Accurate 500kHz frequency meter

Ibrahim Kamal have developed nice and simple frequency meter which can measure frequencies from 5Hz to 500kHz. Frequency measurement is done by counting timer counts between two same amplitude values of incoming signal. After timer counts are done AT89C52 microcontroller calculates the signal frequency by knowing one timer tick duration.   Result is displayed via four seven segment LED displays that are driven dynamically. Whole PCB and display module is placed in old tester case and used same leads. Author provides full schematic, PCB and source code. Continue reading

Programmable DC pover supply

This is must have tool in you LAB. The idea was to build microcontroller based DC power supply witch was easy to build and was cheaper than in market.   Device was built by using only standard components. Device is capable to provide up to 30V 2A. Power supply unit can be controlled by PC using i2ctalk program which can be run under Linux, Windows, Mac OS X and Solaris. Software can be found here. Dont forget to check for an updates. You can order this power supply unit as a kit from Tuxgraphics online shop. Kit includes additional documentations and circuit diagram. Continue reading

AVR DDS waveform generator

This AVR DDS generator can generate signals from 1Hz up to 65535Hz. Thanks to well known DDS algorithm frequency limits can be much higher, but signal resolution drops in higher frequencies. Current range is enough for most of audio signal equipment testing. DDS algorithm is written in software where Atmega8 runs at maximum 16MHz. There are several signal waveforms available: sine, square, sawtooth, triangle and reverse sawtooth and pseudo-random noise.   Signals are stored in lookup tables as DDS algorithm requires. Signal output is organized via simple R-2R ladder DAC. LCD signal goes through shift register, this way only 3 MCU pins are used, while other serves for other purposes – buttons, other outputs. Project is well documented PCB and source files included. Author states that he will build another … Continue reading

Movement tracker with accelerometer

This device so called Station Master is small key ring sized device which tracks movement in the train. As train goes, device vibrates, but when train stops, it generates alarm after predefined number of stops. So you don’t miss your station. Device is based on Atiny13 microcontroller and MMA7260 3 axis accelerometer from Freescale. Alarm is generated by cell phone vibro motor.   Project files include schematic and assembly program which is very compact due to smart program optimisation – especially filter part, where movement signal is detected from noise pattern. Continue reading

8×8 LED animation with PIC

This is simple fun PIC project which may fir Christmas decoration. Circuit is simple – 8×8 LEDs are connected to PIC19F84 via 74HC374 buffer sharing same microcontroller port.   All you have to do is to burn firmware to se demos, or you can program your own patterns by modifying assembler program. And of course be sure to align LEDs perfectly or use 8×8 LED matrix.   Continue reading