This application interfaces a DCF77 receiver module to a BASIC Stamp® microcontroller. The DCF77 module receives time information from the standard time transmitter in Mainflingen, Germany. The BASIC Stamp module converts this information to RS-232. Each second it output’s a complete time string at 2400 bps.

DCF77 is a longwave time signal and standard-frequency radio station. Its primary and backup transmitter are located in Mainflingen, about 25 km south-east of Frankfurt, Germany. It is operated by T-Systems Media Broadcast, a subsidiary of Deutsche Telekom AG, on behalf of the Physikalisch-Technische Bundesanstalt, Germany’s national physics laboratory. DCF77 has been in service as a standard-frequency station since 1959; date and time information was added in 1973.

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With this digital DCF77 clock with LCD and gong,you always get the right time and date.This project make use of a PIC16F628(A) and a DCF77 receiver.The DCF77 is a longwave time signal and standard-frequency radio station. Its primary and backup transmitter are located in Mainflingen, about 25 km south-east of Frankfurt, Germany. It is operated by T-Systems Media Broadcast, a subsidiary of Deutsche Telekom AG, on behalf of the Physikalisch-Technische Bundesanstalt, Germany’s national physics laboratory. DCF77 has been in service as a standard-frequency station since 1959; date and time information was added in 1973.source

The DTMF decoder 2 is a useful tool used for decoding DTMF (Dual Tone Multi frequency) generated by telephones. The decoded digits are viewed on a 16×2 LCD screen. The DTMF decoder can be directly connected to a Serial port to view the digits in HyperTerminal on a computer. The decoder stores the last 234 received digits in EEPROM. The contents of EEPROM can be viewed on the LCD screen via two scroll buttons. Total power consumption is 12mA. The DTMF decoder has two inputs.source

This circuit is used to monitor the battery voltage, using a bi-color LED to indicate the state of the battery. When the LED is “GREEN” the battery voltage is above 11.9 volts. When the LED is “YELLOW”, the battery voltage is between 11.9 and 11.5 volts. When the LED is “RED” the battery voltage is below 11.5 volts. You can of course, modify the trigger points by using the trimmer resistors and/or changing the value of the dropping resistors in the divider.source

This circuit is Undervoltage indicator.The green led light up whenever Vin is larger than approx. 12.5V, while a red led flashes when Vin is below 12.5V. The circuit draws current approx. 15mA.source