Turn-key PCB assembly services in prototype quantities or low-volume to mid-volume production runs

Radio spectrum FFT on Atmega8

This experimental project developed by ChaN. He managed to analyze Radiosignal spectrum and calculate its FFT which is displayed on graphical LCD. When analysing RF frequencies there are some problems with speed. Even when analysing 1MHz radio signal there is over 4000 samples needed for correct ADC.   To solve this problem he managed to shift carrier frequency to lover by using generic method: Frequency conversion, which operates with signals as complex, where operations with negative frequencies are available. So if signal is 100MHz with span ±1MHz, then frequency is shifted to 0MHz±1MHz. This way by Nyquist they there is enough to sample signal at 2MHz. In circuit diagram (PCB (top) and PCB (bottom) )there is seen how this conversion is performed with couple mixer circuits SA612A and reference frequency of 455kHz. Atmega8 program samples converted signal, calculates FFT and draws pattern on LCD with refresh rate of 60 times per second. See movie how it works. Continue reading

Collection of BASIC Stamp projects

Reynolds Electronics have collected several nicely documented BASIC Stamp projects. BASIC Stamp Microchip modules are single board computers that run Paralax PBASIC language interpreter on PIC , 8051 or Parallax Sx microcontrollers. Program code is stored in EEPROM memory from where PBASIC program commands are fetched to execute by interpreter. BASIC stamp gained their popularity because if their simple programing language – BASIC. BASIC stamp is easy to use and program and is good choice in low volume engineering projects.   Among projects you will find: A 4-digit “SERIAL” seven-segment LED display BASIC Stamp project, r IR transmitter to Rf converter, Infrared data communications, RS-232 Data Terminal, RS-232 Analog Voltage Meter, The Mini SSC II Serial Servo Controller. Basic stamp projects may be compiled and edited with PBASIC software which is capable to run under Linux, Mac OS and Windows. Continue reading

Interfacing Nokia 6100 color LCD to AVR controller

Thomas Pfeifer have connected Nokia 6100 132×132 pixel 4096 color LCD to AVR microcontroller. LCD is also used in Nokia 6100, 7200, 6610, 7250 and 6220. He connected LCD to Atmega8 microcontroller:   As there are two types of displays: with Epson chipset(S1D15G10) and Philips(PCF8833), he wrote code for Philips chipset. Firmware is written in AVR-GCC language where image can be uploaded via serial cable. Also there are few videos view sample video on how it works AVR-3D-Engine. Continue reading

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

Digital thermometer DS1820 on PIC16F84

This is very simple design which can be built by everyone who can solder. Device is capable to measure temperatures in range from 0 to 99ºC and display it on LCD.   Firmware is written in C language ready to be compiled with CCS C compiler. Also in source code package is compiled version of program which can be flashed immediately to PIC. Continue reading