by Elle JoeyJanuary 9, 2012
There are many ways to approach pocket watches. This is a great invention. The circuit is even majestic.
There are many pocket watches on the market. Yet, most consist of the same system. To maintain the accuracy of the clock, experts use a small integrated circuit, also of Dallas, which is responsible for counting the time for us. This is the DS1307, 8-pin, which has its own glass (to 32,768 Hz) and a CR-2032 battery backup 3V. This battery provides the energy necessary for the DS1307 continues to operate in the event of failure or disconnection of the mains supply.
This avoids having to put in an hour the pocket watches every time you unplugged it from the mains. To display information for both the hours and minutes as the temperature data, we used four 7-segment LED display approximately 3.5 cm in height. A common cathode displays the time, where each segment consists of two red LEDs in series. The ":" core consists of two 3mm LEDs connected in series, the color of the displays, and are handled from pin 7 of microcontroller. This can be used for many purposes.
You can create your own! Since the multiplex display by using traditional techniques would have required a large number of pins of E / S PIC16F628A microcontroller, we used a shift register built from four chips connected in cascade. Each of the outputs of these integrated controls has one of the segments of the displays. The microcontroller pin 17 (bit 0 of PORTA) is responsible for providing the data to the shift register, while the pin 18 (bit 1 of PORTA) provides the necessary clock pulses.
The same trick of the shift register is used to control 60 LEDs that make up the second hand. This time it took 74HC164N 8 integrated circuits. This will apply to modern models. The circuits can be quite complex. This record has 64 outlets, of which only exploit the first 60. Each of these output controls one of the LEDs through a resistor that limits the current that passes through them.
Since the maximum possible consumption of this pocket watches project is quite high for what we are accustomed, we divided the power stage into three parts, each responsible for providing power to a section of the clock. Thus, a stage built around a LM7805 voltage regulator provides the power needed by the microcontroller, temperature sensor and real time clock. Another stage feeds the displays and the shift register that controls it, and the third does the same with the LEDs on the second hand and control integrated circuits.
News Source: http://www.free-press-release.com/news-about-real-circuit-pocket-watches-functionality-1326163852.html
Official Website: http://www.dinodirect.com/pocket-watches/
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