29-11-2012, 05:53 PM
1Hz Precision Clock Timer
1Hz Precision Clock Timer my project.doc (Size: 473.5 KB / Downloads: 44)
This timer makes an LED flash once every second along with a beep. The timing circuit uses a quartz crystal available in digital watches or clocks which generates precise frequency of 32.768 kHz.
The circuit comprises a 14-stage ripple-carry binary counter and oscillator IC CD4060 (IC1), dual flip-flop CD4013 (IC2), transistors T1, T2 and T3, a speaker, a quartz crystal and a few discrete components. The inbuilt inverter of IC1 (which is between pins 10 and 11) in combination with resistors, capacitors and the quartz crystal forms the oscillator circuit.
The clock signal of 32.768 kHz has a pulse width of about 30 microseconds, which is far too short to be able to count the oscillations. So this frequency is fed to IC1, which divides it by 14 to output a frequency of 2 Hz
Data sheet of ic – cd4060
IC 4060 is an excellent integrated circuit for timing applications. Its ten active high outputs can give time delay from few seconds to hours. With a few components, it is easy to construct a simple but reliable time delay circuit.
IC 4060 is an Oscillator binary counter cum frequency divider. Its inbuilt oscillator is based on three inverters. The basic frequency of the internal oscillator is determined by the value of the capacitor connected to its pin 9 and that of the resistor in its pin 10. By increasing or decreasing the value of capacitor / resistor, time delay can be changed. Each output goes high after the completion of the timing cycle. To get maximum time period, output Q10 is omitted in the IC itself so that double time is available between Q9 and Q11.
Inside the IC, there is an oscillator and 14 series connected bistables (Ripple cascade arrangement). Internally the oscillator signal is applied to the first bistable which drives the second bistable and so on. Since each bistable divides its input signal by two, a total of fifteen signals are available, each of half the frequency of the previous one.
IC 4013 applications
• automotive
• data terminals
• instrumentation
• medical electronics
• alarm system
• industrial electronics
• remote metering
• computers