16 channel car monitor

This device was developed by Velimir have been used for monitoring 16 digital values in the car including fuel level, temperature, door closing. All signal inputs are optically isolated.   Car monitor displays events in LCD display and has sound alert ability. Project is based on 68HC11 microcontroller running at 8MHz frequency. Schematic, PCB and Source are also included. Continue reading

Amateur ECG monitoring device

This is very simple ECG monitorin device with no protection and isolation circuitry. Also signal quality isn’t good enough to interpret data seriously. But circuit works and shows ECG pattern.   Signal is amplified and filtered via Analog devices instrumental amplifier AD620. Signal then is sampled with Atmega8 ADC and sent to LabView via USART. Refik didn’t include the whole circuit, just amplifier module, but it is not hard to recreate microcontroller part as there are standard connections to ADC and USART. Program is written in assembly language where ADC reads data and sends it via USART. Continue reading

Bicycle ride distance meter

Device was developed to measure distance when riding bicycle. Magnet and magnet sensor (proximity effect) contact was used to sense wheel turn. Project consists of Motorola 68HC908QY4 microcontroller which counts pulse signals coming from reed switch. Data is displayed in 1X16 LCD module.   Schematic is very simple and can be rebuilt easily on universal board. Software is written for ICC08 compiler and can be modified easily. Main modification would be adjusting wheel diameter. Continue reading

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