type components. The whole assembly process of this musical call bell is shown in the video attached to this document. The RF remote control module we use in this project consists of a remote control decoder and encoding IC. In our version, the transmitter (key fob) has a PT2262 encoder, and the receiver has a PT2272 decoder IC. In the prototype build, the receiver and transmitter are confi...

IR Clone is an open-source IR remote control analyzer tool. This utility can analyze any IR remote control that modulates the IR signal with a 38kHz carrier signal. This utility has an option to store and retrieve up to 16 IR signals. In addition, it has PC software to analyze and edit captured IR signals. The hardware component of this analyzer is built around the STM8S003F3 MCU. It has 24LC32 EEPROM installed to store the captured IR signals. This unit is designed to operate with a 5V to 9V DC power source or a 3V battery.  Finished prototype of the IR Clone module Operating modes such as capture or replay can be changed using an onboard jumper on the PCB. These operating modes can change at any time without restarting the unit. In addition to the IR clone PCB, the only external component needed to operate this system is a 4×4 matrix keypad . Most of the generally available 4×4 keypads can directly couple with this system. The dimensions of the IR Clone PCB are 41.2mm × 32.1m...

Recently we looked for a replacement class-D power amplifier to replace my old TDA2030 power amplifier build . While searching for a suitable power amplifier IC, we found TPA3001D1 from the local market. This IC is a slightly older 20W Class-D power amplifier manufactured by Texas Instruments . At the time of this writing, it is priced at LKR 180 (0.89 USD) in the local market and is still available at all major electronics stores (including online stores ). Prototype version of TPA3001D1 power amplifier. To minimize assembling difficulties, we used through-hole-type components in this PCB. The only SMD component in this PCB is the TPA3001D1 IC. We installed the power amplifier IC on the bottom of the PCB because then it would receive good airflow. The table below lists all the components required for this project. Designator Quantity Value C1 , C8 , C13 , C14 , C15 , C16  6  1µF/25V C17  1  10µF/25V ...

In this project, we built an STM8S005C6T6 based Ethernet development board for our IoT experiments. This development board consists of ENC28J60 , 10BASE-T stand-alone Ethernet controller, CH340G , USB serial interface, 2 LED indicators, and passive buzzer unit. The firmware framework for this development board has been developed using SDCC . To enable IPv4 support, we convert the EtherCard driver, which is available for the Arduino platform. The current version of this driver supports all other EtherCard functions except TCP support. Finished STM8S005C6T6 IoT development board. In the given design, the SPI terminals of the MCU are connected to the ENC28J60 Ethernet controller. All SPI terminals, such as MISO / PC7 , MOSI / PC6 , and SCK / PC5 , are connected directly to the Ethernet controller. In addition, the PC4 terminal of the MCU is used as ENC28J60, CHIP-SELECT .  The CH340G USB serial interface is connected to the UART2 terminals of the MCU. In STM8S005C6T6, the UAR...

This project introduces a digitally controlled 5.1 channel audio preamplifier system. This amplifier is specifically designed to increase the gain of the multi-channel PC sound cards. The main reason for building this amplifier is the limited gain received from the ASUS Xonar AE sound card with the Creative Inspire T6300 , 5.1 surround speaker system. Before switching to this soundcard, we had a Creative Sound Blaster Z card which provided good audio output with the above-mention speaker system. The key motivation of building this amplifier is to solve these gaining problems. The assembled 5.1 preamplifier PCB. This preamplifier consists of six TL074 / TL072 preamplifier stages and PT2258 electronic volume control. The input stage of this preamplifier consists of six TL074 / TL072 buffer stages. The PIC16F886 microcontroller manages the PT2258 electronic volume control IC. All the volume levels and menu options are displayed on HD44780 , 16x2 character LCD screen . All the ...

A few months ago, our AMD Ryzen™ 5 computer started giving some startup issues. At first, this problem happened randomly, and then it started happening at every bootup. The symptom is that if the computer shuts down after a boot, it will not start on the next power cycle(s). If we turn it off for 30 or 45 minutes and then turn it on, it will start working without any problems. This problem did not occur on warm restarts. After changing power supply units, we realized that the problem was with the PSU. This suspicious unit is a Corsair VS550 PSU . Corsair VS550 PSU PCB. Based on the symptoms, we thought the problem was with a capacitor on the PSU board. We disassembled the PSU and checked all the electrolytic capacitors, but we could not find any faulty capacitor(s). To further investigate this issue, we connected the PS-ON terminal to the ground ( GND ) and started the PSU. During this test, we see that the PSU is performing well on this condition. As we examine further, we find t...

In this project, we extend the shortwave superheterodyne receiver we developed a few years ago . Like the previous design, this receiver operates on the traditional superheterodyne principle.  In this upgrade, we enhanced the local oscillator with Si5351 clock generator module and Arduino control circuit. Compared to the old design, this new receiver uses an improved version of an intermediate frequency amplifier with 3 I.F transformers. In this new design, we divide this receiver into several blocks, which include, mixer with a detector, a local oscillator, and an I.F amplifier. The I.F amplifier builds into one PCB. The filter stage, mixer, and detector stages place in another PCB. Prototype version of 455kHz I.F amplifier. In this prototype build, the Si5351 clock generator drives using an Arduino Uno board. With the given sketch, the user can tune and switch the shortwave meter bands using a rotary encoder. The supplied sketch support clock generation from 5205kHz (tuner f...