Dilshan R Jayakody’s Web Log

This is a high voltage, low current, offline, AC adjustable power supply for electronic/electrical experiments. This power supply is mainly design for switch mode power supply (SMPS) experiments and to drive basic high voltage electrical circuits. Thanks to the isolated step-up transformer this power supply breaks the ground loop and provides shock free – safer high voltage output. This offline (or isolation) feature preventing accidental current from reaching ground through a person's body. This unit generates 50Hz or 60Hz (selectable at runtime) square wave AC output, and it is capable of generating output voltage between 150V – 290V AC (on no-load state). Prototype version of offline high voltage AC power supply As stated above this power supply unit is mainly design for SMPS experiments. This is not work well with liner power supplies because transformers in linear power supplies are get overheating from square wave inputs generated through this unit. This is a hig...

TENMA 72-9390 meter is a cool pen style multimeter. It feels right in the hand and incredibly simple to use, and accurate as professional multimeter. The meter is 181mm long, and comes with a single (negative) test lead, 3V Li-MnO 2 button cell, and instruction leaflet. TENMA 72-9390 Pen Style Multimeter TENMA 72-9390 is 3000 counts, true RMS, pen style multimeter with following core features: Check continuity, AC/DC voltages (up to 300V), resistance (up to 30 MΩ), diode and capacitance (between 0.001nF to 3mF). Sleep mode Digital mode selection with audible feedback Automatic ranging Data hold, Max/Min mode selection Sharp display backlight and test lead LED (for input terminal) to work in poorly lit areas CATIII 300V safety rated This meter keeps the digital display is in your hand and eyesight. This makes for easy reading of the display and one handed access to the function keys. The function key layout of this meter is simple and solid. Because of that you can...

LiteASM is a Light weight and reconfigurable Assembly language compiler and Virtual Machine. It is design to fulfill the following core requirements: As a scripting interface for embedded systems. As a cross platform scripting interface. As a experimental tool for compiler construction. LiteASM compiler is design with minimum static instruction set. Its dynamic instruction set can be easily extend using compilers configuration files. LiteASM compiler generate fixed length binary output file and it can execute on LiteASM Virtual Machine Simulator ( litevm ) or on top of platform specific virtual machine. Virtually LiteASM Virtual Machines can execute on any 8bit to 64bit CPU/MCU/DSP platform. 8bit version of Fibonacci series demo on LiteASM Virtual Machine Simulator LiteASM compiler and Virtual Machine simulator are distribute as a free and open source software (under the terms of GNU GPL version 3.0 ) and available for both Windows and Linux operating systems. This Lite...

This is an easy to construct precision electronic event logger and using this we may be able to measure time differences in two events in range between 0.02 seconds to 6.8 seconds. This system is mainly design around PIC16F73 microcontroller and 4040 binary ripple counters. The main counter clock (reference counter) is oscillated around 2MHz. Most of the counter related components of this system are based on CMOS family of ICs. If you need more precious lower limit it is recommended to replace all these CMOS family of ICs with TTL equivalents (e.g: 4027 by 74HS73 with slight changes and 4040 by 74HC4040). The clock frequency of the existing counter can also increase up to 6.0MHz. The counter gets activate and deactivate in positive edge of the input signal. Thanks to the wider operating voltage of the CMOS ICs this counter may be able to handle +5V to +15V of input signal. At the end of the counter session system release total tick count to the RS232 interface and it can receive t...

This is a high current 5V bench power supply for digital (and analog) electronic experiments. This power supply is based around National Semiconductor's LM338K positive voltage regulator. Virtually this is an indestructible power supply unit with short-circuit protection and thermal overload protection. 5V 5A Power Supply in ATX Power Supply Casing In our prototype we assemble entire power supply (including step-down transformer) in an ATX power supply casing. When assembling this power supply take extra care about wirings and mountings. LM338K need proper heat-sink and make sure to mount it closer to the main PCB. While assembling makes sure that all the wirings are in correct order. Improper wiring and/or shot-circuits may leads to critical component failures (including voltage regulator IC and step-down transformer ).  Schematic diagram of this power supply unit is available to download at google drive

This is an example application for our " Extend PIC Microcontroller‘s RAM by without using EMI " blog post. In this system PIC16F887 microcontroller is interface with four units of UM61512AK – 64K × 8 CMOS SRAMs. Monitoring signal is supplied to the MCU through “ PORT A ” and all the communications are performing through RS232 interface. In my previous post most of the readers ask me about pure C language routine(s) for memory access. To fulfill that request I rewrite both memory read and write operations using C programming language. Compared with the previous Assembly language routines, only performance glitch in this implementation is 16bit address decoding part (which consume some CPU cycles than assembly language implementation) With this given firmware user can operate this system by without installing any driver software in the host side. All the data capturing and reporting operating are done by MCU itself. Originally I design this data logger to do some photo...

Virtually all PIC microcontrollers have some banking mechanism to extend addressing to additional memory space. But this external data memory is not directly addressable (except in some high versions of PIC18 devices, which include PIC18F8520, PIC18F6620, etc.). In this post we describe easy to implement external memory interface for PIC microcontrollers. Theoretically most of the PIC microcontrollers can use this setup to extend its RAM space. At the prototyping stage we test this system with PIC16F877, PIC16F887, PIC18F4550 and PIC18F4620 microcontrollers. With current setup user may be able to address RAM space up to 192KB. But this can be extended up to 448KB by adding more SRAM modules to the system. In this given schematic we use W24512 – 64K x 8 CMOS SRAMs as a memory modules. 74HC373 latch is used as 8bit to 16bit address extender and 74HC138 demultiplexer is used as memory bank selector. All the files (including source codes, EAGLE schematic files, etc.) of this syste...