Dilshan R Jayakody’s Web Log

These days good quality oscilloscope is not an expensive instrument and, we can see it in most workbenches. With the advancement of oscilloscopes, simple testing tools such as logic probes are not as popular these days. However, if the oscilloscope or logic analyzer was out of reach, the logic probe is a handy instrument to check digital circuits.  Also, in some cases, a logic probe is an easy option to check the functionality of low-speed logic circuits because it provides a real-time visual indication of the logic state without adjustments or calibrations. Prototype version of the logic probe. The logic probe design described in this post uses common and inexpensive ICs, including the popular NE555 timer and LM393 low voltage comparator IC. At the time of this writing, both ICs were prevalent in the market and cost less than LKR50 (US$ 0.25). This circuit design using SMD components to minimize the board size. The dimensions of the soldered PCB are around 70mm × 14mm × 6.6mm, ...

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...

UV exposure unit is a vital component in printing and mass-manufacturing industries. I decided to build a UV exposure unit to assist my screen-printing and PCB prototyping needs. After examining the market, I decided to construct this unit using black fluorescent tubes. Those black fluorescent tubes are usually available to purchase in many electrical shops here in Sri Lanka . Finished UV exposure unit with four fluorescent tubes. To drive the exposure unit, I build an electronic controller using ATtiny2313A MCU. This controller is capable to handle the exposure unit for up to 999 seconds ( approximately 16 minutes ). This electronic controller got two high-power relay driver stages, an audible notification unit, a safety lock, and a programmable timer. The fluorescent tubes are drive using four separate chokes and starter units. For this unit, I use four NEC 20W - 60cm (T10) black fluorescent tubes.  12V, 5A SMPS is used to drive the relays and electronic controller unit. PSU, c...

In this article we implement virtual (computer simulation base) microcontroller driven programmable timer using Proteus VSM. This proposed system is design using Microchip PIC16F877A – 8bit microcontroller and its system software is developed using MikroC PRO 3.2 for PIC. Most of the components in this proposed design are based on Proteus VSM - simulation models and we assign standard component names to them to assist in actual prototyping. In this simulation we use PIC16F877A as main system controller and 4 row monochrome LCD display unit with HD44780 compliant controller (in 4bit mode). This proposed simulation model is design to work with +5V supply voltage, but it can also operate using battery power (3 × 1.5V). When implementing this system for the real-life use, it is highly recommended to integrate battery backup facility to this system. It helps to drive this system continuously with minimum amount of disturbances. According to the supplied source code, end user may be a...